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INVESTIGATIONS INTO THE SHELF LIFE AND NUTRITIONAL 
QUALITY OF FRESH TOMATO FRUIT (Solanum Lycopersicon) 
FOLLOWING TWO POST - HARVEST TREATMENTS. 
 
 
This Thesis is submitted to the University of Ghana, Legon  
 
 
By 
 
Linda Afriyie Gyimah (10363085) 
BEd. Home Economics (University of Cape Coast), 2009 
 
 
 
in partial fulfilment of the requirement for the award of                                                          
MPhil Radiation Processing Degree. 
 
 
 
July, 2013 
University of Ghana  http://ugspace.ug.edu.gh ii 
 
DECLARATION 
This thesis is the result of research work undertaken by Linda Afriyie Gyimah in the 
Department of Nuclear Agriculture and Radiation Processing, University of Ghana, 
under the supervision of Dr. Harry Mensah Amoatey and Dr. Rose Boatin.  
Except for references of other peoples’ work which I have cited, this thesis has not 
been presented either in whole or in part for another degree elsewhere. 
 
Sign ………………………………   Date ………………………. 
Linda Afriyie Gyimah 
(Student) 
 
 
Sign ………………………………   Date ………………………. 
Dr Harry Mensah Amoatey 
(Principal Supervisor) 
 
  
Sign ………………………………   Date ………………………. 
Dr Rose Boatin  
(Co-Supervisor) 
 
 
University of Ghana  http://ugspace.ug.edu.gh iii 
 
DEDICATION 
This work is dedicated to the Lord God Almighty for His Love and Grace so rich and 
free and to my role model, Ms. Evelyn Dadzie – Bonney. God richly bless you Mum. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
University of Ghana  http://ugspace.ug.edu.gh iv 
 
ACKNOWLEDGEMENT 
My gratitude goes to my family especially Aba Adadzewa, Maame Panyin, Nana Yaw 
and to my love, Rev. S. D. Ametefio for their support in kind and cash throughout my 
education. 
My deep appreciation goes to my supervisors Dr. Harry Amoatey and Dr. Rose 
Boatin for their commitment, guidance and criticisms throughout the research period. 
I am also indebted to Prof. (Mrs) Victoria Appiah (Department of Nuclear Agriculture 
and Radiation Processing, School of Nuclear and Allied Sciences, University of 
Ghana) for her priceless encouragement and contributions, God bless you Mummy.  
My thanks also go to all staff of the Biotechnology and Nuclear Agric Research 
Institute especially Mr. John Apatey, Ernestina Ayeh, Mr. Joseph Nunoo and Bernard 
Odai and also to Mr. Mba, Sandra, Obed, Mr. Nash and Mr. Crabbe of the Chemistry 
Department of the Ghana Atomic Energy Commission for their support throughout 
my laboratory experiments. I would also like to thank Dr. James Futse and Mr. 
Jonathan Quaye (Animal Science Department, School of Agriculture, University of 
Ghana) for their assistance throughout my laboratory experiments. I also want to 
acknowledge my colleagues for their support. 
 
 
 
 
 
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TABLE OF CONTENTS 
TITLE PAGE…………………………………………………………………………..i 
DECLARATION ....................................................................................................... ii 
DEDICATION ......................................................................................................... iii 
ACKNOWLEDGEMENT ........................................................................................ iv 
TABLE OF CONTENTS ........................................................................................... v 
LIST OF TABLES ................................................................................................. xiii 
LIST OF PLATES .................................................................................................. xvi 
LIST OF FIGURES ............................................................................................... xvii 
ABSTRACT ............................................................................................................ xx 
CHAPTER ONE........................................................................................................ 1 
INTRODUCTION ................................................................................................. 1 
1.1 BACKGROUND .......................................................................................... 1 
1.2 PROBLEM STATEMENT ........................................................................... 3 
1.3 JUSTIFICATION ......................................................................................... 4 
1.3 OBJECTIVES .............................................................................................. 4 
CHAPTER TWO ....................................................................................................... 6 
2.0 LITERATURE REVIEW ................................................................................. 6 
2.1 ORIGIN ........................................................................................................ 6 
2.2 CLASSIFICATION ...................................................................................... 7 
2.3 PLANT DESCRIPTION ............................................................................... 7 
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2.4 TOMATO PRODUCTION ........................................................................... 8 
2.5 QUALITY CHARACTERISTICS OF TOMATO ......................................... 8 
2.5.1 Colour .................................................................................................... 9 
2.5.2 Firmness............................................................................................... 10 
2.5.3 Flavour ................................................................................................. 10 
2.5.4 pH and Total Titratable Acidity ............................................................ 11 
2.5.5 Total Soluble Solid ............................................................................... 11 
2.5.6 Total solids ........................................................................................... 12 
2.6 HEALTH BENEFITS AND NUTRITIVE CONTENT ............................... 12 
2.6.1 USES OF TOMATO ............................................................................ 12 
2.6.2 NUTRITIONAL COMPOSITION ....................................................... 13 
2.6.2.1 Antioxidants .................................................................................. 13 
2.6.2.2 Lycopene ....................................................................................... 14 
2.6.2.3 Vitamins ........................................................................................ 17 
2.6.2.4 Mineral Elements ........................................................................... 17 
2.7 POSTHARVEST LOSSES ......................................................................... 18 
2.8 MICROBIAL INFECTIONS IN TOMATO ................................................ 19 
2.9 FOOD IRRADIATION .............................................................................. 20 
2.9.1 Effects of Radiation on Tomato ............................................................ 22 
2.10 CALCIUM CHLORIDE COATING ......................................................... 22 
2.11 STORAGE TEMPERATURE .................................................................. 24 
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CHAPTER THREE ................................................................................................. 26 
3.0 MATERIALS AND METHODS .................................................................... 26 
3.1 EXPERIMENTAL SITE............................................................................. 26 
3.2 SAMPLE PREPARATION ........................................................................ 26 
3.2.1 Post - harvest Treatment 1 – Gamma Radiation .................................... 26 
3.2.2 Post - harvest Treatment 2 – Calcium Chloride Coating ........................ 27 
3.3 ANALYTICAL PROCEDURES ................................................................ 27 
3.3.1 Shelf Life ............................................................................................. 27 
3.3.2 Physiological Weight Loss (%) ............................................................ 28 
3.3.3 pH ........................................................................................................ 28 
3.3.4 Total Titratable Acidity ........................................................................ 28 
3.3.5 Total Soluble Solids ............................................................................. 29 
3.3.6 Moisture Content .................................................................................. 29 
3.3.7 Vitamin C............................................................................................. 29 
3.3.8 Lycopene ............................................................................................. 29 
3.3.9 Elemental Composition Analyses ......................................................... 30 
3.3.9.1 AAS (Varian AA240FS Model, USA) Analysis ............................. 30 
3.3.9.2 Flame Photometry (Sherwood 420 Model, England U.K.) .............. 32 
3.3.10 Microbial Load ................................................................................... 33 
3.4 Data Analyses ............................................................................................. 33 
 
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CHAPTER FOUR ................................................................................................... 34 
4.0 RESULTS AND DISCUSSIONS ................................................................... 34 
4.1 SHELF LIFE STUDY OF BURKINA TOMATO FRUITS FOLLOWING 
GAMMA RADIATION AND CaCl2 COATING. ............................................. 34 
4.1.1 Shelf Life Study of Tomato Fruits Stored at Ambient Temperature 
(28±1°C) Following Irradiation. .................................................................... 34 
4.1.2 Shelf Life Study of Tomato Fruits Stored at Ambient Temperature 
(28±1°C) following CaCl2 Coating. ............................................................... 37 
4.1.3 Shelf Life Study of Tomato Fruits Stored at Low Temperature (10±1°C) 
following Irradiation. .................................................................................... 38 
4.1.4 Shelf Life Study of Tomato Fruits Stored at Low Temperature (10±1°C) 
following CaCl2 Coating. .............................................................................. 39 
4.2 PHYSICOCHEMICAL PROPERTIES OF BURKINA TOMATO FRUITS 
FOLLOWING GAMMA RADIATION AND CaCl2 COATING. ..................... 42 
4.2.1 Physiological Weight Loss of Tomato Fruits Stored at Ambient 
Temperature (28±1°C) Following Irradiation. ............................................... 42 
4.2.2 Physiological Weight Loss of Tomato Fruits Stored at Ambient 
Temperature (28±1°C) Following CaCl2 Coating. ......................................... 43 
4.2.3 Physiological Weight Loss of Tomato Fruits Stored at Low Temperature 
(10±1°C) Following Irradiation. .................................................................... 44 
4.2.4 Physiological Weight Loss of Tomato Fruits Stored at Low Temperature 
(10±1°C) Following CaCl2 Coating. .............................................................. 46 
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4.2.5 pH of Tomato Fruits Stored at Ambient Temperature (28±1°C) Following 
Irradiation. .................................................................................................... 48 
4.2.6 pH of Tomato Fruits Stored at Ambient Temperature (28±1°C) Following 
CaCl2 Coating. .............................................................................................. 49 
4.2.7 pH of Tomato Fruits Stored at Low Temperature (10±1°C) Following 
Irradiation. .................................................................................................... 51 
4.2.8 pH of Tomato Fruits Stored at Low Temperature (10±1°C) Following 
CaCl2 Coating. .............................................................................................. 52 
4.2.9 Total Titratable Acidity (TTA) of Tomato Fruits Stored at Ambient 
Temperature (28±1°C) Following Irradiation. ............................................... 54 
4.2.10 Total Titratable Acidity (TTA) of Tomato Fruits Stored at Ambient 
Temperature (28±1°C) Following CaCl2 Coating. ......................................... 55 
4.2.11 Total Titratable Acidity (TTA) of Tomato Fruits Stored at Low 
Temperature (10±1°C) Following Irradiation. ............................................... 56 
4.2.12 Total Titratable Acidity (TTA) of Tomato Fruits Stored at Low 
Temperature (10±1°C) Following CaCl2 Coating. ......................................... 58 
4.2.13 Total Soluble Solids (%, °Brix) of Tomato Fruits Stored at Ambient 
Temperature (28±1°C) Following Irradiation. ............................................... 60 
4.2.14 Total Soluble Solids (%, °Brix) of Tomato Fruits Stored at Ambient 
Temperature (28±1°C) Following CaCl2 Coating. ......................................... 61 
4.2.15 Total Soluble Solids (%, °Brix) of Tomato Fruits Stored at Low 
Temperature (10±1°C) Following Irradiation. ............................................... 62 
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4.2.16 Total Soluble Solids (%, °Brix) of Tomato Fruits Stored at Low 
Temperature (10±1°C) CaCl2 Coating. .......................................................... 63 
4.2.17 Moisture Content of Tomato Fruits Stored at Ambient Temperature 
(28±1°C) Following Irradiation. .................................................................... 65 
4.2.18 Moisture Content of Tomato Fruits Stored at Ambient Temperature 
(28±1°C) Following CaCl2 Coating. .............................................................. 67 
4.2.19 Moisture Content of Tomato Fruits Stored at Low Temperature 
(10±1°C) Following Irradiation. .................................................................... 68 
4.2.20 Moisture Content of Tomato Fruits Stored at Low Temperature 
(10±1°C) Following CaCl2 Coating. .............................................................. 70 
4.3 NUTRITIONAL CONTENT OF BURKINA TOMATO FRUITS 
FOLLOWING GAMMA RADIATION AND CaCl2 COATING. ..................... 73 
4.3.1 Vitamin C Content of Tomato Fruits Stored at Ambient Temperature 
(28±1°C) Following Irradiation. .................................................................... 73 
4.3.2 Vitamin C Content of Tomato Fruits Stored at Ambient Temperature 
(28±1°C) Following CaCl2 Coating. .............................................................. 74 
4.3.3 Vitamin C Content of Tomato Fruits Stored at Low Temperature 
(10±1°C) Following Irradiation. .................................................................... 76 
4.3.4 Vitamin C Content of Tomato Fruits Stored at Low Temperature 
(10±1°C) following CaCl2 Coating. ............................................................... 78 
4.3.5 Lycopene Content of Tomato Fruits Stored at Ambient Temperature 
(28±1°C) Following Irradiation. .................................................................... 80 
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4.3.6 Lycopene Content of Tomato Fruits Stored at Ambient Temperature 
(28±1°C) Following CaCl2 Coating. .............................................................. 81 
4.3.7 Lycopene Content of Tomato Fruits Stored at Low Temperature 
(10±1°C) Following Irradiation. .................................................................... 83 
4.3.8 Lycopene Content of Tomato Fruits Stored at Low Temperature 
(10±1°C) Following CaCl2 Coating. .............................................................. 84 
4.3.9 Effect of Irradiation (kGy) on Elemental Composition of Tomato Fruits 
Stored at Ambient Temperature (28±1°C) for 9 days. .................................... 86 
4.3.10 Effect of CaCl2 Concentration (%) on Elemental Composition of 
Tomato Fruits Stored At Ambient Temperature (28±1°C) for 9 days. ............ 89 
4.3.11 Effect of Irradiation dose (kGy) on Elemental Composition of Tomato 
Fruits Stored at Low Temperature (10±1°C) for 25 days. .............................. 91 
4.3.12 Effect of CaCl2 Concentrations (%) on the Elemental Composition of 
Tomato Fruit Stored at Low Temperature (10±1°C) for 25 days. ................... 93 
4.4 MICROBIAL LOAD OF BURKINA TOMATO FRUITS FOLLOWING 
GAMMA RADIATION AND CaCl2 COATING. ............................................. 97 
4.4.1 Total Aerobic Mesophilic Bacteria Count (log cfu/ml) of Tomato Fruits 
at Ambient Temperature (28°C±1) Storage Following Irradiation. ................ 97 
4.4.2 Total Aerobic Mesophilic Bacteria Count (log cfu/ml) of Tomato Fruits 
at Ambient Temperature (28°C±1) Storage Following CaCl2 Coating. .......... 98 
4.4.3 Total Aerobic Mesophilic Bacteria Count (log cfu/ml) of Tomato Fruits 
at Low Temperature (10°C±1) Storage Following Irradiation. ..................... 100 
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4.4.4 Total Aerobic Mesophilic Bacteria Count (log cfu/ml) of Tomato Fruits 
at Low Temperature (10°C±1) Storage Following CaCl2 Coating. ............... 101 
4.4.5 Moulds and Yeasts Count (log cfu/ml) of Tomato Fruits at Ambient 
Temperature (28°C±1) Storage following Irradiation. ................................. 103 
4.4.6 Moulds and Yeasts Count (log cfu/ml) of Tomato Fruits at Ambient 
Temperature (28°C±1) Storage following CaCl2 Coating. ............................ 104 
4.4.7 Moulds and Yeasts Count (log cfu/ml) of Tomato Fruits at Low 
Temperature (10°C±1) Storage Following Irradiation.................................. 105 
4.4.8 Moulds and Yeasts Count (log cfu/ml) of Tomato Fruits at Low 
Temperature (10°C±1) Storage Following CaCl2 Coating. ........................... 107 
CHAPTER FIVE ................................................................................................... 110 
5.0 CONCLUSIONS AND RECOMMENDATION .......................................... 110 
5.1 CONCLUSIONS ...................................................................................... 110 
5.2 RECOMMENDATIONS .......................................................................... 115 
REFERENCES ...................................................................................................... 117 
APPENDICES ....................................................................................................... 133 
 
 
 
 
 
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LIST OF TABLES 
Table                Page 
Table 4.2.3(a) Effect of Irradiation Dose (kGy) on pH of Tomato Fruits Stored at 
Ambient Temperature (28±1°C)…………….………………………………………48 
Table 4.2.3(b) Effect of CaCl2 Concentration (%) on pH of Tomato Fruits Stored at 
Ambient Temperature (28±1°C)…………………………………………………….50 
Table 4.2.4(a) Effect of Irradiation Dose (kGy) on pH of Tomato Fruit Stored at Low 
Temperature (10±1°C)..……………………….…………………………….…….....52 
Table 4.2.4(b) Effect of CaCl2 Concentration (%) on pH of Tomato Fruit Stored at 
Low Temperature (10±1°C)………………………………………….………………53 
Table 4.2.5(a) Effect of Irradiation Dose (kGy) on Total Titratable Acidity (TTA) of 
Tomato Fruit Stored at Ambient Temperature (28±1°C).……………………….......54 
Table 4.2.5(b) Effect of CaCl2 Concentration (%) on Total Titratable Acidity (TTA) 
of Tomato Fruit Stored at Ambient Temperature (28±1°C).………………………...56 
Table 4.2.6(a) Effect of Irradiation Dose (kGy) on Total Titratable Acidity (TTA) of 
Tomato Fruit Stored at Low Temperature (10±1°C)...…………..…………………..57 
Table 4.2.6(b) Effect of CaCl2 Concentration (%) on Total Titratable Acidity (TTA) 
of Tomato Fruit Stored at Low Temperature (10±1°C).……………………….….....58 
Table 4.2.7(a) Effect of Irradiation Dose (kGy) on Total Soluble Solids (°Brix) of 
Tomato Fruit Stored at Ambient Temperature (28±1°C)....………………………….60 
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Table 4.2.7(b) Effect of CaCl2 Concentration (%) on Total Soluble Solids (°Brix) of 
Tomato Fruit Stored at Ambient Temperature (28±1°C) ...…………………….……62 
Table 4.2.8(a) Effect of Irradiation Dose (kGy) on Total Soluble Solids (°Brix) of 
Tomato Fruit Stored at Low Temperature (10±1°C)....……………………………...63 
Table 4.2.8(b) Effect of CaCl2 Concentration (%) on Total Soluble Solids ((°Brix) of 
Tomato Fruits Stored at Low Temperature (10±1°C)..…………………..…….……64 
Table 4.3.5(a) Effect of Radiation Dose (kGy) on Elemental Composition of Tomato 
Fruits Stored At Ambient Temperature (28±1°C) for 9 Days...……………………88 
Table 4.3.5(b) Effect of CaCl2 concentration (%) on Elemental Composition of 
Tomato Fruits Stored at Ambient Temperature (28±1°C) for 9 Days...……………90 
Table 4.3.6(a) Effect of irradiation dose (kGy) on Elemental Composition of Tomato 
Fruits Stored at Low Temperature (10±1°C) for 25 Days..………………………...92 
Table 4.3.6(b) Effect of CaCl2 concentration (%) on Elemental Composition Of 
Tomato Fruits Stored at Low Temperature (10±1°C) for 25 Days...………………94 
Table 4.4.1(a) Effect of Gamma Radiation and Storage (28°C±1) on Total Aerobic 
Mesophiles (log cfu/ml) on Tomato Fruit……………….……….………………....97 
Table 4.4.1(b) Effect of CaCl2 Concentrations (%) and Storage (28°C±1) on Total 
Aerobic Mesophiles (log cfu/ml) on Tomato Fruit....……………………………….99 
Table 4.4.2(a) Effect of Gamma Radiation and Storage (10°C±1) on Total Aerobic 
Mesophiles (log cfu/ml) on Tomato Fruit....………………………………………..100 
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Table 4.4.2(b) Effect of CaCl2 Concentrations (%) and Storage (10°C±1) Total 
Aerobic Mesophiles (log cfu/ml) On Tomato Fruit...……………………………....102 
Table 4.4.3(a): Effect of Gamma Radiation and Storage (28°C±1) on Moulds and 
Yeasts Population (log cfu/ml) on Tomato Fruit...……….………………………..103 
Table 4.4.3(b): Effect of CaCl2 Concentrations (%) and storage (28°C±1) on Moulds 
and Yeasts Population (log cfu/ml) on Tomato Fruit...……………………….…..105 
Table 4.4.4(a): Effect of Gamma Radiation and Storage (10°C±1) on Moulds and 
Yeasts Population (log cfu/ml) on Tomato Fruit...………………………………..106 
Table 4.4.2(d): Effect of CaCl2 Concentrations (%) and Storage (10°C±1) on Moulds 
and Yeasts Population (log cfu/ml) on Tomato Fruit...………….………………...108 
 
 
 
 
 
 
 
 
 
 
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LIST OF PLATES 
Plate                    Page 
Plate 1: Control Tomato Fruits Stored at Ambient Temperature (28±1°C)                              
(a) First Day of Storage (b) 7 Days of Storage....……………………………………36 
Plate 2: Irradiated Tomato Fruits (3kGy) Stored at Ambient Temperature (28±1°C)  
(a) First Day of Storage (b) 12 Days of Storage...…………………………………...36 
Plate 3: CaCl2 treated tomato fruits (2.50%) Stored at Ambient Temperature (10±1°C)   
(a) First Day of Storage (b) 18 Days of Storage...……………………………………36 
Plate 4: Control Tomato Fruits Stored At Low Temperature (10±1°C)                                   
(a) First Day of Storage (b) 25 Days of Storage...……………………………………41 
Plate 5: Irradiated Tomato Fruits (2 kGy) Stored at Low Temperature (10±1°C)  
(a) First Day of Storage (b) 30 Days of Storage...……………………………………41 
Plate 6: CaCl2 Treated Tomato Fruits (2.50%) Stored at Low Temperature (10±1°C)          
(a) First Day of Storage (b) 41 Days of Storage..…………………………………..41
   
 
 
 
 
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LIST OF FIGURES 
Figure             Page 
Fig. 2 Diagram Showing the Proposed Mechanisms for the Role of Lycopene in 
Preventing Chronic Diseases....……………………………………….....………….16 
Fig. 3 Photograph of Milestone microwave laboratory station ETHOS 900 D 
model.….....…………………………………………………………………………32 
Fig. 4.1.1(a) Effect of Gamma Irradiation Dose on The Shelf Life of Tomato Fruits 
Stored at Ambient Temperature (28±1°C).....………………………….....………...34 
Fig. 4.1.1(b) Effect of CaCl2 Concentrations on the Shelf Life of Tomato Fruits Stored 
at Ambient Temperature (28±1°C) ….....…………………….....…………………..37 
Fig. 4.1.2(a) Effect of Gamma Irradiation Dose on Shelf Life of Tomato Fruits Stored 
at Low Temperature (10±1°C).....………………………….....………..….…………38  
Fig. 4.1.2(b) Effect of CaCl2 Concentrations on Shelf Life Of Tomato Fruits Stored At 
Low Temperature (10±1°C) ....…………………………….....………….………….39 
Fig. 4.2.1(a) Effect of Gamma Irradiation Doses (kGy) on Physiological Weight Loss 
of Tomato Fruits Stored at Ambient Temperature (28±1°C) ....…………………….42 
Fig. 4.2.1(b) Effect of CaCl2 Concentration on Physiological Weight Loss Of Tomato 
Fruits Stored at Ambient Temperature (28±1°C) ....……………..……………..…...44 
Fig. 4.2.2(a) Effect of Gamma Irradiation Doses (kGy) on Physiological Weight Loss 
of Tomato Fruits Stored at Low Temperature (10±1°C)…………………….………45  
Fig. 4.2.2(b) Effect of CaCl2 Concentrations on Physiological Weight Loss Of Tomato 
Fruits Stored at Low Temperature (10±1°C) .…………………………….………...46 
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Fig. 4.2.9(a) Effect of Gamma Irradiation Doses (kGy) on Moisture Content of 
Tomato Fruits Stored at Ambient Temperature (28±1°C). ....……………………...66 
Fig. 4.2.9(b) Effect of CaCl2 Concentrations on Moisture Content of Tomato Fruits 
Stored at Ambient Temperature (28±1°C). ....………………………………...……67 
Fig. 4.2.10(a) Effect of Gamma Irradiation Doses (kGy) on Moisture Content of 
Tomato Fruits Stored at Low Temperature (10±1°C).....…………….……………..69 
Fig. 4.2.10(b) Effect of CaCl2 Concentrations on Moisture Content of Tomato Fruits 
Stored at Low Temperature (10±1°C). ....……………………………………...……71 
Fig. 4.3.1(a) Effect of Gamma Irradiation Dose on Vitamin C Content of Tomato 
Fruits Stored at Ambient Temperature (28±1°C). ....……………………………..…73  
Fig. 4.3.1 (b) Effect of CaCl2 Concentration on Vitamin C Content of Tomato Fruits 
Stored at Ambient Temperature (28±1°C). ....……………………………..............75  
Fig. 4.3.2(a) Effect of Gamma Irradiation Dose on Vitamin C Content of Tomato 
Fruits Stored at Low Temperature (10±1°C). ....………………………………….77  
Fig. 4.3.2(b) Effect of CaCl2 Concentration on Vitamin C Content Of Tomato Fruits 
Stored at Low Temperature (10±1°C). ....…………………………………………78  
Fig. 4.3.3(a) Effect of Gamma Irradiation Dose on Lycopene Content Of Tomato 
Fruits Stored at Ambient Temperature (28±1°C)......……………………….…….80  
Fig. 4.3.3(b) Effect of CaCl2 Concentration on Lycopene Content of Tomato Fruits 
Stored At Ambient Temperature (28±1°C).....…………………………………….82  
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Fig. 4.3.4(a) Effect of Gamma Irradiation Dose on Lycopene Content Of Tomato 
Fruits Stored At Low Temperature (10±1°C)…....……………………………..….83 
Fig. 4.3.4(b) Effect of CaCl2 Concentration on Lycopene Content Of Tomato Fruits 
Stored At Low Temperature (10±1°C)………………………..……………..…..…86 
 
 
 
 
 
 
 
 
 
 
 
 
 
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ABSTRACT 
Tomato production in Ghana is characterized by a glut and high post – harvest losses 
during the major season followed by scarcity and high prices during the off season. 
This is the result or absence of a standard method for preservation of fresh fruits. This 
research was conducted to determine an effective method for the post - harvest 
treatment of fresh tomato fruits to enhance shelf life while preserving its 
physicochemical and nutritional properties. Two experiments were conducted, each 
with a factorial design of 5x2. In experiment one, the fruits were subjected to 0, 1, 2, 3 
and 4 kGy gamma radiation and stored at 10±1ºC and 28±1ºC. In experiment two, 
CaCl2 dissolved in distilled water at 0, 1.00, 1.50, 2.00 and 2.50 % concentrations 
were used to coat tomato fruits and stored at 10±1ºC and 28±1ºC. Gamma radiation at 
4kGy extended the shelf life of tomato by 5 and 9 days above control when stored at 
28±1ºC and 10±1ºC respectively. The use of CaCl2 at 2.50% greatly extended the 
shelf life of tomato by 11 days and 18 days above control when stored at 28±1ºC and 
10±1ºC respectively. For both treatments, shelf life increased with increasing dose of 
radiation/ concentration of CaCl2. Weight loss was higher in control fruits as well as 
fruits treated with gamma radiation or CaCl2 coating stored at 28±1ºC temperature 
than treated fruits stored at 10±1ºC. Tomato fruits treated with gamma radiation at 1 
and 2 kGy and untreated fruits showed an increase in pH and Total Soluble Solids 
(TSS) which was paralleled by a decrease in Total Titratable Acidity (TTA) as storage 
period advanced at both storage temperatures. However, fruits treated with CaCl2 at 
1.00% had little effect on pH and TTA of tomato during the storage period. 
Nutritionally, CaCl2 coating significantly maintained the vitamin C and lycopene 
concentrations in tomato fruit more than control and gamma irradiation which 
reduced vitamin C and lycopene contents in the fruits significantly with days of 
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storage. Storage at 10±1ºC better preserved the antioxidants properties of the fruits 
better than storage at 28±1ºC.  Elemental composition (Na, K, Zn, Cu and Mn) of the 
 
tomato fruits analysed on the initial and final days of storage showed K to be the 
element with the highest concentration whilst Zn was the least. Generally, gamma 
 
irradiation led to an increase in the concentration of Na and K for all doses whilst 
CaCl2 coating significantly decreased the concentrations of the same elements at both 
storage temperatures. Concentrations of Zn, Cu and Mn reduced significantly in the 
tomato fruits by the final day of storage for all treatments following storage at 10±1ºC 
whilst there were inconsistencies in the contents of the elements in tomato fruits 
stored at 28±1ºC. Gamma radiation and CaCl2 significantly reduced the microbial load 
in tomato at both temperatures compared to the control. The reduction was 
proportional to increasing dose of irradiation and concentration of CaCl2. However, 
CaCl2 significantly reduced Total Aerobic Mesophiles as well as Mould and Yeast 
growth in tomato fruits compared to gamma irradiation at both temperatures. In 
general, treated tomato fruits stored at lower temperature (10±1ºC) had more stability 
and longer shelf life as well as the ability to maintain nutritional properties than those 
stored at 28±1ºC. 
 
