SOYBEAN (GLYCINE MAX) PROCESSING AND PERFORMANCE 
IN FERMENTED MAIZE DOUGH SYSTEM
BY .
ERIC WILLIAM AMPADU
A Thesis submitted to the Department of Nutrition and 
Food Science, University of Ghana, Legon in partial 
Fulfilment of the requirements for the Award of a 
Master of Philosophy Degree in Food Science.
OCTOBER 1994
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345285
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DECLARATION
This research project was done by me under the supervision 
of Professor S. Sefa-Dedeh, of the Department of Nutrition and 
Food Science, University of Ghana.
Candidate Supervisor
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DEDICATION
To my Family.
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ABSTRACT
The effect of addition of processed soybean flour on the 
physicochemical characteristics of fermented maize dough was 
studied.
Soybean flours; Full-fat, Extruded, and Defatted soy-flours were 
processed and added to maize dough before and after fermentation 
of the dough. The soy were added to the dough at 0,10,and 20 
percent concentrations. The dough samples were also fermented at 
0,6,24 and 4 8 hours respectively. Two traditional food products; 
Ga kenkey and Akasa (Porridge) were also prepared from the soy- 
maize dough samples and subjected to sensory evaluation to assess 
product performance. Physicochemical analysis indicated that pH 
of the soy-fortified, dough was affected significantly by the 
method of addition of the soy flour, soy-flour concentration, and 
the fermentation time. Total titratable acidity of the soy-maize 
doughs were dependent on these factors. Generally pH of the dough 
decreased and total titratable acidity increased with increase 
fermentation time. Addition of Full fat soy flour to the maize 
dough before fermentation was found to promote fermentation 
resulting in higher acidity of dough. Hence increase in sourness 
of the dough. Regression models for pH and total titratable 
acidity were developed to predict various indices in the soy- 
maize dough systems. Water absorption characteristics of the 
samples were observed to be dependent' on the temperature and
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fermentation time. Water absorption at 70°C were generally 
higher than at 29°C.
Amylograph pasting properties indicate that addition of soy- 
flour to maize dough caused a reduction in viscosity. Viscosity 
characteristics generally increased with increase in fermentation 
time. The soy fortified maize dough showed lower viscosity 
characteristics compared to the maize dough(no soy) sample. 
Sensory analysis indicated the Ga-kenkey and Akasa prepared from 
soy-fortified maize dough generally showed lower mean scores 
hence lower consumer preference for colour, taste, flavour and 
texture compared with samples containing no soy flour. General 
acceptability scores indicated no significant difference between 
samples containing no soy flour and that containing Full fat soy 
flour in which soy was added after fermentation of the maize 
dough. The two samples were also most acceptable to the 
consumers. The incorporation of Full-fat soy flour to Ga-kenkey 
and Ak'asa is therefore promising. Difference test (Triangle test) 
also revealed significant differences in colour, taste, texture 
and flavour between the maize dough (no-soy) samples and the soy- 
fortified maize dough samples indicating the influence, of soy- 
flours addition on sensory characteristics.
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VACKNOWLEDGEMENT
I wish to express my sincere gratitude to my supervisor;
Prof. Samuel Sefa-Dedeh for his useful suggestions, tolerance, 
guidance and help which has made this work successful.
I gratefully acknowledge the various help that the general 
workers in the Nutrition and Food Science Department gave to me.
I am indebted very much for this willing cooperation 
throughout the degree course, perticularly the carrying out of 
the research project.
I also wish to recognise with thanks Mr. Frank Anku,
Mr. Mireku-Sarpong, Mr. Acquah and Mr ■ Isaac Quist for their 
effort in making the typing and editing of this report possible.
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vi
TABLE OF CONTENTS
DECLARATION...................................................... 1
DEDICATION..................................................... id-
ABSTRACT....................................................... ii;L
ACKNOWLEDGEMENT ...............................................  v
TABLE OF CONTENTS............................................. vi
LIST OF T A B L E S ................................................. xi
LIST OF FIGURES................................................xiv
1.0 INTRODUCTION .........................................  1
1.1 COMPOSITION OF SOYBEAN ........................ 1
1.2 SOYBEANS IN G H A N A ..............................  2
1.3 FERMENTED MAIZE MEAL-AN INTERMEDIATE 
TRADITIONAL FOOD PRODUCT ....................... 3
1.4 O B J E C T I V E S ..................................... 6
2.0 LITERATURE REVIEW ...................................  7
2.1 THE USE OF PLANT PROTEIN TO SOLVE THE
PROTEIN PROBLEM .............................  7
2.2 WORLD TRENDS IN SOYBEAN PRODUCTION ............  7
2.3 SOYBEAN IN G H A N A ...............................  8
2.4 SOYBEAN - NUTRITIONAL QUALITY ..................  9
2.4.1 ANTINUTRITIONAL FACTORS IN SOYBEA . . 10
2.5 SOYBEANS - PROCESSING AND UTILIZATION .........  13
2.5.1 WHOLE S O Y B E A N ........................  13
2.5.2 SOYFLOURS . . . . .    14
2.5.3 SOYBEAN G R I T S ......................... 15
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2.5.4 SOYBEAN PROTEIN CONCENTRATE .........  16
2.5.5 SOYBEAN PROTEIN ISOLATE .............  16
2.6. THE EFFECT OF PROCESSING ON SOYBEAN PRODUCT
QUALITY.........................................  17
2.6.1 EFFECT OF H E A T I N G .................... 17
2.6.2 EFFECT OF D E H U L L I N G .................. 19
2.6.3 EFFECT OF FERMENTATION...............  20
2.6.4 EXTRUSION OF S O Y B E A N S ...............  2 0
2.7 MAIZE PROCESSING IN GHANA ....................... 23
2.7.1 FERMENTATION OF M A I Z E ..................  26
2.7.2 PHYSICOCHEMICAL CHANGES DURING 
FERMENTATION.......................... 28
2.7.3 2.7.3 MICROBIOLOGICAL, NUTRITIONAL AND SENSORY
CHANGES IN MAIZE FERMENTATION . . .  30
3.0 MATERIALS AND M E T H O D S ..............................  35
3.1 M A T E R I A L S .....................................  35
3.1.1. MAIZE ................................. 35
3.1.2 SOYBEANS - VARIETY TGX 356   35
3.2 MAIZE D O U G H ...................................  3 6
3.3 SOY-FORTIFIED MAIZE DOUGH ....................  3 6
3.4 EXPERIMENTAL METHODS ........................  3 7
3.4.1 CHEMICAL ANALYSIS ....................  37
3.4.1(a) MOISTURE ........................ 37
(b) P R O T E I N ........................ 37
(c) F A T ............................  37
(d) A S H ............................  37
(e) TOTAL TITRATABLE ACIDITY AND pH 3 7
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3.5 FUNCTIONAL PROPERTIES . ...................... 38
3.5.1 WATER ABSORPTION ......................  38
3.5.2 V I S C O S I T Y ............................  38
3.6 FIELD SENSORY EVALUATION ..................... 39
3.7 STATISTICAL ANALYSIS .........................  39
4.0 RESULTS AND DISCUSSION..............................  40
4.1 CHEMICAL EVALUATION ...........................  4 0
4.2 pH CHARACTERISTICS OF SOY-FORTIFIED MAIZE
D O U G H ......................................... 41
4.2.1 REGRESSION MODELS FOR-pH ................ 46
4.3 ACIDITY CHARACTERISTICS OF-SOY MAIZE DOUGH . . ' 54
4.3.1 REGRESSION MODEL FOR ACIDITY .........  58
4.4 WATER ABSORPTION CHARACTERISTICS OF SOY-MAIZE 
D O U G H ...........................................  66
4.5 VISCOSITY CHARACTERISTICS OF SOY-MAIZE DOUGH . 72
4.5.1 PEAK VISCOSITY....................  82
4.5.2 VISCOSITY AT 95°C AND 95°C HOLD . . . .  83
4.5.3 VISCOSITY AT 50°C AND 50°C HOLD . . . .  89
4.5.4 PASTING TEMPERATURE ................. 90
4 .6 CONSUMER PERCEPTION OF SOY-FORTIFIED MAIZE DOUGH IN 
GA-KENKEY AND AKASA ..........................  91
4.6.1 CONSUMER PREFERENCE FOR GA-KENKEY . . .  91
4.6.2 CO L O U R............................  91
4.6.3 T E X T U R E .....................................93
4.6.4 T A S T E ....................................... 95
4.6.5 FLA V O R ....................................... 95
4.6.6 ACCEPTABILITY.............................. 98
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4.S.7 PROCESSORS' EVALUATION OF GA KENKEY . . 100
4.7 DIFFERENCE TEST ANALYSIS ONGA-KENKEY . . . .  101
4.7.1 Set A ...................................  101
4.7.2 Set B ...................................  102
4.7.3 Set C ...............................   102
4.7.4 Set D .................................... 103
4.7.5 Set E .................................... 103
4.7.6 Set F ...........    104
4.8 SENSORY EVALUATION OF AKASA PORRIDGE . . . .  104
4.8.1 CO L O U R ..................................  104
4.8.2 T E X T U R E ................................  105
4.8.3 T A S T E ..................................  106
4.8.4 F L A V O U R ..........., ................   . 107
4.8.5 ACCEPTABILITY.......................... 108
4.9 DIFFERENCE TEST ON A K A S A ...................  110
4.9.1. Set A:   110
4.9.2. Set B ...................................  110.
4.9.3 Set C .....................................  Ill
4.9.4 Set D .....................................  Ill
4.9.5 Set E .....................................  Ill
4.9.6 Set F ...........................   112
4.10 SUMMARY OF COMMENT BY TASTE PANELLISTS . . 112
A GA- KE N K E Y ..................................  112
B A K A S A ....................................... 113
5.0 CONCLUSION..................................  115
6.0 R E F E R E N C E S ......................................... H 8
APPENDIX
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Table 1. COMPOSITION OF S O Y B E A N .......................  3
Table 2 TYPICAL PERCENTAGE COMPOSITION OF SOY-PROTEIN . 14
Table 3. EFFECT OF STEAMING ON FLAVOUR OF SOYBEAN . . .  19
Table 4. PROXIMATE COMPOSITION OF SOME MAIZE VARIETIES IN
G H A N A ...........................................  24
Table 5. COMPOSITION OF PROCESSED SOYBEAN AND MAIZE FLOUR 40
Table 6 . MOISTURE AND PROTEIN CONTENT OF MAIZE DOUGH CONTAINING
DIFFERENT LEVELS OF SOYFLOUR .................  41
Table 7 ANALYSIS OF VARIANCE FOR SOY-MAIZE DOUGH pH . . 45
Table 8 . REGRESSION MODEL FOR pH OF SOY-MAIZE DOUGH . . 47
Table 9 ANALYSIS OF VARIANCE FOR SOY-MAIZE,DOUGH
ACIDITY.........................................  57
Table 10 REGRESSION MODEL FOR A C I D I T Y .................  59
Table 11 ANALYSIS OF VARIANCE FOR WATER ABSORPTION OF SOY-
MAIZE D O U G H ..................................... 67
Table 12 VISCOSITY CHARACTERISTICS OF MAIZE DOUGH (WITH NO
SOY) ...........................................  80
Table 13 VISCOSITY CHARACTERISTICS OF MAIZE DOUGH
FORTIFIED WITH FULLFAT SOYFLOUR (AFF) (10% & 20%
SOY LEVEL) ....................................  8 0
Table 14 VISCOSITY CHARACTERISTICS OF MAIZE DOUGH
FORTIFIED WITH EXTUDED SOYFLOUR (AFF) (10% & 20%
SOYLEVEL)....................................... 80
Table 15 VISCOSITY CHARACTERISTICS OF MAIZE DOUGH FORTIFIED
WITH DEFATTED SOYFLOUR (AFF) (10% & 2 0% SOYLEVEL) 81
LIST OP TABLES V'-\
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Table 16 VISCOSITY CHARACTERISTICS OF MAIZE DOUGH FORTIFIED
WITH FULL FAT (BFF)(10% & 20% SOYLEVEL) . . . .  81
Table 17 VISCOSITY CHARACTERISTICS OF MAIZE DOUGH FORTIFIED
WITH EXTUDED SOYFLOUR (BFF)(10% & 20% SOYLEVEL) 81
Table 18 VISCOSITY CHARACTERISTICS OF MAIZE DOUGH
FORTIFIED WITH DEFATTED SOYFLOUR (BFF) (10% & 20%
SOYLEVEL)................................  82
Table 19. ANALYSIS OF VARIANCE FOR PEAK VISCOSITY . . . .  82
Table 20. ANALYSIS OF VARIANCE FOR VISCOSITY AT 95°C . . 86
Table 21. ANALYSIS OF VARIANCE FOR VISCOSITY AT 95°C
H O L D ....................................  8 6
Table 22. ANALYSIS OF VARIANCE FOR VISCOSITY AT 50°C . 90
Table 23 ANALYSIS OF VARIANCE FOR VISCOSITY AT 5 0°C
H O L D ....................................  90
Table 24. ANALYSIS OF VARIANCE FOR PASTING
TEMPERATURE.............................. 91
Table 25 ANOVA SUMMARY TABLE FOR C O L O U R ........ 92
Table 26 MULTIPLE RANGE ANALYSIS FOR COLOUR OF GA
K E N K E Y ..................................  93
Table 27 ANOVA SUMMARY TABLE FOR TEXTURE OF GA KENKEY . 94
Table 28 MULTIPLE RANGE ANALYSIS FOR TEXTURE OF GA
K E N K E Y ....................................  94
Table 29. ANOVA SUMMARY TABLE FOR TASTE OF GA KENKEY . . 95
Table 3 0 MULTIPLE RANGE ANALYSIS FOR TASTE OF GA KENKEY 96
Table 31 ANOVA SUMMARY TABLE FOR FLAVOUR OF GA KENKEY . . 97
Table 3 2 MULTIPLE RANGE ANALYSIS FOR FLAVOUR OF GA
K E N K E Y ............ or.