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CHAPTER ONE 
INTRODUCTION 
1.1 BACKGROUND 
Tomato (Solanum lycopersicon L.) is a horticultural crop produced and consumed 
throughout the world (Nunes, 2008). Worldwide consumption is second only to potato as a 
vegetable (FAO, 2012; Javanmardi and Kubota, 2006). Tomato belongs to the Solanaceae 
family and has its origin in the South American Andes (Naika et al., 2005). Though 
botanically it is a berry, it is usually considered as a vegetable due to its savoury flavour.  
The health benefits conferred by certain vegetables and fruits have been the result of the 
presence of health-promoting phytochemicals with potent antioxidant properties such as 
carotenoids, flavonoids, phenylpropanoids, tocopherols, and ascorbic acid (vitamin C). 
Ripened fruit of tomato (Solanum lycopersicon L.) contains significant amounts of these 
compounds and are the principal dietary source of the carotenoid lycopene in the human 
diet (Giovannucci, 2002). 
Tomato fruits are versatile; they can be consumed fresh in salads or cooked in sauces, 
soups and meat or fish dishes. They can be processed into purées, juices, ketchup, 
powders, canned whole or chopped.  
Tomatoes contribute to a healthy, well-balanced diet. The fruit is mainly composed of 
water, soluble and insoluble solids (Nikbakht et al., 2011; Pedro and Ferreira, 2007). Total 
solids are the summation of soluble and insoluble solids with soluble solids made up of 
mainly sugars, like sucrose and fructose, and salts and the insoluble solids mainly 
constituted by fibres, such as cellulose and pectin (Pedro and Ferreira, 2005).  Usually, 
excluding seeds and skin, tomato presents 4.5-8.5% total solids, depending on variety, soil 
and climatic conditions (Pedro and Ferriera, 2005). 
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Tomato contains organic acids (mostly citric acid) and such micronutrients as carotenoids, 
and vitamins A and C (Nikbakht et al., 2011; Pedro and Ferreira, 2007). They are also rich 
in minerals, essential amino acids, sugars and dietary fibres. Tomato contains much 
vitamin B, E and K, iron and phosphorus.  
As a tomato fruit ripens, its colour changes from green in the immature fruit to deep dark 
red in the fully mature fruit. Most of the orange, yellow and red colours of leaves, fruits 
and flowers are due to carotenoids. Carotenoids, such as beta-carotene and lycopene, are 
important components of antioxidant defence against lipid peroxidation in living cells 
(Bunghez et al., 2011). They are essential nutrients in the human diet that are thought to 
provide health benefits by decreasing the risk of various diseases, particularly certain 
cancers, cardiovascular and eye diseases.  
In tomato, fruit quality is an important factor that contributes to consumer acceptability. In 
addition to colour and firmness, measurements of acidity, total soluble solids content, and 
sugar-to-acid ratio, are factors that are used to select desirable sweet and sour flavour 
attributes in tomato fruit (Nikbakht et al., 2011; Shao et al., 2007).  
Tomato is considered a low-high acid food with a pH value of between 3.7- 4.5.The pH of 
a food is one of several important factors that determines the survival and growth of 
microorganisms during processing, storage and distribution, thus the final safety of the 
food product. Therefore, determining the pH of foods helps to prevent product 
deterioration and spoilage. Canned and dried tomatoes are economically important 
processed products (Naika et al., 2005). 
 
 
 
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             1.2 PROBLEM STATEMENT 
As a whole product, tomato maintains a delicate tissue structure that is extremely 
susceptible to chilling injury, mechanical damage and the presence of microorganisms. It 
is highly perishable with shelf life stability ranging from three days to three weeks 
depending on the time of harvest and/or variety (Prakash et al., 2002; Ellis et al., 1998). 
Kader (1992) stated that post - harvest losses in tomato as a result of improper storage and 
handling are enormous and can range from 20-50 % in developing countries. 
In Ghana, availability of tomato fruit on the market is variable depending on the season 
and hence, the inability to meet manufacturing demands and an all-year-round production 
of the fruit for consumers. Market women usually display the fruits on table tops, in 
plastic baskets or wooden boxes and leave them in the sun till the close of day. This 
renders the fruit short-lived, due to the action of microorganisms and the inappropriate 
storage conditions under which the fruits are kept. During the peak seasons, the problem 
of glut sets in due to lack of appropriate methods/facilities for long term preservation of 
the fruits in their unprocessed state. Shortages of fresh tomato fruits occur during the lean 
season immediately following the glut, leading to a rise in the price of the fruit. 
Consequently, Ghana imports tomato fruits from neighbouring countries. 
The shelf life, fruit quality characteristics as well as the optimum storage conditions and 
post - harvest treatment of common tomato fruits in Ghana need to be identified to curb 
the problem of postharvest losses. Irradiation has been known to inhibit microbial growth, 
delay ripening and extend the shelf life of minimally processed fruits and vegetables 
(Prakash et al. 2002; Hagenmaier and Baker, 1998). In addition edible coatings create a 
modified atmosphere within the fruit and thus help to preserve it for a longer time. 
Calcium chloride has been proven to reduce post - harvest decay, controls the 
development of physiological disorders, and improves quality and delay aging or ripening 
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(Stanly et al., 1995). Low temperature is also effective in delaying the onset of senescence 
and decay. 
 
1.3 JUSTIFICATION 
There is no standard method of extending shelf life of tomato fruit in Ghana. There is 
therefore the need to investigate the appropriate post - harvest methods and storage 
conditions for the fruit. Utilizing improved post - harvest practices will result in reduced 
losses, improved overall quality and food safety, and higher profits for growers and 
marketers (Talukder et al., 2003). This study also determined the nutritional value, the 
shelf life as well as quality characteristics of tomato fruit stored over a period of time. The 
study identified the suitable dose range and concentration levels of gamma irradiation and 
CaCl2 coating respectively for application without compromising the quality of the fruit in 
any form (that is, physical, nutritional and microbial state). Successful outcome of this 
study should contribute to a reduction in the quantity of tomato imported into the country 
especially by manufacturing companies as well as the problem of food insecurity in the 
area of tomato production. The study facilitated the selection of appropriate storage 
conditions and post - harvest treatment of tomato. 
 
1.3 OBJECTIVES 
The main objective of this study was to determine an effective method for the post - 
harvest treatment of fresh tomato fruits to enhance shelf life while preserving its physico-
chemical and nutritional properties.  
The specific objectives were to;  
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1. Determine the effects of gamma irradiation and CaCl2 coating on the shelf life of fresh 
tomato fruits stored under two temperature regimes.  
2. Identify the effects of gamma irradiation and CaCl2 coating on the physico-chemical 
properties of fresh tomato fruits stored under two temperature regimes. 
3. Determine the effects of gamma irradiation and CaCl2 coating on the nutritional 
composition of fresh tomato fruits stored under two temperature regimes. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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CHAPTER TWO 
2.0 LITERATURE REVIEW 
2.1 ORIGIN 
Tomato (Solanum lycopersicon L.) is a herbaceous crop which originated from the coastal 
strip of western South America, from the equator to about 30° latitude south, especially 
Peru and the Galápagos Islands. It was first domesticated in Mexico and introduced into 
Europe in the mid-16th century (http://www.growtomatoes.com/historical-background/). 
Earlier on before it was considered fit to consume, tomatoes were thought to be poisonous 
because many of the allied species contain alkaloids and were grown only as an 
ornamental garden plant. Today, tomato is recognized as one of the important commercial 
and dietary vegetable crops (Bauer et al., 2004). Tomato is now one of the most popular 
and widely grown crop both privately (home gardening) and on commercial basis. The 
highest producing countries are China, United States, Turkey, India, Egypt and Italy 
(FAO, 2012).  
In Ghana, according to Ellis et al. (1998), tomato is grown on a large scale in the Northern 
(Tono and Vea areas), Ashanti (Akumadan, Kumawu, Agogo areas), Brong Ahafo 
(Techiman, Derma and Techimantia areas) and Greater Accra Regions. Some of the 
varieties commonly cultivated include Roma VF, Marglove, Anecho, Wosowoso, 
Caterpillar, Early Dwarf, Navrongo among others. 
As a result of the numerous potential health benefits of tomato, it has been identified as a 
functional and ‘nutraceutical’ food. A nutraceutical is any substance considered as food, or 
part of a food, that provides medical or health benefits, including disease prevention and 
treatment (Jack, 1995). 
 
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2.2 CLASSIFICATION 
Tomato is a member of the Solanaceae family or the nightshade family which also include 
potato, bell pepper, and eggplant. It belongs to the genus Lycopersicon, sub family 
Solanoideae and tribe Solaneae (Taylor, 1986). Linnaeus, a Swedish botanist named it 
Solanum lycopersicon in 1753. Philip Miller, however, disagreed with it and replaced the 
Linnaeus name with Lycopersicum esculentum (Taylor, 1986). According to Heiser and 
Anderson (1999), taxonomists have recently reintroduced its original name Solanum 
lycopersicon. Thus, the taxonomic classification of tomato is still debated. However, the 
nomenclature adopted in this thesis is Solanum lycopersicon L. 
 
2.3 PLANT DESCRIPTION 
The plant typically grows to 1–3 metres in height and has a weak stem that often sprawls 
over the ground and vines over other plants. Tomato is a perennial, often grown in 
temperate and tropical climates as an annual crop. It is grown in sandy to heavy clay soils 
but well drained soils, like sandy or loamy is ideal. The optimum temperature required for 
its cultivation is 15 to 27°C. It can withstand drought fairly well but does not do well in 
heavy rainfall areas (Purkayastha and Mahanta, 2010).  
Tomato fruit can be red, pink, orange, or yellow, and from 1 to 6 inches in diameter. It 
may be globular, fleshy berry or oblate in shape and round, smooth or furrowed (Naika et 
al., 2005). The ripening of tomato is characterised by the softening of the fruit, the 
degradation of chlorophylls and an increase in the respiration rate, ethylene production, as 
well as the synthesis of acids, sugars and lycopene (Cano et al., 2003).  
 
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2.4 TOMATO PRODUCTION 
Tomato is one of the major vegetables produced worldwide. Global production of tomato 
has increased by 300% in the last four decades with an estimation of 110 million tonnes 
and a total production area of about 4.2 million ha (Costa and Heuvelink, 2005). 
Worldwide production of tomato in 2009 totalled 158,368,530 tonnes, 3.7% up on the 
previous year with the top tomato producer being China, followed by the United States, 
Turkey, India, Egypt and Italy (about 75% of world production). In 2011, China’s 
production of tomato was about 47,116,084 metric tonnes with the United States 
producing about 12,858,700 metric tonnes (FAO, 2012). 
Tomato is an economically attractive crop as it gives high yield (Naika et al., 2005). 
According to FAO (2012), tomato is a rapidly growing crop and a relatively short duration 
crop with a growing period of 90 to 150 days. Tomato production in Ghana has increased 
from 200,300 tonnes in 2005 to an estimate of 350,000 tonnes in 2010. Total land area 
utilized for tomato production in Ghana increased from 28,400ha in 1996 to 37,000ha in 
2000 with an average yield of 7.5 MTs/ha (GIPC, 2001). By 2010, total land area for 
tomato production increased to 60,000ha with an average yield of 58333.33Kg/ha (FAO, 
2012). According to Wolff (1999), vegetables account for 9.6% of total food expenditure 
and 4.9% of total expenditure in Ghana, and tomato alone makes up to 38% of the 
vegetable expenditure. 
 
2.5 QUALITY CHARACTERISTICS OF TOMATO 
Quality, the degree of excellence of fresh fruits and their products is a combination of 
attributes, properties or characteristics that give each commodity value in terms of human 
food (Kader, 1986). Kader (1986) added that producers relate quality to high yield of a 
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commodity, good appearance, easy to harvest and the ability to withstand long – distance 
shipping to markets. Wholesalers and retailers relate the quality of a commodity to 
appearance, firmness and shelf life whilst consumers’ judge quality of fresh fruits based 
on appearance and firmness at the time of initial purchase.  
Ethylene and CO2 production influence the qualitative nature of colour, flavour volatiles, 
sugars, and organic acids in tomato, which taken together determine the concept of fruit 
quality (Saeed et al., 2010). Consumers’ subsequent purchases depend on the flavour of 
the product. In agreement with these attributes, Nunes (2008) noted that the quality of 
fresh tomato fruit is determined by various attributes such as appearance, firmness, 
flavour, and nutritional value.  
Tomato is harvested at different stages for different purposes. Fruits to be processed are 
harvested red ripe for immediate use by processing companies whilst those to be sold on 
the market in the fresh state are harvested at the onset of ripening in order to withstand 
long distance transportation. 
2.5.1 Colour 
Colour is one of the most important quality factors that affect tomato appearance and is 
determined by skin and flesh pigmentation (Brandt et al., 2006). Colour is based on 
human perception of light and refers to one narrow band of the electromagnetic spectrum, 
called the visible spectrum. Colour is an important factor in consumer preference of 
tomato (Batu, 2003). Consumers in Ghana associate yellowish, pale red colour and non-
uniformity in colour to unripenness. Thus, topmost quality in relation to colour is 
attributed to bright red tomato fruit.  
Colour in tomato is due to carotenoids, a class of isoprenoid compounds varying from 
yellow to red colour (Hui, 2006). Hobson and Grierson (1993) stated that, the colour of a 
ripe tomato is determined by the ratio of two pigments, lycopene and β-carotene. As 
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tomato progresses from mature green stage to red ripe stage, there is loss of chlorophyll 
and accumulation of lycopene (Costa and Heuvelink, 2005).  
2.5.2 Firmness 
Firmness of tomato is an important quality decisive factor because it is associated with 
good eating quality and longer postharvest life. As tomato ripens, firmness decreases, and 
so ripe fruits are much softer than mature-green fruits (Wann and McFerran, 1960). A 
good eating quality tomato should be firm and not easily deformed because softening is 
often associated with overripeness. 
2.5.3 Flavour 
Flavour, is an important food quality attribute. The flavour of tomato fruit is perceived 
through a blend of aroma, taste, and mouth feel and can be defined as a balance among 
sugars, organic acids, volatile compounds, and free amino acids (Baldwin et al., 1998). 
Sugars, acids and their interactions are important to sweetness, sourness and overall 
flavour intensity in tomatoes.  
The taste of tomato can be good, tasteless, bland or tart. High acidity and high sugar 
content produce good taste. Tart taste is attributed to high acidity and low sugar. When the 
fruit has low acid but high sugar content, it has a bland taste whilst a tasteless fruit has low 
acidity and low sugar content. High sugars and relatively high acids are thus, required for 
best flavour development. Therefore, acidity of the fruit is also important as a contributor 
to the flavour of tomato products. 
About 2 - 2.5% of the total dry matter of tomatoes are free amino acids. Organic acids, 
soluble sugars, amino acids, pigments and over 400 aromatic compounds contribute to the 
taste, flavour and aroma volatile profiles of the tomato (Petro-Turza, 1987).  
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The longer the fruit remains on the plant, the more flavourful it becomes. Thus, tomato 
fruit not ripened on the plant does not have the same flavour and aroma as fruit that has 
developed its red colour (or final fruit colour) on the plant. Less handling reduces the 
incidence of bruising, and it has been suggested that flavour is reduced with increased 
handling (Saeed et al., 2010). Another aspect of fruit flavour is fruit size; smaller fruits are 
more flavourful as compared to larger ones (Thorne and Alvarez, 1982).  
2.5.4 pH and Total Titratable Acidity 
Two important quality attributes of processing tomato are pH and titratable acidity 
(Anthon et al., 2011). The pH of tomato can vary depending on the variety and degree of 
ripeness. The more ripened a tomato is the higher its pH and thus, the less acidic. The pH 
of tomato is determined primarily by the acid content of the fruit. The acidity of the fruit is 
also important as a contributor to the flavour of the tomato products (Anthon et al., 2011). 
Citric acid is the most abundant acid in tomato and the largest contributor to the total 
titratable acidity (Stevens, 1972). Gallic and glutamic acid also contribute significantly to 
total titratable acid. Glutamic acid is an important contributor to tomato flavour (Anthon et 
al., 2011). Anthon et al. (2011) stated further that tomato is not a low-acid food and thus 
requires less drastic thermal treatments than foods classified as low acid (pH>4.6) for the 
destruction of spoilage microorganisms to ensure food safety. A pH value of 4.4 is 
considered the maximum desirable for safety while the optimum target pH should be 4.25. 
This is because higher values would mean susceptibility of the pulp to thermophilic 
pathogens during processing of tomato (Monti, 1980).  
2.5.5 Total Soluble Solid 
Total soluble solid content (TSS) is one of the main components of tomato flavour and it 
is the property in tomato most likely to match consumer perception of internal quality 
(Kader, 1986). Water content and soluble solids exert a profound influence on the length 
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of storage period, mechanical properties and quality characteristics of fruits and vegetables 
(Sharma et al., 2006). The percentage of solids in tomato varies depending on the variety, 
character of the soil and especially the amount of irrigation and rainfall during the growing 
and harvesting season (Jongen, 2002). According to Mizrahi et al. (1988), total soluble 
solids content is the most important quality criterion for tomato paste processing and 
serves as the base for fixing the price to be paid to the producer. In a study by Saliba-
Colombani et al. (2001), it was reported that there is a positive correlation between sugar 
content and total soluble solids content in tomato fruit and in most cases this correlation is 
high. Thus, measurement of soluble solids content can give a fair estimate of the sugar 
level in tomato fruit. The sugars are mostly glucose and fructose and constitute about 65% 
of total soluble solids in expressed fruit juice (Winsor et al., 1962).  
2.5.6 Total solids 
Total solids are the dry matter that remains after moisture removal (Nielsen, 2010). High 
dry matter is a desirable characteristic for the canned tomato industry since it improves the 
quality of the processed product and consequently reduces processing cost (DePascale et 
al., 2001). Chemical analysis revealed that sugar and organic acids make major 
contribution to the total dry solids (Davies and Hobson, 1981). 
 
2.6 HEALTH BENEFITS AND NUTRITIVE CONTENT 
2.6.1 USES OF TOMATO 
Tomato is a significant fruit in the global agricultural market due to its wide use in the 
food industry, both for fresh consumption and as processed products (Nikbakht et al., 
2011). Three major processed products of tomato include tomato preserves (examples are 
whole peeled, tomato juice, tomato pulp, tomato puree, tomato paste, pickled tomatoes); 
dried tomatoes (examples are tomato powder, tomato flakes and dried tomato fruits); and 
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tomato-based foods (including tomato soup, tomato sauce, chilli sauce, ketchup) (Costa 
and Heuvelink, 2005). It can also be used in sauces, soups and meat or fish dishes. Raw or 
unripe green fruits are used for the preparation of pickles and chutney. Tomato is also a 
very good appetizer and its soup is said to be a good remedy for patients suffering from 
constipation.  
2.6.2 NUTRITIONAL COMPOSITION 
The beneficial effects of tomato is primarily attributed to the occurrence of vitamins, 
minerals and secondary phytochemicals such as carotenoids, anthocyanins, flavonoids, 
and other phenolic compounds that are widely distributed throughout the plant kingdom 
(Anttonen and Karjalainenb, 2005). Indeed, tomato fruit is a reservoir and predominant 
source of a diverse range of antioxidant molecules, such as phenolic acids, ascorbic acid 
and vitamin E. Thus a high amount of tomato in the diet contributes significantly to the 
supply of the antioxidants required by humans. Ripening of tomato involves a number of 
physiological processes that include the visible breakdown of chlorophyll accompanied by 
a build-up of carotenoids, with massive accumulation of such antioxidant components as 
lycopene and carotene (Lai et al., 2007).   
2.6.2.1 Antioxidants 
Interest in tomato antioxidants and their potential protective role in the prevention of 
chronic diseases stems largely from the epidemiological observations on normal and at 
risk populations (Agarwal and Rao, 2000). Consumption of tomato and its products can 
significantly reduce the risk of developing of colon, rectal, and stomach cancer. 
Antioxidants are protective agents that inactivate reactive oxygen species or excess free 
radicals and therefore significantly delay or prevent oxidative damage. Many biological 
processes can lead to the spontaneous formation of free radicals in the body. 
Environmental sources such as cigarette smoke, UV radiation and oxidizing agents may 
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also increase the production of free radicals. Excessive accumulation of these free radicals 
may damage cells by the oxidation of lipids, proteins and DNA, and induce peroxidation 
and DNA strand-breaks (Del Mastero, 1980).  
The intake of fruits and vegetables makes an important contribution to the levels of 
antioxidants in the body though antioxidants such as superoxide dismutase, catalase and 
glutathione peroxidase are naturally present within human cells (Agarwal and Rao, 2000).  
Carotenoids, such as beta-carotene and lycopene, are important components of antioxidant 
defence against lipid peroxidation in living cells (Bunghez et al., 2011). They are natural 
pigments synthesized by plants and microorganisms, but not by animals (Paiva and 
Russell, 1999).  
2.6.2.2 Lycopene 
Lycopene is a member of the carotenoid family of phytochemicals and is the natural 
pigment responsible for the deep red colour of several fruits, most notably tomato 
(http://www.whfoods.com/genpage.php?tname=nutrient&dbid=121) and also in red fruits 
and vegetables, including watermelon, pink grapefruit, apricot, and pink guava. Lycopene 
is also present in processed tomato products such as juice, ketchup, paste, sauce and soup. 
However, lycopene is more bioavailable in this state than in raw tomatoes. It is the most 
abundant carotenoid present in ripe red tomato, comprising up to 90% of the pigments 
present. Lycopene is a very labile compound and, in its pure form, will break down 
quickly in the presence of light, heat and oxygen (Nguyen & Schwartz, 1999). This 
property of lycopene could be due to water preventing oxygen and heat build-up within 
cells as well as the presence of even more reactive compounds which absorb the 
destructive power of light, oxygen and heat before they react with lycopene (Cox, 2001).  
Lycopene, an aliphatic hydrocarbon, has received particular attention as a result of studies 
indicating that it has a highly efficient antioxidant and free radical scavenging capacity 
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(Bunghez et al., 2011). It is the most predominant carotenoid in human plasma. In human 
plasma, it is present in an isomeric mixture, with 50% as cis isomers. Its formula is C40H56.  
Strong evidence exists from numerous studies which associate high serum or plasma 
lycopene with decreased risks of cancer of the lung, stomach, gastrointestinal tract and 
cancers of the colorectal (Edhardt et al., 2003). Recent studies have also reported a 
decrease in the risk of total cardiovascular disease with higher concentrations of plasma 
lycopene by inhibiting free radical damage to Low Density Lipoprotein cholesterol 
(http://www.whfoods.com/genpage.php?tname=nutrient&dbid=121). 
In addition to its antioxidant activity, lycopene has been shown to suppress the growth of 
tumours in vitro (test tube) and in vivo (animal) experiments by limiting tumour growth 
via stimulating cell to cell communication. Researchers now believe that poor 
communication between cells is one of the causes of the abnormal growth of cells, a 
condition which ultimately leads to the development of cancerous tumours 
(http://www.whfoods.com/genpage.php?tname=nutrient&dbid=121). Recent research has 
suggested that lycopene can boost sperm concentrations in infertile men. 
(http://www.whfoods.com/genpage.php?tname=nutrient&dbid=121).  
Lycopene levels in tomato may vary based on the type of cultivar, stage of ripeness and 
growing conditions. Lycopene is also used in many antioxidant dietary supplements.  
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Fig. 2 Diagram showing the proposed Mechanisms for the role of Lycopene in preventing 
Chronic Diseases (Agarwal and Rao, 2000).  
According to (Agarwal and Rao, 2000), dietary lycopene may increase the lycopene status 
in the body and, acting as an antioxidant, may trap reactive oxygen species, increase the 
overall antioxidant potential or reduce the oxidative damage to lipid (lipoproteins, 
membrane lipids), proteins (important enzymes) and DNA (genetic material), thereby 
lowering oxidative stress. This reduced oxidative stress may lead to reduced risk for 
cancer and cardiovascular disease. Alternatively, the increased lycopene status in the body 
may regulate gene functions, improve intercellular communication, modulate hormone 
and immune response, or regulate metabolism, thus lowering the risk for chronic disease 
(Fig. 2). 
Excessive intake of lycopene can lead to the discolouration of the skin, a condition known 
as lycopenodermia. Stahl and Sies (1996) reported of a middle aged woman who had 
prolonged and excessive consumption of tomato juice, her skin and liver were coloured 
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orange-yellow and she had elevated levels of lycopene in her blood. However, after three 
weeks on a lycopene-free diet her skin colour returned to normal. 
2.6.2.3 Vitamins 
Vitamins only account for a small portion of the total dry matter of tomato (Turhan and 
Seniz, 2009). Tomato is an excellent source of free radical-scavenging vitamin C which 
prevents the onset of scurvy and maintains skin and blood vessels (Lee and Kader, 2000). 
Tomato also contains vitamin A as well as bone-healthy vitamin K. It is a very good 
source of vitamin B6, vitamin B1 and vitamin E 
(http://www.whfoods.com/genpage.php?tname=foodspice&dbid=44).  
2.6.2.4 Mineral Elements 
Mineral elements considered essential in the human body are the major elements (which 
include sodium, magnesium, phosphorus, chloride, potassium and calcium) and the minor 
elements (including chromium, manganese, iron, cobalt, copper, zinc, selenium, 
molybdenum and iodine). In addition to these major and minor elements, there are the 
newer trace elements, which are possibly essential. They are lithium, boron, fluorine, 
silicon, vanadium, nickel, arsenic and lead (Crews, 1998). 
These essential elements function as constituent of bones and teeth, as soluble salts which 
help to control the composition of body fluids and cells and serve as essential adjuncts to 
many enzymes and other functional proteins (Dashti et al., 2004). 
Mineral elements commonly found in tomato fruit are Potassium, Calcium, Magnesium 
and Phosphorus and may constitute about 8% of the dry matter (Davies and Hobson, 
1981). They have an effect on pH and titratable acidity and have buffering capacity which 
influences the taste of tomato. 
 
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2.7 POSTHARVEST LOSSES 
It is estimated that post - harvest losses of tomato in Ghana ranges between 30 and 70% 
and that the rate and extent of spoilage of tomato depends on handling practices, storage 
conditions, temperature and microbial infections (Ellis et al., 1998). In Ghana, tomato is 
mishandled though the fruit is highly perishable. It goes through a long chain at the hands 
of farmers who produce, harvesters, packers, drivers who transport, wholesalers and 
retailers before reaching the final consumer. At any stage in this chain quality is reduced 
such that by the time the produce reaches the retailer, half of the fruit gets rotten leading to 
high postharvest loss.  
Post-harvest loss as defined by De Lucia and Assennato (1994) is “measurable 
quantitative and qualitative loss of a given product at any moment along the post-harvest 
chain”. FAO (1989) also defines it as “change in the availability, edibility, wholesomeness 
or quality of the food that prevents it from being consumed” (FAO, 1989). 
In a case study on tomatoes in Ghana by Robinson and Kolavalli (2010), it was observed 
that Ghana’s tomato sector is characterized by low-productivity and high-cost. They 
mentioned further that Ghana is increasingly dependent on imported tomato paste and, 
from January through May every year, imported fresh tomato from Burkina Faso. They 
added that yields in the country are low with two-thirds of farmers having yields of less 
than 10 tons/ha. Furthermore, they added that the variety of tomato grown is an important 
determinant of yield, yet there is absence of breeding in the country and efforts to supply 
farmers with appropriate varieties and certified seeds. 
For improved food security in developing countries, Kader (2005) mentioned that the 
reduction of post-harvest losses of perishables is of major importance. 
 
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2.8 MICROBIAL INFECTIONS IN TOMATO 
The surfaces of raw vegetables are contaminated with a variety of microorganisms 
depending on factors such as; the microbial population of the environment from which the 
food was taken, the condition of the raw product, the method of handling, the time and 
conditions of storage (Pelczar et al., 2006). 
Tomatoes grown close to the ground and indeterminate types produce numerous branches 
which sprawl. Thus they can be contaminated in the field by soil, water used in irrigation, 
wild and domestic animals or improperly composted manure. Bacteria may also be 
transferred during and after harvest from handling, storing and transporting. When tomato 
fruits are not handled and stored properly to maintain a pH at or below 4.7, Clostridium 
botulinum growth will occur. Indeed, the fruits contain large amounts of water which 
makes them more susceptible to spoilage by the action of various microorganisms.  
Acid-tolerant bacteria and fungi (yeasts and moulds) can use the fruit as a substrate. This 
action leads to spoilage, which in turn produces off flavours and odours, discoloration of 
the product, and if the contaminating micro-organisms are pathogens can also cause 
human illness (Tournas et al., 2006). This makes the transportation and storage of this 
vegetable difficult and its transportation too. According to Ghosh (2009), fungi were the 
source of spoilage in most of tomatoes samples accessed rather than bacteria. In his work, 
Ghosh (2009) identified that among the fungi, Aspergillus niger and Fusarium sp. were 
found in most of the spoiled samples with a few samples containing Penicillium sp.  
Aspergillus species and Fusarium species are a source of potent mycotoxins which 
exhibits a wide spectrum of diseases which can even be fatal (Ibrahim et al., 2011). 
Aspergillus niger is a source of ochratoxin which is considered to be a potent carcinogen 
and suspected of playing a role in the etiology of oesophageal cancer and Balkan endemic 
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nephrotoxicity. Fusarium produces Trichothecenes. Hence spoiled tomatoes should not be 
consumed under any circumstances and should not be fed to cattle as well (Ghosh, 2009).  
Tomato producers, handlers, and marketers are required to take the necessary precautions 
in preventing contamination of the fruits to reduce possible risks of mycotoxins, 
enterotoxins and other metabolites that are deleterious to human health. 
2.9 FOOD IRRADIATION 
Food irradiation is a food safety and preservation technology. It is a processing technique 
that exposes food to electron beams, X-rays or gamma rays (Tiwari. et al., 2009). The 
process produces a similar effect to pasteurisation, cooking or other forms of heat 
treatment, but with less effect on look and texture. The World Health Organization 
considers ionizing radiation an important process toward ensuring food safety (Diehl, 
1995). The shelf life of many fruits and vegetables, meat, poultry, fish and seafood can be 
considerably prolonged by treatment with irradiation (ICGFI, 1999). 
Ionizing radiation can dissipate its energy by ionization or excitation. These excitations 
and ionizations can produce free radicals, break chemical bonds produce new chemical 
bonds and cross-linkage between macromolecules, damage molecules such as DNA, 
RNA, and proteins that regulate vital cell processes. Food irradiation reduces food losses 
by reducing the level of bacteria and parasites that contaminate food and cause food borne 
illness. It also slows down the ripening or sprouting of certain fruits and vegetables, 
making it possible to store food longer and in better condition. Irradiating food presents an 
effective treatment for post-harvest damage by destroying bacteria, moulds and yeasts 
which cause food to spoil, and control insect and parasite infestation. The major purpose 
of irradiating food is to cause changes in living cells such as contaminating organisms, to 
reduce pathogenic microorganisms or cells of the living foods to achieve better quality. 
University of Ghana  http://ugspace.ug.edu.gh 21 
 
Chemical effects or changes occur when there is the breakdown of the excited molecules 
and ions and their reaction with neighbouring molecules, giving a cascade of reactions 
during irradiation. Some of the primary reactions include isomerisation and dissociation. 
These reactions occur within molecules as well as with neighbour≤ing species which 
produces a series of new products including the highly reactive free radicals. The free 
radicals generated in food during irradiation have a short life time. However, in dried or 
frozen foods containing hard components such as bone, free radicals have limited mobility 
and thus, persist for a longer period of time (Grandison. 2006; Stewart, 2001).  
Water radiolysis is another important chemical reaction that occurs from ionizing 
radiation. Hydroxyl radicals and hydrogen peroxide are generated upon the irradiation of 
water molecules and are highly reactive. They readily react with most aromatic 
compounds, carboxylic acids, ketones, aldehydes, and thiols (Stewart, 2001). These 
chemical changes are important as they contribute to the elimination of living food 
contaminants in foods. However, undesirable side effects, such as off-flavour, will be 
inevitable for certain food commodities if condition of irradiation is not well controlled 
(Grandison, 2006). For fruits and vegetables, especially tomatoes, most researchers 
recommend a maximum of dose 3kGy dose for elimination of food contaminants and 
extension of shelf life (Youssef et al., 2011; Prakash et al., 2002). 
Nutritional changes in food from cooking, canning, pasteurising, blanching and other 
forms of heat processing are similar to changes that occur during food irradiation (Diehl, 
1995). Macronutrients (protein, lipid and carbohydrate) as well as mineral quality are not 
affected during irradiation, they remain stable. Different types of vitamins have varied 
sensitivity to radiation. Riboflavin, niacin, and vitamin D, are fairly insensitive to 
radiation. However, vitamins A, B1 (thiamine), E and K are relatively sensitive. Their 
sensitivities depend on the complexity of the food, whether the vitamins are soluble in 
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water or fat, and the atmosphere in which irradiation occurs. At low doses (up to 1 kGy), 
the effects of radiation on nutritional value of foods are insignificant, but may be greater at 
medium doses (1-10kGy) if food is irradiated in the presence of air.  
2.9.1 Effects of Radiation on Tomato 
Irradiation at low doses (1kGy or lower) has no significant effects on vitamin C content of 
fruits and vegetables (Lee and Kader, 2000). Irradiation at 0.5kGy can reduce microbial 
counts substantially to improve microbial shelf life without adverse effects on sensory 
qualities (Prakash et al., 2002). According to Fan and Sokorai (2008), irradiation at 1kGy, 
potentially inactivates E. coli O157:H7 by 5 log cycles on fresh vegetables. Youssef et al. 
(2011) reported that irradiating tomato juice at a dose of 3kGy could reduce total aerobic 
bacterial counts greatly as well as the counts of total moulds and yeasts without affecting 
sensory properties of tomato juice. At this dose, lactic acid bacteria also reduced to 
undetectable level (<10 cfu/ml) and coliform bacteria were eliminated completely.  
Youssef et al. (2011) reported that the ascorbic acid content of tomato juice was reduced 
significantly and the reduction was proportional to the dose (1.5kGy, 3.0kGy and 4.5kGy) 
used. In contrast, the same doses did not show significant effect on the total lycopene 
content in the tomato juice. Irradiating at a dose of 4.5 kGy, however, affects the sensory 
properties of tomato juice, thus it is recommended to use 3.0 kGy. According to Prakash et 
al. (2002), treatment of diced tomatoes with 3.7 kGy decreased firmness by 50% as 
compared to 20% with 0.5 kGy. 
 
2.10 CALCIUM CHLORIDE COATING 
Calcium chloride is obtained from calcium chloride brine which is drawn from naturally 
occurring underground reservoirs. Calcium plays an important role in maintaining cell 
wall structure in fruit. It interacts with pectic acid to form calcium pectate, which has a 
University of Ghana  http://ugspace.ug.edu.gh 23 
 
firming effect on cell walls (Poovaiah, 1986). Calcium forms cross links or bridges 
between free carboxyl groups of the pectin chains, resulting in strengthening of the walls. 
The addition of calcium chloride obstructs enzymes such as polygalcturonase from 
reaching their active sites, thereby retarding tissue softening and delaying ripening. Post - 
harvest calcium application maintains cell turgor by making the cell wall and tissues more 
resistant and less accessible to the enzymes produced by fungi and bacteria limiting 
infection (De-Souza et al., 1999; Scott and Wills, 1979). It also maintains membrane 
integrity and delays membrane lipid catabolism thus extending storage life of fresh fruits.  
As a result of the role calcium plays in maintaining cell walls, researchers have 
investigated the use of post-harvest calcium treatments to increase the quality and shelf-
life of fruit after harvest (Martin-Diana et al., 2007). Different studies have explained that 
calcium chloride reduces post - harvest decay, controls development of physiological 
disorders, improves quality and delays aging or ripening (Shehla and Tariq, 2007; Stanly 
et al., 1995; Grant et al. 1973). Senevirathna and Daundasekera (2010), treated tomato 
fruits with CaCl2 and this resulted in a delay in fruit colour development, lowering of 
ethylene production rates and delay in the time taken to reach the ethylene climacteric 
were observed with increased CaCl2 concentration. 
Nutritionally, addition of calcium chloride improved the lycopene contents and ascorbic 
acid contents (Garcia et al., 1996) and this was confirmed in the work of Upadhayaya and 
Sanghavi (2001) where treating strawberry fruits with 1, 2 and 3% CaCl2 retained the 
highest level of total sugars, acidity and ascorbic acid and exhibited the highest overall 
acceptability. The shelf life was extended to 7 days while the control fruit had a shelf life 
of one day. 
 
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2.11 STORAGE TEMPERATURE  
Ball (1997) mentioned that, temperature plays an important role in maintaining post-
harvest quality of tomato fruits. The effect of storage temperature on physicochemical 
quality and quantity changes in tomatoes, varies with the cultivar (Abou-Aziz et al., 1976) 
and harvesting conditions (Auito and Bramlage, 1986). Low temperature is the most 
important factor in maintaining quality and extending the shelf-life of fruits and vegetables 
after harvest due to its effects on reducing respiration rate, transpiration, ethylene 
production, ripening, senescence and rot development (Majidi et al., 2011). According to 
Lee and Kader (2000), vitamin C content of many crops can be lowered with more 
frequent irrigation, by bruising the fruits, and other mechanical injuries, and by excessive 
trimming. They added that, temperature management after harvest is the most important 
factor to maintain vitamin C content of fruits and vegetables; losses are accelerated at 
higher temperatures and with longer storage durations. It is generally agreed that for 
longer period ripe tomato can be stored at a temperature of 10-15°C and 85-95% relative 
humidity (De Castro et al., 2005). Tomato can also be stored at ambient temperatures for a 
period of up to 7 days.  
Shewfelt (1986), defined shelf life as the period in which a product should maintain a 
predetermined level of quality under specified storage conditions. During shelf storage in 
vegetables and fruits, a number of chemical and physical processes take place. Fruit and 
vegetables deteriorate through the action of spoilage microorganisms, which become 
activated because of the changing physiological state of the fruit and vegetables (Saeed et 
al., 2010). Water loss during storage which is as a result of temperature and relative 
humidity conditions also affects the quality of most fruits and vegetables (Perez et al., 
2003). 
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In a study by Ait-Oubahou and Dilley (1990), tomato fruit kept within sealed packages 
resulted in an atmosphere with high carbon dioxide and low oxygen contents which 
retained flesh firmness, low acidity and soluble solids concentration and delayed fruit 
lycopene development.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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CHAPTER THREE 
3.0 MATERIALS AND METHODS 
3.1 EXPERIMENTAL SITE 
The study was conducted at the Food and Medical Laboratory, Polymer Laboratory, 
Sensory Evaluation Laboratory, Dosimetry Laboratory (Gamma Irradiation Facility - GIF) 
of the Radiation Technology Centre, and the Nuclear Chemistry and Environmental 
Research Centre, all of the Ghana Atomic Energy Commission (GAEC). Microbial 
analysis was conducted at the Animal Science Microbiology Laboratory at University of 
Ghana, Legon. 
 
3.2 SAMPLE PREPARATION 
Tomato fruits at the red riped stage were sorted and fruits with uniform shape, size and 
weight without any injuries or defects were selected, hand washed in brine to destroy all 
forms of contaminants that may be present on the fruit and dried with tissue paper. The 
Burkina variety was used in this experiment as it was the only variety available during the 
experimental period. The Burkina variety was obtained from distributors at the Accra 
market in Accra, Ghana.  
3.2.1 Post - harvest Treatment 1 – Gamma Radiation 
Ten tomato fruits were then packaged in sealed Low Density Polyethylene bag (LDPE) 
thickness 0.025mm. The packaged samples were taken to the GIF for irradiation at the 
following doses; 0kGy (control), 1kGy, 2kGy, 3kGy and 4kGy at a dose rate 1.962kGy. 
The irradiated samples were then transported to the Food and Medical Laboratory for 
analysis.  
 
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3.2.2 Post - harvest Treatment 2 – Calcium Chloride Coating 
Different concentrations of CaCl2 solutions were prepared by dissolving in 100 ml of 
distilled water and making the volume up to 1000 ml/1L of distilled water. The 
percentages were 0% (control), 1.00% (10g CaCl2), 1.50% (15g CaCl2), 2.00% (20g 
CaCl2) and 2.50% (25g CaCl2). Fruits were dipped in CaCl2 solution for 1 minute, 
removed and dried. The fruits were then packaged in sealed Low Density Polyethylene 
bag (LDPE) thickness 0.025mm and stored. 
The storage conditions used were 10±1°C (low temperature) and 28±1°C (ambient 
rd th
temperature). The analysis was conducted every 3  and 5  day for samples stored at 
ambient and low temperatures respectively throughout the period of study. The analysis 
lasted for 9 days for samples stored at 28±1°C and 25 days for those stored at 10±1°C. 
Those stored at ambient temperature were placed in plastic baskets in duplicates and 
stored on shelves whilst those to be stored at 10±1°C were stored in LDPE bags. 
To obtain a homogenate sample of the juice, the fruits were placed in a stomacher bag and 
subjected to a Stomacher- 400 laboratory blender (Seward Scientific, London, England) 
for 3 minutes to bring out the juice. The juice was filtered through a muslin cloth to 
remove the seed and skin. All measurements were done in triplicate. 
 
3.3 ANALYTICAL PROCEDURES 
3.3.1 Shelf Life 
The shelf life was calculated by counting the number of days required when fruit remained 
acceptable for marketing. The shelf life of fruits was decided based on the appearance and 
spoilage of fruits but up to the stage where they remained still acceptable for marketing 
(Mondal, 2000). Each day, the tomatoes stored at ambient temperature were sorted to 
remove fruits with signs of spoilage so as to prevent the whole batch from getting infected 
University of Ghana  http://ugspace.ug.edu.gh 28 
 
quickly. When 50% of fruits showed symptoms of shrinkage or spoilage due to pathogens 
and chilling injury, that lot of fruits were considered to have reached the end of shelf life. 
3.3.2 Physiological Weight Loss (%) 
The weight loss of tomato fruit sample was recorded to an accuracy of 0.01g using a 
Scientech balance model SL5000. Percentage weight loss was calculated by differences 
between initial weight and final weight (fruit weight on the final day of observation) 
divided by initial weight and expressed as percentage (AOAC, 1992).  
PLW (%) = Initial fruit weight – Fruit weight on the day of observation × 100 
Initial fruit weight 
3.3.3 pH 
The Mettler Toledo pH meter (model T3KFTLH) was used to determine the pH of the 
homogenate samples (AOAC, 1992). 
3.3.4 Total Titratable Acidity 
Titratable acidity was determined by the method of Srivastava and Kumar (1993). 
Extracted tomato juice of 10ml was thoroughly mixed in 50ml of distilled water and 
titrated against 0.1N NaOH with three drops of phenolphthalein as indicator until a pH of 
8.1 was attained.  Milli-equivalent weight of citric acid = 0.06404. 
The percentage acid was calculated using the following equation; 
% acid = Titre value x Normality x Milli-equivalent weight of acid × 100 
                                                 Volume of sample 
 
 
 
 
 
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3.3.5 Total Soluble Solids 
The total soluble solids of the fruits were determined by putting a drop of homogenate 
tomato juice on Westover RHB-32ATC hand refractometer held at 20°C and expressed as 
°Brix (AOAC, 1992). 
3.3.6 Moisture Content 
A quantity of 5g of homogenate juice of each of the varieties of tomato was weighed into 
petri – dishes (pd) and dried overnight (16hrs) in an oven at 105°C (Basoglu and Uylaser, 
2000). The dishes were allowed to cool in a desiccator and final weight recorded with an 
AccuLab ALC-150.3. The moisture content was determined using the following equation; 
% Moisture content = Wt of pd+ sample – Wt of pd + dry sample × 100  
                                        Wt of pd + sample – Wt of empty pd 
3.3.7 Vitamin C 
An amount of 100g of tomato was added to 50 mL of distilled water in a 250 mL conical 
flask and 1 mL of starch indicator solution was added. The sample was titrated with 
0.005M iodine solution. The endpoint of the titration was be identified as the first 
permanent trace of a dark blue-black colour was seen due to the starch-iodine complex.  
3.3.8 Lycopene 
An amount of 0.5g of tomato paste was put into screw top vials and wrapped with 
aluminium foil to reduce the penetration of light. A volumetric burette was used to deliver 
5.0ml of 0.05% garlic acid in acetone into vials containing the sample with 5.0ml absolute 
ethanol and 10.0ml hexane. Vials were introduced into ice and subjected to an orbital 
shaker to mix the content at 200 rpm for 15 minutes. After shaking, 3ml deionised water 
was added to each vial and shaken for another 5minutes. The vials were left at room 
temperature to allow for phase separation for 5minutes. The absorbance of the upper layer 
(hexane) was measured using a Shimadzu UV-VIS Spectrophotometer model UV-1201 in 
University of Ghana  http://ugspace.ug.edu.gh 30 
 
1cm path length quartz cuvettes at 503nm blanked with hexane solvent. The absorbance of 
the hexane layer was read thrice and the lycopene estimation was calculated using the 
equation by Fish et al. (2002); 
3 
Lycopene (mg/Kg tissue) =  A503 ×   536.9g   ×   1L   ×  10 mg   ×    10.0ml 
4    3   
    17.2x10 /M × cm × mole × 10 mL × 1g × kg tissue 
              =   A503 × 0.0312 
                   kg tissue   
             =             A503 × 31.2 
                g tissue 
4 
Where the molar extinction coefficient of 17.2x10 / M × cm is the lycopene in hexane 
(Zechmeister et al., 1943); A503 is absorbance at 503 nm and kg tissue is the quantity of 
sample used. The lycopene values were expressed in mg/kg. 
3.3.9 Elemental Composition Analyses 
Elemental Composition Analyses were determined using the Atomic Absorption 
Spectrophotometer (AAS) and the Flame Photometer. 
3.3.9.1 AAS (Varian AA240FS Model, USA) Analysis 
0.5g of the samples prepared was weighed into a labelled 100mL polytetrafluoroethylene 
Teflon bombs. 6 mL of conc. HNO3 (65%) and 1 mL of H2O2 (30%) were added to the 
samples in a fume chamber. The samples were then loaded on a microwave carousel. The 
vessel caps were secured tightly. The complete assembly was microwave irradiated for 20 
minutes in a milestone microwave laboratory station ETHOS 900 D model (Fig. 3) using 
the following parameters; 250W  for 2 minutes, 0 W for 2 minutes, 250 W for 6 minutes, 
o o
400W for 5 minutes, 600 W for 5 minutes with 100 pressure, 400 C and 500 C. 5 minutes 
was allowed for venting. 
University of Ghana  http://ugspace.ug.edu.gh 31 
 
After digestion, the Teflon bombs mounted on the microwave carousel were cooled in a 
water bath to reduce internal pressure to allow volatilized materials to re-solubilise. The 
digest was made up to 20 mL with distilled water and assayed for the presence of copper, 
zinc and manganese in an acetylene-air flame. 
Reference standards for the elements of interest, blanks and repeats of the samples were 
digested the same way as the actual samples. These served as internal positive controls.  
The digested samples were then aspirated using Varian AA240FS fast sequential Atomic 
Absorption Spectrophotometer. The instrument was initially calibrated before the reading 
of any element with a standard solution of the element. A linearity of the calibration curve 
was always checked before the samples were aspirated. The final concentration was 
obtained as stated below: 
Final concentration (ppm) = (concentration × nominal volume)  
                                                   Weight of sample in grams 
Concentration recorded = given on the monitor attached to the instrument  
Nominal volume = 20ml 
Weight of sample = 0.5g 
 
University of Ghana  http://ugspace.ug.edu.gh 32 
 
 
Fig. 3 Milestone microwave laboratory station ETHOS 900 D model. 
3.3.9.2 Flame Photometry (Sherwood 420 Model, England U.K.) Analysis 
The flame photometer was allowed to warm up for about 20 minutes. Five (5) ml of the 
blank (distilled or deionised water) and 2ml of lithium standard of concentration 100mg/l 
were mixed thoroughly and then aspirated by placing the capillary tube in the solution. 
Some seconds were allowed to elapse for a reaction to occur in the nebuliser, and then the 
knob for the blank was pressed for calibration to complete. Five (5) ml of the Na/K 
standard was measured and 2ml of the lithium standard added to it. It was thoroughly 
mixed and aspirated. Five (5) ml of the filtered tomato sample and 2ml of the lithium 
standard were measured and thoroughly mixed. The solution was aspirated and the 
concentration of Na/K recorded in mg/L of the sample.  
 
 
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3.3.10 Microbial Load Determination 
Total Aerobic Mesophiles, Yeast and Mould colony forming units (cfu) were determined 
by standard spread plate methodology using Plate Count Agar (PCA) (Difco,Detroit, MI) 
or Potato Dextrose Agar (PDA) (Difco) containing 25 mg /ml chloramphenicol (Sigma, St. 
Louis, M O). One (1) ml of the homogenate tomato sample was poured into sterile Petri 
dishes and 10 ml of hot agar was gently dispensed on it. The plate was swirled gently and 
was inverted after it had solidified. The plates were inverted and incubated at 37°C for 24 
hours. The colonies were counted and the number of colonies per plate was multiplied by 
the dilution factor to obtain the total viable counts per ml of the original sample 
(Babarinde and Fabunmi, 2009).  
 
3.4 DATA ANALYSES 
The data obtained were analysed using Statgraphics Centurion XVI.I. One – way Analysis 
of Variance (ANOVA) and multi factor Analysis of Variance were used to assess the 
significant differences (p≤ 0.05) among properties analysed with respect to storage period, 
storage conditions and treatment used (gamma radiation doses and CaCl2 levels). The 
Fisher’s least significant difference (LSD) was used to discriminate among the means. The 
data for both storage conditions were analysed separately as the number of days for 
evaluation were different for each storage condition (ambient temperature storage was 
rd th
analysed every 3  day whilst fruits stored at low temperature were analysed every 5  
day). 
 
 
 
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CHAPTER FOUR 
4.0 RESULTS AND DISCUSSION 
4.1 SHELF LIFE STUDY OF BURKINA TOMATO FRUITS FOLLOWING 
GAMMA RADIATION AND CaCl2 COATING. 
4.1.1 Shelf Life Study of Tomato Fruits Stored at Ambient Temperature (28±1°C) 
Following Irradiation. 
Fig. 4.1.1(a) shows the effect of increasing dose of gamma radiation on storage life (in 
days) of ripe fruits of tomato variety Burkina, stored at ambient temperature (28±1°C). 
The shelf life of fruits was reached when more than 50% of the fruits showed signs of 
spoilage. 
 
Fig. 4.1.1(a) Effect of radiation dose on the shelf life of tomato fruits stored at ambient temperature 
(28±1°C). 
 
University of Ghana  http://ugspace.ug.edu.gh 35 
 
th
Control fruits showed the minimum shelf life with 80% fruit spoilage on the 7  day (Plate 
1b). Therefore, further analysis was discontinued on day 9 throughout this research for 
control fruit. Fruits treated with gamma radiation however lasted from 11-12 days as 
demonstrated in Fig. 4.1.1(a) above. Fruits treated with 3 and 4 kGy showed the longest 
shelf life with 12 days (Plate 2b) whilst 1 and 2 kGy lasted for 4 days more than the 
control fruits. The shelf life increased with increasing dose. This result confirms work 
done by Nasarin et al., (2008) when non-treated tomato kept in ambient condition without 
packaging showed the minimum shelf life of 7 days. 
 
 
 
 
 
 
 
 
 
 
 
University of Ghana  http://ugspace.ug.edu.gh 36 
 
1a 1b 
a       
Plate 1: Control tomato fruits stored at ambient temperature (28±1°C).                                             
(a) First day of storage (b) 7 days of storage. 
    
2a 2b 
      
Plate 2: Irradiated tomato fruits (3kGy) stored at ambient temperature (28±1°C).                                    
(a) First day of storage (b) 12 days of storage.  
 
3a 3b 
      
Plate 3: CaCl2 treated tomato fruits (2.50%) stored at ambient temperature (10±1°C).                    
(a) First day of storage (b) 18 days of storage.  
 
 
University of Ghana  http://ugspace.ug.edu.gh 37 
 
4.1.2 Shelf Life Study of Tomato Fruits Stored at Ambient Temperature (28±1°C) 
Following CaCl2 Coating. 
From Fig. 4.1.1(b), fruits treated with CaCl2 showed the longer shelf life with 7-11 days 
longer than the control fruits which lasted for 7 days. After 14 days, CaCl2 treated fruits 
started shrinking as seen in Plate 3(b). 
 
Fig. 4.1.1(b) Effect of CaCl2 concentration on the shelf life of tomato fruits stored at ambient 
temperature (28±1°C). 
 
Concentration at 1.00, 1.50, 2.00 and 2.50 % of CaCl2 treatment extended shelf life of 
tomato fruit by 7, 8, 9 and 11 days respectively. The shelf life increased with increasing 
level of concentration. This confirms work by Nirupama et al. (2010) where treatment of 
0.50%, 1.00%, 1.50% of CaCl2 on tomato fruits caused the extension of storage life to 15, 
17 and 18 days respectively, as compared to that of fruits of control set (7 days).  
Comparatively, tomato fruits treated with CaCl2 showed the longest shelf life with 7-11 
days more above control fruits and 4-6 days more above irradiated fruits. Extension of the 
University of Ghana  http://ugspace.ug.edu.gh 38 
 
shelf life of the tomato fruit may be attributed mainly to the increased firmness and 
retarded ethylene production rates in CaCl2 treated fruits as explained by Senevirathna and 
Daundasekera (2010). Gamma radiation was also able to extend the shelf life of tomato 
fruits by 3-4 days over control. This is as a result of its ability to prolong the shelf life of 
fruits and vegetables. 
 
4.1.3 Shelf Life Study of Tomato Fruits Stored at Low Temperature (10±1°C) 
Following Irradiation. 
Fig. 4.1.2(a) shows the effect of gamma radiation dose on the shelf life of tomato fruit 
stored at low temperature (10±1°C). Control fruits lasted for 25 days after which more 
than 50 % of the fruit showed signs of spoilage (Plate 4b). 
 
Fig. 4.1.2(a) Effect of irradiation dose on the shelf life of tomato fruits stored at low temperature 
(10±1°C). 
 
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Irradiated fruits lasted between 28-34 days. After 28 - 30 days, fruits treated with 1 and 2 
kGy had more than 50% spoilage (Plate 5b) whilst fruits irradiated at 3 and 4 kGy lasted 
for 33-34 days as seen in Fig. 4.1.2(a). Therefore, the shelf life of tomato fruits increased 
with increasing dose.  
 
4.1.4 Shelf Life Study of Tomato Fruits Stored at Low Temperature (10±1°C) 
following CaCl2 Coating. 
Fig. 4.1.2(b) shows the effect of CaCl2 concentrations on the shelf life of tomato fruit 
stored at low temperature (10±1°C). Control fruits lasted for 25 days whilst fruits treated 
with CaCl2 lasted between 38-43 days. 
 
Fig. 4.1.2(b) Effect of CaCl2 concentration on the shelf life of tomato fruits stored at low temperature 
(10±1°C). 
 