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Table 33. ANOVA SUMMARY TABLE FOR ACCEPTABILITY OF GA
K E N K E Y ..............................................98
Table 34 MULTIPLE RANGE ANALYSIS FOR ACCEPTABILITY OF GA
K E N K E Y ..............................................99
TABLE 35 PROCESSORS EVALUATION OF GA-KENKEY ..........  100
TABLE 36 RESULTS OF DIFFERENCE TEST FOR GA-KENKEY . . . 101
Table 37. ANOVA SUMMARY TABLE FOR COLOUR OF AKASA . . . .  105
Table 3 8 MULTIPLE RANGE ANALYSIS FOR COLOUR OF AKASA . . 105
Table 39. ANOVA SUMMARY TABLE FOR TEXTURE OF A K A S A ........ 10 6
Table 40 MULTIPLE RANGE ANALYSIS FOR TEXTURE OF AKASA . 106
Table 41. ANOVA SUMMARY TABLE FOR TASTE OF AKASA . . . .  107
Table 42 MULTIPLE RANGE ANALYSIS FOR TASTE OF AKASA . . 107
Table 43. ANOVA SUMMARY TABLE FOR FLAVOUR OF AKASA . . . 108
Table 44 MULTIPLE RANGE ANALYSIS FOR FLAVOUR OF AKASA . 108
Table 45. ANOVA SUMMARY TABLE FOR ACCEPTABILITY OF
A K A S A ...........................................  109
Table 46. MULTIPLE RANGE ANALYSIS FOR ACCEPTABILITY OF
A K A S A ...........................................  109
TABLE 47 RESULTS ON DIFFERENCE TEST ON A K A S A ..........  110
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xiii
LIST OF FIGURES
FIGURE 1 AKASA (KOKO) PORRIDGE PREPARATION ...........  25
FIGURE 2 GA KENKEY PROCESSING ..........................  27
FIGURE 3. EFFECT OF FERMENTATION TIME ON pH OF SOY-
FORTIFIED MAIZE DOUGH (SOY ADDED BEFORE
FERMENTATION OF MAIZE DOUGH) .................  42
FIGURE 4. EFFECT OF FERMENTATION TIME ON pH OF SOY-
FORTIFIED MAIZE DOUGH (SOY ADDED AFTER
FERMENTATION OF MAIZE DOUGH) .................  43
FIGURE 5 RESPONSE SURFACE PLOT ON THE EFFECT OF
FERMENTATION AND SOY CONCENTRATION ON pH OF 
DEFATTED SOY FORTIFIED MAIZE DOUGH (DFAF) . . 48
FIGURE 6 RESPONSE SURFACE PLOT ON THE EFFECT OF
FERMENTATION AND SOY CONCENTRATION ON pH OF 
EXTRUDED SOY FORTIFIED MAIZE DOUGH (EXAF) . . 49
FIGURE 7 RESPONSE SURFACE PLOT ON THE EFFECT OF
FERMENTATION AND SOY CONCENTRATION ON pH OF FULL
FAT SOY FORTIFIED MAIZE DOUGH (FFAF)......... 50
FIGURE 8 RESPONSE SURFACE PLOT ON THE EFFECT OF
FERMENTATION AND SOY CONCENTRATION ON pH OF 
DEFATTED SOY FORTIFIED MAIZE DOUGH (DFBF) . . 51
FIGURE 9 RESPONSE SURFACE PLOT ON THE EFFECT OF
FERMENTATION AND SOY CONCENTRATION ON pH OF 
EXTRUDED SOY FORTIFIED MAIZE DOUGH (EXBF) . . 52
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FIGURE 10 RESPONSE SURFACE PLOT ON THE EFFECT OF
FERMENTATION AND SOY CONCENTRATION ON pH OF 
FULL-FAT SOY FORTIFIED MAIZE DOUGH (FFBF) . - 53
FIGURE 11 EFFECT OF FERMENTATION TIME ON ACIDITY OF SOY-
FORTIFIED MAIZE DOUGH (SOY ADDED BEFORE
FERMENTATION OF MAIZE DOUGH) .................  55
FIGURE 12 EFFECT OF FERMENTATION TIME. ON ACIDITY OF SOY-
FORTIFIED MAIZE DOUGH (SOY ADDED AFTER
FERMENTATION OF MAIZE DOUGH) .................  56
FIGURE 13 RESPONSE SURFACE PLOT ON THE EFFECT OF
FERMENTATION AND SOY CONCENTRATION ON ACIDITY 
OF DEFATTED SOY FORTIFIED MAIZE DOUGH (DFBF) . 60
FIGURE 14 RESPONSE SURFACE PLOT ON THE EFFECT OF
FERMENTATION AND SOY CONCENTRATION ON ACIDITY OF 
EXTRUDED SOY FORTIFIED MAIZE DOUGH (EXAF) . . 61
FIGURE 15 RESPONSE SURFACE PLOT ON THE EFFECT OF
FERMENTATION AND SOY CONCENTRATION ON ACIDITY OF 
FULL-FAT SOY FORTIFIED MAIZE DOUGH (FFAF) . . 62
FIGURE 16 RESPONSE SURFACE PLOT ON THE EFFECT OF
FERMENTATION AND SOY CONCENTRATION ON ACIDITY OF 
DEFATTED SOY FORTIFIED MAIZE DOUGH (DFAF) . . 63
FIGURE 17 RESPONSE SURFACE PLOT ON THE EFFECT OF
FERMENTATION AND SOY CONCENTRATION ON ACIDITY OF 
EXTRUDED SOY FORTIFIED MAIZE DOUGH (EXBF) . . 64
FIGURE 18 RESPONSE SURFACE PLOT ON THE EFFECT OF
FERMENTATION AND SOY CONCENTRATION ON ACIDITY OF 
FULL-FAT SOY FORTIFIED MAIZE DOUGH (FFBF) . . 65
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FIGURE 19. EFFECT OF FERMENTATION TIME ON WATER ABSORPTION 
OF SOY-FORTIFIED MAIZE DOUGH AT 29°C 
(SOY ADDED AFTER FERMENTATION OF MAIZE DOUGH) 68
FIGURE 20. EFFECT OF FERMENTATION TIME ON WATER ABSORPTION 
OF SOY-FORTIFIED MAIZE DOUGH AT 29°C 
(SOY ADDED BEFORE FERMENTATION OF MAIZE DOUGH) 69
FIGURE 21. EFFECT OF FERMENTATION TIME ON WATER ABSORPTION 
OF SOY-FORTIFIED MAIZE DOUGH AT 70°C (SOY ADDED
AFTER FERMENTATION OF MAIZE DOUGH) ........... 70
FIGURE 22. EFFECT OF FERMENTATION TIME ON WATER ABSORPTION 
OF SOY-FORTIFIED MAIZE DOUGH AT 70°C (SOY ADDED
BEFORE FERMENTATION OF MAIZE DOUGH) ......... 71
FIGURE 23 BRABENDER VISCOSITY CHARACTERISTICS OF MAIZE
DOUGH (WITH NO SOY) ..........................  73
FIGURE 24 BRABENDER VISCOSITY CHARACTERISTICS OF SOY-
FORTIFIED MAIZE DOUGH (WITH 10% FULL FAT SOY) 74
FIGURE 25 BRABENDER VISCOSITY CHARACTERISTICS OF SOY-
FORTIFIED MAIZE DOUGH (WITH 20% FULL FAT SOY) 75
FIGURE 26 BRABENDER VISCOSITY CHARACTERISTICS OF SOY-
FORTIFIED MAIZE DOUGH (WITH 10% DEFATTED SOY) 76
FIGURE 27 BRABENDER VISCOSITY CHARACTERISTICS OF SOY-
FORTIFIED MAIZE DOUGH (WITH 20% DEFATTED SOY) 77
FIGURE 28 BRABENDER VISCOSITY CHARACTERISTICS OF SOY-
FORTIFIED MAIZE DOUGH (WITH 10% FULL-FAT SOY) 78
FIGURE 29 BRABENDER VISCOSITY CHARACTERISTICS OF SOY-
FORTIFIED MAIZE DOUGH (WITH 20% EXTRUDED SOY) 79
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FIGURE 3 0 EFFECT OF SOY FORTIFICATION AND FERMENTATION ON PEAK
VISCOSITY OF MAIZE DOUGH (SOY ADDED BEFORE
FERMENTATION OF DOUGH) ........................ 84
FIGURE 31 EFFECT OF SOY FORTIFICATION AND FERMENTATION ON PEAK
VISCOSITY OF MAIZE DOUGH (SOY ADDED AFTER FERMENTATION
OF DOUGH) ..................................... 85
FIGURE 32 EFFECT OF SOY FORTIFICATION AND FERMENTATION ON
VISCOSITY AT 95°C OF MAIZE DOUGH (SOY ADDED
BEFORE FERMENTATION OF DOUGH) ...............  87
FIGURE 33 EFFECT OF SOY FORTIFICATION AND FERMENTATION ON
VISCOSITY AT 95°C OF MAIZE DOUGH (SOY ADDED 
AFTER FERMENTATION OF D O U G H ) ...............  88
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1.0 INTRODUCTION
Economic, social and anthropological factors contribute 
to the incidence of protein malnutrition in developing 
countries. These factors, coupled with the present world food 
crisis particularly in the developing countries, calls for 
research into local food sources that can act as supplements 
to alleviate the problem of protein-energy malnutrition. 
Plant protein foods have important source of relatively good 
quality protein and they make substantial contribution to 
energy. The legumes are rich in the essential amino acid 
lysine but deficient in sulphur-containing amino acids such 
as cysteine and methionine (Bressani, 1974).
Among the legumes include soybean, cowpeas, groundnut, bambara 
beans, pigeon beans, mung beans, kidney bean.
1.1 COMPOSITION OF SOYBEAN
Soybean is a leguminous plant and the most prominent 
among the legumes. The economic value of soybeans lies in 
their protein and fat content. Nutritionally, soybean rank 
high on protein quality in relation to other plant proteins 
e.g. the cereals,maize, rice, millet. It however ranks below 
fish, beef muscle, whole milk and whole egg. The.amino acid 
pattern of soybean protein approaches the optimum recommended 
by the Food and Agricultural Organisation (FAO). In addition 
soybeans appears to be a good source of required vitamins and 
minerals (Table 1). The lipid in soybean consists of a large 
proportion of polyunsaturated essential fatty acids and 
appreciable amount of carotene which is desirable (Table 1 )
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However, the proportion of unsaturated fatty acids depends on 
location, cultivar, environmental factors and the type of 
soil. (Fredler, 1971).
Soybean like many other legumes contains over 20 
antinutritional factors such as Trypsin inhibitors, phytates, 
haemaglutinins, amino acid analogues and flatus factors which 
elicit adverse nutritional and physiological responses 
(Plahar, 1976; Rackis, 1972; Yoshida, 1988).
Identification of these antinutritive factors and 
development of methods to eliminate them have led to the 
increasing use of soybeans and its products.
1.2 SOYBEANS IN GHANA
The usage of soybeans is limited in Ghana as far as its 
cultivation and utilisation for human consumption is 
concerned.
As a new and minor crop, soybean has attracted only a limited 
breeding research attention in Ghana. Previous breeding 
efforts were restricted to introduction and extensive 
evaluation of exotic germ plasm after which promising 
varieties were recommended to farmers for cultivation (Asafo- 
Adjei and Atuahene Amankwa, 1991) . The extent or scale of 
production of the crop however will depend among others on the 
extent of utilisation. In Ghana, widespread acceptance by 
consumers may only be a matter of time. Hence the promotion 
of soybean products or recipes which favour soybeans as part 
of normal Ghanaian food will be an important step towards 
increasing its utilisation.
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3Table 1. COMPOSITION OF SOYBEAN
Essential Amino acid 
Isoleucine
Amino acid content mq/Q Protein 
-------  370 ----
Ueuci ne
Lysine
Phenyalamine
Tyrosine
Methionine
Cysti ne
Threonine
Trytophane
Valine
430
400
310
200
80
110
250
90
330
Fatty Acid comDosition Ranqe (%)
(Saturated Acids)
Lauri c 0.0 - 0.2
Myristic 0.1 - 0.4
Palmitic 0.5 - 9.8
Stearic 2.4 - 5.5
Arachidic 0.2 - 0.9
Li gnoceri c 0.0 - 0.1
Total Saturated Acid
Unsaturated Acids
Uedecenoic
Tetradecenoic 0.05 - 0.64
Hexadecenoic & Palmitoleic 0.42 - 1.60
Oleic 10.9 - 60.0
Linoleic 25.0 - 64.8
Linolenic 0.3 - 12.1
Arachidonic Traces
Total Unsaturated Acid 85.0
Mineral Meal Percentage
CaIcium 0.24 -0.31 "
Phosphorus 0.60
Magnesi un 0.24 - 0.30
Zinc (mg/kg) 55 - 77
Iron 140
Vitamins Meal Percentaae
Riboflavin
Niacin
Pyridoxine
Biotin
Panthotheic acid 
Folic Acid 
Inositol
2.7 - 3.3 
19.0 - 40.0 
8.8 
1.1 - 1.7 
13.3 - 16.0 
3.7 
2500 - 390
Source: Fe rrie r L.K 1976 Simple Processing of whole Soybean as Food. Expanding use o f Soybeans. Proceedings o f a conference For A s ia  and Oceania IWT SOY 
Pub). No. 10 pl30.
1.3 FERMENTED MAIZE MEAL-AN INTERMEDIATE TRADITIONAL FOOD 
PRODUCT
Maize is eaten in many forms in Ghana such as fermented 
paste, porridge, roasted maize snacks, boiled and germinated 
and other preparations of the grain. The grains are generally 
milled and processed further into other products. Of all the 
processes used in preparation of the grain, fermentation is 
one of the most important process as fermented maize meal is 
used extensively in Ghana and other West African countries as 
part of their main diet and for various other food product 
(Plahar and Leung, 1983).
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Among the traditionally known fermented maize products are 
namely:
(i) Akasa or Koko which is fermented maize dough 
cooked into porridge.
(ii) Kenkey fermented maize dough in which one-third 
of dough is cooked and mixed with the other 
uncooked portion and boiled.
(iii) Maasa :- which is spiced and fried fermented maize 
dough.
(iv) Kaffa fermented maize dough treated differently
and cooked into solid pap.
(v) Banku :- fermented maize dough mixed with or 
without fermented cassava dough (Agbelima) and 
cooked into solid dumpling. (Sefa-Dedeh, 1993)
In all these processed fermented maize products,
fermented maize dough is the intermediate base product. The 
products are also important for several reasons which include 
increased shelf-life, attractive flavour, texture, improvement 
of palatability and nutritional value and reduction of bulk 
and required cooking time.
These fermented maize food products have low protein 
quality and therefore call for the development of high protein 
mixtures in Ghana. The solution lies in the use of
intermediate cereal products with widespread utilisation (eg. 
fermented maize dough) as base material for the fortification 
or blending. Such blending or fortification can be achieved
with the use of high protein seeds such as soybeans. However,
there is the need to investigate the impact or effect of
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incorporated soybeans on the sensory and functional properties 
requirements for the intended food uses. This may be an 
important step in the development and maintenance of the
desired quality of the soy-fortified product. It is also
essential that the criteria of quality applied to each
traditional product be identified. This will require intimate 
and accurate knowledge of the nature (colour, texture, taste 
and flavour) of the traditional food and the behaviour 
(physical and chemical) of the processed soybean being used 
or incorporated into the traditional food product.
In order to derive maximum benefits and desired
acceptability from the soy fortified maize dough product two 
or more of the under-listed factors must be considered or 
achieved.
(i) The product must be low cost with easy method of 
preparation.
(ii) The product must be designed to meet local 
acceptability requirements. Thus the product must be 
engineered or modified to resemble a traditionally 
acceptable product with respect to taste, texture, 
flavour and colour.
(iii) The product should have a relatively long shelf-life 
at ambient conditions.
(iv) The product must have easy handling and storage 
characteristics.
Thus, the challenge is not only in formulating a nutritious 
food but also in fabricating a protein rich food that has the 
identical intrinsic or more desirable colour, flavour, texture
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and functional characteristics of the traditionally accepted 
food and at low cost.
1.4 OBJECTIVES
The following objectives were set for this study.
1. General Objective:
(a) Determine the effect of processed soybeans on the 
physicochemical and sensory characteristics of soy 
flour-maize dough blends.