CaCl2 concentration of 1.00 and 1.50 % treated fruits lasted for 38 and 40 days 
respectively after which tomato fruits started showing signs of microbial infections (Plate 
University of Ghana  http://ugspace.ug.edu.gh 40 
 
6b). Fruits treated with CaCl2 at 1.00, 1.50, 2.00 and 2.50 % concentrations extended shelf 
life of tomato fruit by 13, 15, 16 and 18 days respectively over control which lasted for 25 
days. These results supports the view of Cheour et al. (1990) who reported that the use of 
CaCl2 prolonged the storage life of strawberries, as measured by a delay in accumulation 
of sugars (°Brix), decrease in organic acids and  mould development. 
In comparison with gamma radiation, fruits treated with CaCl2 at concentrations of 1.00, 
1.50, 2.00 and 2.50 % resulted in extended shelf lives of 10, 10, 8 and 9 days respectively 
over radiation treated fruits.  
From the shelf life study, it could be observed that fruits stored at low temperature 
(10±1°C) generally experienced longer shelf life than at ambient temperature (28±1°C). 
For example, fruits in the control set which were kept under ambient temperature 
(28±1°C) were able to last for 7 days whilst the same set of fruits kept at low temperature 
(10±1°C) had an were able to last for 25 days. Fruits treated with gamma irradiation and 
stored at low temperature (10±1°C) extended shelf life of 18 days whilst fruits treated with 
CaCl2 and stored at the same low temperature lasted 24-25 days over fruits stored at 
ambient temperature (28±1°C).  
Gamma radiation extended the shelf life of tomato fruit by slowing down senescence 
making it possible to store the produce longer and in better conditions through 
preservation of nutrients, chemical and physical properties (Tiwari et al., 2009). The use 
of CaCl2 was able to extend the shelf life as a result of its ability to maintain membrane 
integrity and delay membrane lipid catabolism (Martin-Diana et al., 2007). 
 
University of Ghana  http://ugspace.ug.edu.gh 41 
 
4a 4b 
      
Plate 4: Control tomato fruits stored at low temperature (10±1°C).                                                     
(a) First day of storage (b) 25 days of storage. 
 
5a 5b 
       
Plate 5: Irradiated tomato fruits (2 kGy) stored at low temperature (10±1°C).                                  
(a) First day of storage (b) 30 days of storage. 
  
6a 6b 
        
Plate 6: CaCl2 treated tomato fruits (2.50%) stored at low temperature (10±1°C).                            
(a) First day of storage (b) 41 days of storage.  
  
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4.2 PHYSICOCHEMICAL PROPERTIES OF BURKINA TOMATO FRUITS 
FOLLOWING GAMMA RADIATION AND CaCl2 COATING. 
4.2.1 Physiological Weight Loss of Tomato Fruit Stored at Ambient Temperature 
(28±1°C) Following Irradiation. 
Fig. 4.2.1(a) shows the effect of irradiation dose (kGy) on the physiological weight of 
tomato fruit stored at ambient temperature (28±1°C). Weight loss in the control fruits 
ranged from 2.80 - 15.66 % (mean of 8.01%) whilst irradiated fruits showed between 2.48 
– 14.55 % (mean of 6.24%) throughout storage period of 9 days.  
 
Fig. 4.2.1(a) Effect of irradiation dose (kGy) on physiological weight loss of tomato fruits stored at 
ambient temperature (28±1°C). 
 
From Fig. 4.2.1(a), the control fruits showed the largest weight loss throughout the study 
with 15.66% weight loss on the final day. Control fruits also increased significantly 
(P<0.05) in weight loss with increasing storage days. Generally, weight loss increased 
University of Ghana  http://ugspace.ug.edu.gh 43 
 
significantly (Appendix 17a) in irradiated fruits with increasing radiation dose and also 
with advancement of storage. There were significant differences in weight loss of tomato 
fruits between storage days. With tomato fruits treated with radiation doses, 4kGy showed 
the largest weight loss throughout the storage period reaching 14.55 % on the final day 
whilst fruits treated with 1kGy showed the least weight loss (6.78 %) on the final day of 
assessment. These results confirm the work by Bhattarai and Gautam (2006) who 
observed that weight loss was larger in fruits without any treatment. This could be 
attributed to the fact that after harvest, climateric fruits like tomato generate heat which 
contributes to weight loss. The heat lost to the environment contributes to increased 
evaporation of water. Under ambient conditions, the heat generated is more rapid as a 
result of increased respiration rate. This leads to rapid weight loss of the fruit characterised 
by excessive softness making the fruit no longer marketable (Davies and Hobson, 1981; 
Padmini, 2006). 
 
4.2.2 Physiological Weight Loss of Tomato Fruits Stored at Ambient Temperature 
(28±1°C) Following CaCl2 Coating. 
Fig. 4.2.1(b) depicts tomato fruits treated with CaCl2 and stored at ambient temperature 
(28±1°C) with weight loss ranging between 1.35 and 6.93 % (3.46% mean) whiles control 
fruits ranged from 2.80 - 15.66 % (8.01% mean). Weight loss in control fruits increased 
significantly (P ≤ 0.05) with increasing storage days and showed the largest weight loss of 
15.66 % on the final day. Weight loss increased with increasing CaCl2 concentrations and 
also as storage days advanced. Tomato fruits treated with CaCl2 at 2.50% concentration 
rd th
showed the largest weight loss at 2.57% on the 3  day and 6.93% on the 9  day. Fruits 
treated with 1.50% concentration showed the least weight loss on the final day at 4.11%. 
University of Ghana  http://ugspace.ug.edu.gh 44 
 
Weight loss was larger in control fruits (8.01%) as compared to CaCl2 treated fruits (3.46 
%).  
 
Fig. 4.2.1(b) Effect of CaCl2 concentration on physiological weight loss of tomato fruits stored at 
ambient temperature (28±1°C).  
 
In all treatments used, weight loss was larger in control fruits (8.01 %) than gamma 
radiation (6.24 %) and CaCl2 treatments (3.46 %). This is in agreement with Bhattarai and 
Gautam (2006) who observed that weight loss was least in fruits treated with CaCl2 and 
higher in fruits without any treatment. Physiological weight loss was greater in the 
irradiated samples than the CaCl2 treated tomato fruits.  
 
4.2.3 Physiological Weight Loss of Tomato Fruit Stored at Low Temperature 
(10±1°C) Following Irradiation. 
Fig. 4.2.2(a) depicts the physiological weight loss of tomato fruits treated with gamma 
radiation dose. Weight loss in radiated fruits showed least weight loss as compared to 
University of Ghana  http://ugspace.ug.edu.gh 45 
 
fruits in the control set. Control fruits showed 22.93 % mean weight loss whilst irradiated 
fruits resulted in 1.85 % mean weight loss throughout the 25 day storage period. 
 
Fig. 4.2.2(a) Effect of irradiation doses (kGy) on physiological weight loss of tomato fruit stored at low 
temperature (10±1°C).  
 
Weight loss for irradiated fruits increased significantly (Appendix 17b) throughout the 
storage period. Fruits treated with 1, 2, 3 and 4 kGy showed a percentage weight loss of 
2.34, 2.76, 2.73 and 3.00 % respectively from the initial to the final day of evaluation. 
Thus, weight loss increased with increasing dose of gamma radiation. Fruits in the control 
set showed the largest percentage mean weight loss of 22.93 % with a significant increase 
(P ≤ 0.05) in percentage weight loss throughout storage.  
 
 
University of Ghana  http://ugspace.ug.edu.gh 46 
 
4.2.4 Physiological Weight Loss of Tomato Fruit Stored at Low Temperature 
(10±1°C) Following CaCl2 Coating. 
Fig. 4.2.2(b) shows the effect of CaCl2 concentration on physiological weight loss of 
tomato fruit stored at low temperature (10±1°C). Fruits in the control set showed the 
largest mean weight loss of 22.93%. Fruits treated with CaCl2 showed the least percentage 
mean weight loss of 0.97 % throughout the 25 day storage period. 
 
Fig. 4.2.2(b) Effect of CaCl2 concentrations on physiological weight loss of tomato fruit stored at low 
temperature (10±1°C). 
 
Weight loss increased significantly with 2.00 and 2.50 % CaCl2 but not the other 
concentrations (1.00 and 1.50 %). Generally, weight loss increased with decreasing 
concentrations of CaCl2 but increased with increasing storage days. There were significant 
differences (Appendix 18) in weight loss of tomato fruits among storage period. 
In general, weight loss for all the treatments ranged between 0.41 – 38.67 % throughout 
the storage period as seen in Fig. 4.2.2(a) and Fig. 4.2.2(b).  Percentage mean weight loss 
University of Ghana  http://ugspace.ug.edu.gh 47 
 
was greater in control fruits (22.93%) as compared to fruits treated with CaCl2 (0.97%) 
and radiation treated (1.85%). The softening of tomato fruit after irradiation was as a result 
of biochemical and physiological processes like membrane damage, specific cell wall 
enzyme among others (Barka et al., 2000). This confirms the fact that irradiation affects 
the texture of some fruits as reported by Lee et al. (1968).  The use of CaCl2 on the other 
hand, improves the skin strength making the cell wall and tissues more resistant by 
controlling ripening and softening (Poovaiah, 1986), thus reducing loss in weight of the 
fruit.  
Fruits stored at 28±1°C showed the largest percent weight loss as compared to those 
stored at 10±1°C for all treatments and their various levels throughout the storage period. 
For instance, control fruits showed percent weight loss of 15.66% after the 9th day when stored 
at ambient temperature whilst after 10 days weight loss was 12.47% for the same control fruits 
stored at 10°C. Postharvest recommendations indicate that tomatoes, including cherry and 
grape tomatoes, should be stored at 10°C or higher to avoid chilling injury (Roberts et al., 
2002).  
Nunes (2008) reported that maximum acceptable weight loss values before a tomato becomes 
unsalable ranges from 6-7%. With reference to the results, at ambient temperature, tomato 
fruits treated at 4kGy, 2kGy and control fruits experienced weight losses of 14.55%, 10.29% 
and 15.66% respectively on the 9th day, far in excess of 7.0%. Therefore, these fruits were 
beyond the salable range on the 9th day. At low temperature, fruits treated with gamma 
radiation and CaCl2 are within the maximum acceptable weight loss range. However, control 
fruits throughout storage period were considered as fruits beyond the salable range. 
Basically, evaporation and respiration are responsible for weight loss of fresh tomato 
fruits. In transpiration, water is lost due to differences in vapour pressure of water in the 
atmosphere and the transpiring surface. Respiration, on the other hand, causes a weight 
University of Ghana  http://ugspace.ug.edu.gh 48 
 
reduction because a carbon atom is lost from the fruit each time a carbon-dioxide molecule 
is produced from an absorbed oxygen molecule and evolved into the atmosphere 
(Bhowmik and Pan, 1992). High respiration rate of the fruit therefore results in higher 
evaporation of water from the fruit surface which leads to increase in percentage of weight 
loss. 
 
4.2.5 pH of Tomato Fruits Stored at Ambient Temperature (28±1°C) Following 
Irradiation. 
Table 4.2.3(a) shows the effect of irradiation dose on pH of tomato fruit stored at ambient 
temperature (28±1°C). pH for control fruits ranged between 4.35 – 4.38 whilst that of 
irradiated fruits were between 4.26 – 4.62.  The pH for control fruits reduced significantly 
rd th
after the 3  day but increased on the 6  day.  
Table 4.2.3(a) Effect of irradiation dose (kGy) on pH of tomato fruit stored at 
ambient temperature (28±1°C). 
pH of Tomato Fruits 
Storage Period 
(Days) 0 1 kGy 2 kGy 3 kGy 4 kGy 
Aa Cb Fc Jd Me 
0 4.39 4.32  4.40 4.42 4.26
Bf Cg Gh Jh Ni 
3 4.35  4.33  4.43 4.44 4.37
Aj Dj Hk Kl Om 
6 4.38  4.38 4.47 4.57 4.59
En Io Lo Pp 
9 **ND 4.39 4.51 4.52  4.62
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not 
significantly (P>0.05) different from each other and means with the same letters in the same row (lower 
case, doses) are not significantly different (P>0.05) from each other.  
**ND – not determined. 
University of Ghana  http://ugspace.ug.edu.gh 49 
 
There was no significant difference between pH on the initial day and the final day of 
control fruits. However, there were significant differences in pH among storage days and 
irradiation doses (Appendix 1a and 1b).  
It could be observed from the table (Table 4.2.3a) that fruits treated with gamma radiation 
generally showed an increase in pH throughout the storage period. For fruits irradiated at 2 
and 4 kGy, the increase in pH was significant (P<0.05) with the advancement of days 
reaching 2.43 and 7.80 % respectively above the initial value by the final day (day 9). As 
fruits approach senescence or decay, the level of acidity reduces and this accounts for the 
reason why the pH increased after some few days of exposure to ambient conditions. 
This result agress with Padmini (2006) who stated that pH increases with the advancement 
of storage days. Generally, there were significant differences in pH of tomato fruits in the 
radiation doses used among each storage day. Among storage days, pH of control fruits 
varied significantly from the irradiated fruits. 
  
4.2.6 pH of Tomato Fruits Stored at Ambient Temperature (28±1°C) Following 
CaCl2 Coating. 
Table 4.2.3(b) reveals the effect of CaCl2 concentration (%) on pH of tomato fruit stored at 
ambient temperature (28±1°C).  pH for control fruits ranged between 4.35 and 4.38 whilst 
that for fruits treated with CaCl2 ranged between 4.10 and 4.41. pH reduced by the final 
th
day of evaluation (6  day) in control fruits, however, there was no significant difference 
between pH on the initial day and the final day for control fruits. The pH for tomato fruits 
treated with CaCl2 ranged between 4.10 and 4.41 as depicted in table (4.2.3b). 
Generally, there was no consistent relationship between CaCl2 concentrations and pH. 
th
However, by the 9  day, pH of all treatment levels of CaCl2 had reduced significantly. The 
University of Ghana  http://ugspace.ug.edu.gh 50 
 
decrease in pH could be attributed to the fact that pH increases to a maximum at or soon 
after the climacteric and then usually shows a slight fall as ripening progresses 
(Simmonds, 1969). 
Table 4.2.3(b) Effect of CaCl2 concentration (%) on pH of tomato fruit stored at 
ambient temperature (28±1°C). 
pH of Tomato Fruits 
Storage Period 
(Days) 0 1.00% 1.50% 2.00% 2.50% 
Aa Cb Ga Ib Lb 
0 4.39 4.29 4.37 4.27 4.27
Bc Dd Gc Je Lf 
3 4.35 4.33 4.34 4.41 4.28
Ag Eh Gi Kh Mj 
6 4.38 4.25 4.34 4.25 4.16
Fk Hl Im Nn 
9 **ND 4.10 4.22 4.27 4.24
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not 
significantly (P>0.05) different from each other and means with the same letters in the same row (lower 
case, doses) are not significantly different (P>0.05) from each other.  
**ND – not determined. 
There were significant differences in pH among storage days and irradiation doses 
(Appendix 2a and 2b).  CaCl2 treatment on pH of tomato fruits showed no consistency 
during storage and this confirms work by Bhattarai and Gautam (2006). This observation 
also agrees with reports on fruits like mango (Tirmazi and Wills, 1981) and strawberry 
(De Souza et. al., 1999). Among storage days, there was no consistent relationship 
between pH for control fruits and CaCl2 treated fruits. 
Generally, fruits treated with CaCl2 exhibited comparatively lower pH as compared to that 
of the fruits in the control set and radiation treated fruits. This may be attributed to the 
effect CaCl2  has on obstructing enzymes such as polygalcturonase from reaching their 
University of Ghana  http://ugspace.ug.edu.gh 51 
 
active sites, thereby retarding tissue softening, limiting infection and delaying ripening 
(Scott and Wills, 1979; De-Souza et al., 1999).  
The tomato fruit is a commodity with a variably low pH (3.4 - 4.7) depending on variety 
and state of ripeness (Lund, 1992). The suitable range for fruits and vegetables according 
to Harris et al. (1991) is between 3.0 and 5.0. Hence, pH values of the tomato fruits 
obtained following various treatments fell within this range and would hinder the growth 
of microorganisms as most bacteria grow well over a range of pH range of 6 to 9 (Atlas, 
1994). 
 
4.2.7 pH of Tomato Fruits Stored at Low Temperature (10±1°C) Following 
Irradiation. 
Table 4.2.4(a) displays pH of tomato fruits subjected to increasing doses of gamma 
radiation and stored at 10±1°C. pH of unirradiated tomato fruits fluctuated between 4.22 - 
4.49 throughout the storage period whilst that of irradiated fruits ranged between 4.23 - 
4.49 but did not reflect any consistent relationship with radiation doses. There were 
significant differences in pH among storage days and irradiation doses (Appendix 3a and 
3b). 
By the final day, pH had increased in all doses throughout the storage period. There were 
significant differences (P<0.05) in pH among each storage day at different doses at which 
tomato fruits were irradiated. 
 
 
 
University of Ghana  http://ugspace.ug.edu.gh 52 
 
Table 4.2.4(a) Effect of irradiation dose (kGy) on the pH of tomato fruit stored at low 
temperature (10±1°C). 
pH of Tomato Fruits 
Storage Period 
(Days) 0  1 kGy 2 kGy 3 kGy 4 kGy 
Aa Fb Jc Nd Qe 
0 4.22 4.23 4.30 4.35 4.36
Bf Gg Jh Pi Rj 
5 4.40 4.32 4.34 4.44 4.42
Ck Hl Km Pn Ro 
10 4.35 4.40 4.38 4.44 4.43
Dp Fq Jr Ns St 
15 4.49 4.25 4.34 4.39 4.31
Bu Ivw Mu Ouv Tw 
20 4.39 4.45 4.39 4.42 4.47
Ex Hy Lz Oα Uβ 
25 4.43 4.39 4.37 4.41 4.49
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not 
significantly (P>0.05) different from each other and means with the same letters in the same row (lower 
case, doses) are not significantly different (P>0.05) from each other.  
 
Control fruits were also significantly different from irradiated fruit on all storage days. 
The results contradicts those obtained by Youssef et al. (2011) who reported that 
irradiating tomato fruits at 1.5, 3.0 and 4.5 kGy showed no significant effect on the acidity 
(pH) of tomato juice, working at a storage temperature of 4ºC. pH recorded for all 
irradiated fruits varied significantly but inconsistently over storage period.  
 
4.2.8 pH of Tomato Fruits Stored at Low Temperature (10±1°C) Following CaCl2 
Coating. 
Table 4.2.4(b) displays effect of CaCl2 concentrations (%) on the pH of tomato fruit stored 
at 10±1°C. The pH of control fruits fluctuated between 4.22 - 4.49 throughout the storage 
period. Mean pH values for fruits treated with CaCl2 ranged from 4.05 – 4.56 as depicted 
in Table 4.2.4(b).  
University of Ghana  http://ugspace.ug.edu.gh 53 
 
From the table, it could be observed that the fruits did not show any consistent relationship 
among the concentrations used although by the final day, pH values had increased 
significantly. CaCl2 treated fruits at all concentrations increased in acidity from the initial 
th th
to the 10  day whilst acidity reduced from the 15  to day 25. Generally, pH varied 
significantly within and among all CaCl2 treated fruits and control fruits throughout 
storage.  
The fluctuations in pH of the fruit could be due to maturity differences (Kirk and Sawyer, 
1997). This is because, the more ripe a fruit the less acidic it becomes. The pH of 
climacteric fruits rises to a maximum and then usually shows a slight fall as ripening 
progresses (Simmonds, 1969). However, there were significant differences in pH among 
storage days and irradiation doses (Appendix 4a and 4b). 
Table 4.2.4(b) Effect of CaCl2 concentration (%) on the pH of tomato fruit stored at 
low temperature (10±1°C). 
pH of Tomato Fruits 
Storage Period 
(Days) 0 1.00% 1.50% 2.00% 2.50% 
Aa Fb Jc Nab Tab 
0 4.22 4.29 4.37 4.27 4.27
Bd Ge Kf Og Uh 
5 4.40 4.27 4.23 4.24 4.12
Ci Gj KLk Pl Vm 
10 4.35 4.27 4.24 4.13 4.05
En Ho Lp Qo Wq 
15 4.49 4.33 4.28 4.34 4.45
Br Fs Jt Ru Xv 
20 4.39 4.30 4.36 4.31 4.43
Dw Ix My Sz Ya 
25 4.43 4.41 4.45 4.50 4.56
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not 
significantly (P>0.05) different from each other and means with the same letters in the same row (lower 
case, doses) are not significantly different (P>0.05) from each other.  
 
University of Ghana  http://ugspace.ug.edu.gh 54 
 
Simmonds (1969) explained further that the pH of a produce depends on the genotype, the 
soil type for cultivation and fertilizer application. For this study, though the same variety 
was used, there could have been a difference in the soil treatment the fruits received. 
In all treatments used, irradiated fruits showed the highest pH range throughout the storage 
period. Mean pH values for fruits stored at low temperature ranged between 4.05 – 4.56 
throughout the 25 days of storage whilst those stored at ambient temperature were 
between 4.10 – 4.62 for 9 days of analysis. Low temperature therefore reduced the pace at 
which ripening occur in the fruit which consequently showed in the mean pH values being 
lesser than those stored at ambient temperature. 
 
4.2.9 Total Titratable Acidity (TTA) of Tomato Fruit Stored at Ambient 
Temperature (28±1°C) Following Irradiation. 
Table 4.2.5(a) displays effect of radiation dose (kGy) on the TTA of tomato fruit stored at 
ambient temperature (28±1°C).  
Table 4.2.5(a) Effect of irradiation dose (kGy) on the Total Titratable Acidity (TTA) 
of tomato fruit stored at ambient temperature (28±1°C). 
Total Titratable Acidity (%) of Tomato Fruits 
Storage Period 
(Days) 0 1 kGy 2 kGy 3 kGy 4 kGy 
Aa Cb Gc Lc Pd 
0 0.36 0.38 0.33 0.33 0.46
Be Df Ig JKh Mi 
3 0.27 0.33 0.26 0.29 0.32
Bj Ek Hl Jm Nn 
6 0.28 0.28 0.28 0.29 0.29
Fo Hp Kp Os 
9 **ND 0.35 0.29 0.28 0.23
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not 
significantly (P>0.05) different from each other and means with the same letters in the same row (lower 
case, doses) are not significantly different (P>0.05) from each other.  
**ND – not determined. 
University of Ghana  http://ugspace.ug.edu.gh 55 
 
TTA in control fruits reduced significantly from 0.36 – 0.28 % throughout the storage 
period resulting in 22.2 % reduction. TTA of irradiated tomato fruit also ranged between 
0.23 – 0.46 % resulting in a mean of 0.32%. 
Generally, fruits treated with gamma radiation reduced in TTA during the first 6 days but 
increased on the final day in all doses. The result confirms the findings of De Castro et al. 
(2006) who observed that titratable acidity decreased in the first 7 days storage period. 
th
The rise in TTA after the 6  day could be related to the increase of titratable acidity 
caused by the gaseous conditions (elevation of CO2 concentration and reduction of O2) 
during storage as period reported by De Souza et al. (1999). There were significant 
differences in pH among storage days and irradiation doses (Appendix 5a and 5b). 
Fruits treated with 4kGy however, reduced significantly in TTA throughout the storage 
period. This confirms the fact that the amounts of organic acids usually decrease during 
maturity, because organic acids are substrates of respiration (Wills et al., 1981). 
Generally, TTA among storage days differed significantly in all irradiated fruits and 
control fruits. 
 
4.2.10 Total Titratable Acidity (TTA) of Tomato Fruit Stored at Ambient 
Temperature (28±1°C) Following CaCl2 Coating. 
Table 4.2.5(b) displays the effect of CaCl2 concentration (%) on Total Titratable Acidity 
(TTA) of tomato fruit stored at ambient temperature (28±1°C). TTA in control fruits 
resulted in a mean of 0.30% whilst that for fruits treated with CaCl2 is 0.41%. Control 
fruits showed a decrease in %TTA during storage. In general, TTA of tomato fruits 
th
increased with increasing concentration of CaCl2 but only up to the 6  day of storage. By 
th
the 9  day, however, TTA decreased in all CaCl2  treatments. This result confirms work 
University of Ghana  http://ugspace.ug.edu.gh 56 
 
done by Senevirathna and Daundasekera (2010). However, there were significant 
differences in pH among storage days and irradiation doses (Appendix 6a and 6b). 
Table 4.2.5(b) Effect of CaCl2 concentration (%) on Total Titratable Acidity (TTA) 
of tomato fruit stored at ambient temperature (28±1°C). 
Total Titratable Acidity (%) of Tomato Fruits 
Storage Period 
(Days) 0 1.00% 1.50% 2.00% 2.50% 
Aa Cb Fb Ic Md 
0 0.37 0.42 0.41 0.47 0.48
Be Df Gg Ji Nh 
3 0.28 0.43 0.38 0.36 0.44
Bj Ek Fk Kl Mm 
6 0.28 0.40 0.41 0.37 0.49
En Ho Lp Oo 
9 **ND 0.41 0.35 0.33 0.36
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not 
significantly (P>0.05) different from each other and means with the same letters in the same row (lower 
case, doses) are not significantly different (P>0.05) from each other.  
**ND – not determined. 
 
Comparatively, irradiated tomato samples and control fruits showed lower TTA 
throughout the storage period than CaCl2 treatment. This may be attributed to the 
obstructing effect CaCl2 has on enzymes such as polygalcturonase from reaching their 
active sites, thereby retarding tissue softening and delaying ripening which leads to 
slowing down the reduction of acidity in the fruit (De Souza et al., 1999; Scott and Wills, 
1979). 
 
4.2.11 Total Titratable Acidity (TTA) of Tomato Fruit Stored at Low Temperature 
(10±1°C) Following Irradiation. 
Table 4.2.6(a) shows effect of gamma radiation doses (kGy) on the TTA of tomato fruit 
stored at low temperature (10±1°C). Control fruits showed mean of 0.33% TTA 
University of Ghana  http://ugspace.ug.edu.gh 57 
 
throughout the storage period and displayed significant differences (P≤ 0.05) among 
storage days. For irradiated fruits, mean TTA ranged was 0.32% as in table 4.2.6(a). 
Table 4.2.6(a) Effect of irradiation dose (kGy) on the TTA of tomato fruit stored at 
low temperature (10±1°C). 
Total Titratable Acidity (%) of Tomato Fruits 
Storage Period 
(Days) 0 1 kGy 2 kGy 3 kGy 4 kGy 
Aa Gb Mc Qd Ud 
0 0.51 0.47 0.34 0.36 0.37
Be Ff Kg Rh STi 
5 0.28 0.28  0.28 0.28 0.28
Cj Fl Lk Om Tjk 
10 0.33 0.28 0.29 0.31 0.29
Dn Ho Np Pq Vo 
15 0.25  0.38 0.35 0.32 0.38
Er Is KLt Or Wr 
20 0.32 0.26  0.29 0.31 0.31
Eu Ju Mv OPu Sw 
25 0.31 0.32 0.34 0.32 0.28
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not 
significantly (P>0.05) different from each other and means with the same letters in the same row (lower 
case, doses) are not significantly different (P>0.05) from each other.  
 
Generally, there were significant differences in %TTA among radiation doses used on 
each storage day though the differences were not consistent (Appendix 7a and 7b). 
Similarly, there were significant differences among storage days which reduced %TTA at 
all levels. Control fruits represented a greater percentage of TTA as compared to irradiated 
fruits. 
The reason for reduction in TTA during storage was due to the amount of organic acids 
which usually decreases during maturity. This is because organic acids are substrates for 
respiration (Wills et al.,1981) and the acids are converted into salts and sugars by enzymes 
especially invertase (Deka, 2000). 
 
University of Ghana  http://ugspace.ug.edu.gh 58 
 
4.2.12 Total Titratable Acidity (TTA) of Tomato Fruit Stored at Low Temperature 
(10±1°C) Following CaCl2 Coating. 
Table 4.2.6(b) shows the effect of CaCl2 concentration (%) on the TTA of tomato fruit 
stored at 10±1°C. Control fruits showed a decrease in %TTA and among storage days, 
there were significant differences (P≤ 0.05) in TTA (Appendix 8a and 8b). Fruits treated 
with CaCl2 showed mean TTA of 0.41% as seen in Table 4.2.6(b).  
Table 4.2.6(b) Effect of CaCl2 concentration (%) on the TTA of tomato fruit stored at 
low temperature (10±1°C). 
%Total Titratable Acidity of Tomato Fruits 
Storage Period 
(Days) 0 1.00% 1.50% 2.00% 2.50% 
Aa Fb Jb PRc TUc 
0 0.51 0.42 0.41 0.47 0.48
Bd Ge Ke Qf Tg 
5 0.28 0.45 0.44 0.41 0.49
Ch Fi Lh Pi Ui 
10 0.33 0.42 0.34 0.46 0.47
Dj Hk Jl Rm Vn 
15 0.25 0.37 0.41 0.48 0.31
Eo Ip Mo Sq Wr 
20 0.32 0.35 0.31 0.39 0.38
Es Ft Nu Ts Xt 
25 0.31 0.42 0.47 0.32 0.41
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not 
significantly (P>0.05) different from each other and means with the same letters in the same row (lower 
case, doses) are not significantly different (P>0.05) from each other.  
 
Generally, there were significant differences (P ≤ 0.05) in %TTA among CaCl2 
concentrations during storage as %TTA generally increased with increasing concentration. 
Similarly, among storage days, %TTA showed significant differences as %TTA decreased 
though not consistently. These fluctuations have also been confirmed by Senevirathna and 
Daundasekera (2010) when tomato fruits were treated with CaCl2.   
University of Ghana  http://ugspace.ug.edu.gh 59 
 
In all treatments used, fruits treated with gamma radiation showed the least mean TTA of 
0.31% throughout the study period whilst control fruits and fruit treated with CaCl2 
showed 0.33 and 0.41% respectively.  
The %TTA from fruits stored at ambient temperature was least (0.23 – 0.49%) as 
compared to those stored in the low temperature (0.26 – 0.51%). 
Fluctuations in the %TTA in all treatments used with respect to advancement in storage 
could be related to differences in maturity stage of the fruits (Kirk and Sawyer, 1997). 
This is because, as the fruit matures, pH increases which results in a corresponding 
reduction in %TTA. Therefore, %TTA of tomato was expected to reduce parallel to 
advancement in storage. Salunkhe et al. (1974) explained further that the inconsistencies 
in %TTA in tomato fruits may also be related to the acidity declining after the first 
appearance of yellow colour in normal ripening. The %TTA then starts to increase again 
but after that increase, acidity starts to decrease, probably due to disappearance of citric 
acid. 
According to Bhattacharya (2004), acidity is often used as an indication of maturity, as 
acid decreases on ripening of fruit. He reported further that during the ripening of 
tomatoes, acids such as malic and citric acid disappear which may be the main factor 
responsible for the reduction in titratable acidity during the storage. The microorganisms 
use citric acid as a carbon source, resulting in reduction in the titratable acidity. 
Comparatively, as pH increases, %TTA reduces as the acids are converted to sugars as the 
fruit ripens.  Therefore, the lower the acidity the more riped the fruit. 
 
 
University of Ghana  http://ugspace.ug.edu.gh 60 
 
4.2.13 Total Soluble Solids (%, °Brix) of Tomato Fruit Stored at Ambient 
Temperature (28±1°C) Following Irradiation. 
Table 4.2.7(a) displays effect of gamma radiation doses (kGy) on Total Soluble Solids 
(TSS) of tomato fruits stored at ambient temperature (28±1°C). Control fruits showed 
rd
significant differences in TSS as storage days advanced. TSS reduced on the 3  day and 
th
increased on the 6  day in control fruits. In irradiated fruits, TSS ranged from 4.03 - 5.00 
%.  
Table 4.2.7(a) Effect of Irradiation Dose (kGy) on Total Soluble Solids (TSS, %) of 
Tomato Fruit Stored at Ambient Temperature (28±1°C). 
Total Soluble Solids (%) of Tomato Fruits 
Storage Period 
(Days) 0 1 kGy 2 kGy 3 kGy 4 kGy 
Aa Cb Ec Gb Ib 
0 4.10 4.29 4.37 4.27 4.27
Ba Cb Ec Hd Ie 
3 3.50 4.33 4.34 4.41 4.28
Cg Cgh Egh Hgh Jgh 
6 4.00 4.30 4.27 4.40 4.40
Di Fj Gk Kl 
9 **ND 4.87 5.00 4.17 4.03
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not 
significantly (P>0.05) different from each other and means with the same letters in the same row (lower 
case, doses) are not significantly different (P>0.05) from each other.  
**ND – not determined. 
 
Tomato samples treated with gamma radiation showed no significant differences in TSS 
on days 0 and 6, however, there were significant differences on days 3 and 9. Similarly, 
there were no significant differences within each dose during storage. Fruits treated with 
gamma radiation increased in TSS from day 0 to day 9 whilst from day 3 to day 6, TSS 
reduced in fruits treated with 1, 2 and 3 kGy. On days 0 and 9, TSS increased with 
decreasing concentration radiation dose whilst on days 3 and 6, it increased with 
University of Ghana  http://ugspace.ug.edu.gh 61 
 
increasing dose. Fruits treated with gamma radiation showed the higher TSS content as 
compared to control (Table 4.2.7a). 
The increase in TSS agrees with results obtained by Salunkhe et al. (1974) who stated that 
the sugar content of tomato fruit juices increases after the first appearance of yellow 
colour in normal ripening. Also, TSS have been shown to increase during ripening then 
remain constant with over-maturity (Gautier et al., 2008). The results confirm those of 
Akter and Khan (2012), Prakash et al. (2002) that there were no significant differences in 
TSS as a result of irradiation as observed in this research. The significant changes in TSS 
in control fruits however, contradicts results by Akter and Khan (2012) in control tomato 
fruits stored at 25°C. 
 
4.2.14 Total Soluble Solids (%, °Brix) of Tomato Fruit Stored at Ambient 
Temperature (28±1°C) Following CaCl2 Coating. 
Table 4.2.7(b) shows effect of CaCl2 concentration (%) on Total Soluble Solids (TSS) of 
tomato fruit stored at ambient temperature (28±1°C). Control fruits showed between 3.50 
– 4.10 % whilst that of fruits treated with CaCl2 ranged from 3.30 - 4.17 %. 
Control fruits showed significant differences in TSS as storage days advanced and reduced 
significantly. Fruits treated with CaCl2 decreased insignificantly in TSS as storage days 
progressed. Generally, within each storage day, there were no significant differences 
among CaCl2 concentrations.   
Fruits treated with CaCl2 showed lower TSS percentages as compared to the irradiated and 
control fruits. According to Sammi and Masud (2007), the significantly low TSS contents 
in treated fruits were the result of delayed ripening by the action of CaCl2 treatment. 
 
University of Ghana  http://ugspace.ug.edu.gh 62 
 
Table 4.2.7(b) Effect of CaCl2 Concentration (%) on Total Soluble Solids (TSS, %) of 
Tomato Fruit Stored at Ambient Temperature (28±1°C). 
Total Soluble Solids (%) of Tomato Fruits 
Storage Period 
(Days) 0 1.00% 1.50% 2.00% 2.50% 
Aa Eb Hb Kb Nc 
0 4.1 4.00 4.00 4.00 4.17
Bd Ef He Kde Mf 
3 3.50 3.90 3.67 3.60 4.00
Ch Fg Ii Kj Og 
6 4.00 3.50 3.30 3.73 3.57
Dk Gk Jk Mk 
9 **ND 4.00 4.00 4.00 4.00
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not 
significantly (P>0.05) different from each other and means with the same letters in the same row (lower 
case, doses) are not significantly different (P>0.05) from each other.  
**ND – not determined. 
 
CaCl2 treatment had little or no effect on TSS content as it did not show any significant 
differences in tomato fruits, this observation agrees with reports on fruits like mango 
(Tirmazi and Wills, 1981) and strawberry (De Souza et al., 1999). 
 
4.2.15 Total Soluble Solids (%, °Brix) of Tomato Fruit Stored at Low Temperature 
(10±1°C) Following Irradiation.  
Table 4.2.8(a) shows effect of gamma radiation doses (kGy) on Total Soluble Solids (TSS, 
°Brix) of tomato fruit stored at low temperature (10±1°C). TSS of control fruits showed 
between 3.90 and 4.33 % whilst irradiated fruits were between 4.00 and 5.13 % TSS. 
Control fruits showed no significant differences in TSS during storage, however, TSS 
reduced slightly as storage progressed. Irradiated fruits showed no significant differences 
within the storage days. 
University of Ghana  http://ugspace.ug.edu.gh 63 
 
Table 4.2.8(a) Effect of Irradiation Dose (kGy) on Total Soluble Solids (TSS,  %) of 
Tomato Fruit Stored at Low Temperature (10±1°C). 
Total Soluble Solids (%) of Tomato Fruits 
Storage Period 
(Days) 0 1 kGy 2 kGy 3 kGy 4 kGy 
Aa Ca Ha La Pa 
0 4.33 4.29 4.37 4.27 4.27
Cb Cc Hc Lc Qd 
5 3.93 4.27 4.23 4.24 4.12
Be Dg Hef Mg Pf 
10 4.13  5.00 4.20 4.90 4.33
Ch Ek Ji Ni Rh 
15 4.00  4.43 5.13 5.00 4.00
Co Fo Ko Oo Ro 
20 4.00  4.00 4.00 4.00 4.00
Cm Gq Iq Or Rr 
25 3.90  4.50 4.50 4.00 4.00
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not 
significantly (P>0.05) different from each other and means with the same letters in the same row (lower 
case, doses) are not significantly different (P>0.05) from each other.  
 
Generally, during storage there were no significant differences in TSS within the doses 
throughout storage. Gamma radiation therefore did not have any effect on TSS. Similar 
results were found in tomato fruits stored at 12°C (Akter and Khan, 2012; Prakash et al., 
2002) and dragon fruits stored at 10°C (Wall and Khan, 2008).  
 
4.2.16 Total Soluble Solids (%, °Brix) of Tomato Fruit Stored at Low Temperature 
(10±1°C) CaCl2 Coating. 
Table 4.2.8(b) shows the effect of CaCl2 concentrations (%) on Total Soluble Solids (TSS) 
of tomato fruit stored at low temperature (10±1°C). Control fruits ranged between 3.90 - 
4.33 % and did not show any significant difference in TSS as storage progressed though it 
reduced slightly. Fruits treated with CaCl2 had TSS of 3.43 - 4.07% throughout storage 
period. 
University of Ghana  http://ugspace.ug.edu.gh 64 
 
Table 4.2.8(b) Effect of CaCl2 Concentrations (%) on Total Soluble Solids (TSS, %) 
of Tomato Fruit Stored at Low Temperature (10±1°C). 
Total Soluble Solids (%) of Tomato Fruits 
Storage Period 
(Days) 0 1.00% 1.50% 2.00% 2.50% 
Aa Db Gb Hb Kb 
0 4.33 4.00 4.00 4.00 4.00
Cc Dc Gc Hc Jd 
5 3.93  4.07 4.00 3.90 3.50
Be Ef Gg Hg Kg 
10 4.13  3.53 4.00 4.00 4.00
Ch Fj Gh Ii Kh 
15 4.00  3.77 4.00 3.53 4.00
Cl Fk Gl Hl Kl 
20 4.00  3.77 4.00 4.00 4.00
Cm En Gm Hn Jn 
25 3.90  3.50 3.93 4.00 3.43
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not 
significantly (P>0.05) different from each other and means with the same letters in the same row (lower 
case, doses) are not significantly different (P>0.05) from each other.  
 
Fruits treated with CaCl2 also showed no significant differences during storage among the 
concentrations. A similar trend showed within the CaCl2 concentrations of each day of 
storage, thus no significant differences were observed. 
These results agree with reports on fruits like mango (Tirmazi and Wills, 1981) and 
strawberry (De Souza et al., 1999) where CaCl2 treatment had little or no effect on TSS 
content as it did not show any significant differences. Comparing all treatments used, 
irradiated fruits displayed the highest TSS (3.90 - 5.13%) throughout storage as seen in the 
Table 4.2.8(a) followed by control fruit (3.90 - 4.33 %) whilst CaCl2 treated fruits showed 
the least (3.50 – 4.00 %). The TSS for all treatments used for fruits stored at low 
temperature ranged between 3.43 - 5.13 % which recorded the largest TSS whilst those 
stored at ambient temperature ranged from 3.30 – 5.00%. 
University of Ghana  http://ugspace.ug.edu.gh 65 
 
The total soluble solids content (TSS) shows high positive correlation with sugars content, 
and therefore is generally accepted as an important quality trait of fruits. About 50 to 65% 
of soluble solids contents are sugars (glucose and fructose) and their amounts and 
proportions influences the organoleptic quality of tomatoes (Adedeji et al., 2006). 
The TSS content in fruits is an important criterion in determining the suitability of 
varieties for processing. High TSS is desirable to yield higher recovery of processed 
products. Guold and Berry (1972) worked on tomatoes for canning and formulated that for 
varieties suitable for processing, TSS content should be more than 5%. In the results 
obtained, however, the fruits can be said to be not suitable for canning purposes because 
the TSS readings were all less than 5 % on the initial day.  
 
4.2.17 Moisture Content of Tomato Fruit Stored at Ambient Temperature (28±1°C) 
Following Irradiation. 
Fig. 4.2.9(a) shows the moisture contents of tomato fruits stored at ambient temperature 
(28±1°C) following gamma radiation of varying doses (kGy).  Control fruits ranged 
between 94.49 – 95.45 % moisture content. Irradiated tomato fruits showed between 94.62 
– 96.53 % moisture content. 
Control fruits showed no difference in moisture content on day 0 to day 3. However, % 
th
moisture content decreased significantly on the 6  day in control fruits. Generally, during 
storage, there were no significant differences in % moisture content within radiation doses. 
However, days 0 and 9 differed significantly in fruits treated with 2 and 4 kGy. 
 
University of Ghana  http://ugspace.ug.edu.gh 66 
 
 
Fig. 4.2.9(a) Effect of Irradiation Dose (kGy) on Moisture Content of Tomato Fruit Stored at Ambient 
Temperature (28±1°C).  
 
From the figure above (Fig. 4.2.9a) it can be observed that on day 0, tomato fruits 
irradiated at 2 and 4 kGy resulted in significantly higher % moisture content than those 
treated with 1 and 3 kGy both of which were different from that of control fruits. On the 
rd
3  day, tomato fruits treated at 1 kGy showed a significantly higher % moisture content 
th
than the other doses including the control. On the 6  day, irradiated tomato fruits treated at 
th
all doses did not differ from each other including control fruits. On the 9  day, tomato 
fruits treated at 1 and 2 kGy resulted in lower % moisture content than tomato fruits 
treated at 3 and 4 kGy.  
rd
The highest moisture content was recorded by 1 kGy on the 3  day whilst the least was 
shown by 2 kGy on day 9.  
University of Ghana  http://ugspace.ug.edu.gh 67 
 
4.2.18 Moisture Content of Tomato Fruit Stored at Ambient Temperature (28±1°C) 
Following CaCl2 Coating. 
Fig. 4.2.9 (b) displays effect of CaCl2 concentration on moisture content of tomato fruit 
stored at ambient temperature (28±1°C). Control fruits displayed between 94.49 – 95.45 % 
Moisture Content which was comparatively higher than that of irradiated tomato fruits 
(94.62 – 96.53 %).  
 
Fig. 4.2.9(b) Effect of CaCl2 concentration on moisture content of tomato fruit stored at ambient 
temperature (28±1°C). 
Control fruits showed no difference in moisture content between day 0 and day 3, 
th
however, % moisture content increased significantly on the 6  day. From the figure (Fig. 
4.2.9b), tomato fruits treated with 1.50 and 2.50 % CaCl2 concentration resulted in 
significantly higher % moisture content than those treated with 1.00 and 2.00 %, but did 
not differ from that of control fruits on day 0. 
University of Ghana  http://ugspace.ug.edu.gh 68 
 
rd
On the 3  day, tomato fruits treated at 1.50, 2.00 and 2.50 % CaCl2 concentration resulted 
in significantly higher % moisture content than those treated at 1.00% as well control 
th
fruits. On the 6  day, tomato fruits treated at 1.50, 2.00 and 2.50 % CaCl2 concentration 
resulted in significantly higher % moisture content and did not differ from control fruits 
th
than those treated at 1.00% concentration. On the 9  day, tomato fruits treated at 1.00% 
concentration resulted in significantly lower % moisture content than tomato fruits treated 
at 1.50, 2.00 and 2.50 % CaCl2 concentration. Tomato fruits treated at 2.00 % showed the 
highest moisture content on day 3 whilst the least was 1.00 % on day 6.  
The mean moisture content varied from 94.09 to 96.53 % and this falls within the ranges 
reported by Amanat et al. (2009) on other tomato varieties. Tomato fruits irradiated 
showed between 94.62 – 96.53 % moisture content which was comparatively higher than 
that of CaCl2 treated fruits (94.09 to 95.51 %) and control fruits (94.49 – 94.57 %). 
The use of CaCl2 interacts with pectic acid to form calcium pectate, which has a firming 
effect on cell walls (Poovaiah, 1986). This prevents the loss of moisture from fruits which 
accounted for the reduction in moisture loss of CaCl2 treated fruits. Irradiation on the other 
hand causes softening to fruits (Barka et al., 2000) and the softening gives the fruit less 
total solids.  
 
4.2.19 Moisture Content of Tomato Fruit Stored at Low Temperature (10±1°C) 
Following Irradiation. 
Fig. 4.2.10(a) shows the effect of gamma radiation doses on moisture content of tomato 
fruit stored at low temperature (10±1°C). Moisture content of control fruits ranged 
between 94.49 and 95.60 % which resulted in no significant differences during storage. 
Moisture content of irradiated fruits ranged between 94.32 - 95.97 %.  
University of Ghana  http://ugspace.ug.edu.gh 69 
 
   
     
Fig. 4.2.10(a) Effect of Radiation Dose (kGy) on Moisture Content of Tomato Fruit Stored at Low 
Temperature (10±1°C).  
 
Among radiation doses, there were no significant differences in % moisture content 
throughout the storage period. On day 0, tomato fruits treated with 3kGy gamma radiation 
showed a significant difference in % moisture content. However, 2 and 4 kGy were not 
significantly different and this was the same case for 1kGy and control fruits. On day 5, 
fruits treated with 2, 3 and 4 kGy showed no significant differences in moisture content. 
On day 10, fruits treated with 1, 2 and 3 kGy showed no significant changes and did not 
differ from 3 and 4 kGy and control fruits.  On day 15, fruits treated with 4kGy were 
significantly different from all the other treatments including the control fruits. On day 20, 
all treatments showed no significant differences. On day 25, 1 and 4 kGy were not 
significantly different. Similarly, 2 and 3 kGy and control fruits were also not different.   
University of Ghana  http://ugspace.ug.edu.gh 70 
 
4.2.20 Moisture Content of Tomato Fruit Stored at Low Temperature (10±1°C) 
Following CaCl2 Coating. 
Fig. 4.2.10(b) depicts the effect of CaCl2 concentration on the moisture content of tomato 
fruit stored at 10±1°C over a period of 25 days. Control fruits ranged between 94.49 to 
95.60 % moisture content. Moisture content for CaCl2 treated fruits ranged from 94.16 and 
95.85 %. Generally, during storage, no significant differences resulted in control fruits. All 
fruits treated with of calcium chloride did not show any significant difference in % 
moisture content of tomato fruits during storage. 
On day 0, fruits treated with 1.00, 2.00 and 2.50 % CaCl2 concentration resulted in no 
significant differences but all were different from the control and 1.50% treated fruits. On 
day 5, all treatments showed significant differences. Day 10 resulted in no significant 
differences in all treatments. On day 15, fruits treated with 1.00, 1.50 and 2.00 % CaCl2 
concentrations were the same whilst 2.50% and control fruits were not significantly 
different. However, 1.50% treated fruits were not significantly different from 2.50% and 
the control fruits. On day 20, all fruits subjected CaCl2 treatment were not significantly 
different from each other. Day 25 resulted in no significant differences in 1.00, 1.50 and 
2.50 % CaCl2 concentration. However, control fruits did not differ from fruits treated with 
2.00 % on day 20 and 25. CaCl2 application on tomato fruits therefore did not show any 
effect on % moisture content during storage. 
University of Ghana  http://ugspace.ug.edu.gh 71 
 
 
Fig. 4.2.10(b) Effect of CaCl2 Concentration on Moisture Content of Tomato Fruit Stored at Low 
Temperature (10±1°C). 
 
Generally, % moisture was greater in irradiated fruits (94.14 – 95.85 %) than CaCl2 treated 
fruits (94.32 – 95.97 %) and control (94.49 – 95.60 %). Irradiation causes softening to 
fruits as a result of biochemical processes like cell wall enzyme and membrane damage 
(Barka et al., 2000) which gives the fruit a greater moisture content and a lesser amount of 
total solids. On the other hand, the use CaCl2 has a firming effect on cell walls (Poovaiah, 
1986). This prevents the loss of moisture from fruits which accounted for the high content 
in total solids of CaCl2 treated fruits. High total solids is a desirable characteristic for the 
canned tomato industry since it improves the quality of the processed product and 
consequently reduces processing cost (DePascale et al., 2001).  
Among storage conditions, % moisture content was greater at ambient temperature than 
low temperature storage due to the minimal ripening of fruits upon exposure of to low 
temperature. This has been confirmed by Shewfelt et al., (1986) and De Castro et al., 
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(2005) that for longer period, ripe tomato can be stored at a temperature of 10-15°C as 
chilling injury and ripening are minimal. 
The quality of most fruits and vegetables is affected by water loss during storage, which 
depends on the temperature and relative humidity conditions (Perez et al., 2003). 
Irradiation did not have any significant effect on the moisture content among storage days. 
Yaman and Bayoindril (2002) reported the changes in firmness diffusion driven by a 
gradient of water vapour pressure at different locations as the reason for primary 
mechanism of moisture loss from fresh fruits and vegetables. 
 
 
 
 
 
 
 
 
 
 
 
 
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4.3 NUTRITIONAL CONTENT OF BURKINA TOMATO FRUITS FOLLOWING 
GAMMA RADIATION AND CaCl2 COATING. 
4.3.1 Vitamin C Content of Tomato Fruits Stored at Ambient Temperature (28±1°C) 
Following Irradiation.  
Fig. 4.3.1(a) displays effect of irradiation dose on vitamin C content of tomato fruit stored 
at ambient temperature (28±1°C). From the figure, it can be observed that vitamin C 
content in control fruits ranged from 19.11 – 19.80 mg/100 g whilst that of irradiated fruits 
ranged from 8.65 to 15.24 mg/100g. 
 
Fig. 4.3.1(a) Effect of irradiation dose on vitamin C content of tomato fruits stored at ambient 
temperature (28±1°C).  
 
rd
Vitamin C content of fruits in the control set increased on the 3  day from 19.11 to 19.80 
th
mg/100g but decreased on the 6  day. The same result has been shown by Pamplona-
Roger (2003) who found out that the vitamin C level for tomato is 19.10mg/100g. The 
University of Ghana  http://ugspace.ug.edu.gh 74 
 
initial increase in vitamin C in control fruit is due to an increase in vitamin C during 
ripening then a decrease during senescence (Selvaraj et al., 1982, Lazan et al. 1990). 
Vitamin C content of irradiated fruits ranged between 8.65 to 15.24 mg/100g as seen in 
Fig. 4.3.1(a) above. There were no significant differences in vitamin C content among all 
doses used on days 0 and 3. Similarly, on days 6 and 9, vitamin C content for 1 and 2 kGy 
did not differ. However, there were significant differences in vitamin C content of fruits 
irradiated at 3 and 4 kGy.  
Unlike fruits in the control set, irradiation caused a decrease in vitamin C of tomato fruit 
as depicted in Fig. 4.3.1(a). However, fruits in the control set increased in vitamin C 
rd th
content on the 3  day but reduced significantly on the 6  day though the amount of 
vitamin C was not significantly different from that of the initial day. Generally, all the 
radiation treatments used significantly (p < 0.05) decreased vitamin C content of tomato 
fruits. However, vitamin C content of fruits in the control set was significantly higher than 
irradiated fruits. This was expected because vitamin C is sensitive to oxidation but gamma 
radiation causes water radiolysis of tomato juice producing free radicals which are strong 
oxidizing agent (Variyar et al., 2004). During storage, Fig. 4.3.1(a) illustrated that vitamin 
C content of irradiated tomato fruits significantly decreased (p < 0.05) but at different 
levels among various treatments. 
 
4.3.2 Vitamin C Content of Tomato Fruits Stored at Ambient Temperature (28±1°C) 
Following CaCl2 Coating.  
Fig. 4.3.1 (b) displays the effect of CaCl2 concentration on the vitamin C content of tomato 
fruit stored at ambient temperature (28±1°C) for 9 days. Control fruit ranged from 19.11 – 
University of Ghana  http://ugspace.ug.edu.gh 75 
 
19.80 mg/100 g vitamin C. For fruits treated with CaCl2, vitamin C content ranging from 
14.79 to 23.21 mg/100 g as depicted in Fig. 4.3.1 (b). 
 
Fig. 4.3.1 (b) Effect of CaCl2 concentration on the vitamin C content of tomato fruits stored at ambient 
temperature (28±1°C).  
 
For all concentrations of CaCl2 applied, vitamin C content of the fruits increased from day 
0 to day 3 but reduced gradually though not significantly by the final day. Vitamin C 
content of fruits in the control set was highest (19.11 mg/100 g) at the onset of the storage 
but dropped slightly with storage period, though not significantly. This initial value was 
statistically higher than values recorded for fruits subjected to the various concentrations 
of CaCl2 coating tested. However, fruits subjected to 2.00 and 2.50 % CaCl2 coating 
recorded significantly higher levels of vitamin C compared to the control and lower levels 
rd th
of CaCl2 coating by the 3  and 6  day of storage. The use of CaCl2 coating appears to 
have stimulated vitamin C production in the fruits but this waned with storage time.  
University of Ghana  http://ugspace.ug.edu.gh 76 
 
The results agree with those obtained by Sammi and Masud (2007) who stated that fruits 
treated with calcium chloride showed the highest vitamin C content. The slowing down of 
vitamin loss in CaCl2 treated fruits is attributed to the low oxygen permeability of the 
coating film formed on the surface of the fruit (Ayranci and Tune, 2003).  
On the whole, vitamin C content of the tomato fruit used ranged from 8.65 to 23.21 
mg/100 g fruit and this falls outside the range obtained by Grierson and Kader (1986) who 
observed that the vitamin C content of ripe tomato ranges from 15 to 23 mg/100 g fruit. It 
must, however, be noted that the content of vitamin C in tomato could vary according to 
the variety of tomato, plant origin, condition of planting, harvesting, and maturity stage of 
the fruit among others.  
 
4.3.3 Vitamin C Content of Tomato Fruits Stored at Low Temperature (10±1°C) 
Following Irradiation.  
Fig. 4.3.2(a) shows the effect of irradiation dose on vitamin C content of tomato fruit 
stored at low temperature (10±1°C) for 25 days. Control fruits recorded between 9.33 – 
22.07 mg/100g vitamin C content throughout the storage period. Vitamin C content of 
irradiated fruits ranged between 7.85 – 20.25 mg/100 g. 
Generally, vitamin C reduced significantly in control fruits during storage though there 
th
was an increase on the 5  day of storage. Vitamin C content of irradiated tomato fruit 
ranged between 7.85 – 20.25 mg/100g. Similar results were obtained by Purkayastha and 
Mahanta (2010) who also found out that the vitamin C levels in five tomato cultivars 
ranged from 12.68 mg/100 g - 21.54 mg/100g. 
University of Ghana  http://ugspace.ug.edu.gh 77 
 
 
Fig. 4.3.2(a) Effect of irradiation dose on vitamin C content of tomato fruits stored at low temperature 
(10±1°C).  
 
After day 0, vitamin C increased significantly in all doses used but then decreased 
gradually throughout the storage period. The initial increase in vitamin C can be related to 
ongoing ripening process in the fruits after which vitamin C content started to decline 
(Selvaraj et al., 1982).  
The eventual decrease in vitamin C during storage with advancement of storage period 
was probably due to the sensitivity of vitamin C to oxygen, light and heat as well as being 
easily oxidized in the presence of oxygen by both enzymatic and non-enzymatic catalysts 
of oxidation process in tomato (Mapson, 1970; Moore et al., 1995). 
 
 
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4.3.4 Vitamin C Content of Tomato Fruits Stored at Low Temperature (10±1°C) 
following CaCl2 Coating.  
Fig. 4.3.2(b) shows effect of CaCl2 concentration on the vitamin C content of tomato fruit 
stored at 10±1°C. Vitamin C content of fruits treated with CaCl2 ranged from 10.47 – 
23.66 mg/100g and 9.33 – 22.07 mg/100g in fruits in the control set.  
 