2. Specific Objectives:
(a) Evaluate the effects of
(i) fermentation time
(ii) soy-flour type
(iii) soy-flour concentration
(iv) method of addition of soy flour
on the physico-chemical and functional indices 
of soy-fermented maize dough mixtures.
(b) Evaluate consumer perception or preference for soy- 
maize dough blends in selected Ghanaian foods; case 
study on Ga-kenkey and "Akasa" porridge.
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2.0 LITERATURE REVIEW
2 .1 THE USE OF PLANT PROTEIN TO SOLVE THE PROTEIN PROBLEM
The protein food crisis in the developing countries has 
led to research into promising under-exploited and non- 
conventional protein source that can act as supplements to 
available foods (Fulmer, 1989). The use of vegetable source 
of protein for dietary supplementation is highly relevant in 
developing countries (Lockmiller,1973; Fulmer, 1989). The 
production of vegetable products requires lesser use of 
scarce resources than the production of animal products though 
wide variation exists according to the nature of individual 
products and the geographical location. Vegetable products 
as a class are generally cheaper than animal products. The 
protein nutritive value of some vegetable foods are comparable 
to meat and fish (Fulmer, 1989) . Of the vegetable protein 
source the legumes are important protein source. Among the 
legumes, soybean which is easy to cultivate in most soils has 
been recommended for developing countries.
2.2 WORLD TRENDS IN SOYBEAN PRODUCTION
There has been unprecedented growth in the worldwide 
production and utilization of soybean due to the high 
concentration of excellent protein and a moderate content of 
oil useful for oil and industrial uses (Fredler, 1971) .
This has resulted in the development of a worldwide 
marketing and processing technology covering the seeds and its 
main products. Soybeans and its products are the most
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exported agricultural commodities running into billions of 
dollars annually (Fredler, 1971). It has also received the 
active attention of almost every facet of private and public 
agri-business. The meal and oil fractions are finding their 
way into more and more highly sophisticated applications for 
human use.
2.3 SOYBEAN IN GHANA
As at 1992 no official figures were available on soybean 
production in Ghana. Among some of the problems encountered 
in the introduction of soybeans in Ghana include the
following:
(a) low yielding ability of varieties of soybean grown by 
farmers.
(b) lack of varieties resistant to shattering, disease and 
insect pests.
(c) some processing techniques carried out domestically may 
be difficult to establish in areas to which they are not 
indigenous. Products made by these techniques may also 
have low acceptability outside the area or locality 
particularly where they have.a characteristic flavour.
(d) where soybean has been introduced as a cash crop its 
possibilities as a foodstuff are not recognised or 
exploited because the traditional methods of processing 
do not make the intended product acceptable to 
consumers.
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Research and introduction of new processes can therefore be 
used to make soybean products which are bland in taste and 
which mix with a variety of dishes commonly found in the 
country.
Recently the Grain development Project of Ghana 
introduced a new high yielding soybean varieties named 
'Bengbie' (wonderful bean). Compared to other soybean 
varieties in the country 'Bengbie' is
(i) resistant to shattering
(ii) nodulate freely with the indigenous cowpea/groundnut 
rhizobia in Ghana soils
(iii) have seed storagebility. Yield ranges from lOOOkg/ha 
in the coastal savanna to about 2 00 0kg/ha in the 
transitional and Guinea savanna zones (GGDP, 1993) .
2.4 SOYBEAN - NUTRITIONAL QUALITY
Soybean can produce the highest yield of protein per unit 
land area of any plant or animal food source (Arai et al. , 
1970). Compared with the other legume it provides the highest 
protein per gram.
Trace amount of starch has been reported in soybean. 
(Bressani, 1974) . The protein in soybean is known to be a good 
source of all essential amino acid except methionine and 
tryptophan (Sosulski 1983). The protein also has high lysine 
and therefore can be used to complement low lysine level in 
cereal based products. This reciprocal enhancement can 
upgrade the nutrition of people who subsist on protein 
deficient diets
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2.4.1 ANTINUTRITIONAL FACTORS IN SOYBEAN
Despite it's relatively good nutritional quality, soybean 
like other legumes contain various antinutritional factors 
which elicit adverse nutritional, biological and physiological 
responses (Holmes et al. 1982). The utilisation of soybeans 
has not paralleled production due to the presence of these 
antinutritional factors and toxic compounds which contribute 
to lower absorption rate and poor utilisation in the body 
(Grant, 1989). These factors include trypsin inhibitors, 
phytates, haemagglutinin, amino acid analogs, flatus factors 
and lipoxidase which affect overall nutritional value (Plahar, 
1976) .
Rackis (1972) reported that raw soybeans and underheated 
beans and their products may inhibit growth, depress 
metabolisable energy and fat absorption, reduce protein 
digestibility, cause pancreatic hypertrophy and reduce amino 
acid and mineral availability. In vitro evidence has shown 
that the human trypsin is weakly inhibited by soybean trypsin 
inhibitor (Grant, 1989). The haemagglutinin protein also has 
the unique property of being able to agglutinate red blood 
cells.
It has been shown that phytic acid in its natural form 
as phytate-mineral-protein complex in the seed decreases the 
availability of zinc, magnesium, phosphorus, calcium and iron 
(Spiller and Shipley, 1977).
Sosulski et al. (1982) reported the production of
intestinal gas following ingestion of dry mature legumes. 
This has been attributed to the presence oligosaccharides;
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raffinose and stachyose which pass into the large intestine 
where they are fermented anaerobically to produce gas.
The lipoxidase enzyme which causes the development of off 
flavour in soybean products has also attracted a lot of 
attention by researchers in recent times (Homma et al. , 1985) . 
The action of lipoxygenase during the rapturing of soybean 
results in the formation of compounds with objectionable beany 
flavour which are responsible for low acceptability of some 
soy-products. Investigation has identified a range of 
oxidation products of linoleic acid generated by lipoxygenase 
action which includes aldehydes, ketones and alcohol.
A raw green bean odour which is undesirable is produced 
by ethylvinyl ketone (an oxidation product) as reported by 
Wang and Toledo ( 1985) . The identification of these
antinutritive factors and development of methods to eliminate 
them have led to the increasing use of soybean and its 
products. Various methods that remove or inactivate the 
antinutritive factors have been reported (Ologhobo and 
Fetuga,1982) .
Many of these antinutritive factors can be eliminated or 
inactivated to a large degree by appropriate heat and 
processing during food preparation. The treatment may include 
dehulling, pre-soaking, steaming, cooking and germination, 
extrusion and fermentation. The various methods of heating 
include toasting (Gardiner, 1975), dry roasting (Johnson et 
al. 1980), heating in boiling water (Collins and Beaty, 1980) 
and micronisation (Hutton and Foxcroft, 1975) . Wang and 
Toledo (1987) showed that lipoxygenase activity was greatly
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reduced by microwave treatments. They reported that during 
microwave heating the time needed for enzymatic inactivation 
was shorter and the retention of protein solubility higher in 
comparison with other conventional methods. Pour et al. 
(1981) also indicate that dielectric heating at 42 MHz and 
2450 MHz is also efficient in improving the biological 
properties of soybeans.
Cheman et al. (1989) also showed that the inactivation
of lipoxygenase with acid was possible. They reported that 
inactivation of the enzyme was irreversible when treated at 
pH 3.0 and below irrespective of the acid used.
Fermentation has been shown to also reduce off-flavours 
and improve the sensory and nutritive value of 
soybeans(Parades-Lopez et al. 1989; Nishiya et al 1990).
Nishiya et al. (19 90) used three microorganisms including
Saccharomyces cerevisae to improve the flavour of commercial 
soy protein isolates (CPI). They reported that the 
microorganisms decrease such typical bean flavour due to 
hexanal, hexanol and l-octen-3-ol and increased preferable 
fermented flavour due to diacetyl and acetoin. The beany 
flavour has also been shown to be reduced by hydrating the soy 
product with a solution containing a water soluble primary 
yeast extract (from eg Saccharomyces cerevisae) prior to 
incorporation the soy product into a food (Swartz et al. 
1985) .
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2.5 SOYBEANS - PROCESSING AND UTILIZATION
Soybean utilisation and product quality are influenced 
by numerous factors including the beans characteristics 
(structural and chemical composition), specific soybean 
product types and • processing (pH, processing time and 
temperature). Soybean has a wide range of uses. The various 
category of soybean products which have a number of food 
applications are: (a) whole soybeans (b) soy flours (c)
soybean protein concentrate (70% protein) (d) soybean protein 
isolate (90% protein) (e) soy grits (f) extruded soy products. 
The food uses of the soybean products depend on a number of 
factors which must be recognised in considering soybean 
products for their ■functional properties such as enzyme 
activity, water soluble protein, fiber and carbohydrate 
content, flavour, particle size, presence or absence of 
lecithin and for their nutritional and economic value. Table 
2 shows the typical percent composition of the soy products.
2.5.1 WHOLE SOYBEAN
The whole soybean may be dehulled or boiled or roasted. 
It may be eaten as snack or as an intermediate product for 
intended food application.
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Table 2 TYPICAL PERCENTAGE COMPOSITION OF SOY-PROTEIN
PRODUCTS
14
ITEM 'WHOLE DEFATTED SOYPROTEIN SOYPROTEIN
SOYBEANS SOYFLOUR CONCENTRATES ISOLATES
MOISTURE 10 7 . 0 4 . 0 4 . 0
PROTEIN 30 52 . 0 68 . 0 92 . 0
FAT 18 1.0 1.0 0.1
FIBER 5 3.5 4.5 0.1
ASH 5 6 . 0 5 . 0 3.5
SOLUBLE
CARBOHYDRATE 12 12.5 2 . 0 0
INSOLUBLE
CARBOHYDRATE 12 18.5 28 . 0 0.1
Source: Orr E. and Adair D (1967). The Production of Protein 
Foods and Concentrates from oil seeds. Tropical Products Inst 
Report G31.
2.5.2 SOYFLOURS
Soy flours are obtained by solvent extraction or variable 
heat treatments which yield soyflours with different 
functional properties and chemical characteristics. Some soy 
flour are white, cooked or toasted and others are full fat or 
fat free (Bressani, 1974) . Soy flours are used in bakery 
products, soybean milk, high protein foods and protein 
supplements for cereal grain. The enzyme activity in full 
fat soy flour is taken advantage of to bleach wheat flour
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during baking. The full fat soy flour is made by cleaning the 
beans, dehulling and grinding to a fine flour. The enzyme 
active is used at 0.5 to 0.75% based on wheat flour. The 
flour may have a beany bitter flavour but at the level used 
shows little difference in flavour.
The action of the lipoxygenase enzyme system which is 
taken advantage of is the bleaching effect it exerts on the 
wheat flour pigments. The lipoxygenase system results in the 
formation of hydroperoxides which in turn reacts to give a 
bleaching effect with improvement in crumb color, crumb 
softness, keeping quality and flavour.
2.5.3 SOYBEAN GRITS
Soybean grits are obtained from defatted flakes and are 
similar to soybean flour with differing only in particle size. 
Soybean grits are coarser than soybean flour. The flour that 
passed through a 100 mesh US sieve or finer are referred to 
as flour products and those that are coarsely ground and 
screened referred to as grits. The soybean flour product are 
used for their functional characteristics such as water and 
fat absorption capacity which are influenced by the protein 
dispersion index (PDI) and particle size (Johnson, 1975) .
2.5.4 SOYBEAN PROTEIN CONCENTRATE
This is a soybean product with 70% protein in contrast 
to the flour or grits which contain 50% protein 
(Bressani,1974).
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It is obtained from defatted flakes after removal of the 
soluble carbohydrate fraction. In the process aqueous alcohol 
is used to extract the soluble carbohydrate, minerals and 
other components. The concentrate produced by the method has 
the least beany flavour. Such concentrate has the ability to 
absorb moisture and fat, hence are used in meat products, 
breakfast cereal bread, calf milk replacers etc. The soy 
protein produced by the acid leach process is neutralised at 
a pH of about 6.8 and spray dried. In the third process for 
producing concentrate the flakes or flour are heated to such 
a point to cause almost completely denatured proteins so that 
strong water wash remove solubles and give a product that has 
water and fat absorption.
2.5.5 SOYBEAN PROTEIN ISOLATE
This is a soy-product with not less than 90% protein and 
is usually obtained from defatted flakes after alkaline 
extraction and . isoelectric precipitation of the fraction 
(Visser et al. 1987) The products are high in protein, bland 
in flavour and have good functionality (Kim,1976).
Isolated soy proteins are essentially free of 
carbohydrates, fiber and fat. The have also a variety of 
properties different from concentrate and soyflours (Shiga et 
al. , 1987) . Among the important functional properties include 
emulsifying, fat binding, water- absorption, adhesiveness 
, cohesiveness, film forming, thickening, stabilizing and foam. 
They have been used successfully in imitating dairy type 
products as binder or emulsifier in commuted meat products.
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2.6. THE EFFECT OF PROCESSING ON SOYBEAN PRODUCT QUALITY
2.6.1 EFFECT OF HEATING
The nutritive value of soybean may be improved by heat 
treatment. The degree of nutritional improvement by heating 
depends among others on the temperature, duration of heating 
and pressure. The beneficial effects of heat treatment on the 
nutritive value is related to the inactivation of biologically 
active compounds (trypsin inhibitors and hemaglutinin which 
are thermolabile).
Boiling is essential to produce an acceptable texture and 
for practical purposes the desired texture dictate the boiling 
time required (Shiga et al. 1987) . The use of softened water 
(pH about 7.5 to 7.9) or 0.5% sodium bicarbonate solution 
results in rapid tenderization and reduce the cooking time to 
about one-third required in tap water. The use of the sodium 
bicarbonate results in slightly different taste compared to 
that of tap water. A high pH will increase the loss of 
thiamine . Soaking and boiling also removes about one-third 
of the oligosaccharides in soybeans which are partly 
responsible for the production of intestinal gas or flatus. 
Steam blanched soybean results in products which are bland in 
taste, chewy to tender in texture. Water blanched soybean 
contains 50% to 70% moisture and steam blanched have between 
20% to 30% moisture. Blanching simultaneously destroys the 
trypsin inhibitors, hemaglutinin and other known toxic factors 
present in the raw bean. The length of time required to 
destroy these components decreases with increased moisture 
content of the soybeans.
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The effect of steam on soybean flavour is summarised in 
Table 3 . The raw soybean meal is usually described as tasting 
beany, bitter and green. The green taste is reported to 
disappear after steaming for 3 mins at atmospheric pressure. 
The beany, bitter flavor, nutty sweet and toasted flavours 
varied in intensity with continued steaming. The data show 
that steaming longer than 2 0 mins which is approximately the 
time required for maximum nutritive value did not improve 
flavour score.
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Table 3. Effect of Steaming on Flavour of Soybean
19
Steaming time (mins) Flavour Score Flavour Description
0 1.5 beany, bitter, green
3 4.5 beany, bitter,
nutty,toasted, sweet
10 6 . 0 beany, nutty, bitter
toasted, sweet.
20 6.3 beany, nutty, bitter
toasted, sweet.
40 6 .1 beany, nutty, bitter
toasted, sweet.
1 = strong 10 = bland.
SOURCE: Smith and Circle (1972).