Fig. 4.3.2(b) Effect of CaCl2 concentration on the vitamin C content of tomato fruits stored at low 
temperature (10±1°C).  
 
Generally, all fruits decreased in vitamin C significantly by the final day of analysis as 
compared to the vitamin C content on day 0 at 50.00, 5.07, 17.58 and 15.79 % in control 
fruits and fruits treated at 1.00, 2.00, and 2.50 % CaCl2 concentrations respectively. It was 
clear that the percentage loss of vitamin C content during storage of samples treated with 
CaCl2 was much lower than that of samples in the control group. However, after the initial 
day, vitamin C increased significantly in all CaCl2 concentrations used except for 2.50 % 
University of Ghana  http://ugspace.ug.edu.gh 79 
 
which increased after day 10. The increase in vitamin C content in CaCl2 treated fruits 
could probably be due to the slowing down of the ripening process by CaCl2, hence 
keeping vitamin C out of the oxidation that occurs during normal ripening. Generally, the 
different levels of CaCl2 concentrations used did not cause any significant changes in the 
vitamin C content of tomato fruits including control samples throughout the storage 
period. 
Comparatively, fruits treated with radiation showed the least vitamin C content (7.85 – 
20.25 mg/100g) as compared to fruits treated with CaCl2 (10.47 – 23.66 mg/100g) and 
control fruits (9.33 – 22.07 mg/100g).  
In all treatments used and at both storage temperatures, vitamin C content reduced with 
the advancement of storage days and this could be attributed to its sensitivity to oxygen, 
light and heat (Moore et al., 1995). All fruits treated with CaCl2 showed the higher vitamin 
C content under all storage conditions as compared to the other treatments used. The use 
of CaCl2 in fruits leads to the favourable effect of reduction of antioxidants such as vitamin 
C loss in horticultural commodities such as strawberries (Luna-Guzman and Barrett, 2000) 
and an increase in vitamin C content in CaCl2 treated fruits like pineapples and guavas 
(Mohammed et al., 1993) and papayas (Poovaiah, 1986). Loss of ascorbic acid in radiated 
fruits and vegetables could be due to irradiation-induced oxidation of ascorbic acid to 
dehydroascorbic acid (Fan and Sommers, 2013). 
Preservation of vitamin C content during storage is a difficult task since it undergoes 
oxidation. The presence of higher oxygen concentrations in the storage atmosphere 
hastens this process (Okolie and Sannie, 2012). However in the present investigation, the 
ascorbic acid content of fruits was significantly influenced by various post - harvest 
treatments and storage conditions.  
University of Ghana  http://ugspace.ug.edu.gh 80 
 
4.3.5 Lycopene Content of Tomato Fruits Stored at Ambient Temperature (28±1°C) 
Following Irradiation.  
Fig. 4.3.3(a) displays effect of irradiation dose on lycopene contents of tomato fruits 
stored at ambient temperature (28±1°C) for 9 days. . Lycopene content of irradiated fruits 
ranged between 15.10 and 71.01 mg/kg whiles control fruits ranged between 55.85 and 
115.63 mg/kg. 
 
Fig. 4.3.3(a) Effect of irradiation dose on lycopene content of tomato fruits stored at ambient 
temperature (28±1°C).  
 
Lycopene content was highest in control fruits but decreased significantly throughout the 
storage period. Similarly, lycopene content reduced in all doses as storage days 
progressed. In each radiation dose used, days 0 and 3 did not differ significantly in 
lycopene content. In like manner, days 6 and 9 were also not significantly different from 
each other in all doses except for fruits irradiated with 1kGy.  
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Generally, among storage days, lycopene content in tomato fruits at all doses did not differ 
significantly. The results indicated that gamma radiation at doses of 1, 2, 3 and 4 kGy did 
not show significant effect on the total lycopene content in tomato. These results confirm 
that of Youssef et al., (2011) that gamma irradiation at doses of 1.5, 3.0 and 4.5 kGy did 
not have any significant effect on the total lycopene content in tomato juice. However, in a 
few cases there were significant differences and this may be related to the maturity 
differences of the fruit (Kirk and Sawyer, 1997).  
On the whole, irradiated fruits showed lower reduction in lycopene content than control 
fruits. 
  
4.3.6 Lycopene Content of Tomato Fruits Stored at Ambient Temperature (28±1°C) 
Following CaCl2 Coating. 
Fig. 4.3.3(b) shows effect of CaCl2 concentration on the lycopene content of tomato fruit 
stored at ambient temperature (28±1°C) for 9 days. Lycopene content in CaCl2 treated 
samples ranged between 38.56 and 125.45 mg/kg whiles that of control fruits ranged 
between 55.85 and 115.63 mg/kg. 
Generally, changes in lycopene content at the end of the storage period were proportional 
th
to the CaCl2 concentration used. By the 9  day, lycopene had reduced significantly by 
53.31, 55.72, 59.53 and 57.51 % for fruits treated with 1.00, 1.50, 2.00 and 2.50 % CaCl2 
concentrations respectively. Lycopene content of fruits in the control set ranged between 
55.85 and 115.63 mg/kg showing a significant decrease (51.70 %) throughout the 6 days 
of storage which was higher compared to 40.60, 41.64, 20.88 and 30.73 % for fruits 
treated with 1.00, 1.50, 2.00 and 2.50 % CaCl2 concentrations respectively. 
 
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Fig. 4.3.3(b) Effect of CaCl2 concentration on the lycopene content of tomato fruit stored at ambient 
temperature (28±1°C).  
 
Generally, there were significant differences in lycopene content as storage days 
progressed within the different CaCl2 concentrations used. In contrast, within each storage 
day, lycopene content did not show any significant difference in all CaCl2 concentration.  
Lycopene content of irradiated fruits ranged between 15.10 – 71.01 mg/kg as depicted in 
Fig. 4.3.3(a) whilst CaCl2 treated samples showed between 38.56 – 125.45 mg/kg (Fig. 
4.3.3b). Control fruits ranged between 55.85 – 115.63 mg/kg. It is clear that lycopene 
content was high in CaCl2 treated samples than control and irradiated fruits. The lycopene 
content in all treatment used falls within the results obtained by Quartey (2010) for tomato 
lines ranging from 148 – 0.6 mg/kg. The use of CaCl2 was able to reduce loss of lycopene 
in tomato fruits because CaCl2 prevents the loss of antioxidants in fruits as a result of low 
permeability of oxygen of the coating formed on the fruit surface (Luna-Guzman and 
Barrett, 2000). 
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4.3.7 Lycopene Content of Tomato Fruits Stored at Low Temperature (10±1°C) 
Following Irradiation.  
Fig. 4.3.4(a) depicts the effect of irradiation dose on vitamin C content of tomato fruit 
stored at low temperature (10±1°C) for 25 days. Lycopene content in control fruits ranged 
from 30.07 – 86.20 mg/kg whiles irradiated fruits also ranged from 24.44 – 99.92 mg/kg 
in lycopene content. 
 
Fig. 4.3.4(a) Effect of Irradiation Dose on Lycopene Content of Tomato Fruit Stored at Low 
Temperature (10±1°C).  
 
Generally, there were no significant differences in lycopene content in control fruits 
during storage except for days 15 and 25. Fruits treated with 1 and 4 kGy showed no 
significant difference except in a few cases which differed. However, fruits treated with 2 
and 3 kGy differed significantly during storage. Among the storage days, lycopene content 
was at par with each other among the doses used. 
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Lycopene content had reduced significantly by 50.45, 51.75, 61.29, 79.15 and 55.76 % in 
0, 1, 2, 3 and 4 kGy by the final day. Therefore, loss of lycopene content was generally 
proportional to the dose used. Loss of lycopene in control fruits was lower than in 
irradiated fruits and this result contradicts result by Youssef et al. (2011) who stated that 
loss in total lycopene content of irradiated tomato samples was lower than non irradiated 
samples.  
 
4.3.8 Lycopene Content of Tomato Fruits Stored at Low Temperature (10±1°C) 
Following CaCl2 Coating.  
Fig. 4.3.4(b) shows effect of CaCl2 concentration on the lycopene content of tomato fruit 
stored at low temperature (10±1°C) for 25 days. Control fruits recorded 30.07 and 86.20 
mg/kg lycopene content with about 50.45% reduction on the final day. Fruits treated with 
CaCl2 ranged between 51.71 and 97.03 mg/kg lycopene content. 
At 1.00, 1.50 and 2.00 % CaCl2 concentration, lycopene content showed no significant 
differences as storage progressed. Generally, lycopene content in all doses did not differ 
significantly from each other within each storage day except for day 0. 
th
However, by the 25  day, all concentrations used reduced by 14.93, 42.62, 35.95 and 
37.27 % in 1.00, 1.50, 2.00 and 2.50 % respectively. It was clear that reduction in 
lycopene content was greater in control fruits (50.45%) than in samples treated with CaCl2. 
However, lycopene content was greater in fruits treated with CaCl2 than control fruits as 
seen in Fig. 4.3.4(b).   
 
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Fig. 4.3.4(b) Effect of CaCl2 Concentration on the Lycopene Content of Tomato Fruit Stored at Low 
Temperature (10±1°C).  
 
Comparatively, fruits treated with CaCl2 effectively maintained lycopene content (51.71 – 
97.03 mg/kg) as seen in Fig. 4.3.4(b) compared to irradiated fruits which reduced 
significantly from 99.92 - 24.44 mg/kg (Fig. 4.3.4a) and control fruits (30.07 – 86.20 
mg/kg) which also reduced. However, the highest lycopene content was redored by 3kGy 
irradiated fruits on the initial day. The use of CaCl2 produces a low oxygen permeability 
coating on the surface of the fruit which prevents loss of antioxidants (Luna-Guzman and 
Barrett, 2000). This was earlier noted by Subbiah and Perumal (1990) who stated that 
calcium chloride increases the lycopene contents in tomatoes. 
Decrease in lycopene content with time may be related to lycopene degradation as a result 
of storage (Nguyen and Schwartz, 1999). The main causes of lycopene degradation are 
isomerization and oxidation. The reversible isomerization of all-trans-lycopene to less 
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coloured, more oxidizable cis isomers is the first stage of lycopene degradation (Boskovic, 
1979).  
Generally, all samples stored at low temperature showed higher lycopene content than 
those in ambient temperature. This is because lycopene is sensitive to light, heat and 
oxygen (Nguyen & Schwartz, 1999) and since at ambient temperature the fruit is exposed 
to these elements more readily than those kept in refrigerator at low temperature, loss in 
lycopene would be greater at ambient temperature.  
 
4.3.9 Effect of Irradiation (kGy) on Elemental Composition of Tomato Fruits Stored 
at Ambient Temperature (28±1°C) for 9 days. 
Table 4.3.1a depicts the elemental composition (Na, K, Zn, Cu and Mn) of irradiated 
tomato fruits stored at ambient temperature and observed on the initial and final days 
(after 9 days of storage) of the study. In general, Na, K, Zn, and Cu concentrations in the 
fruits decreased with time over the storage period while that of Mn increased across 
irradiation doses. Na contents reduced by 93, 97, 87 and 86 % for 1, 2, 3 and 4 kGy 
respectively and 97 % for the control over the nine day storage period. Similarly, K 
concentration in the fruits reduced by 35, 29, 10 and 30 % for 1, 2, 3 and 4 kGy 
respectively and 44% for the control over the storage period. In like manner, Zn 
concentration in the fruits decreased by 23, 24, 18 and 19 % for 1, 2, 3 and 4 kGy 
respectively and 46% for the control and irradiation doses 1, 2, 3 and 4 kGy respectively 
over the storage period. Also the concentration of Cu in the tomato fruits reduced by 7, 67, 
65 % for 1, 3 and 4 kGy respectively and 97 % for the control. However, 2kGy treated 
fruits increased by 12%. By contrast, the concentration on Mn in the tomato fruits 
University of Ghana  http://ugspace.ug.edu.gh 87 
 
increased by 44, 4, 18 % for 2, 3 and 4 kGy respectively and 57 % for the control while it 
decreased by 5.83% for irradiation dose 1 kGy the over storage period. 
The composition of Zn, Cu and Mn in irradiated tomato fruits showed the lower content as 
seen in table 4.3.1(a) as compared to Na and K. Zn element was the least composition in 
tomato fruits ranging from 0.37 – 1.07 mg/kg whilst Cu and Mn ranged from 3.33 – 14.58 
mg/kg and 2.03 – 2.87 mg/kg respectively. The greatest reduction in elemental 
composition was observed in Cu and Na by 97% in control fruits over a nine day storage 
period. On the other hand, control fruits illicited the highest increase in Mn element by 
57% over the storage period.  
 
Na concentration in radiated tomato ranged from 2.67 – 118 mg/kg throughout the storage 
 
period whilst K ranged between 1881.67 and 3696.67 mg/kg. These results confirm those 
  
obtained by Quartey (2010) where Na and K content in tomato were 170.77 and 32600 
mg/kg respectively. The results for Cu also confirm that obtained by Quartey (2010) 
which ranged from 2.39 – 21.89 mg/kg.   
 
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Table 4.3.5(a) Effect of radiation dose (kGy) on the elemental composition of tomato fruits stored at ambient temperature (28±1°C) for 9 
days. 
  Na (mg/kg) K (mg/kg) Zn (mg/kg) Cu (mg/kg) Mn (mg/kg) 
GAMMA 
RADIATION 
DOSES (kGy) INITIAL FINAL INITIAL FINAL INITIAL FINAL INITIAL FINAL INITIAL FINAL 
0 102.67Aa 3.00Eb 2298.33Aa 1292.33Ab 0.87Aa 0.47Ab 4.82ABa 0.13Ab 0.47Aa 1.10Ab 
1 116.33Bc 8.33Fd 2888.33Bc 1881.67Bd 0.66Bc 0.51Bd 5.71Bc 4.55Bd 2.06Bc 1.94Bc 
2 103.00Ae 2.67Ef 3516.67Ce 2511.67Cf 0.37Ce 0.49Ce 1.11Ae 3.33Cf 1.30Cd 2.34Be 
3 108.67Cg 14.67Gh 3271.67Dg 2928.33Dh 0.77ABf 0.63Dg 14.58Cg 5.13Dh 1.94Bf 2.03Bf 
4 118.67Dj 16.67Hi 3696.67Ej 2598.67Ei 1.07Dh 0.87Eh 1.91ABi 1.77Ej 2.87Dg 3.50Cg 
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not significantly (P>0.05) different from each other and means with the 
same letters in the same row (lower case, doses) are not significantly different (P>0.05) from each other.  
 
 
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4.3.10 Effect of CaCl2 Concentration (%) on Elemental Composition of Tomato 
Fruits Stored at Ambient Temperature (28±1°C) for 9 days. 
Table 4.3.2(b) shows the concentrations of Na, K, Zn, Cu and Mn elements in tomato 
fruits treated with CaCl2 at different concentrations and stored at ambient temperature  
 
for analysis on the initial and final days (9 day storage period).  K showed the higher 
concentration in tomato (1281.00 - 3503.33 mg/kg). Generally, there were no significant 
differences among treatment concentrations on both the initial and final days including 
 
control fruits. However, storage caused a significant reduction in K concentration by 44, 
63, 30, 43 and 52 % for the control and CaCl2 concentrations of 1.00, 1.50, 2.00 and 
 
2.50 % respectively over the storage period. Na concentration reduced significantly on 
the final day and also varied significantly among treatment levels as in Table 4.3.2(b). 
Na reduced by 97, 56, 48, 40 and 56 % for the control and CaCl2 concentrations of 1.00, 
1.50, 2.00 and 2.50 % respectively over the storage period. Generally, the concentration 
of Zn reduced significantly for all concentrations by 46, 45, 63 and 7 % for the control 
and for the control and CaCl2 concentrations of 1.00, 1.50 and 2.00 % respectively over 
the storage period, however, at 2.50%, Zn concentration increased by only 6%. In like 
manner, Cu concentration reduced significantly by 97, 32, 54 and 12 % for the control 
and CaCl2 concentrations of 1.00, 1.50, 2.00 and 2.50 % respectively over the storage 
period but increased by 7% at 2.50%. Mn concentration reduced by 6, 63 and 11 % for 
CaCl2 concentrations of 1.00, 1.50 and 2.00 % respectively over the storage period but 
increased by 57 and 30 % for control and 2.50%. 
The greatest reduction in elemental composition was recorded in Na (97%) in control 
fruits over the nine day storage period. On the other hand, control fruits recorded the 
largest increase in Mn element by 57% over the storage period.  
 
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Table 4.3.5(b) Effect of CaCl2 Concentration (%) on the elemental composition of tomato fruits stored at ambient temperature (28±1°C) for 
9 days. 
 Na (mg/kg) K (mg/kg) Zn (mg/kg) Cu (mg/kg) Mn (mg/kg) 
CaCl2 
CONCENTRATIONS 
(%) INITIAL FINAL INITIAL FINAL INITIAL FINAL INITIAL FINAL INITIAL FINAL 
0 102.67Aa 3.00Fb 2298.33Aa 1292.33Db 0.87Ca 0.47Ab 4.82Aa 0.13Ab 0.47Ba 1.10Db 
1.00 55.97Bc 24.43Gd 3460.00Bc 1281.00Dd 2.05Bc 1.13BCd 4.47Ac 3.05Bd 5.27Ac 4.97ABd 
1.50 47.77Ce 24.87Hf 2386.67Ae 1676.33Ef 1.87Ae 0.70ABf 4.49Ae 2.06Cf 5.29Af 1.94Ce 
2.00 48.87Dg 29.20Ih 2726.33Cg 1566.33Fh 1.49Dg 1.39Ch 3.78Bh 3.33Dg 5.39Ah 4.79Ag 
2.50 60.80Ei 26.33Jj 3503.33Bi 1693.33Ej 1.97ABi 2.10Dj 4.57Aj 4.91Ei 3.73Cj 5.33Bi 
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not significantly (P>0.05) different from each other and means with the same 
letters in the same row (lower case, doses) are not significantly different (P>0.05) from each other.  
 
 
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4.3.11 Effect of Irradiation dose (kGy) on Elemental Composition of Tomato Fruits 
Stored at Low Temperature (10±1°C) for 25 days. 
Table 4.3.2(a) depicts the elemental composition (Na, K, Zn, Cu and Mn) of radiated 
 
fruits stored at 10±1°C for 25 days and analysed day 0 and day 25. K showed the higher 
mean content of 2997 mg/kg. At 0 and 1 kGy, K concentration increased by 16 and 20 
% whilst decreasing insignificantly by 14, 21 and 12 % at 2, 3 and 4 kGy on the final 
  
day. Among the doses used, there were significant differences (p<0.05) in K content on 
both the initial and final days. Generally, K increased with increasing dose. Gamma 
 
radiation therefore significantly affected concentration of K. Na concentration was 
between 16 and 118 mg/kg and decreased significantly by 84, 68, 64, 85 and 79 % for 
the control fruits and irradiation doses of 1, 2, 3 and 4 kGy respectively over storage 
period. 
Zn content ranged between 0.37 and 1.51 mg/kg whilst Cu and Mn ranged from 1.06 – 
14.58 and 0.47 – 2.90 mg/kg respectively throughout the storage period. Zn content 
increased significantly at 37, 41, 76 and 9 % for the control fruits and irradiation doses 
of 1, 2 and 3 kGy respectively but decreased at 20% for fruits treated with irradiation 
dose of 4kGy. In contrast, Cu content decreased significantly by 76, 81, 79 % for the 
control fruits and irradiation doses of 1 and 3 kGy respectively but increased at 38 and 
51 % for irradiation doses of 2 and 4 kGy respectively. Mn also decreased by 32 and 3 
% for irradiation doses 1 and 4 kGy respectively while increasing by 84, 69 and 3 % for 
control and irradiation doses 2 and 3 kGy respectively. Storage period generally 
affected concentrations of Zn, Na, K, Mn and Cu significantly.  
The greatest reduction in elemental composition was observed in Na by 85% at 3 kGy 
irradiation dose. On the other hand, control fruits illicited the largest increase in Mn 
element by 84% over the storage period.  
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Table 4.3.6(a) Effect of irradiation doses (kGy) on the elemental composition of tomato fruit stored at low temperature (10±1°C) for 25 days. 
 Na (mg/kg) K (mg/kg) Zn (mg/kg) Cu (mg/kg) Mn (mg/kg) 
GAMMA 
RADIATION 
DOSES (kGy) INITIAL FINAL INITIAL FINAL INITIAL FINAL INITIAL FINAL INITIAL FINAL 
0 102.67Aa 16.00Ab 2298.33Aa 2750.00Ab 0.87Aa 1.37Ab 4.82ABa 1.18Ab 0.47Aa 2.90Ab 
1 116.33Bc 37.33Bc 2888.33Bc 3620.33Bc 0.66Bc 1.11Bd 5.71Bd 1.06Bc 2.06Bc 1.41Bd 
2 103.00Ae 37.00Bd 3516.67Ce 3029.67Cd 0.37Ce 1.51Af 1.11Ae 1.79Cf 1.30Ce 4.20Cf 
3 108.67Cg 16.00Af 3271.67Dg 2590.00De 0.77ABg 0.85Ch 14.58Ch 3.10Dg 1.94Ag 2.62Bh 
4 118.67Dj 25.33Dg 3696.67Ej 3268.33Ef 1.07Di 0.86Cj 1.91ABi 3.92Ej 2.87Di 2.78ABi 
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not significantly (P>0.05) different from each other and means with the same letters in 
the same row (lower case, doses) are not significantly different (P>0.05) from each other.  
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4.3.12 Effect of CaCl2 Concentrations (%) on the Elemental Composition of 
Tomato Fruit Stored at Low Temperature (10±1°C) for 25 days. 
Table 4.3.2 (b) shows the concentrations of Na, K, Zn, Cu and Mn in tomato fruits 
 
treated with CaCl2 at different concentrations and stored at 10±1°C. K recorded the 
largest mean of 2761mg/kg in treated fruits whilst fruits in the control set showed 
2524 mg/kg. K concentration decreased significantly by 27 and 35 % for 2.00 and 
2.50 % CaCl2 concentrations respectively while increasing by 16, 2 and 8 % for the 
control fruits and 1.00 and 1.50 % CaCl2 concentration respectively. On day 25 and 0 
  
day, there were significant differences in K and Na concentrations respectively at all 
levels of CaCl2. Na concentration reduced significantly in all concentrations by 84, 
23, 40, 38 % of 1.00, 1.50, 2.00 and 2.50 % respectively and 13 % for the control 
and CaCl2 concentrations.   
Zn concentration in tomato fruits reduced by 46, 14 and 8 % for the control and 
CaCl2 concentrations of 1.00 and 1.50 % respectively but increased by 35 and 18 % 
of 2.00 and 2.50 % CaCl2 concentrations respectively over the storage period. In 
contrast, Cu content reduced significantly in all concentrations by 97, 20, 40, 8 and 
19 % in the control and 1.00, 1.50, 2.00 and 2.50 % CaCl2 concentrations 
respectively. In like manner, Mn reduced significantly by 57, 49, 40 and 22 % for the 
control and 1.00, 1.50 and 2.00 % CaCl2 concentrations respectively but increased by 
21% at 2.50% CaCl2 concentration over the storage period. 
Generally, from the study, fruits treated with radiation and control fruits showed a 
greater loss in the elements studied than those treated with CaCl2. Also, fruits stored 
at ambient temperature showed greater loss of the elements than those stored in low 
temperature.  
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Table 4.3.6(b) Effect of CaCl2 concentrations (%) on the elemental composition of tomato fruit stored at low temperature (10±1°C) for 25 days. 
 Na (mg/kg) K (mg/kg) Zn (mg/kg) Cu (mg/kg) Mn (mg/kg) 
CaCl2 
CONCENTRATIONS (%) INITIAL FINAL INITIAL FINAL INITIAL FINAL INITIAL FINAL INITIAL FINAL 
0 102.67Aa 16.00Ab 2298.33Aa 2750.00Ab 0.87Ca 0.47Ab 4.82Aa 0.13Ab 0.47Ba 1.10Db 
1.00 55.97Bc 43.33Bd 3460.00Bc 3520.00Bd 2.05Ba 1.76Aa 4.47Aa 3.57Ab 5.27Aa 2.69Bb 
1.50 47.77Ce 28.67Cf 2386.67Ae 2602.00Cf 1.87Aa 1.74Aa 4.49Aa 2.71Bb 5.29Aa 3.17Cb 
2.00 48.87Dg 30.33Ch 2726.33Cg 2002.33Dh 1.49Da 2.28Bb 3.78Bb 3.47Ab 5.39Aa 4.18Db 
2.50 60.80Ei 52.67Dj 3503.33Bi 2278.67Ej 1.97ABa 2.39Bb 4.57Aa 3.71Ab 3.73Ca 4.73Eb 
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are not significantly (P>0.05) different from each other and means with the same letters in the 
same row (lower case, doses) are not significantly different (P>0.05) from each other. 
 
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The mineral content of tomatoes is important for both the conservation and the 
nutritional value of the product. The major mineral element studied in this research 
include Potassium and Sodium. Potassium is a major intracellular cation in the human 
body and it facilitates the transmission of nerve impulses. Its deficiency causes nerve 
irritability, cardiac and mental disorder, muscular weakness and paralysis. Sodium is a 
primary extra–cellular cation in humans. Sodium together with Potassium are 
electrolytes that maintain normal fluid balance inside and outside cells and a proper 
balance of acids and bases in the body. Deficiency of this element may result in 
muscle cramp and hypertension (Adotey et al., 2009).  
Trace metals play an essential biological role in plant and human metabolism. Trace 
metals like Cu, and Mn together with Fe are considered as essential elements for 
normal life processes. Copper and zinc are activators and coenzymes and are 
considered as good source of protein (Durdana et al., 2007). Dara, (1993) stated that 
the recommended daily dietary intake of Zn and Cu is about 15 and 2 - 3 mg 
respectively. From this research, Zn ranged between 0.37 and 1.51 mg/kg which 
shows that tomato when included in ones diet can contribute to providing about 10 - 
40% of the recommended daily intake when the fruit is taken with other food items. 
Ingestion of 15-75 mg of copper causes gastrointestinal disorders. From the study, it 
could be seen that Cu ranged between 0.13 -14.58 mg/kg which is within the 
acceptable range of Cu consumption by humans. 
Magnesium is an essential element and its main functions in the body include bone 
mineralization, building of proteins and maintenance of teeth. A daily dietary intake 
of 2.5 to 5 mg of manganese by human contributes to the well being of the cells 
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(Dara, 1993). The result obtained in this research revealed a concentration of 0.47 – 
3.50 mg/kg Mn in all the treatments which is within the range of daily dietary intake.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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4.4 MICROBIAL LOAD OF BURKINA TOMATO FRUITS FOLLOWING 
GAMMA RADIATION AND CaCl2 COATING. 
4.4.1 Total Aerobic Mesophilic Bacteria Count (log cfu/ml) of Tomato Fruit at 
Ambient Temperature (28°C±1) Storage Following Irradiation. 
Table 4.4.1a shows counts of total aerobic mesophiles bacteria on irradiated tomato 
stored for 9 days at ambient temperature. Fruits irradiated at 1, 2, 3 and 4 kGy showed 
no or below detectable count (<10 cfu/ml) through days 0 – 3 whiles control fruits 
showed detectable counts (˃10 cfu/ml) throughout the storage period. 
Table 4.4.1a. Effect of gamma radiation and storage (28°C±1) on total aerobic 
mesophiles (log cfu/ml) of tomato fruit. 
 Gamma Radiation Dose (kGy) 
Storage Period 
(Days) 0 1 2 3 4 
Ab
0 0.44  <1 <1 <1 <1 
Ba
3 1.61  <1 <1 <1 <1 
Ca Eb Gc Id
6 1.74  1.65  0.86  0.48  <1 
Da Fb Hc Jd
9 3.85  3.19  1.04  0.82  <1 
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are 
not significantly (P>0.05) different from each other and means with the same letters in the same row 
(lower case, doses) are not significantly different (P>0.05) from each other.  
<1 = below detectable limit (<10 cfu/ml). 
 
Fruits irradiated at 4kGy showed growth that was below the detectable limit 
throughout the storage period of 9 days. By contrast, control fruits showed a 
progressive and continuous increase in total microbial count from 0.44 log cfu/ml on 
th
the initial day to 3.85 log cfu/ml on the 9  day. As storage period increased, total 
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aerobic mesophiles increased in counts in all doses and the increase was inversely 
proportional to dose applied. Counts of total aerobic mesophiles in irradiated fruits at 
ambient temperature storage were significantly different (P≤ 0.05) from each other 
among doses and storage periods (Appendix 9). Gamma radiation significantly 
reduced microbial counts by inactivating spoilage micro organisms compared to 
control which showed increasing growth. Higher radiation doses (3 and 4 kGy) 
significantly reduced microbial counts to no counts or below detectable counts while 
the lower doses (1 and 2 kGy) showed fewer counts throughout storage period.  
 
4.4.2 Total Aerobic Mesophilic Bacteria Count (log cfu/ml) of Tomato Fruit at 
Ambient Temperature (28°C±1) Storage Following CaCl2 Coating. 
Table 4.4.1b shows counts of total aerobic mesophiles on tomato fruits treated with 
varying concentrations of calcium chloride and stored for 9 days at ambient 
temperature. Fruits treated with CaCl2 at all concentrations showed no or below 
detectable counts (<10 cfu/ml) through days 0 – 3 unlike control fruits. 
Fruits treated with 2.50% showed below detectable count throughout the storage 
period. However, control fruits showed increasing total aerobic mesophilic bacteria 
throughout the study. On days 6 and 9, total aerobic mesophilic bacteria counts 
decreased with increasing concentration of CaCl2. Fruits treated at 1.00 and 2.00 % 
showed an increase in total aerobic mesophilic bacteria from 1.03 – 1.15 and 0.85 – 
0.90 log cfu/ml respectively on days 6 and 9. Counts of total aerobic mesophiles in 
treated fruits at ambient temperature storage were significantly different (P≤ 0.05) 
from each other among concentrations and storage periods (Appendix 10). 
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Table 4.4.1b. Effect of CaCl2 concentration (%) and storage (28°C±1) on total 
aerobic mesophiles (log cfu/ml) of tomato fruit. 
 CaCl2 Concentration (%) 
Storage Period 
(Days) 0 1.00 1.50 2.00 2.50 
Aa
0 0.44  <1 <1 <1 <1 
Ba
3 1.61  <1 <1 <1 <1 
Ca Eb Gc 
6 1.74  1.03 0.85 <1 <1 
Da Fb Hc Id 
9 3.85  1.15 0.90 0.48 <1 
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are 
not significantly (P>0.05) different from each other and means with the same letters in the same row 
(lower case, doses) are not significantly different (P>0.05) from each other.  
<1 = below detectable limit (<10 cfu/ml). 
 
In comparison with irradiated fruits, calcium chloride treated fruits showed a reduced 
count of total aerobic mesophilic bacteria throughout storage. The highest count for 
irradiated samples was 3.19 log cfu/ml at 1kGy whilst the highest for CaCl2 treatment 
was 1.15 log cfu/ml at 1% concentration. Irradiation of fruits could affect the tissue of 
the fruit causing softening (De Costa, 2000) and consequently, easy access by 
microorganisms. CaCl2 treatment reduced contamination of the fruits as its use 
enhanced tissue resistance to fungal or bacterial attack by stabilizing or strengthening 
cell walls (Bolin and Huxsoll, 1989) while the control showed for increasing growth. 
Higher temperature could have enhanced growth of the microorganisms. 
 
 
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4.4.3 Total Aerobic Mesophilic Bacteria Count (log cfu/ml) of Tomato Fruit at 
Low Temperature (10°C±1) Storage Following Irradiation. 
Table 4.4.2a shows counts of total aerobic mesophilic bacteria in irradiated tomato 
stored for 25 days at low temperature. Fruits that were irradiated showed reduced 
count of total aerobic mesophilic bacteria of between 0.43 – 3.50 log cfu/ml whiles 
control fruits showed counts of between 0.44 – 4.10 log cfu/ml.  
Table 4.4.2a. Effect of gamma radiation and storage (10°C±1) on total aerobic 
mesophilic bacteria (log cfu/ml) of tomato fruit.  
Gamma Radiation Dose (kGy) 
 
Storage Period 
(Days) 0 1 2 3 4 
A
0 0.44  <1 <1 <1 <1 
Ba Gb
5 1.05  0.43  <1 <1 <1 
Ca Hb Lc
10 1.69  0.80  1.50  <1 <1 
Da Ib Mc Pd Sd
15 2.96  1.50  0.68  1.01  0.92  
Ea Jb Nb Qc Td
20 3.43  2.92  2.84  1.75  4.37  
Fe Kf Og Rh Ui
25 4.10  3.50  2.93  2.79  2.40  
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are 
not significantly (P>0.05) different from each other and means with the same letters in the same row 
(lower case, doses) are not significantly different (P>0.05) from each other.  
<1 = below detectable limit (<10 cfu/ml). 
 
On day 0, irradiated fruits showed no or below detectable microbial count (<10 
cfu/ml). Fruits irradiated at 3 and 4 kGy did not show any bacterial count from day 0 
to 10, thus, total aerobic mesophiles increased with decreasing radiation doses. These 
results coincide with previous finding by Prakash et al. (2002) that tomato fruits 
University of Ghana  http://ugspace.ug.edu.gh 101 
 
irradiated at 3.70 kGy showed no microbial count from day 0 to day 9. Total aerobic 
mesophiles in irradiated fruits at 10°C±1 were significantly different (P ≤ 0.05) from 
each other among doses and storage periods (Appendix 11). In all doses used, total 
aerobic count increased with advancement in days except for 4kGy treated fruits 
th th
whose changes fluctuated with an increase on the 20  day and a reduction on the 25  
day. Among radiation doses, total aerobic mesophiles decreased with increasing dose. 
2
The bacterial count in control fruit increased from 0.44 log cfu/ml (1.70×10 ) to 4.10 
6 th
log cfu/ml (4.90×10 ) throughout storage. On the 15  day, the dose with the largest 
mean total aerobic counts was in control fruits at 3.50 log cfu/ml followed by 1kGy 
with 2.64 log cfu/ml whilst 4kGy showed the least with 2.56 log cfu/ml. 
  
4.4.4 Total Aerobic Mesophilic Bacteria Count (log cfu/ml) of Tomato Fruit at 
Low Temperature (10°C±1) Storage Following CaCl2 Coating. 
The table (4.4.2b) shows total aerobic mesophilic bacteria of tomato fruits treated 
with calcium chloride and stored for 25 days at 10°C±1. Unlike control fruits which 
showed counts of between 0.44 – 4.10 log cfu/ml, fruits treated with CaCl2 showed no 
detectable count (<10 cfu/ml) on the initial day. 
Generally, all concentrations increased in total aerobic counts throughout storage 
period except the 2.5% concentration. There were significant differences (P ≤ 0.05)  
in total aerobic counts throughout the storage period and between concentrations 
(Appendix 12). Control fruits showed the highest count with 4.10 log cfu/ml as 
compared to treated fruits which decreased in counts with increasing concentration. 
 
This can be attributed to the ability of CaCl2 to provide an inhibitory effect on 
microbial growth while control allowed for spore spreading, increasing counts.  
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Table (4.4.2b) Effect of CaCl2 concentration (%) and storage (10°C±1) on total 
aerobic mesophilic bacteria (log cfu/ml) contaminating tomato fruit. 
CaCl2 Concentration (%) 
 
     
Storage Period 
(Days) 0 1.00 1.50 2.00 2.50 
A
0 0.44  <1 <1 <1 <1 
Ba Gb Lc Qc Vd
5 1.05  0.67  0.41 0.31  0.85  
Ca Hb Mc Rd VWd
10 1.69  0.12  1.28  0.79  0.81  
Da Ib Nc Sd We
15 2.96  2.07  0.28  1.30  0.89  
Ef Jg Lh Th Xj
20 3.43  2.97  0.48  0.56  2.62  
Fa Kb Pc Ud Ye
25 4.10  3.21  0.87  0.61  0.27  
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are 
not significantly (P>0.05) different from each other and means with the same letters in the same row 
(lower case, doses) are not significantly different (P>0.05) from each other.  
<1 = below detectable limit (<10 cfu/ml). 
 
Compared to irradiated samples which recorded between 0.43-4.37 log cfu/ml 
compared to 0.12-3.31 log cfu/ml in fruits treated with CaCl2, CaCl2 reduced 
microbial load more than fruits that were irradiated. However, growth started on day 5 
in all concentrations in fruits treated with CaCl2 whiles fruits treated with 1kGy 
gamma irradiation recorded bacterial count on day 5 as displayed in Tables 4.4.2a and 
4.4.2b. CaCl2 reduces the availability of moisture in the fruits which prevents the 
activities of microbes (Luna-Guzman and Barrett, 2000). Low temperature is also an 
important factor in maintaining quality and extending the shelf-life of fruits and 
vegetables after harvest due to its effects on reducing respiration rate, ripening, 
senescence and rot development (Majidi et al., 2011) in contrast to ambient 
temperature which hastens these processes. 
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4.4.5 Moulds and Yeasts Count (log cfu/ml) of Tomato Fruits at Ambient 
Temperature (28°C±1) Storage following Irradiation. 
Table 4.4.3a shows the growth of moulds and yeasts in irradiated tomato fruits stored 
th
for 9 days at ambient temperature. Generally, moulds and yeasts increased after the 6  
day in control fruits whiles irradiated fruits increased on the final day. Control fruits 
recorded the highest moulds and yeasts growth of 3.16 log cfu/ml. There were 
significant differences in moulds and yeasts growth on day 9 among all doses 
(Appendix 13).  
Table (4.4.3a): Effect of gamma radiation and storage (28°C±1) on moulds and 
yeasts count (log cfu/ml) of tomato fruit. 
 Gamma Radiation Dose (kGy) 
Storage Period 
(Days) 0 1 2 3 4 
0 <1 <1 <1 <1 <1 
3 <1 <1 <1 <1 <1 
Aa
6 0.80  <1 <1 <1 <1 
Ba Cb Dc Ed
9 3.16  1.50  1.04  0.44  <1 
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are 
not significantly (P>0.05) different from each other and means with the same letters in the same row 
(lower case, doses) are not significantly different (P>0.05) from each other.  
<1 = below detectable limit (<10 cfu/ml). 
 
Generally, irradiation caused a significant (P ≤ 0.05) decrease in moulds and yeasts 
count on the final day which was proportional to irradiation doses. 
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However, 4kGy did not record any moulds and yeasts through all the storage days. 
Thus, the higher doses (3 and 4 kGy) were more effective in controlling moulds and 
yeasts than the lower doses (1 and 2 kGy) This is in accordance with studies by 
Prakash et al. (2002), which indicated no detection for moulds and yeasts growth 
th th th
when tomato was irradiated at 3.75 kGy on the 6 , 9  and 12  day of analysis 
contrary to samples treated with 0.5 and 1.24 kGy. Previous work by Youssef et al., 
(2011) demonstrates that moulds and yeasts growth increased with reducing radiation 
doses. 
 
4.4.6 Moulds and Yeasts Count (log cfu/ml) of Tomato Fruits at Ambient 
Temperature (28°C±1) Storage following CaCl2 Coating. 
Table 4.4.3b shows the moulds and yeasts growth in tomato fruits treated with 
calcium chloride and stored for 9 days at 28°C±1. Fruits treated with CaCl2 showed 
reduction in moulds and yeasts of between 0.30 and 0.94 log cfu/ml over storage 
period whilst control fruits recorded between 0.80 and 3.16 log cfu/ml. 
th
Generally, moulds and yeasts remained at low levels up to day 9  day when they 
increased which agrees with the findings by Luna-Guzman and Barrett (2000). 
th
However, the control fruits started increasing after the 6  day and recorded the 
highest growth of moulds and yeasts with 3.16 log cfu/ml as compared to 
concentrations of 1.00 and 1.50 % which recorded 0.94 and 0.30 log cfu/ml 
respectively. Yeasts and moulds counts on the final day were significantly different 
from each CaCl2 concentrations (Appendix 14). Concentrations of 2.00 and 2.50 % 
did not show any detectable count of moulds and yeasts throughout the storage days. 
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Table (4.4.3b): Effect of CaCl2 concentration (%) and storage (28°C±1) on 
moulds and yeasts count (log cfu/ml) of tomato fruit. 
CaCl2 Concentration (%) 
 
     
Storage Period 
(Days) 0 1.00 1.50 2.00 2.50 
0 <1 <1 <1 <1 <1 
3 <1 <1 <1 <1 <1 
Aa
6 0.80  <1 <1 <1 <1 
Ba Cb Dc
9 3.16  0.94  0.30  <1 <1 
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are 
not significantly (P>0.05) different from each other and means with the same letters in the same row 
(lower case, doses) are not significantly different (P>0.05) from each other.  
<1 = below detectable limit (<10 cfu/ml). 
 
From Table 4.4.3a and 4.4.3b, fruits treated with CaCl2 showed lower counts of 
moulds and yeasts than irradiated fruits, however, control fruits showed the highest 
population. The reason for the lower counts in fruits treated with CaCl2 could be 
related to the effect CaCl2 has on tomato fruits by reducing the availability of 
moisture in the fruit which prevents the activities of microbes (Luna-Guzman and 
Barrett, 2000).   
 
4.4.7 Moulds and Yeasts Count (log cfu/ml) of Tomato Fruits at Low 
Temperature (10°C±1) Storage Following Irradiation. 
Table 4.4.4a shows the growth of moulds and yeasts in irradiated tomato fruits stored 
for 25 days at low temperature.  
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Table (4.4.4a): Effect of gamma radiation and storage (10°C±1) on moulds and 
yeasts count (log cfu/ml) of tomato fruit. 
Gamma Radiation Dose (kGy) 
 
 
Storage Period 
(Days) 0 1 2 3 4 
0 <1 <1 <1 <1 <1 
5 <1 <1 <1 <1 <1 
Aa Db Fc Id Ld 
10 2.32 0.61 1.28 0.79 0.79
Be Eef Gf Jf Mg 
15 3.61 3.18 3.03 2.81 0.31
Bh Ehi Hhi Jhi Ni 
20 3.55 3.84 2.84 2.84 2.57
Cj Ek Il Km On 
25 4.15 3.87 3.61 3.24 2.90
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are 
not significantly (P>0.05) different from each other and means with the same letters in the same row 
(lower case, doses) are not significantly different (P>0.05) from each other.  
<1 = below detectable limit (<10 cfu/ml). 
 
Fruits treated with gamma radiation showed reduced count of moulds and yeasts of 
between 0.61 – 3.87 log cfu/ml whiles control fruits increased from 2.32 – 4.15 log 
cfu/ml counts during the storage period. 
At all radiation doses, the few spores which remained after irradiation began to grow 
and increase during storage but the counts were lower in the higher doses 3 and 4 
kGy. Control fruits however, showed the highest growth with 4.15 log cfu/ml by the 
end of the storage period compared to 3.87, 3.61, 3.24 and 2.90 log cfu/ml for 1, 2, 3 
and 4 kGy respectively.  This trend confirms the work by Prakash et al. (2002) and 
Youssef et al., (2011) that tomato fruits irradiated at high doses reduced counts of 
moulds and yeasts. There were no significant differences in irradiated fruits on day 
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20, however, significant differences were portrayed throughout the other storage days 
as seen in Appendix 15. 
 
4.4.8 Moulds and Yeasts Count (log cfu/ml) of Tomato Fruits at Low 
Temperature (10°C±1) Storage Following CaCl2 Coating. 
The table (Table 4.4.4b) shows the growth of moulds and yeasts in tomato fruits 
treated with calcium chloride and stored for 25 days at 10°C±1.  
Table (4.4.4b): Effect of CaCl2 concentration (%) and storage (10°C±1) on 
moulds and yeasts count (log cfu/ml) of tomato fruit. 
CaCl2 Concentrations (%) 
 
     
Storage Period 
(Days) 0 1.00 1.50 2.00 2.50 
0 <1 <1 <1 <1 <1 
5 <1 <1 <1 <1 <1 
Aa 
10 2.32 <1 <1 <1 <1 
Da Gb Jc Da Gb 
15 3.91 1.27 1.08 3.91 1.27
Ea Hb Kc Ea Hb 
20 3.55 2.77 1.75 3.55 2.77
Fa Ib Lc Fa Ib 
25 4.15 1.61 2.46 4.15 1.61
 
Least Significant Difference. Means with the same letters (upper cases, days) in the same column are 
not significantly (P>0.05) different from each other and means with the same letters in the same row 
(lower case, doses) are not significantly different (P>0.05) from each other.  
<1 = below detectable limit (<10 cfu/ml). 
 
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Moulds and yeasts growth started on day 15 in fruits treated with CaCl2 at all 
concentrations used. However, growth of moulds and yeast started increasing in 
th
control fruits on the 10  day of observation. 
In all concentrations, there were significant increases in population of moulds and 
yeast throughout storage. Control fruits and 2.00% CaCl2 treated fruits recorded the 
same values on day 25 and the count was the highest (4.15 log cfu/ml) as compared to 
the other concentrations; 2.46 log cfu/ml for 1.50 % and 1.61 log cfu/ml for both 1.00 
and 2.50 %). There were significant differences in moulds and yeasts counts from 
days 15 to 25 (Appendix 16).  
th
In comparison with irradiated fruits, growth of moulds and yeasts started on the 10  
day in contrast with CaCl2 samples which started increasing on day 15. 
Notwithstanding, irradiated samples recorded the least counts of moulds and yeasts of 
3.87 log cfu/ml compared to 4.15 log cfu/ml for CaCl2 samples though both results 
7 
were below 10 cfu/ml.  
7
Microbial counts from this study did not exceed 10  and were almost similar to those 
obtained in other fresh products (Nguyen-the and Carlin, 1994) which did not exceed 
9
10 . The International Commission on Microbiological Specifications for Foods 
(ICMSF, 1974), recommends that the microbiological criterion of aerobic plate count 
6
for salad vegetables or fruits must not exceed 10  (Microbiological Reference Criteria 
6 
for Food, 1995). From the study, none of the samples showed counts exceeding 10
cfu/ml and therefore are considered as microbiologically safe.  
At low temperature storage, the treatment that showed the least total aerobic count 
and moulds and yeasts count by the end of the 25 day storage period was at 2.50 % 
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CaCl2 concentration. At ambient temperature storage, the treatments that showed the 
least total aerobic count were at 4kGy and 2.50 %. Similarly, tomato fruits treated at 
4kGy, 2.00 and 2.50 % showed the least moulds and yeasts count by the end of the 25 
day storage period at low temperature storage. 
The comparatively high contamination levels of microorganisms in untreated tomato 
fruits (control) was expected and could be due to the high natural microflora of the 
raw tomato, that come from soil, water or the hands of workers, as well as the 
contamination during blending and packaging. The results also indicate that moulds 
and yeasts are relatively more resistance to gamma irradiation than aerobic mesophilic 
bacteria as confirmed by Youssef et al., (2011) and Fan and Sokorai (2008).  
 
 
 
 
 
 
 
 
 
 
 
 
 
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CHAPTER FIVE 
5.0 CONCLUSIONS AND RECOMMENDATIONS 
5.1 CONCLUSIONS 
The versatility of the tomato fruit as well as its nutritional properties makes it an 
important horticulture crop in the diets or many people world-wide. This study has 
provided information on the appropriate and effective means of preserving fresh 
tomato fruits to prevent post - harvest losses without compromising on physico – 
chemical and nutritional properties. The use of different temperatures (28±1°C and 
10±1°C) and different levels of the two treatments used (gamma radiation and CaCl2 
coating) in this study helped to bring out the effects of the treatment combinations on 
the shelf life as well as the physicochemical and nutritional properties of tomato 
fruits. 
The following conclusions were drawn based on results obtained. 
1. Shelf Life Extension 
a) Gamma radiation at 4kGy followed by low temperature storage (10°C±1) 
extended shelf life of tomato fruits by 9 and 5 days compared to unirradiated 
fruits stored at same temperature and ambient temperature (28°C±1) 
respectively. Similarly, fruits irradiated at 3kGy also extended shelf life by 7 
and 5 days compared to unirradiated fruits stored at low (10°C±1) and ambient 
(28°C±1) temperature storage respectively. 
b) Similarly, 2.50% calcium chloride concentrations followed by low 
temperature storage (10°C±1) also extended shelf life of tomato fruits by 18 
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and 11 days over untreated fruits stored at same temperature and ambient 
temperature (28°C±1) respectively. 
c) In general, storage at low temperature (10±1°C) increased the storage life of 
tomato fruits by a maximum of 18 and 25 days in control and treated fruits 
respectively.  
d) The use of gamma radiation and CaCl2 coating greatly extended the shelf life 
of tomato fruits more than control fruits. However, CaCl2 coating extended the 
shelf life of tomato fruits better than gamma radiation. 
 
2. Physicochemical properties 
a) Weight loss was greatest in untreated fruits (2.80 – 15.66 %) 
followed by those subjected to gamma irradiation (2.48 – 14.55 
%) with CaCl2 coating showing the least (1.30 – 6.93 %) at 
ambient temperature storage (28±1°C). Similarly, at low 
temperature storage, irradiated fruits and fruits treated with CaCl2 
showed weight loss ranging between 0.59 – 3.00 and 0.41 – 1.77 
% respectively compared to 12.33 – 38.67 % in untreated fruits. 
b) In general, weight loss was significantly low in all treated fruits at 
low temperature storage compared to high temperature storage. 
However, weight loss exhibited by CaCl2 treatments was 
significantly lower than irradiation or no treatment.  
c) pH of fruits treated with CaCl2 exhibited comparatively inceased 
pH from 4.10 – 4.41 compared to that of the fruits in the control 
set (4.35 – 4.39) and irradiated fruits (4.26 – 4.62) at ambient 
temperature storage (28±1°C). In contrast, irradiated fruits (4.22 – 
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4.49) and control fruits (4.23 – 4.49) were at par and showed the 
longest pH range than CaCl2 treated fruits (4.05 – 4.56) at low 
temperature storage (10±1°C). 
d) Generally, fruits stored at 10±1°C were a more acidic state as 
compared to those stored at 28±1°C in all treatments.  
e) Total Titratable Acidity (TTA) in irradiated tomato fruits (0.23 – 
0.46 %) and control fruits (0.36 – 0.28 %) were lower throughout 
the storage period than CaCl2 coating (0.33 – 0.49) at ambient 
temperature storage (28±1°C). At low temperature storage 
(10±1°C), fruits treated with gamma radiation showed the least 
%TTA (0.26 – 0.47 %) compared to control fruits (0.25 – 0.51 %) 
and fruits treated with CaCl2 (0.31 – 0.49 %). 
f) Generally, TTA was larger in all treatments at low temperature 
storage as compared to high temperature storage. 
g) At ambient temperature (28±1°C), control fruits (3.50 – 4.10 %) 
exhibited lower Total Soluble Solids (TSS) as compared to the 
irradiated fruits (4.03 – 5.00 %) and fruits treated with CaCl2 
(3.30 - 4.17 %). Similarly, at low temperature storage (10±1°C), 
irradiated fruits displayed the largest TSS (4.00 - 5.13%) as 
compared to CaCl2 treated fruits showed the least (3.90 – 4.33 %) 
and control fruits (3.43 – 4.07). 
h) Control fruits displayed between 94.49 – 95.45 % moisture 
content which was comparatively larger than that of irradiated 
tomato fruits (94.62 – 96.53 %) and CaCl2 treated fruits (94.11 to 
95.51 %) at ambient temperature storage (28±1°C). In contrast, at 
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low temperature storage (10±1°C), moisture content was greater 
in irradiated fruits (94.43 – 95.87 %) than CaCl2 treated fruits 
(94.32 – 95.97 %) and control (94.49 – 95.60 %). 
 
3. Nutritional Properties 
a) At ambient temperature storage (28±1°C), tomato fruits treated 
with CaCl2 coating at 2.50% showed the highest vitamin C 
content of 20.02 mg/100 g over storage period. Similarly, at low 
temperature storage (10±1°C), vitamin C content of fruits treated 
with CaCl2 showed the largest content 14.56 mg/100 g compared 
to 12.96  mg/100 g (2.5 and 1.5 %) in irradiated fruits over 
storage period. 
b) In general, fruits treated with CaCl2 showed the largest content at 
both temperatures over the storage period. 
c) Lycopene content was high in CaCl2 treated fruits at 2.50% (53.30 
mg/kg) by the final day of storage than irradiated fruits at 1kGy 
(23.05 mg/kg) at ambient temperature storage (28±1°C). 
Similarly, at low temperature storage (10±1°C), CaCl2 coating at 
2.5% showed the largest lycopene content of 60.87 mg/kg. 
d) In general, contents of Na, K, Zn, and Cu in irradiated tomato 
fruits decreased with time over the storage period while that of 
Mn increased across irradiation doses at ambient temperature 
storage (28±1°C). In like manner, contents of Na, K, Zn, Mn and 
Cu in fruits treated with CaCl2 decreased with time over the 
storage period. 
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e) In general, Na and Cu showed a greater reduction in content in 
irradiated fruits than CaCl2 treated fruits at both temperatures 
over storage period. K and Zn content also exhibited more 
reductions in CaCl2 treated fruits than irradiated fruits at ambient 
temperature storage (28±1°C). However, at low temperature 
storage (10±1°C), there were fluctuations in the content of K and 
Mn in both treatments.  
 
4. Microbial Load 
a) Total aerobic mesophilic bacteria counts at ambient temperature 
(28±1°C) reduced with increasing radiation doses and CaCl2 
concentrations. However, fruits treated with CaCl2 showed a 
reduced count (0.48 – 1.15 log cfu/ml) over the storage period 
than irradiated fruits (0.48 - 3.19 log cfu/ml) whilst control fruits 
showed the largest counts (0.44 - 3.85 log cfu/ml). Similarly, at 
low temperature (10±1°C), total aerobic mesophilic counts 
reduced with increasing radiation doses and CaCl2 concentrations.  
Treatment of fruits with CaCl2 at 2.50% concentration was best able to reduce 
microbial load (0.27 log cfu/ml) more than fruits that were irradiated (2.40 log cfu/ml) 
when stored at 10±1°C for 25 days which were all acceptable by The International 
Commission on Microbiological Specifications for Foods (ICMSF, 1974). 
b) Mould and yeast counts reduced with increasing radiation doses 
or CaCl2 concentration throughout storage at both temperatures 
(28±1°C and 10±1°C). At low temperature (10±1°C), fruits 
treated with CaCl2 at all concentrations reduced growth of moulds 
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6 
and yeasts below an acceptable level of 10 by ICMSF (1974) 
standards. 
c) In general, fruits treated at 2.50% and 4kGy were best able to 
reduce microbial load in tomato fruits at both temperatures. 
However, fruits treated with CaCl2 exhibited a reduced microbial 
load at both storage temperatures. 
In summary, it appears that doses of 3 and 4 kGy significantly extends shelf life of 
tomato by inactivating spoilage micro organisms, however, it caused a reduction in 
the nutritional properties of fresh tomato fruits and also changes in appearance 
(softening) of the fruit which affected the fruits’ physicochemical properties. 
Similarly, CaCl2 coating at 2.00 and 2.50 % also extended the shelf life of tomato 
longer than gamma radiation and reduced microbial content as well. CaCl2 coating is 
also better able to maintain the nutritional properties as well as physicochemical 
properties of fresh tomato fruits than gamma irradiation or no treatment.  Based on the 
results from this study, CaCl2 application is a feasible solution for farmers, retailers 
and consumers to reduce post - harvest losses. 
 
5.2 RECOMMENDATIONS 
The following recommendations are made following results obtained from this 
research; 
1. Gamma radiation should be combined with calcium chloride to determine the 
effects of the combination treatments on tomato preservation. 
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2. Other postharvest treatments like applications of Chitosan, Sodium 
Hypochlorite, Potassium Permanganate and their combination with gamma 
radiation should be investigated. 
3. Research into the combined use of various post - harvest treatments and 
packaging materials on storage properties of fresh tomato fruits should be 
undertaken. This would provide information to retailers who package tomato 
fruits using Modified Atmosphere Packaging. 
4. CaCl2 coating is an approved processing aid for organic food production and is 
relatively inexpensive, and easily accessible.  
5. Sensory evaluation should be conducted on the effects of these post - harvest 
treatments on the organoleptic properties (taste, texture, colour, sweetness) of 
fresh tomato fruits. 
 