2.6.2 EFFECT OF DEHULLING
Soy hull has been reported to affect physical and sensory 
characteristic of food system (Ashraf et al. 1988)
Properties such as bulk volume, water holding capacity, oil 
holding capacity, ion exchange and particle size are affected 
(Ashraf et al. 1988) . They reported that soy-hulls constitute 
approximately 8% of the whole soybean with a representative 
composition of soy hulls as follows: 9.0% protein, 0 .9% fat,
86.2% total carbohydrate and 4.0% ash. The total carbohydrate 
may contain 29-34% hemicellulose, 42-49% cellulose and 1.4 to 
2.7% lignin.
Dehulling of soybean have been reported to have little 
relative effect on the specific trypsin inhibitor activity 
since it is higher in the cotyledon than in the cuticle.
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2.6.3 EFFECT OF FERMENTATION
Fermentation of soybean has been reported to improve 
digestibility. Ebine (1976) reported that during fermentation 
of koji, an oriental soybean product, digestibility is 
remarkably improved as a result of the enzyme in the koji and 
digestion of soybeans by salt-resistant microrganisms. He 
reported also that through fermentation of rice Miso, 60% of 
the protein is reduced to a water soluble form containing 
polypeptides and amino acids. Antinutritional factors and 
beany flavor which are problems affecting utilisation of 
soybean products have been reported to be reduced by 
fermentation.
2.6.4 EXTRUSION OF SOYBEANS
Extrusion cooking of soybean and soybeans product 
formulations is becoming an important and popular unit 
operation because of the versatility of the process. It is 
increasingly used in the manufacture of ready-to-eat (RTE) 
soy-cereal products. To maintain high quality of extrudate 
in a process that occurs at relatively short residence times, 
the flow of the dough and factors affecting it must be 
carefully controlled. The extruder die plays an important 
role in determining the texture characteristics of the 
finished product. In the developing countries the use of low 
cost extruder cookers (LCE's) in producing nutritious , 
precooked foods based on cereals and legumes is increasing 
(Brookwalter et al. 1971). The low cost extruders are single 
screw autogenous extruders that operate at low moisture (less
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than 20%) and require minimal auxiliary equipment( Harper and 
Jansen, 1985) All cooking heat is developed by friction 
through viscous dissipation of mechanical energy applied to 
the shaft of the extruder. Important processing parameters 
for product quality include moisture content of the food 
material, residence time which is influenced by feeding rate, 
screw speed configuration, die geometry, temperature and 
pressure (Harper and Jansen, 1981).
The extrusion process has been reported to increase 
digestibility, palatability and reduces antinutritive 
component. Maga and Lorenz (1978) observed that the overall 
aroma, and flavour intensity increased with increased 
temperature in extruding blends of corn and soy. They 
reported that moisture content of the feed material in the 
extruder significantly affected the expansion and product 
breaking strength of extrudates.
Temperature and moisture have significant effect in raw 
flour aroma of extrudate (Chen et al.. 1991; Molinna et al.. 
1983) Low temperature and high moisture results in high raw 
flour aroma. In addition high temperature and low moisture 
result in low raw flour aroma.
Several reasons have been advanced for the palatability 
of extrudates. During extrusion, starch is broken down into 
simpler components. Unpleasant volatile flavour components 
such as the beany taste of soybean are flashed of as the 
product is extruded from the barrels (Niele et al. 1980)
The cooking action of extruder increases the 
digestibility of protein and in some cases the availability
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of amino acids by breaking down the secondary bonds of the 
protein molecules. The heat produced and short dwell time are 
not sufficient to destroy the amino acids. Extrusion also 
denatures antinutritive factors such as trypsin inhibitors and 
harmful enzymes.
The digestibility of starch is greatly improved by extrusion 
through a combination of gelatinisation and expansion. As the 
product passes through the extruder it gelatinises due to the 
effect of heat and moisture under pressure.
Extrusion affects fat in several ways:
(i) the attrition and shear action cause walls of the 
oil bearing cells to rupture. This increases the 
availability of oil for digestion and hence the 
energy value of the raw material. In the extrusion 
of soybeans the bean is cooked and expand rapidly 
to deactivate the antimetabolites and rupture the 
oil cell. The liberated oil gives a product of 
liquid.quality and as it flows across a shovel the 
extruded meal absorbed the oil (Brookwalter et al. 
1971, Harper and Jansen,1985) .
(ii) Extrusion also results in improved stability
of fat by destroying lipase which causes 
rancidity. The shear action and attrition also 
causes an increase in the proportion of 
digestible fibres.
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2.7 MAIZE PROCESSING IN GHANA
Maize like other cereal provides a relatively good source 
of carbohydrate, protein and lipid which is essential to a 
balanced healthy diet.
\
Many varieties of maize are grown in Ghana. The 
varieties have different physical, chemical and functional 
characteristics which tend to affect their use in specific 
food product. The Proximate composition of some of the maize 
varieties are shown in Table 4. Ghana like most African 
countries has strong tradition associated with the type of 
food eaten and the processes applied for effective utilisation 
(Sefa-Dedeh,1988).
Traditional food processing methods play an important 
role in the processing and utilisation of maize foods in Ghana 
(Sefa-Dedeh, 1993; Dovlo, 1970). Most of the maize products 
available on the market for direct use are ready to eat foods 
or the food ingredient is processed using simple traditional 
technologies. The method of preparation is deep rooted in 
tradition and among the techniques employed in processing is 
the method of fermentation.
Some of the fermented maize products are associated 
with some ethnic groups in Ghana. For example Ga kenkey (or 
komi) for the Gas and Fante kenkey for the fantes. Some of 
the products involving fermentation of maize during 
preparation include Ga kenkey, Fanti Kenkey, Hausa Koko, 
Maasa, etc. Spontaneous fermentation is used in the
development of desired quality attributes (flavour, texture, 
taste, colour). e.g akasa (Fig.l).
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Table 4. PROXIMATE COMPOSITION OF SOME MAIZE VARIETIES IN
GHANA
VARIETY
MOISTURE
CONTENTS
PERCENT
ASH
CRUDE
PROTEIN FIBRE FAT
ABUROTIA 10 . 78 1.15 9 .49 5.70 7.38
COMPOSITE 15 . 06 0 . 88 9 .41 2 .31 3 . 06
DOBIDI 12.31 0 . 84 10 .12 2.17 5.93
HILYSINE 12 .36 1.29 11.30 2.70 5.88
LOCAL 10 .42 1.19 ■ 10.37 2.30 2 . 66
SAFITA 11.42 1.08 10.44 2 .20 5.13
SOURCE: Sefa-Dedeh (1988)
Interim report research on maize varieties grown on 
Ghana. University of Ghana, Legon.
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25
FIGURE 1 AKASA (KOKO) PORRIDGE PREPARATION
Maize
Soak
Mill
Meal
Ferment
Slurry
Cook
Porridge
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In Hausa koko preparation spices are added before 
fermentation. In addition combination of sorghum and corn can 
be used. In maasa processing spices are added before the 
fermentation stage and the milled maize dough obtained 
prepared into Aflata, fermented and fried.
2.7.1 FERMENTATION OF MAIZE
Methods of fermented dough preparation are not standard 
and wide variations exist in preparation and may depend on 
type of food product. Traditionally, maize dough preparation 
involves the general steps of steeping grains, milling, mixing 
into dough with water and spontaneous fermentation (1-3 days) . 
Each of the stages in the maize dough preparation is important 
in achieving the desired characteristics, e.g. in Ga-kenkey 
processing (Fig. 2) .
The soaking process softens the seed coat and the 
endosperm of the grain. Soaking also stimulates enzyme 
activity leading to breakdown of starch and increased 
proteolysis (Sefa-Dedeh, 1989) (Nyarko Mensah, 1972) The 
softening of the grain facilitates smooth milling and serves 
as first stage fermentation. Poor or inadequate softening 
results in chaffiness. Sefa-Dedeh, (1988) reported that the 
local variety of maize possesses good swelling characteristics 
compared to other high yielding varieties.
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FIGURE 2 Ga kenkey processing
Maize
27
Clean
Steep (18 - 48hrs) 
Mill (10 - 15mins)
Meal
Dough
[Fermentation] 48-72hrS'
Cook (30-45mins) Raw
[Mix 30-60min
Aflata
Mould & Package (2.3hr)
Boil (1 - 2.5hrs)
Ga Kenkey
Source: Sefa-Dedeh, S. (1993)
Fanti kenkey production also follows the same process with
difference only in the packaging material used.
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Milling of the soaked grain serves several purposes such 
as to increase the surface area of maize grain to facilitate 
processes such as mixing, fermentation and cooking. The 
milling also helps develop desired sensory quality such as 
taste, colour and texture (Sefa-Dedeh, 1988). With increase 
in flour fineness, water absorption increased whereas 
properties such as bulk density and cooked paste viscosity 
decreased (Sefa-D'edeh, 1989) . It was indicated that consumers 
preferred finely ground sample o f .fermented product.
Fermentation is an important step for development of 
flavour, texture, and aroma of food. The alteration of 
flavour and aroma is the result of microbial action which 
initiates a complex series of reactions involving namely 
carbohydrate, protein and fats.
The physicochemical, microbiological nutritional and 
sensory changes in fermented maize dough system has been 
documented by numerous researchers (Banigo and Muller, 1972; 
Plahar and Leung, 1982).
2.7.2 PHYSICOCHEMICAL CHANGES DURING FERMENTATION
Banigo and Muller (1972) identified eleven carboxylic 
acids in maize meal during fermentation of Ogi. The important 
acids they mentioned were lactic acid, acetic acid and butyric 
acid. Plahar and Leung (1982) working on the effects of 
moisture content on the development of carboxylic acids in 
traditional maize dough fermentation reported that the 
production of carboxylic acids during maize meal fermentation 
was influenced by the moisture content of dough. They
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mentioned that high moisture content of 65% and 80% results 
in high concentration of acids. However the desired volatile 
to non volatile acids was achieved with 52% moisture level and 
at pH of 3.7.
Acetic acid, propionic acid and butyric acids are the major 
volatile acids they identified. The average maize dough has 
been reported to contain 49.3% moisture content, 37.5 starch, 
titrable acidity of 4.3mg/NaoH/g and pH of 3.76 (Plahar and 
Leung 1983).
The acid produced has several purposes according to 
Steinkrauss (1982):
(i) it renders food resistant to spoilage by undesirable 
microorganism and development of food toxin.
(ii) makes the food less likely to transfer pathogenic 
organism
(iii) it modifies the flavour of original ingredient as in
maize dough fermentation
(iv) it enhances organoleptic and nutritional quality of 
the fermented product.
Associated with acid production is a corresponding decrease 
or fall in pH of maize dough during fermentation (Nketia 1979, 
Wayoe, 1987, Djokoto, 1982, Ackom-Quayson, 1993)
The lowering or reduction of pH of the dough which can 
be used to monitor the extent of fermentation is attributed 
to lactic acid and acetic acid production which are the end 
products of metabolism of sugar by glycolytic pathway. 
Functional properties such as water absorption capacity and 
swelling are affected by pH of the dough.
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Plahar (1983) reported on storage stability of air-dried 
fermented maize dough. He observed that total soluble 
carbohydrate increase during storage when the dough was air 
dried. He also reported that changes in pasting properties 
occur during storage. Adeyemi et al. (1986) investigating
into the storage stability of agidi, a Nigeria fermented maize 
product reported that the value of stability and index of 
gelatinisation were higher when the dough was prepared from 
dry milled flour than the wet milled.
2.7.3 MICROBIOLOGICAL, NUTRITIONAL AND SENSORY CHANGES
IN MAIZE FERMENTATION
Microbiologically it has been reported that during 
fermentation of maize dough a mixed population of microflora 
develops in the dough. Dyer (1986) assessing the microflora 
and nutritional enhancement of corn meal during fermentation 
identified some of the microorganisms involve in fermentation 
as Lactobacillus brevis. Streptococus faecalis. Aeromonas 
hvdrophila. Enterobacter cloacae, Aarobacterium s d p . Moraxella 
spp. These he mentioned produce vitamin B12 except 
Streptococus faecalis which produces riboflavin. A mixed 
population of lactic acid bacteria and yeast in the dough has 
also been reported (Chompeeda et al■. 1984; Djokoto, 1982) 
Field et al. (1981) reported that natural lactic fermentation 
occurs when water is mixed with corn meal and incubated at 
37°C. They isolated Lactobacillus fermentatum. Lactobacillus 
cellobiosus and Pediococcus acidilactic. They reported that 
viable coliforms, yeasts and molds disappear from the
30
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fermentation by the second day.
Djokoto, (1982) indicated that Aspergillus penicillin and 
Rhizopus spp were involved in initial stage of maize dough 
fermentation. However at the start of the fermentation Lactic 
acid bacteria, Leuconostoc mesentoroides. Pediococus cerevisae 
were present. Aspergillus niger, Aspergillus flavus and 
Leuconostoc mesentoroides were all observed from the sixth 
hour and persisted and proliferated throughout the 
fermentation period.
Yeasts such as Endomvcopsis , Saccharomyces Candida, 
Torula and Saccharomvcoides have been reported to be present 
during fermentation (Djokoto, 1982; Akinrele, 1970) . Thus, the 
moisture content and storage temperature influence the growth 
and survival of the microorganism.
Frazier (1978) reported that bacteria and mold population 
decrease rapidly in corn meal with 13% moisture. Aspergillus 
niger and Aspergillus flavus were observed to be growing on 
the surface of the dough (Mensah et al.. 1990).
Nutritionally the relative ■ nutritive value(RNV) of 
fermented maize dough has been observed to increase during 
fermentation (Fields and Yao 1990; Lin et al.. 1988)
Field et al. (1990) reported on the nutritional improvement
of maize meal by fermentation of Baccillus Iincheniformis and 
Enterobacter cloacae. The fermentation by the organism 
significantly increases the percent RNV. Amino acids such as 
methionine and Tryptophan content were reported to increase 
significantly. Enterobacter cloacae increased the lysine 
content and Total folacin significantly. Liu et al. (1988)
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investigating the production of panthothenic acid by 
microorganism isolated from fermented corn meal observed that 
during fermentation panthothenic acid increased from 
0.44mg/l00g to 1.84 mg/lOOg samples after 3, days fermentation. 
Baccillus lincheniformis they indicate was partly responsible 
for the production of panthothenic acid. Fermentation by 
Baccillus lincheniformis and Enterobacter cloacae on corn meal 
results in the production of folic acid thus increase the 
percent relative nutritive value (Yao, 1989) . Mixed culture 
of the two bacteria increased lysine, methionine, tryptophan 
and total folacin when compared to non-fermenting corn meal 
(Field et al., 1990).
Nanson et al. (1986) assessing the influence of pH on
available amino acid concentration in fermented corn meal 
observed that the production of available amino acid and pH 
of the fermenting corn meal are related. They noticed that 
lysine is best produced at pH of 5. 0-5. 5. They also indicated 
that fermentation for 24 to 48hrs produces the highest 
concentration of available amino acids which decreases by the 
third or fourth day. Mold fermentation of maize gluten meal 
by Aspergillus orvzae and Rhizopus oliaosporus has been 
mentioned to increase lysine content (Neuman et al., 1984)
Maize fermentation at 45°C also showed a high relative 
nutritive value and amino acid level (Nanson and Fields, 1984) 
Murdock et al. (1984) investigating the B-vitamin content of 
natural lactic and fermented corn meal observed that the maize 
fermentation results in increase in levels of vitamin B12, 
riboflavin and folacin. They also reported that fermentation
32
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for 96hrs increased panthothenic acid. However no significant 
difference in niacin and biotin content was observed. The 
increase of riboflavin levels in .fermenting maize meal was 
also confirmed by Dyer et al. (1986) . Fluorometric measurement 
showed greater amount of riboflavin in the meal.
Adeyemi et al. (1986) investigating the effect of maize
fermentation and souring on chemical properties and amylograph 
pasting viscosity of ogi reported that starch content 
decreases from 89.2% to 70.5%. Dry milling they observed 
increase starch damage. Amylograph stability, set back value 
or index of gelatinisation they observed decreases with 
fermentation.
Tongnual et al. (1981) also confirmed the increase in
free amino acid and change in amino acid balance during 
natural fermentation of corn by proteolytic bacteria 
Pseudomonadaceae. The population of the bacteria decreased 
after 3 days of fermentation. Akobundu (1981) working on 
the development and evaluation of corn cowpea mixture as 
protein sources reported that fermentation has a marked effect 
on salt soluble protein of the mixture.
Fermentation by yeast he stated results in a significant 
reduction in the level of raffinose and stachyose. Little 
degradation of aflatoxin by fermentation of maize has been 
reported (Lillehoj, 1979).
The effect of addition of soyflour to fermented maize 
dough studied by Chompeeda et al. (1984) indicated that blends 
of autoclaved soybean meal and maize undergoing fermentation 
reduce raffinose and stachyose and increase lysine, methionine
33
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and tryptophan in the blends. These increases in limiting 
amino acid result in increase in percent relative nutritive 
value. Addition of soybean meal to maize meal was found to 
decrease phosphorus (P) and Iron (Fe).
Plahar (1983) reported that consumer preference for 
maize dough fortified with 10% defatted soyflour was 
acceptable to Ghanaians. Soy fortification at 10% level he 
stated improved sensory preference and increase the protein 
quality of the blends.
34
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3.0 MATERIALS AND METHODS
3.1 MATERIALS 
3.1.1. MAIZE
Maize was obtained from the local market at Madina, a 
suburb of Accra. The local variety was purchased. This is 
the variety commonly used by the local food processors due to 
its desirable quality characteristics.
3.1.2 SOYBEANS - VARIETY TGX 356°
Processed soybean flour were obtained from the Department 
of Nutrition and Food Science (University of Ghana). The soy 
flour were (a) Full-fat soy-flour (b) extruded soy-flour (c) 
Defatted soy-flour
(a) Full-fat Sov-flour
Soybeans were dehulled and milled in the laboratory 
hammer mill (CHRISTY AND NORRIS, ENGLAND) into fine flours and 
sieved.
(b) Extruded Sov-flour
Extruded soybean meal was prepared by passing partially 
defatted flour through a thermoplastic extruder.
(c) Defatted Sov-flour .
Defatted soyflour was prepared by pressing oil from 
soybeans.
35
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3.2 MAIZE DOUGH
Maize dough was prepared by adoption of traditional 
Ghanaian process described by Muller and Nyarko-Mensah (1972) . 
Maize grains were washed and steeped in water for 18 hours and 
milled using the disc attrition mill (Straub Co. U.S.A., size 
2A) . The meal was kneaded in water (approximately 1:3 maize- 
water ratio) to form a dough of moisture content of about 50%. 
The dough was placed in plastic bowls and allowed to ferment 
at room temperature (29°C) for 0, 6, 24 and 4 8 hours.
3.3 SOY-FORTIFIED MAIZE DOUGH
The soy-flour was added at concentrations of 0%, 10% and 
20% (dry matter basis) either (a) before, or (b) after 
fermentation of maize dough.
(a) ADDING SOY FLOUR BEFORE FERMENTATION
Soy flour (Full-fat, extruded and defatted) was added , each 
at concentrations of 10% and 20% (dry matter basis) to the 
maize dough. The mixture was thoroughly mixed and fermented 
for 0, 6, 24 and 48 hours respectively.
(b) ADDING SOY FLOUR AFTER FERMENTATION
Soy flour (Full-fat, extruded and defatted), was each mixed 
at concentration of 10% and 20% (DMB) with maize dough that 
was fermented at 0, 6, 24, and 48 hours.
36
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37
3.4 EXPERIMENTAL METHODS
3.4.1 CHEMICAL ANALYSIS
3.4.1 (a) MOISTURE
The American Association of Cereal Chemists (AACC) method 
44-40 was used. Approximately 2.Og of sample was used.
(b) PROTEIN
Protein content was determined using Macro-Kjeldahl 
method (Association of Official Analytical Chemists (AOAC) 
1975 method 47-021).
(c) FAT
The (AOAC) method. 7-066 (1975) was used.
(d) ASH
The (AOAC) method 2-049 was used.
(e) TOTAL TITRATABLE ACIDITY AND pH
Ten grams (dry matter basis) of sample was weighed 
and mixed with lOOmL of carbon dioxide free distilled water. 
The slurry was stirred for 10 minutes using a magnetic 
stirrer. The pH of the slurry was measured using the pH meter 
at 25°C (TOA pH meter MODEL 30s). The slurry was allowed to 
settle and 5mL aliquots in triplicates pipetted in 250ml 
flasks. 50ml of distilled water was added and titrated 
against 0.IN NaOH to a phenolphthalein end point. The total 
acidity was calculated as percent lactic acid.
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3.5 FUNCTIONAL PROPERTIES
38
3.5.1 WATER ABSORPTION
Five grams of sample was mixed with 2 0mL of water in a 
centrifuge tube and left to stand for 3 0 mins at 29°C. The 
mixture was then centrifuged in a Denley BS 400 centrifuge 
(Page Scientific Inst., Hillside Berth, U.K.) at 3000 rpm for 
3 0mins. The supernatant was poured out and the sample 
weighed. The amount of water retained in the sample was 
reported as water absorbed per 10Og of sample (dry matter 
basis). Triplicate analysis was done. The measurement was 
repeated at 70°C.
The water absorption capacity was measured also at 70°C for 
comparison.
3.5.2 VISCOSITY
The pasting properties of 10% (dmb) slurries of the 
samples were determined using the Brabender viscoamylograph 
(Brabender Instrument Co, Duisburg, Germany) equipped with a 
700 cmg sensitivity cartridge. The sample was heated at 
1.5°C/min from 25°C to 95°C, held at 95°C for 30mins and then 
cooled at the same rate to 50°C and held at 50°C for another 
15mins.
3.6 FIELD SENSORY EVALUATION
Two Ga-kenkey processors were selected among six 
processors who were identified and interviewed. The two 
processors were selected based on their long experience in the
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kenkey industry. Thirty one panellists were selected by 
preliminary compilation of names of consumers who patronise 
the kenkey processors product.
The selection was based on their level of education, frequency 
of consuming the product and their ability to read and 
understand a copy of the questionnaire used for the 
evaluation.
For fermented maize dough porridge , Akasa, 15 panellists 
were used. Soy-maize dough fortified with 20% soy-flour and 
fermented for 48hrs were used in the preparation of Ga kenkey 
and Akasa porridge.
The preference and difference tests were used in the 
evaluation. In the preference evaluation, panellists were 
asked to evaluate the coded sample by ranking the samples 
based on their degree of liking or preference on a 10 point 
scale for attributes of colour, texture, flavour, taste and 
acceptability.
In the difference test, ie. Triangle test, panellists 
were presented with three samples (two identical) in coded 
containers. Panellists were asked to select the different 
samples on the basis of colour, texture, flavour and taste.
The two processors were also asked to comment on the Soy 
Ga-kenkey.
3.7 STATISTICAL ANALYSIS
Data obtained Was analyzed using STATGRAPHICS Version 4.2 
Copyright 1985 by STSC Inc. Serial no, 30.
39
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4.0 RESULTS AND DISCUSSION
4.1 Chemical Evaluation
The chemical composition of the soybean samples (Table 5) 
followed the known chemical characteristics of soybean which are 
high in protein and fat (Harper and Jansen, 19 81; Ferrier, 1976; 
Lie et al. , 1974). The soy-maize dough (Table 6) had moisture 
content ranging from 49.01% to 54.24%. The protein content of 
the soy-maize dough also ranged from 16.72% to 23.27% which are 
high in contrast to that of maize dough without soy flour. 
Addition of soy-flour to maize dough can therefore be said to 
offer desired quality attributes such as the increase in protein 
contents.
Table 5. COMPOSITION OF PROCESSED SOYBEAN AND MAIZE FLOUR
40
MOISTURE
(%)
PROTEIN 
N x 5.71
FAT
(%)
ASH
(%)
FULL-FAT 
SOYFLOUR
11. 50 40.47±0.3 24.50+0.39 4 . 93±0.55
EXTRUDED
SOYFLOUR
7.16 43.15±0.17 15.8 9±0.07 5 . 49±0.71
DEFATTED
SOYFLOUR
7.59 50 . 36±0.22 8.44±0.13 6.14±0.04
MAIZE
FLOUR
11.42 * 9 . 83 ±0.47. 5.71±0.03 1.07+0.09
Protein, Fat and Ash values on dry matter basis * - N x 6.25
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Table 6. MOISTURE AND PROTEIN CONTENT OF MAIZE
DOUGH CONTAINING DIFFERENT LEVELS OF SOYFLOUR
41
SOY TYPE
CONCENTRATION
(D.M.B)
MOISTURE
•(%)
PROTEIN 
N x 6.25
NO-SOY 0% 54 .24 10.2 ± 0.36
FULL FAT 10% 52 .29 16.72 + 0.42
FULL FAT 20% 50 .21 20.54 ± 0.71
EXTRUDED 10% 49 .27 17.39 ± 0.66
EXTRUDED 20% 49.01 21.56 + 0.87
DEFATTED 10% 50.31 20.71 ± 0.04
DEFATTED 20% 49 . 77 23.27 ± 0.16
1 - Mean + Standard Deviation 
D.M.B. - dry matter basis
4.2 pH Characteristics of Soy-fortified maize dough
One of the principal outcome of fermentation of maize dough 
is the production of acids and the concomitant changes in pH of 
the dough. Souring of fermented dough is a quality attribute 
affecting the flavour of fermented maize products.
The pH characteristics of soy-maize dough at 10% and 20% 
soy-level are shown in Figures 3 and 4.
Decrease in pH with increasing fermentation time was 
observed in all the samples irrespective of soy additions.
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EFFECT OF FERMENTATION TIME ON pH OF SOY-FORTIFIED MAIZE DOUGH 
(SOY ADDED BEFORE FERMENTATION OF MAIZE DOUGH)
FIGURE 3.
A = 10% soy 
B = 20% soy
NS = No soy 
EX = Extruded soy 
DF = Defatted soy 
FF = Full fat
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pH 
of 
do
ug
h
10% soy
Formonlnllon lime (H)
NS = No soy 
EX = Extruded soy 
DF = Defatled soy 
FF = Full fat
20% soy
FermonlaUon lime (H)
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EFFECT OF FERMENTATION TIME ON pH OF SOY-FORTIFIED MAIZE DOUGH 
(SOY ADDED AFTER FERMENTATION OF MAIZE DOUGH)
FIGURE 4.
A = 10% soy 
B = 20% soy
NS = No soy 
EX = Extruded soy 
DF = Defatted soy 
FF = Full fat
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pH 
of 
do
ug
h
10% soy
Fermentation time (H)
20% soy
Fermentation time (H)
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At 10% soy-level, extruded soy fortified dough showed similar 
trends as sample without the soy. This was observed when the 
soy-flour was added to the maize dough before fermentation. At 
20% soy level, the defatted soy, extruded soy and the no-soy 
with no soybean dough respectively showed similar trends in pH 
characteristics.
The presence of full-fat soy flour in the dough may have 
stimulated acid production, with a concomitant lowering of the 
pH. This implies that addition of soybeans to maize dough prior 
to fermentation enhances the reduction in pH of the system. 
Except for the full-fat dough system all the dough with soybeans 
behaved close to the maize dough system.
Addition of soyflour to the dough after fermentation of the 
maize dough results in products with relatively high pH at all 
fermentation times. This was observed at different soy levels. 
The differences in pH in the effect due to different soy flours 
were more evident. This could result in reduction in sourness due 
to the soybean addition. Under the system, the dough without soy 
flour showed the lowest pH after 48 hours of fermentation 
followed by Full fat, defatted and Extruded samples respectively. 
Analysis of variance (ANOVA) on the data on pH (Table 7) shows 
that the method of addition of the soy, and fermentation time 
have significant effect (P<0.05) on dough pH. pH values in 
samples containing soyflour added before fermentation were lower 
than samples with soy added after fermentation.
The ANOVA also showed that the soyflour type added to the 
dough and concentration does not influence pH significantly. 
Further analysis from significant interaction shows that the pH
44
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of dough at different fermentation time is affected by type of 
soy flour added and the method of addition.
45
Table 7 ANALYSIS OF VARIANCE FOR SOY-MAIZE DOUGH pH
Source of Variation SS df MS F Sig Level
Main Effects 34 . 744 8 4.3430 134.32 0.000*
Method of Addition 0 .3886 1 0.3886 12.021 0.0013*
Soy flour type 0 .12457 2 0.6228 1.927 0.1589
Soy-level 0.20725 2 0.1036 3.205 .0.0512
Fermentation time 34 . 02367 3 11.3412 350.775 0.000*
* = significant at p s 0.05
Multiple range analysis (LSD) for pH by Method of Addition
Method of 95 Percent Confidence Intervals
Addition Count Average Homogeneous Groups
Before fermentation 36 4.8025000 A
After fermentation 36 4.9494444 B
Multiple range analysis for pH by Fermentation Time
Fermentation 95 Percent Confidence Intervals
time (H)___________ Count_____ Average_____ Homogeneous Groups
48 18 4.2283333 A
24 18 4.4366667 B
6 18 4.8333333 C
0________________  18__________ 6.0055556 D________
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46
4.2.1 Regression Models for pH
A regression model was developed for pH of the dough for 
predictive evaluation of the dough (Table 8).
The model for the pH used is shown below:
Y-j. = ax + b-jX! + b2X2 + b3X!2 + b4X22 + CX-lX2 .... 
where
Y = pH of the dough 
Xx = Fermentation time 
X2 = Soy flour concentration or level 
a!, b1# b2, b3, b4, C - coefficients.
The Regression equation for pH of the dough samples are shown in 
Table 8. For each of the Soy fortified maize dough, the 
relationship between pH, fermentation time and Soy level can be 
predicted based on the equation. The lowest pH attained for each 
sample in the system can be calculated. The response surface 
plots indicate the lowest pH for the models can be attained at 
a fermentation time of about 36 hours (Fig. 5-10) . The pH of the 
dough did not change with increase in soy level for models of 
soy-fortified maize dough where full fat was added after 
fermentation (FFAF) or where extruded soy (EXBF) or defatted soy 
were added before fermentation (DFBF)'. The pH of the model 
containing full fat (FFBF), extruded (EXAF), defatted (DFAF) 
respectively changes with change in soy level in the dough. For 
each of the model therefore the pH of the dough can be predicted 
from the fermentation time and soy-level in the dough.