 
 
 
 
 
 
 
 
 
 
 
 
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III juice from whole fruit and locules at different stages of ripeness. J. Sci. Food 
Agric., 13:108. 
 
Wolff, H. (1999). Economics of tomato production with special reference to aspects 
of plant protection: a case study of two tomato production systems in Brong-Ahafo 
Region, Ghana. Ghanaian-German Project for Integrated Crop Protection, GTZ 
Eschborn. Pp131. 
 
Yaman, O. and L. Bayoindril. (2002). Effects of an edible and cold storageon shelf 
life and quality of cherries. Lebensm. Wiss. Und. Technol., 35: 146-150. 
 
Youssef, K. A., Hammad, A. I., Abd El-Kalek, H. H. and Abd El-Kader, R. M. 
(2011). Ensure Microbial Safety and Extending Shelf-Life of Tomato Juice by γ 
Irradiation. Nature and Science 9(11):154-163.  
 
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Zechmeister, L., Lerosen, A. L., Shroeder, W. A., Polgar A. and Pauline, L. (1943). 
Spectral characteristics and configuration of some stereo isomeric carotenoids 
including prolycopene and pro-beta-carotene. J. Am. Chem. Soc. 65:1940-1951. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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APPENDICES 
Appendix 1a: ANOVA Table for pH of Tomato Fruits Following Gamma Radiation Application 
and Storage at Ambient Temperature (28±1°C). 
DAY 0 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0536933 4 0.0134233 335.58 0.0000 
Within groups 0.0004 10 0.00004   
Total (Corr.) 0.0540933 14    
 
DAY 3 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.026 4 0.0065 195.00 0.0000 
Within groups 0.000333333 10 0.0000333333   
Total (Corr.) 0.0263333 14    
 
DAY 6 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.12516 4 0.03129 586.69 0.0000 
Within groups 0.000533333 10 0.0000533333   
Total (Corr.) 0.125693 14    
 
DAY 9 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0778667 3 0.0259556 283.15 0.0000 
Within groups 0.000733333 8 0.0000916667   
Total (Corr.) 0.0786 11    
 
Appendix 1b: Multifactor ANOVA Table for pH of Tomato Fruits Following Gamma Radiation 
Application and Storage at Ambient Temperature (28±1°C) - Type III Sums of Squares 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A: DOSE - 0kGy 0.00295556 2 0.00147778 26.60 0.0010 
RESIDUAL 0.000333333 6 0.0000555556   
TOTAL (CORRECTED) 0.00328889 8    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A: DOSE  - 1 kGy 0.00886667 3 0.00295556 118.22 0.0000 
RESIDUAL 0.0002 8 0.000025   
TOTAL (CORRECTED) 0.00906667 11    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A: DOSE  -  2 kGy  0.0204667 3 0.00682222 136.44 0.0000 
RESIDUAL 0.0004 8 0.00005   
TOTAL (CORRECTED) 0.0208667 11    
 
 
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Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A: DOSE - 3 kGy 0.0427583 3 0.0142528 171.03 0.0000 
RESIDUAL 0.000666667 8 0.0000833333   
TOTAL (CORRECTED) 0.043425 11    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A: 4 kGy  0.269492 3 0.0898306 1796.61 0.0000 
RESIDUAL 0.0004 8 0.00005   
TOTAL (CORRECTED) 0.269892 11    
 
Appendix 2a: ANOVA Table for pH of Tomato Fruits Following CaCl2 Coating and Storage at 
Ambient Temperature (28±1°C). 
DAY 3 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0285733 4 0.00714333 357.17 0.0000 
Within groups 0.0002 10 0.00002   
Total (Corr.) 0.0287733 14    
 
DAY 6 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0895067 4 0.0223767 839.13 0.0000 
Within groups 0.000266667 10 0.0000266667   
Total (Corr.) 0.0897733 14    
 
DAY 9 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0483667 3 0.0161222 322.44 0.0000 
Within groups 0.0004 8 0.00005   
Total (Corr.) 0.0487667 11    
 
Appendix 2b: Multifactor ANOVA Table for pH of Tomato Fruits Following CaCl2 Coating and 
Storage at Ambient Temperature (28±1°C) - Type III Sums of Squares. 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 0 % 0.00295556 2 0.00147778 26.60 0.0010 
RESIDUAL 0.000333333 6 0.0000555556   
TOTAL (CORRECTED) 0.00328889 8    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 1.0 0% 0.0891 3 0.0297 1188.00 0.0000 
RESIDUAL 0.0002 8 0.000025   
TOTAL (CORRECTED) 0.0893 11    
 
 
 
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Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 1.50% 0.0428917 3 0.0142972 13.40 0.0017 
RESIDUAL 0.00853333 8 0.00106667   
TOTAL (CORRECTED) 0.051425 11    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 2.00% 0.0524667 3 0.0174889 419.73 0.0000 
RESIDUAL 0.000333333 8 0.0000416667   
TOTAL (CORRECTED) 0.0528 11    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 2.50% 0.026825 3 0.00894167 268.25 0.0000 
RESIDUAL 0.000266667 8 0.0000333333   
TOTAL (CORRECTED) 0.0270917 11    
 
Appendix 3a: ANOVA Table for pH of Tomato Fruits Following Gamma Radiation Application 
and Storage at Low Temperature (10±1°C). 
DAY 0 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0501733 4 0.0125433 470.38 0.0000 
Within groups 0.000266667 10 0.0000266667   
Total (Corr.) 0.05044 14    
 
DAY 5 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0295333 4 0.00738333 369.17 0.0000 
Within groups 0.0002 10 0.00002   
Total (Corr.) 0.0297333 14    
 
DAY 10 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.01664 4 0.00416 208.00 0.0000 
Within groups 0.0002 10 0.00002   
Total (Corr.) 0.01684 14    
 
DAY 15 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.09764 4 0.02441 135.61 0.0000 
Within groups 0.0018 10 0.00018   
Total (Corr.) 0.09944 14    
 
 
 
 
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DAY 20 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0158267 4 0.00395667 8.02 0.0036 
Within groups 0.00493333 10 0.000493333   
Total (Corr.) 0.02076 14    
 
 
DAY 25 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0274667 4 0.00686667 206.00 0.0000 
Within groups 0.000333333 10 0.0000333333   
Total (Corr.) 0.0278 14    
 
Appendix 3b: Multifactor ANOVA Table for pH of Tomato Fruits Following Gamma Radiation 
Application and Storage at Low Temperature (10±1°C) - Type III Sums of Squares. 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSE 0 kGy 0.113783 5 0.0227567 163.85 0.0000 
RESIDUAL 0.00166667 12 0.000138889   
TOTAL (CORRECTED) 0.11545 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSE 1 kGy 0.120583 5 0.0241167 54.95 0.0000 
RESIDUAL 0.00526667 12 0.000438889   
TOTAL (CORRECTED) 0.12585 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSE 2 kGy 0.00657778 5 0.00131556 78.93 0.0000 
RESIDUAL 0.0002 12 0.0000166667   
TOTAL (CORRECTED) 0.00677778 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A: DOSE 3 kGy 0.0125111 5 0.00250222 112.60 0.0000 
RESIDUAL 0.000266667 12 0.0000222222   
TOTAL (CORRECTED) 0.0127778 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A: DOSES 4 kGy 0.0998944 5 0.0199789 719.24 0.0000 
RESIDUAL 0.000333333 12 0.0000277778   
TOTAL (CORRECTED) 0.100228 17    
 
 
 
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Appendix 4a: ANOVA Table for pH of tomato fruits following CaCl2 coating and storage at low 
temperature (10±1°C). 
DAY 0 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0332267 4 0.00830667 9.58 0.0019 
Within groups 0.00866667 10 0.000866667   
Total (Corr.) 0.0418933 14    
 
DAY 5 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.115307 4 0.0288267 2162.00 0.0000 
Within groups 0.000133333 10 0.0000133333   
Total (Corr.) 0.11544 14    
 
DAY 10 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.176307 4 0.0440767 300.52 0.0000 
Within groups 0.00146667 10 0.000146667   
Total (Corr.) 0.177773 14    
 
DAY 15 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0931067 4 0.0232767 91.88 0.0000 
Within groups 0.00253333 10 0.000253333   
Total (Corr.) 0.09564 14    
 
DAY 20 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0333067 4 0.00832667 624.50 0.0000 
Within groups 0.000133333 10 0.0000133333   
Total (Corr.) 0.03344 14    
 
DAY 25 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.04324 4 0.01081 540.50 0.0000 
Within groups 0.0002 10 0.00002   
Total (Corr.) 0.04344 14    
 
Appendix 4b: Multifactor ANOVA Table for pH of Tomato Fruits Following CaCl2 Coating and 
Storage at Low Temperature (10±1°C)  - Type III Sums of Squares. 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL- 0 0.110978 5 0.0221956 99.88 0.0000 
RESIDUAL 0.00266667 12 0.000222222   
TOTAL (CORRECTED) 0.113644 17    
 
 
 
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Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL – 1.00% 0.0431111 5 0.00862222 517.33 0.0000 
RESIDUAL 0.0002 12 0.0000166667   
TOTAL (CORRECTED) 0.0433111 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 2.00% 0.228778 5 0.0457556 457.56 0.0000 
RESIDUAL 0.0012 12 0.0001   
TOTAL (CORRECTED) 0.229978 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 2.5% 0.594733 5 0.118947 3058.63 0.0000 
RESIDUAL 0.000466667 12 0.0000388889   
TOTAL (CORRECTED) 0.5952 17    
 
Appendix 5a: ANOVA Table for TOTAL TITRATABLE ACIDITY of Tomato Fruits Following 
Gamma Radiation Application and Storage at Ambient Temperature (28±1°C). 
DAY 0 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0375007 4 0.00937516 311.73 0.0000 
Within groups 0.000300749 10 0.0000300749   
Total (Corr.) 0.0378014 14    
 
DAY 3 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0107675 4 0.00269187 67.62 0.0000 
Within groups 0.000398082 10 0.0000398082   
Total (Corr.) 0.0111655 14    
 
DAY 6 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.000375225 4 0.0000938063 490.14 0.0000 
Within groups 0.00000191386 10 1.91386E-7   
Total (Corr.) 0.000377139 14    
 
DAY 9 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0202698 3 0.0067566 197.70 0.0000 
Within groups 0.000273408 8 0.000034176   
Total (Corr.) 0.0205432 11    
 
 
 
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Appendix 5b: Multifactor ANOVA Table for TOTAL TITRATABLE ACIDITY of Tomato 
Fruits Following Gamma Radiation Application and Storage at Ambient Temperature (28±1°C) 
– Type III Sums of Squares 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSE - 0 kGy  0.0154378 2 0.0077189 257.83 0.0000 
RESIDUAL 0.000179629 6 0.0000299382   
TOTAL (CORRECTED) 0.0156174 8    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSES 1 kGy  0.0163847 3 0.00546157 200.01 0.0000 
RESIDUAL 0.000218453 8 0.0000273067   
TOTAL (CORRECTED) 0.0166032 11    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSES 2 kGy  0.00835371 3 0.00278457 90.43 0.0000 
RESIDUAL 0.000246341 8 0.0000307926   
TOTAL (CORRECTED) 0.00860005 11    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSES 3 kGy  0.00429251 3 0.00143084 52.07 0.0000 
RESIDUAL 0.00021982 8 0.0000274775   
TOTAL (CORRECTED) 0.00451233 11    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSES 4 kGy  0.0886045 3 0.0295348 2155.11 0.0000 
RESIDUAL 0.000109637 8 0.0000137046   
TOTAL (CORRECTED) 0.0887141 11    
 
Appendix 6a: ANOVA Table for TOTAL TITRATABLE ACIDITY of Tomato Fruits Following 
CaCl2 Coating and Storage at Ambient Temperature (28±1°C) - Type III Sums of Squares. 
DAY 0 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0226273 4 0.00565681 172.42 0.0000 
Within groups 0.00032809 10 0.000032809   
Total (Corr.) 0.0229553 14    
 
DAY 3 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0514003 4 0.0128501 491.63 0.0000 
Within groups 0.000261378 10 0.0000261378   
Total (Corr.) 0.0516617 14    
 
 
 
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DAY 6 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0684279 4 0.017107 195.47 0.0000 
Within groups 0.000875179 10 0.0000875179   
Total (Corr.) 0.0693031 14    
 
DAY 9 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.00991104 3 0.00330368 80.56 0.0000 
Within groups 0.00032809 8 0.0000410112   
Total (Corr.) 0.0102391 11    
 
Appendix 6b: Multifactor ANOVA Table for TOTAL TITRATABLE ACIDITY of Tomato 
Fruits Following CaCl2 Coating and Storage at Ambient Temperature (28±1°C)  
- Type III Sums of Squares. 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 0  0.0169744 2 0.00848718 334.39 0.0000 
RESIDUAL 0.000152288 6 0.0000253814   
TOTAL (CORRECTED) 0.0171266 8    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 1.00% 0.00110389 3 0.000367962 17.94 0.0007 
RESIDUAL 0.000164045 8 0.0000205056   
TOTAL (CORRECTED) 0.00126793 11    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 1.50% 0.00854059 3 0.00284686 83.30 0.0000 
RESIDUAL 0.000273408 8 0.000034176   
TOTAL (CORRECTED) 0.00881399 11    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 2.00% 0.0333934 3 0.0111311 465.29 0.0000 
RESIDUAL 0.000191386 8 0.0000239232   
TOTAL (CORRECTED) 0.0335848 11    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 2.50% 0.0324535 3 0.0108178 85.55 0.0000 
RESIDUAL 0.00101161 8 0.000126451   
TOTAL (CORRECTED) 0.0334652 11    
 
 
 
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Appendix 7a: ANOVA Table for TOTAL TITRATABLE ACIDITY of Tomato Fruits Following 
Gamma Radiation Application and Storage at Low Temperature (10±1°C). 
DAY 0 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.069566 4 0.0173915 334.79 0.0000 
Within groups 0.000519475 10 0.0000519475   
Total (Corr.) 0.0700854 14    
 
DAY 5 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.00012112 4 0.0000302799 369.17 0.0000 
Within groups 8.20224E-7 10 8.20224E-8   
Total (Corr.) 0.00012194 14    
 
DAY 10 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.00527678 4 0.00131919 37.12 0.0000 
Within groups 0.000355431 10 0.0000355431   
Total (Corr.) 0.00563221 14    
 
DAY 15 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0357344 4 0.00893361 217.83 0.0000 
Within groups 0.000410112 10 0.0000410112   
Total (Corr.) 0.0361446 14    
 
 
DAY 20 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.00640869 4 0.00160217 58.60 0.0000 
Within groups 0.000273408 10 0.0000273408   
Total (Corr.) 0.00668209 14    
 
DAY 25 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.00674224 4 0.00168556 205.50 0.0000 
Within groups 0.0000820224 10 0.00000820224   
Total (Corr.) 0.00682427 14    
 
Appendix 7b: Multifactor ANOVA Table for TOTAL TITRATABLE ACIDITY of Tomato 
Fruits Following Gamma Radiation Application and Storage at Low Temperature (10±1°C) - 
Type III Sums of Squares. 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSES 0 kGy  0.1261 5 0.0252199 737.45 0.0000 
RESIDUAL 0.000410386 12 0.0000341988   
TOTAL (CORRECTED) 0.12651 17    
 
 
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Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSES 1 kGy  0.0973853 5 0.0194771 711.79 0.0000 
RESIDUAL 0.000328363 12 0.0000273636   
TOTAL (CORRECTED) 0.0977137 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSES 2 kGy  0.0158805 5 0.0031761 137.10 0.0000 
RESIDUAL 0.000278 12 0.0000231667   
TOTAL (CORRECTED) 0.0161585 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSES 3 kGy  0.00894603 5 0.00178921 56.05 0.0000 
RESIDUAL 0.000383045 12 0.0000319204   
TOTAL (CORRECTED) 0.00932907 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:DOSES 4 kGy  0.0323843 5 0.00647686 315.86 0.0000 
RESIDUAL 0.000246067 12 0.0000205056   
TOTAL (CORRECTED) 0.0326303 17    
 
Appendix 8a: ANOVA Table for TOTAL TITRATABLE ACIDITY of Tomato Fruits Following 
CaCl2 Coating and Storage at Low Temperature (10±1°C)  
DAY 0 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0208228 4 0.00520569 105.78 0.0000 
Within groups 0.000492135 10 0.0000492135   
Total (Corr.) 0.0213149 14    
 
DAY 5 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0739182 4 0.0184795 482.44 0.0000 
Within groups 0.000383045 10 0.0000383045   
Total (Corr.) 0.0743012 14    
 
DAY 10 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0503454 4 0.0125863 270.79 0.0000 
Within groups 0.000464794 10 0.0000464794   
Total (Corr.) 0.0508102 14    
 
DAY 15 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0881194 4 0.0220299 619.81 0.0000 
Within groups 0.000355431 10 0.0000355431   
Total (Corr.) 0.0884749 14    
 
DAY 20 
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Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0156225 4 0.00390563 158.72 0.0000 
Within groups 0.000246067 10 0.0000246067   
Total (Corr.) 0.0158686 14    
 
DAY 25 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.0554089 4 0.0138522 266.66 0.0000 
Within groups 0.000519475 10 0.0000519475   
Total (Corr.) 0.0559284 14    
 
Appendix 8b: Multifactor ANOVA Table for TOTAL TITRATABLE ACIDITY of Tomato 
Fruits Following CaCl2 Coating and Storage at Low Temperature (10±1°C) - Type III Sums of 
Squares. 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL- 0 0.1261 5 0.0252199 737.45 0.0000 
RESIDUAL 0.000410386 12 0.0000341988   
TOTAL (CORRECTED) 0.12651 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 1.00% 0.0204714 5 0.00409429 224.63 0.0000 
RESIDUAL 0.000218726 12 0.0000182272   
TOTAL (CORRECTED) 0.0206902 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL -1.50% 0.0581926 5 0.0116385 243.25 0.0000 
RESIDUAL 0.000574157 12 0.0000478464   
TOTAL (CORRECTED) 0.0587668 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 2.00% 0.0525057 5 0.0105011 158.93 0.0000 
RESIDUAL 0.000792884 12 0.0000660736   
TOTAL (CORRECTED) 0.0532986 17    
 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
MAIN EFFECTS      
 A:LEVEL 2.50% 0.0702385 5 0.0140477 362.68 0.0000 
RESIDUAL 0.000464794 12 0.0000387328   
TOTAL (CORRECTED) 0.0707033 17    
 
 
 
 
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Appendix 9: ANOVA Table for TOTAL AEROBIC MESOPHILES of Tomato Fruits Following 
Gamma Radiation Application and Storage at Ambient Temperature (28±1°C)  
DAY 0 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.471732 4 0.117933 637.97 0.0000 
Within groups 0.00184857 10 0.000184857   
Total (Corr.) 0.473581 14    
 
DAY 3 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 6.20351 4 1.55088 31569.61 0.0000 
Within groups 0.000491256 10 0.0000491256   
Total (Corr.) 6.204 14    
 
DAY 6 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 6.77479 4 1.6937 2337.98 0.0000 
Within groups 0.00724429 10 0.000724429   
Total (Corr.) 6.78203 14    
 
DAY 9 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 89.6818 4 22.4204 7099.68 0.0000 
Within groups 0.0315795 10 0.00315795   
Total (Corr.) 89.7133 14    
 
 
Appendix 10: ANOVA Table for TOTAL AEROBIC MESOPHILES of Tomato Fruits Following 
CaCl2 Coating Application and Storage at Ambient Temperature (28±1°C)  
DAY 0 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.471732 4 0.117933 637.97 0.0000 
Within groups 0.00184857 10 0.000184857   
Total (Corr.) 0.473581 14    
 
DAY 3 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 6.20351 4 1.55088 31569.61 0.0000 
Within groups 0.000491256 10 0.0000491256   
Total (Corr.) 6.204 14    
 
DAY 6 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 6.59181 4 1.64795 7842.07 0.0000 
Within groups 0.00210142 10 0.000210142   
Total (Corr.) 6.59391 14    
 
 
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DAY 9 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 27.0748 4 6.76869 18056.03 0.0000 
Within groups 0.00374871 10 0.000374871   
Total (Corr.) 27.0785 14    
 
Appendix 11: ANOVA Table for TOTAL AEROBIC MESOPHILES of Tomato Fruits Following 
Gamma Radiation Application and Storage at Low Temperature (10±1°C)  
DAY 0 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.471732 4 0.117933 637.97 0.0000 
Within groups 0.00184857 10 0.000184857   
Total (Corr.) 0.473581 14    
 
DAY 5 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 2.55822 4 0.639555 690.93 0.0000 
Within groups 0.00925646 10 0.000925646   
Total (Corr.) 2.56748 14    
 
DAY 10 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 7.68616 4 1.92154 8582.37 0.0000 
Within groups 0.00223894 10 0.000223894   
Total (Corr.) 7.6884 14    
 
DAY 15 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 9.97901 4 2.49475 807.16 0.0000 
Within groups 0.0309079 10 0.00309079   
Total (Corr.) 10.0099 14    
 
DAY 20 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 10.9371 4 2.73427 1342.10 0.0000 
Within groups 0.0203731 10 0.00203731   
Total (Corr.) 10.9574 14    
 
DAY 25 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 5.30212 4 1.32553 871.48 0.0000 
Within groups 0.0152101 10 0.00152101   
Total (Corr.) 5.31733 14    
 
 
 
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Appendix 12: ANOVA Table for TOTAL AEROBIC MESOPHILES of Tomato Fruits Following 
CaCl2 Coating and Storage at Low Temperature (10±1°C)  
DAY 0 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 0.471732 4 0.117933 637.97 0.0000 
Within groups 0.00184857 10 0.000184857   
Total (Corr.) 0.473581 14    
 
DAY 5 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 1.11911 4 0.279777 80.29 0.0000 
Within groups 0.0348461 10 0.00348461   
Total (Corr.) 1.15395 14    
 
DAY 10 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 4.16603 4 1.04151 3009.43 0.0000 
Within groups 0.00346082 10 0.000346082   
Total (Corr.) 4.16949 14    
 
DAY 15 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 13.0627 4 3.26567 2621.19 0.0000 
Within groups 0.0124587 10 0.00124587   
Total (Corr.) 13.0751 14    
 
DAY 20 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 23.3728 4 5.84319 2023.06 0.0000 
Within groups 0.0288829 10 0.00288829   
Total (Corr.) 23.4016 14    
 
DAY 25 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 35.841 4 8.96026 1784.75 0.0000 
Within groups 0.0502047 10 0.00502047   
Total (Corr.) 35.8913 14    
 
Appendix 13: ANOVA Table for MOULDS AND YEASTS GROWTH of Tomato Fruits 
Following Gamma Radiation Application and Storage at Ambient Temperature (28±1°C)  
DAY 6 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 1.53779 4 0.384448 1286.68 0.0000 
Within groups 0.00298792 10 0.000298792   
Total (Corr.) 1.54078 14    
 
 
University of Ghana  http://ugspace.ug.edu.gh 147 
 
DAY 9 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 18.3421 4 4.58553 1101.51 0.0000 
Within groups 0.0416294 10 0.00416294   
Total (Corr.) 18.3837 14    
 
Appendix 14: ANOVA Table for MOULDS AND YEASTS GROWTH of Tomato Fruits 
Following CaCl2 Coating and Storage at Ambient Temperature (28±1°C)  
DAY 9 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 1.98693 4 0.496732 2847.60 0.0000 
Within groups 0.00174439 10 0.000174439   
Total (Corr.) 1.98867 14    
 
Appendix 15: ANOVA Table for MOULDS AND YEASTS GROWTH of Tomato Fruits 
Following Gamma Radiation Application and Storage at Low Temperature (10±1°C)  
DAY 10 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 5.84049 4 1.46012 5736.01 0.0000 
Within groups 0.00254554 10 0.000254554   
Total (Corr.) 5.84304 14    
 
DAY 15 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 20.4743 4 5.11857 78.61 0.0000 
Within groups 0.651156 10 0.0651156   
Total (Corr.) 21.1254 14    
 
DAY 20 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 3.5111 4 0.877775 1.92 0.1830 
Within groups 4.5628 10 0.45628   
Total (Corr.) 8.0739 14    
 
DAY 25 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 2.93206 4 0.733015 359.57 0.0000 
Within groups 0.0203857 10 0.00203857   
Total (Corr.) 2.95244 14    
 
 
 
 
 
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Appendix 16: ANOVA Table for MOULDS AND YEASTS GROWTH of Tomato Fruits 
Following CaCl2 Coating and Storage at Low Temperature (10±1°C)  
DAY 10 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 12.9664 4 3.2416 35288.44 0.0000 
Within groups 0.000918601 10 0.0000918601   
Total (Corr.) 12.9673 14    
 
DAY 15 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 26.0584 4 6.51461 104.66 0.0000 
Within groups 0.622484 10 0.0622484   
 Total (Corr.) 26.6809 14     
DAY 20 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 11.7176 4 2.9294 4344.83 0.0000 
Within groups 0.00674226 10 0.000674226   
Total (Corr.) 11.7243 14    
 
DAY 25 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 17.166 4 4.2915 4261.94 0.0000 
Within groups 0.0100693 10 0.00100693   
Total (Corr.) 17.1761 14    
 
Appendix 17a: ANOVA Table for WEIGHT LOSS of Tomato Fruits Following Gamma 
Radiation Application and Storage at Ambient Temperature (28±1°C)  
DAY 3 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 8.1783 4 2.04458 179300.90 0.0000 
Within groups 0.00011403 10 0.000011403   
Total (Corr.) 8.17841 14    
 
DAY 6 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 55.5207 4 13.8802 28502.05 0.0000 
Within groups 0.00486989 10 0.000486989   
Total (Corr.) 55.5256 14    
 
DAY 9 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 410.506 4 102.627 3696.50 0.0000 
Within groups 0.277632 10 0.0277632   
Total (Corr.) 410.784 14    
 
 
University of Ghana  http://ugspace.ug.edu.gh 149 
 
Appendix 17b: ANOVA Table for WEIGHT LOSS of Tomato Fruits Following Gamma 
Radiation Application and Storage at Low Temperature (10±1°C)  
DAY 5 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 319.621 4 79.9052 5051755.66 0.0000 
Within groups 0.000158173 10 0.0000158173   
Total (Corr.) 319.621 14    
 
DAY 10 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 285.473 4 71.3683 7632012.38 0.0000 
Within groups 0.0000935118 10 0.00000935118   
Total (Corr.) 285.473 14    
 
 
DAY 15  
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 1034.05 4 258.512 16225637.79 0.0000 
Within groups 0.000159323 10 0.0000159323   
Total (Corr.) 1034.05 14    
 
DAY 20  
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 1656.99 4 414.248 301024074.11 0.0000 
Within groups 0.0000137613 10 0.00000137613   
Total (Corr.) 1656.99 14    
 
DAY 25  
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 3103.92 4 775.98 2996075928.03 0.0000 
Within groups 0.00000258999 10 2.58999E-7   
Total (Corr.) 3103.92 14    
 
 
Appendix 18a: ANOVA Table for WEIGHT LOSS of Tomato Fruits Following CaCl2 Coating 
and Storage at Low Temperature (10±1°C)  
DAY 5 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 334.378 4 83.5946 175821.38 0.0000 
Within groups 0.00475452 10 0.000475452   
Total (Corr.) 334.383 14    
 
DAY 10  
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 336.369 4 84.0922 169606.41 0.0000 
Within groups 0.00495808 10 0.000495808   
Total (Corr.) 336.374 14    
 
 
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DAY 15 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 1133.72 4 283.43 362470.89 0.0000 
Within groups 0.00781939 10 0.000781939   
Total (Corr.) 1133.73 14    
 
DAY 20 
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 1777.8 4 444.449 963613.99 0.0000 
Within groups 0.00461231 10 0.000461231   
Total (Corr.) 1777.8 14    
 
DAY 25  
Source Sum of Squares Df Mean Square F-Ratio P-Value 
Between groups 3112.88 4 778.221 465055.26 0.0000 
Within groups 0.0167339 10 0.00167339   
Total (Corr.) 3112.9 14