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47
Table 8. REGRESSION MODEL FOR pH OF SOY-MAIZE DOUGH
SOY MAIZE DOUGH TYPE R2 REGRESSION EQUATION
FULL-FAT (FFBF) 0.7728 5.98-0.126(xj 
0 . 007 (x2) + (0 . OOlXi2)
EXTRUDED (EXBF) 0 . 8169 5.74-0.0976(xj - 
+ 0 . 008 (x2) + (0 . 0013X*2)
DEFATTED (DFBF) 0.8447 5.67-0093(Xj 
+ 0 . 002 (X2) + (0 . 0013X]2)
FULL-FAT (FFAF) 0 . 6828 5 . 76-0 . 099 (X^
+ 0.005 (X2) + (0.001X12)
EXTRUDED (EXAF) 0 . 6331 5.43-0.064 (Xx)
+ 0 . 016 (X2) + (0 . 0008X!2)
DEFATTED (DFAF) 0.7837 5 .496-0.076 (XJ 
+ 0 . 014 (X2) + (0 . OOIX^)
Xx Fermentation time X2 Soy-level
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RESPONSE SURFACE PLOT ON THE EFFECT OF FERMENTATION AND SOY 
CONCENTRATION ON pH OF DEFATTED SOY FORTIFIED MAIZE DOUGH (DFAF)
FIGURE 5
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RESPONSE SURFACE PLOT ON THE EFFECT OF FERMENTATION AND SOY 
CONCENTRATION ON pH OF EXTRUDED SOY FORTIFIED MAIZE DOUGH (EXAF)
FIGURE 6
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ft \\S ^  1% $
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RESPONSE SURFACE PLOT ON THE EFFECT OF FERMENTATION AND SOY 
CONCENTRATION ON pH OF FULL FAT SOY FORTIFIED MAIZE DOUGH (FFAF)
FIGURE 7
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RESPONSE SURFACE PLOT ON THE EFFECT OF FERMENTATION AND SOY 
CONCENTRATION ON pH OF DEFATTED SOY FORTIFIED MAIZE DOUGH (DFBF)
FIGURE 8
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RESPONSE SURFACE PLOT ON THE EFFECT OF FERMENTATION AND SOY 
CONCENTRATION ON pH OF EXTRUDED SOY FORTIFIED MAIZE DOUGH (EXBF)
FIGURE 9
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RESPONSE SURFACE PLOT ON THE EFFECT OF FERMENTATION AND SOY 
CONCENTRATION ON pH OF FULL-FAT SOY FORTIFIED MAIZE DOUGH (FFBF)
FIGURE 10
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4.3 ACIDITY CHARACTERISTICS OF-SOY MAIZE DOUGH
The acidity of fermented foods is very important because it 
affects the flavour and aroma.The effect of fermentation on 
acidity of soy-maize dough are shown in Figs. 11 and 12 The
Acidity increases as fermentation proceeds. This was noted for 
all the dough sample irrespective of the method of addition of 
Soy and concentration of soy in the sample. However differences 
exist in the rates of acid development in the dough. For samples 
containing soyflour added before fermentation differences in 
sample acidity after 24 and 48 hours of fermentation was noted. 
By comparing the acidity results with the pH - fermentation time 
graph the differences in trends indicate that not all acids 
produced in the soy-dough samples may be easily ionizable to be 
detected by the pH meter. It can be indicated that even though 
the pH of the dough samples appear similar (Figs 9 & 10), the 
acidity measured through titration showed wide differences.
The dough containing the Full-fat soy showed the highest 
acid production at both 10% and 20% Soy-fortification level. This 
suggests that the full-fat soy seems to promote acid production. 
Addition of soyflour to the maize dough after fermentation 
generally leads to the reduction of the acid produced.
The extent of the dilution effect was greater with extruded 
soy, defatted soy and full fat soy respectively and in order of 
decreasing dilution effect. The dilution effect of the soy 
appears to increase with increasing soy concentration.
54
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EFFECT OF FERMENTATION TIME ON ACIDITY OF SOY-FORTIFIED MAIZE 
DOUGH (SOY ADDED BEFORE FERMENTATION OF MAIZE DOUGH)
FIGURE 11
A = 
B =
NS
EX
DF
FF
10% soy 
2 0% soy
= No soy 
= Extruded soy 
= Defatted soy 
= Full fat
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Fermentation Tinne(hr)
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EFFECT OF FERMENTATION TIME ON ACIDITY OF SOY-FORTIFIED MAIZE 
DOUGH (SOY ADDED AFTER FERMENTATION OF MAIZE DOUGH)
FIGURE 12
A = 10% soy 
B = 20% soy
NS = No soy 
EX = Extruded soy 
DF = Defatted soy 
FF = Full fat
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Ac
id
ity
 
(g/
1 
OO
g 
of 
do
ug
h)
10% 20% soy
Fermenlalion lime (H) Fermentation lime (H)
NS =No soy 
EX = Extruded soy 
DF = Defatted soy 
FF =Full fat soy
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Analysis of Variance (ANOVA) Table 9 on Acidity indicate 
that the method of soy addition, the soy flour type and 
concentration in the dough and fermentation time influenced the 
acid production significantly. Generally, acid production was 
higher in the dough to which the. soy was added before 
fermentation. In addition the acid production was even higher 
at 20% soy level irrespective of the soy flour type. Multiple 
Range analysis(LSD) also indicate there was no significant 
difference in Acidity between soy-fortified maize dough 
containing 0% and 10% soylevel respectively. Multiple range 
analysis also showed that total acidity values of soy-fortified 
maize dough prepared by adding soy to the maize dough before 
fermentation were generally higher than the dough in which the 
soy was added after fermentation.
Table 9 ANALYSIS OF VARIANCE FOR SOY-MAIZE DOUGH ACIDITY
Source of Variation SS______df______MS________ F Sicr Level
57
Main Effects 0.1948 8 0 . 024 56.61 0.000*
Method of Addition 0.0177 1 0.017 41. 05 0.000*
Soy flour type 0.0088 2 0 . 004 10.33 0 . 002*
Soy-level 0.0032 2 0.0016 3.71 0.332
Fermentation time 0.1650 3 0 . 055 127.91 0 . 000*
* = significant at p s 0.05
MULTIPLE RANGE ANALYSIS FOR TOTAL ACIDITY 
ACIDITY BY FERMENTATION TIME
Fermentation 95 Percent Confidence Intervals
Time (hrs) Count Average Homogeneous Groups
0 18 0.045 A
6 18 0.088 B
24 18 0.124 C
48 18 0.175 D
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58
ACIDITY BY SOY-LEVEL
Soy level 95 Percent Confidence Intervals
Count Average Homogeneous Groups
10% 24 0.100 A
0% 24 0.108 A
20% 24 0.116 B
MULTIPLE RANGE ANALYSIS LSD) FOR ACIDITY BY SOY FLOUR TYPE
Soy flour 95 Percent Confidence Intervals 
Type Count Average Homogeneous Groups
Extruded 24 0.096 A
Defatted 24 0.104 A
Full fat 24 0.123 B
Method of Addition
After fermentation 36 0.092 A
Before fermentation 36 0.123 B
4.3.1 Regression Model for Acidity
A regression model was also developed to predict the
acidity at different soy level and fermentation time. From the
model equation (Table 10) and corresponding plots acidity of the 
soy-maize dough system can be predicted. Response surface plot 
for acidity indicate the following (Figs. 13-18)
(i) In the products containing Full fat soy (FFAF) , the model 
suggests that acidity does not change with change in soy-flour 
level.
(ii) In the products containing Extruded soy and Defatted soy 
the model suggests that the highest acidity was obtained at high 
fermentation time (48hrs) and lower soy concentration.
At lower fermentation time, soy concentration can be increased 
without change in acidity.
(iii) In products containing defatted soy (DFBF), Full-fat 
(FFBF), respectively, higher acidity was achieved at long 
fermentation time and soy level in the dough.
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Table 10 REGRESSION MODEL FOR ACIDITY
59
SOY MAIZE 
DOUGH TYPE R 2
REGRESSION
EQUATION
FULL-FAT (FFBF) 0.9575 0.047 + 0.0047 (Xj +
0 . 0008 (X2) - 0 . 000048 (X^ 2 
+ 0 . 000172 (XiXj)
EXTRUDED (EXBF) 0.7304 0 . 056 + 0 . 002 (X1) +0 . 0004 (X2)
DEFATTED (DFBF) 0.8616 0 . 058 + 0 . 002 (XJ +0 . 0006 (X2) 
+ 0.000047 (X1xX2)
FULL-FAT (FFAF) 0.9179 0.062 + 0.0022 (XJ - 
0.00065 (X2)
EXTRUDED (EXAF) 0.7720 0.059 + 0.002 (Xj - 
0 . 0004 (X2) -0 . 000064 (XzxX2)
DEFATTED (DFAF) 0.8679 0.054+0.002 (Xi) 
+ 0. 00002 (X2) - 
(0.000071 (Xj.2)
X x = Fermentation time 
X2 = Soy flour level
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RESPONSE SURFACE PLOT ON THE EFFECT OF FERMENTATION AND SOY 
CONCENTRATION ON ACIDITY OF DEFATTED SOY FORTIFIED MAIZE DOUGH 
(DFBF)
FIGURE 13
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l*l
C 
ID
I 
T
V
FERMEHIATION H U E  (H)
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RESPONSE SURFACE PLOT ON THE EFFECT OF FERMENTATION AND SOY 
CONCENTRATION ON ACIDITY OF EXTRUDED SOY FORTIFIED MAIZE DOUGH 
(EXAF)
FIGURE 14
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H
e
n
o
a
 
do 
a
i
l
a
i
c
FERHEHTATIOH TIKE (H)
University of Ghana                              http://ugspace.ug.edu.gh
RESPONSE SURFACE PLOT ON THE EFFECT OF FERMENTATION AND SOY 
CONCENTRATION ON ACIDITY OF FULL-FAT SOY FORTIFIED MAIZE DOUGH 
(FFAF)
FIGURE 15
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FERMEtlTATlOH H U E  <H)
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RESPONSE SURFACE PLOT ON THE EFFECT OF FERMENTATION AND SOY 
CONCENTRATION ON ACIDITY OF DEFATTED SOY FORTIFIED MAIZE DOUGH 
(DFAF)
FIGURE 16
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FERHEHTM! HUE (H)'
ACIDITY OR DOUGH
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RESPONSE SURFACE PLOT ON THE EFFECT OF FERMENTATION AND SOY 
CONCENTRATION ON ACIDITY OF EXTRUDED SOY FORTIFIED MAIZE DOUGI 
(EXBF)
FIGURE 17
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FERHEHTATIOH TINE (H)
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RESPONSE SURFACE PLOT ON THE EFFECT OF FERMENTATION AND SOY 
CONCENTRATION ON ACIDITY OF FULL-FAT SOY FORTIFIED MAIZE DOUGH 
(FFBF)
FIGURE 18
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Ms 
no 
a: 
jo 
a
x
i
c
e
i
c
FERMENTATION TIKE (H)
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4.4 WATER ABSORPTION CHARACTERISTICS OF SOY-MAIZE DOUGH
Water absorption capacity changes in the Soy-maize samples 
as fermentation proceeds shows different trends and patterns 
which appear to have same relationship with the fermentation 
process and temperature (Fig.19-22). Generally water absorption 
at 70°C was higher than 29°C. Proteins are the primary sites for 
water absorption (Sefa-Dedeh, et al. , 1988) and the binding sites 
become more exposed on application of mild heat treatment 
resulting in increased water absorption (Holmes et al., 1982), 
Philips et al., 1988).
Water absorption also appears to increase as fermentation 
proceeds especially in the samples in which the soyflour was 
added after fermentation of the dough. The water absorption of 
the Soy fortified-maize dough is generally higher when the soy 
flour was added to the maize dough after fermentation than before 
dough fermentation. The defatted soy fortified samples generally 
appear to show high water absorption perhaps due to higher 
increased binding sites. This may indicate the effect of soy 
processing on water absorption.
Increasing soy level from 10% to 20% has no significant 
change in the water absorption capacity. ANOVA (Table 11) 
indicates the temperature of dough and fermentation time are the 
only significant factors that influence water absorption.
Thus the soyflour type, amount added ' or whether it is added 
before or after fermentation do not inluence the water absorption 
capacity of the product at any given temperature.
Multiple range analysis indicated that water absorption 
after 48 hours was not significantly different from the 24 hours 
fermentation time but was significantly different from the 
samples fermented for 0 and 6 hours.
66
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67
Table 11
ANALYSIS OF VARIANCE FOR WATER ABSORPTION OF SOY-MAIZE DOUGH
Source ofVariation SS________ df_______ MS__________F______Sicr Level
Main Effects 1289930.1 9 143325.6 33.078 0.000*
Method of Addition 10392.8 1 10392.8 2.398 0.1241
Temperature 1219835.4 1 1219835.4 281.479 0.000*
Soyflour type 7915.6 2 3957.8 0.913 0.4040
Soy flour level 5866.5 2 2933 .2 0.677 0.5101
Fermentation time 48249.8 3 16083.3 3.711 0.0135
* = significant at p s 0.05
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FIGURE 19.
EFFECT OF FERMENTATION TIME ON WATER ABSORPTION OF SOY-FORTIFIED 
MAIZE DOUGH AT 29°C (SOY ADDED AFTER FERMENTATION OF MAIZE DOUGH)
A = 10% soy 
B = 20% soy
NS = No soy 
EX = Extruded soy 
DF = Defatted soy 
FF = Full fat
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W
at
er
 
ab
so
rb
ed
(g
/1
00
g 
of 
do
ug
h)
10% soy 20% soy
Fermentation time (H) Fermentation time (H)
'N S  = No soy 
DF = Defatted soy 
E X  = Extruded soy 
FF = Full fat soy
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EFFECT OF FERMENTATION TIME ON WATER ABSORPTION OF SOY-FORTIFIED
MAIZE DOUGH AT 29 °C (SOY ADDED BEFORE FERMENTATION OF MAIZE 
DOUGH)
FIGURE 20.
A = 10% soy 
B = 20% soy
NS = No soy 
EX = Extruded soy 
DF = Defatted soy 
FF = Full fat
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W
at
er
 
ab
so
rb
ed
(g
/1
(J
5g
 
of 
do
ug
h)
10%
soy
Fermentation time (H)
NS.f No soy 
DF = Defatted soy 
EX = Extruded soy 
FF = Full fat
20% soy
0 6 24 48
Fermentation time (H)
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FIGURE 21.
EFFECT OF FERMENTATION TIME ON WATER ABSORPTION OF SOY-FORTIFIED 
MAIZE DOUGH AT 70°C
(SOY ADDED AFTER FERMENTATION OF MAIZE DOUGH)
A = 10% soy 
B = 20% soy
NS = No soy 
EX = Extruded soy 
DF = Defatted soy 
FF = Full fat
University of Ghana                              http://ugspace.ug.edu.gh
W
at
er
 
ab
so
rb
ed
(g
/1
00
g 
of 
do
ug
h)
10% soy 20% soy
Formenlalion time (H) Fermentation time (h)
NS = No soy 
DF = Detailed soy 
EX = Extruded soy 
FF = Full fat
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EFFECT OF FERMENTATION TIME ON WATER ABSORPTION OF SOY-FORTIFIED
MAIZE DOUGH AT 70°C
(SOY ADDED BEFORE FERMENTATION OF MAIZE DOUGH)
FIGURE 22.
A = 10% soy 
B = 20% soy
NS = No soy 
EX = Extruded soy 
DF = Defatted soy 
FF = Full fat
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W
at
er
 
ab
so
rb
ed
(g
/1
00
g 
of 
do
ug
h)
300
200
0
0 6 24 48
Fermentation time (H)
NS = Soy 
DF = Defatted soy 
EX = Extruded soy 
FF = Full fat soy
0 6 24
Fermentation time (H)
20% soy10% soy
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4.5 VISCOSITY CHARACTERISTICS OF SOY-MAIZE DOUGH
The cooked paste viscosity changes in texture when soy maize 
dough is cooked is measured by its viscosity characteristics. 
Tables 12 summarises key information or indices from the 
Brabender hot paste viscosity curves of maize dough.
Viscosity indices ( Peak vis, Vis 95°C, Vis 95°C Hold Vis 
50°C Hold) increase with fermentation time and the Brabender 
viscosity curve obtained was characteristics of maize starch 
(Radley 1968) .
An examination of the Brabender patterns (Figs 24-29) and 
viscosity indices (Tables 13-18) when soyflours were added to the 
maize dough showed interesting differences.
All the soy-maize dough also showed characterstics 
viscosity increase with increase in fermentation time 
irrespective of the method of addition of the soyflour. However 
their viscosity indices were lower than that of maize dough (no 
soy)
This suggests dough fermentation apart from flavour 
development also contributed to improve the rate and degree of 
starch gelatinisation and therefore promotes ease of cooking 
(Sefa-Dedeh, 1988). Addition of soyflour to the maize dough 
appears to decrease cooking properties but the degree of change 
depends on the soy-flour type and concentration. Increasing the 
soyflour concentration in dough reduces viscosity
characteristics.
72
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73
FIGURE 23
BRABENDER VISCOSITY CHARACTERISTICS OF MAIZE DOUGH
(WITH NO SOY)
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Vi
sc
os
it
y 
(B
.U
.)
Heating time (MIN)
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BRABENDER VISCOSITY CHARACTERISTICS OF SOY-FORTIFIED MAIZE 
DOUGH (WITH 10% FULL FAT SOY)
FIGURE 24
Soy added after dough fermentation
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Vi
sc
os
it
y 
(B
.U
.)
Soy added after dough fermentation.
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BRABENDER VISCOSITY CHARACTERISTICS OF SOY-FORTIFIED MAIZE 
DOUGH (WITH 2 0% FULL FAT SOY)
FIGURE 25
Soy added before dough fermentation
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Vi
sc
os
it
y 
(B
.U
.)
* Soy added before dough fermentation
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BRABENDER VISCOSITY CHARACTERISTICS OF SOY-FORTIFIED MAIZE 
DOUGH (WITH 10% DEFATTED SOY)
FIGURE 2 6
Soy added after dough fermentation
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Vi
sc
os
it
y 
(B
.U
.)
Soy added after dough fermentation
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FIGURE 27
BRABENDER VISCOSITY CHARACTERISTICS OF SOY-FORTIFIED MAIZE 
DOUGH (WITH 20% DEFATTED SOY)
Soy added after dough fermentation
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Vi
sc
os
it
y 
(B
.U
.)
* Soy added after fermentation of maize 
dough
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FIGURE 28
BRABENDER VISCOSITY CHARACTERISTICS OF SOY-FORTIFIED MAIZE 
DOUGH (WITH 10% FULL-FAT SOY)
Soy added before dough fermentation
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Vi
sc
os
it
y 
(B
.U
.)
48H
Heating time (MIN)
Soy added before dough fermentation
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BRABENDER VISCOSITY CHARACTERISTICS OF SOY-FORTIFIED MAIZE 
DOUGH (WITH 20% EXTRUDED SOY)
FIGURE 29
Soy added before dough fermentation
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Vi
sc
os
it
y 
(B
.U
.)
* Soy added before dough fermentation
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80
Table 12 V is c o s ity  cha ra c te r is t ic s  o f  Maize dough (with no soy)
Fermentation 
Time (Hrs)
Pasting 
Temp. °C
Peak (BU) 95°C (BU) 95H (BU) 50°C 50H (BU)
0 72.1 360 330 320 820 1000
6 76.6 500 490 460 1140 1180
24 79.8 700 630 540 1200 1500
48 80.1 600 660 520 1340 1780
Table 13 Viscosity Characteristics of Maize dough fortified with Full fat soyflour (AFF)
(10* & 20* soylevel)
Fermentati on 
Time (Hrs)
PASTING 
TEMP. °C
PEAK (BU) 95°C (BU) 95H (BU) 50°C (BU) 50°C (BU)
10* 20* 10* 20* 10* 20* 10* 20* 10* 20* 10* 20*
0 73.9 74.9 80 15 80 15 120 60 280 160 300 160
6 74.1 75.0 120 80 120 80 110 70 630 400 650 420
24 74.5 75.1 440 320 440 300 350 280 980 740 1160 840
48 77.4 75.5 460 340 460 310 380 290 1350 1000 1400 1020
Table 14 Viscosity Characteristics of Maize dough fortified with Extuded soyflour (AFF)
(10* & 20* soylevel)
Fermentation 
Time (Hrs))
Pasti ng 
Temp. °C
Peak (BU) 95°C (BU) 95H (BU) 50°C (BU) 50H (BU)
10* 20* 10* 20* 10* 20* 10* 20* 10* 20* 10* 20*
0 74.9 75.2 280 230 270 230 260 230 760 800 820 780
6 75.3 75.7 320 250 300 250 290 240 850 820 900 800
24 77.7 76.2 430 310 420 300 350 280 960 750 1020 820
48 77.6 77.6 500 390 490 380 390 340 1360 1120 1400 1140
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81
Table 15 V is c o s ity  ch a ra c te r is t ic s  o f Maize dough fo r t if ie d  with Defatted soy flou r (AFF)
(10* & 20* soylevel)
Fermentation 
Time (Hrs)
Pasting 
Temp °C
Peak (BU) 95° C (BU) 95H (BU) 50°: (BU) 5 OH (BU)
10* 20* 10* 20* 10* 20* 10* 20* 10* 20* 10* 20*
0 72.3 75.4 230 160 220 150 200 120 560 480 640 490
6 73.2 75.9 290 220 290 200 280 210 700 500 720 510
24 77.5 76.1 420 410 420 400 330 300 1080 600 1180 860
48 78.4 78.7 480 390 480 380 380 320 1000 1320 1400 1160
Table 16 Viscosity characteristics of Maize dough fortified with Full fat (BFF)
(10* & 20* soylevel)
Fermentati on 
Time (Hrs)
Pasting 
Temp °C
Peak (BU) 95°C (BU) 95H (BU) 50°C (BU) 50H (BU)
10* 20* 10* 20* 10* 20* 10* 20* 10* 20* 10* 20* ’
0 70.6 73.0 150 50 140 60 140 60 360 120 380 160
6 73.0 73.7 210 110 180 110 180 100 630 280 700 380
24 73.6 74.. 5 480 320 480 320 360 280 1440 960 1410 1140
48 73.9 75.2 530 370 530 360 360 300 1500 1080 1400 1120
Table 17 Viscosity characteristics of Maize dough fortified with Extuded soyflour (BFF)
(10* & 20* soylevel)
Fermentati on 
Time (HRS)
Pasting 
Temp. °C
Peak (BU) 95°C (BU) 95H (BU) 50°C (BU) 50H (BU)
10* 20* 10* 20* 10* 20* 10* 20* 10* 20* 10* 20*
0 72.1 73.2 150 180 120 190 130 200 400 670 400 660
6 73.0 73.6 220 90 200 80 200 80 580 250 660 260
24 74.9 75.4 370 230 360 230 350 240 1020 700 1180 900
48 75.3 76.0 430 290 420 290 370 290 1360 1080 1400 1100
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Table 18 V is c o s ity  C ha racte rist ic s  o f  Maize dough fo r t if ie d  w ith Defatted Soyflou r (BFF)
(10* & 20* soylevel)
Fermentation 
Time (Hrs)
Pasting 
Temp. °C
Peak (BU) 95° (BU) 95H (BU) 50°C (BU) 50H (BU)
10* 20* 10*
<
20* 10* 20* 10* 20* 10* 20* 10* 20*
0 76.7 74.4 160 140 150 130 160 120 500 400 540 400
6 76.5 75.7 160 100 160 90 160 90 540 390 580 300
24 74.8 77.9 420 260 330 240 370 240 1440 1020 1380 990
48 74.3 78.2 500 340 500 340 380 ' 290 1300 1150 1440 1100
4.5.1 Peak Viscosity
Peak viscosity indicates the maximum or highest viscosity 
encountered during the preparation or cooking of the paste 
irrespective of the temperature. The peak viscosity decreases 
with increase in soyflour concentration in the dough. The 
reduction effect was more pronounced when the maize dough was 
fortified with Fullfat soy flour after fermentation.
ANOVA (Table 19). suggests method of addition, soyflour type, 
soyflour level and fermentation time significantly affect the 
peak viscosity of the soy-maize paste.
Table 19. ANALYSIS OP VARIANCE FOR PEAK VISCOSITY
Source of Variation______SS______df MS_____F ratio Sia.Level
Main Effects 2379455.6 8 297431.94 238.1 0.000*
Method of addition 12933.7 1 12933.7 10 .35 0.0026*
Soyflour type 9127.1 2 4563.5 3.65 0.035*
Soyflour level 1294893.7 2 647446.9 518 .3 0 . 000*
Fermentation time 1052501.n 3 354167.0 283 . 5 0.000*
* = significant at p £ 0.05
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4.5.2 Viscosity at 95°C and 95°C Hold
The viscosity of the paste at 95°C reflects the ease of 
cooking the starch and the viscosity at 95°C Hold indicates the 
stability breakdown of the paste. The doughs with high viscosity 
at 95°C are therefore easy to cook.
83
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FIGURE 30
EFFECT OF SOY FORTIFICATION AND FERMENTATION ON PEAK VISCOSITY 
OF MAIZE DOUGH (SOY ADDED BEFORE FERMENTATION OF DOUGH)
A = 10% soy 
B = 20% soy
NS = No soy 
EX = Extruded soy 
DF = Defatted soy 
FF = Full fat
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Peak viscosity (B.U)
£>- cn q? ~-j Q>o o o o o
Peak viscosity (B.U.)
O
O
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FIGURE 31
EFFECT OF SOY FORTIFICATION AND FERMENTATION ON PEAK VISCOSITY
OF MAIZE DOUGH (SOY ADDED AFTER FERMENTATION OF DOUGH)
A = 10% soy 
B = 20% soy
NS = No soy 
EX = Extruded soy 
DF = Defatted soy 
FF = Full fat
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10% soy 20% soy
Fermentation lime (H) Fermentation time (H)
NS =No soy 
EX=Extruded soy 
DF=Defatled soy 
FF=Full fat soy
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The fullfat soy fortified dough sample appears to show 
difficulty in cooking than the samples containing extruded and 
defatted soy. Analysis of variance (ANOVA Table 2 0 & 21) shows 
that viscosity at 95°C and 95°C Hold respectively were influenced 
by the method of addition of soyflour, soyflour type, soy level 
and the fermentation time.
Table 20. ANALYSIS OF VARIANCE FOR VISCOSITY AT 95°C
Source of Variation SS_______df MS______F ratio____Sicr.Level
86
Main Effects 1463988.9 8 182998.6 149.760 0.000*
Method of addition 11628 .1 1 11628 .1 9.516 0.0037*
Soyflour type 9027.1 2 4513.54 3 . 694 0.0337*
Soyflour level 725893 . 9 2 362946 .9 297.02 0 . 000*
Fermentation time 717439.9 3 239146 . 6 195.71 0 . 000*
* = significant at p £ 0.05
Table 21. ANALYSIS OF VARIANCE FOR VISCOSITY AT 95°C HOLD
Source of Variation SS df MS F ratio Sicr. Level
Main Effects 132866.7 8 166033.3 197.63 0 . 00.0*
Method of addition 7401.4 1 7401.39 8 . 81 0.005*
Soy flour type 13669 .4 2 6834.72 8 .13 0.0011*
Soy flour level 809702 . 8 2 404851.4 481.88 0.000*
Fermentation time 497493 .1 3 165831.0 197 .384 0.000*
* = significant at p £ 0.05
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FIGURE 32
EFFECT OF SOY FORTIFICATION AND FERMENTATION ON VISCOSITY AT 95°C 
OF MAIZE DOUGH (SOY ADDED BEFORE FERMENTATION OF DOUGH)
A = 10% soy 
B = 20% soy
NS = No soy 
EX = Extruded soy 
DF = Defatted soy 
FF = Full fat
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Vi
sc
os
ity
 
(B
.U
.)
Fermentation time (H)
NS = No soy 
EX =Extruded soy 
DF = Defattef soy 
FF = Full fat
Fermentation time (H)
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FIGURE 33
EFFECT OF SOY FORTIFICATION AND FERMENTATION ON VISCOSITY AT 95°C
OF MAIZE DOUGH (SOY ADDED AFTER FERMENTATION OF DOUGH)
A = 10% soy 
B = 20% soy
NS = No soy 
EX = Extruded soy 
DF = Defatted soy 
FF = Full fat
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10% soy
Fermentation Ume (H)
20% soy
Fermentation line  (H)
NS =No soy 
EX=Extruded soy 
DF=Defatted soy 
FF=Full fat soy
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The dough containing fullfat and defatted soy flour 
respectively showed easier cooking when the soyflour was added 
before fermentation than after. It may be indicated that 
extruded soy dough sample appears to show easier cooking when the 
soyflour was added after fermentation of the dough. Increasing 
the soy flour concentration in the dough significantly reduces 
its ease of cooking and therefore lowers viscosity 
characteristics.
On holding the samples at 95°C for 30 minutes slight 
reduction in viscosity occurs in dough samples containing Fullfat 
soy and Defatted soy respectively indicating little breakdown of 
the paste. No change in viscosity was observed in the dough 
containing extruded soy flour (EXBF). .
4.5.3 Viscosity at 50°C and 50°C Hold
The increase in viscosity of paste when the paste is cooked 
from 95°C to 50°C is an indication of retrogradation or set back. 
Brabender viscosity at 50°C and 50°C Hold were found to increase 
with fermentation time for all the samples irrespective of the 
method of addition of the soyflour. Dough samples with low 
viscosity at 50°C may therefore exhibit soft texture on cooling 
and in addition its acceptability will depend on the intended 
food uses. Hence maize dough containing Fullfat soyflour and 
Extruded soy (BFF) respectively may have relatively softer 
texture compared to the samples containing defatted soyflour.
ANOVA results (Table 22 & 23) indicate that viscosity at 
50°C and 50°C hold respectively were affected significantly by 
the soy level and fermentation time.
89
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Table 22. ANALYSIS OF VARIANCE FOR VISCOSITY AT 50°C
Source of Variatinn_____SS_____df_____MS______F ratio Sicr.Level
90
Main Effects 3873480.6 8 484185.1 33.749 0.000*
Method of addition 13 8.9 1 138.89 0 . 010 0.9232
Soy flour type 52636.1 2 26318.1 1.834 0.1729
Soy flour level 1217411.1 2 608705.56 42 .43 0 . 0000*
Fermentation time 2603 2 94.4 3 867764 .31 60 .485 0.0000
* = significant at p <; 0.05
Table 23 ANALYSIS OF VARIANCE FOR VISCOSITY AT 50° C HOLD
Source of Variation SS df MS F ratio Sicr. Level
Main Effects 12272906 8 1534113.2 170.41 0.000*
Method of addition 5168 1 5168.1 0.574 0.4611
Soy flour type 55069 2 27534.7 3 . 059 0.0570
Soy flour level 4964653 2 2482326.4 275.79 0.000*
Fermentation time 7248015 3 2416005.1 268 .4 0 . 000
* = significant at p s 0.05 
The method of addition of soy flour and soyflour type had no 
significant effect on the viscosity at 50°C and 50°C Hold 
respectively. Results indicate viscosity characteristics 
decreased with increase in soy level due to dilution effect by 
the soy flour. The viscosity at 50°C hold which indicate the 
stability of the cooked paste due to mechanical treatment follows 
the same pattern as viscosity at 50°C. Maize dough containing no 
soy flour appears to show good textural characteristics than the 
soy fortified doughs.
4.5.4 Pasting Temperature
The beginning of swelling of starch as indicated or measured 
by the pasting temperature increases with fermentation time.
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ANOVA results (Table 24) indicate the method of addition of soy­
flour, soy-type, soy-level and fermentation time significantly 
affect the pasting temperature. Pasting temperature also 
increases with increase in soy-level in the dough. It appears 
the addition of soyflour tends to restrict or delay swelling of 
the starch granules in the dough.
91
Table 24. ANALYSIS OF VARIANCE FOR PASTING TEMPERATURE
Source of Variation SS df MS F ratio Sicr.Level
Main Effects 311.56 8 38 . 94 37.13 0 . 000*
Method of addition 12.168 1 12 .16 11.60 0 .0015*
Soy flour type 15 .44 2 7.72 7.3 0 .0019*
Soy flour level 69 . 87 2 34.93 33.319 0 . 000*
Fermentation time 214.078 3 71.35 68 . 04 0.000
* = significant at p s 0.. 05
4.6 CONSUMER PERCEPTION OF SOY-FORTIFIED MAIZE DOUGH IN GA- 
KENKEY AND AKASA
The sensory evaluation was conducted to evaluate acceptance 
of Ga-kenkey and Akasa Porridge prepared from Soy-fortified maize 
doughs.
4.6.1 Consumer Preference for Ga-Kenkey
The sensory evaluation or perception of Ga-Kenkey from soy- 
maize dough shows wide variation in consumer responses to the 
color taste, flavor, texture and general acceptability of the 
product.
4.6.2 COLOUR
The colour of a food product is a very important attribute. 
For most foods, changes in the colour can be recognised by the
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consumer. Such changes may be due to raw materials, ingredients 
additions or processing techniques. Based on the mean scores 
(Table 26) the colour of the maize dough with no soy was most 
preferred with mean score of (8.3) compared with the soy- 
fortified Ga kenkey with mean scores ranging from (3.5) to (6.2) . 
This indicated that addition of soyflour produces differences in 
consumer preferences for colour. Among the soy-fortified Ga- 
kenkey, the colour of the product containing full fat (FFAF) was 
the most preferred with a mean score of 6.2 followed by the 
extruded (EXBF); 4.87, full fat (FFBF); (4.5) and Defatted soy;
(3.5) respectively.
Results of ANOVA' (Table 25) shows that the preference of 
Soy-fortified Ga-kenkey were significantly different with respect 
to colour. This suggests that incorporating processed soybeans 
into Ga-kenkey produced significant changes in colour. Further 
analysis using LSD (Table 26) showed that Ga-kenkey containing 
defatted soy was not significantly different in colour from that 
containing full-fat (FFBF). This suggests that defatted soy and 
Full-fat (FFBF) seem to have the same effect on colour when 
incorporated into Ga-kenkey.
92
Table 25 ANOVA SUMMARY TABLE
Source of Variation SS df
FOR COLOUR
MS F ratio Sicr. Level
Main Effects 575 .4 33 17 ,.436 2 . 923 0.000*
Panelist 174-. 53 29 6 . 0183 1.009 0.4645
Sample 400.866 4 100 .216 16.801 0.0000*
Residual 691.933 116 5 . 9649
Total corr 1267 . 33 149
* = significant at p s 0.05
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93
Table 2 6 MULTIPLE RANGE ANALYSIS FOR COLOUR OF GA KENKEY
SAMPLE MEAN SCORE LSD INTERVALS 
(Homogenous gps)
Maize dough + Defatted Soy 
(DFBF)
3 .533 A
Maize dough + Full fat (FFBF) 4 . 500 A
Maize dough + Extruded (EXBF) 4.866 B
Maize dough + Full fat (FFAF) 6.167 C
Maize dough + 0% Soy 3.267 D
Similarly it can be said that extruded soy (EXBF) and the 
full fat (FFBF) showed no significant difference in colour 
preference when added to Ga-kenkey.
However, there was relatively good preference for Soy- 
fortified Ga kenkey containing Full fat when the soy was added 
after fermentation of the dough (FFAF)
Thus adding full fat soyflour to the maize dough after 
fermentation produced more preferred colour characteristics than 
when the soy was added before fermentation of the maize dough.
4.6.3. TEXTURE
The texture of Ga-kenkey is important or critical in the Ga- 
kenkey industry. It determines to a greater extent the 
marketability of the processors' product.
Mean scores for texture (Table 28) shows that the Ga-kenkey with 
no soy had the most preferred texture (S.87), followed by soy- 
fortified Ga-kenkey containing extruded (EXBF), Full fat (FFAF)
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Defatted (DFBF) and Full fat (FFBF) respectively. Analysis of 
variance (Table 27) shows that the texture of Ga-kenkey was 
influenced by the sample types. Further analysis(LSD) indicated 
the preference for texture of Ga kenkey containing no soy was 
significantly different from all the soy-fortified products with 
the exception of extruded soy-fortified Ga-kenkey.
94
Table 27 ANOVA SUMMARY TABLE FOR TEXTURE OF GA KENKEY
Source of Variation SS df MS_____ F ratio Sicr.Level
Main Effects 
Panelist 
Sample 
Residual 
Total corr
372.700
291.233
81.466
856.133
1228.83
33
29
4
116
149
11.29392 
10 . 0425 
20.366 
7.380
1.530
1.361
2.760
0.0517 
0.1282 
0.0310*
* = significant at p s 0.05
Table 2 8 MULTIPLE RANGE ANALYSIS FOR TEXTURE OF GA KENKEY
SAMPLE MEAN SCORE LSD INTERVALS 
(Homogenous gps)
Maize dough + Full fat (FFBF) 4 . 933 A
Maize dough + Defatted (DFBF) 5 .400 B
Maize dough + Full fat (FFAF) 5 .433 B
Maize dough + Extruded (EXBF) 6 . 533 C
Maize dough + 0% Soy 6.867 C
This suggests that extruded soyflour (EXBF) when added to Ga- 
kenkey exhibits textural characteristics similar to the product 
from 100% maize dough. Soy-fortified Ga-kenkey containing Full
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fat (FFBF), defatted Soy (DFBF) and Full fat (FFAF) appears to 
show no significant differences in texture.
An interesting observation made during the processing of Ga- 
kenkey, the product containing the defatted soyflour showed high 
flow characteristic or "watery texture" during the aflata 
preparation making it difficult for the dough to hold in the corn 
sheath or husk. However upon cooking, a very hard texture was 
obtained which consequently had lower consumer preference for 
texture.
4.6.4 TASTE
The taste of Ga-kenkey is' also an important quality index 
which is used by consumers to access the acceptability of the 
product. To many consumers, taste provides the criteria for 
preferring a processors product to another. •
Based on Mean score (Table 3 0) the most preferred Ga-kenkey 
was the one that contained no soyflour which had the highest mean 
score (8.133) followed by the soy fortified Ga-kenkey containing 
Full fat (FFAF), Extruded soy (EXBF), Defatted (DFBF) and Full 
fat (FFBF) respectively
Anova results (Table 29) indicated significant differences 
in the consumer preferences for taste of the samples.
Table 29. ANOVA SUMMARY TABLE FOR TASTE OF GA KENKEY
95
Main Effects 596.546 33 18.077 3 . 271 0.000*
Panelist 176.373 29 6.0818 1.101 0.3494
Sample 420 .173 4 105.043 19 . 009 0 . 000*
Residual 641.026 116 5 . 5260
Total corr 1237.57 149
* = significant at p s 0.05
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96
Table 30 MULTIPLE RANGE ANALYSIS FOR TASTE OF GA KENKEY
SAMPLE MEAN SCORE LSD INTERVALS 
(Homogenous gps)
Maize dough + Full fat (FFBF) 3 .467 A
Maize dough + Defatted (DFBF) 4 .700 B
Maize dough + Extruded (EXBF) 4 . 867 B
Maize dough + Full fat (FFAF) 6 . 900 C
Maize dough + 0% Soy 8 .133 D
Further analysis showed that Ga kenkey containing no soy 
flour was significantly different in taste from all the soy- 
fortified samples. Even among the soy-fortified samples 
differences in taste exist indicating the effect of soy 
processing on the taste. There was no differences in taste of 
soy-fortified Ga-Kenkey containing extruded and defatted soy 
respectively.
The characteristic taste of Ga-kenkey is partly due to the 
sourness developed during the fermentation process. The low 
preference for taste of Ga-kenkey with Full fat soy (FFBF) may 
be related to the high acidity developed as a result of the 
fermentation. Some of the panellists commented on the high 
sourness in the product.
4.6.5. FLAVOR
Results on the mean scores (Table 32) indicated Ga-kenkey 
with no soy had the most preferred flavor (7.8) followed by the
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product containing defatted Soy (DFBF), Full fat (FFAF), Extruded 
(EXBF) and Full Fat (FFBF) respectively.
Anova (Table 31) shows there was differences in flavor of 
the samples.
Table 31 ANOVA SUMMARY TABLE FOR FLAVOUR OF GA KENKEY
97
Source of Variation SS df MS F ratio Sicr. Level
Main Effects 500 .413 33 15.164 2 .396 0 . 003*
Panelist 224 . 240 29 7.732 1.222 0 .2263
Sample 276.173 4 69.043 10.908 0 .000*
Residual 734 .226 116 6.329
Total corr 1234.640 149
* = significant at p s 0.05
Table 32 MULTIPLE RANGE ANALYSIS FOR FLAVOUR OF GA KENKEY
SAMPLE MEAN SCORE LSD INTERVALS 
(Homogenous gps)
Maize dough + Full fat (FFBF) 3 .733 A
Maize dough + Extruded (EXBF) 4 . 633 A
Maize dough + Full fat (FFAF) 5.667 B
Maize dough + Defatted (DFBF) 5.367 B
Maize dough + 0% Soy 7.800 C
However further analysis LSD (Table 32) shows that among 
soy-fortified Ga-kenkey no differences' in flavor exist between
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the product containing defatted (DFBF), full fat (FFAF), extruded 
(EXBF) respectively.
98
4.6.6. ACCEPTABILITY
Acceptability is the sum of preferences for colour, texture, 
taste and flavor as judged by the taste panelists.
Based on the mean scores (Table 34) for acceptability Ga- 
kenkey containing no soy flour was most acceptable to the 
panellists followed by the products with Fullfat soy (FFAF) 
(7.17), Extruded soy (EXBF) (5.27), Defatted soy (5.10) and Full 
fat (FFBF), (4.17) respectively. It appears from the mean scores 
that acceptability was affected by the method of addition of 
full-fat flour to Ga-kenkey.
Table 33. ANOVA SUMMARY TABLE FOR ACCEPTABILITY OF GA KENKEY
Source of Variation SS df________ MS__F ratio Sig. Level
Main Effects 540.10 33 16.366 2 .592 0.001*
Panelist 221.63 29 7.642 1.210 0.2366
Sample 318.46 4 79.616 12.604 0.000*
Residual 732.73 116 6.316
Total corr_________ 1272.83 149
* = significant at p s 0.05
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99
Table 34 MULTIPLE RANGE ANALYSIS FOR ACCEPTABILITY OF GA KENKEY
SAMPLE MEAN .SCORE LSD INTERVALS 
(Homogenous gps)
Maize dough + Full fat (FFBF) 4 .167 A
Maize dough + Defatted Soy (DFBF) 5.100 A
Maize dough + Extruded (EXBF) 5.267 A
Maize dough + Full fat (FFAF) 7 .167 B
Maize dough + 0% Soy 8 .133 B
Thus Ga-kenkey containing full-fat soy was more acceptable 
when the soy was added after fermentation of the dough. Anova 
(Table 33) indicates differences in acceptability of Ga-kenkey 
containing no soy was not significantly different from the 
product containing Full-fat when soy was added after fermentation 
of the maize dough.
There was also no significant difference in acceptability 
in soy-fortified Ga-kenkey containing extruded soy, defatted soy 
and the Full fat soy (FFBF) respectively. This indicated that 
where acceptability or performance was concerned addition of the 
three processed soy-flours showed no significant differences.
The Full-fat Soy-flour is the easiest of all the soybean 
flour processed and can be prepared using simple traditional 
methods especially in the rural communities.
The soybean can be dehulled by steaming in traditional 
steamers and cracked to dehull in the disc attrition mill which 
is commonly used in the rural areas.
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4.6.7. Processors' Evaluation of Ga Kenkey
Following the evaluation two Ga-kenkey processors were asked 
to examine the products, evaluate and comment on the products 
with respect to their acceptability and marketability in the Ga- 
kenkey industry. Their observation are summarised in Table 35. 
From the evaluation the following deductions were made;
(a) that the colour of the products were generally acceptable.
Thus the colour differences observed were in their view not
significant.
(b) that maize dough containing no soy is the most acceptable
with respect to taste, flavour and texture which can
therefore be considered as a standard.
(c) that Ga-kenkey containing full fat soy (FFAF) was more
acceptable among the soy fortified Ga -Kenkey especially 
its flavour.
(d) that Ga-Kenkey containing Full-fat Soy (FFBF) had the
strongest flavor which was unacceptable for Ga-Kenkey (the 
results of taste panel support this observations)
100
TABLE 35 PROCESSORS EVALUATION OF GA-KENKEY
SAMPLE COLOUR TEXTURE TASTE ' FLAVOR
Maize Dough 
+
0% Soy
(i)Acceptable and 
appealing (good)
(i)Elastic and 
acceptable
Sweet(which is 
acceptable 
(normal taste
(i)Acceptable for 
kenkey
Maize dough 
+
20V Full fat 
{FFBF)
(i)Okay.(not much 
different from 
normal.)
(i)Elastic and quite 
acceptable
(i) Too sweet (not 
so good for kenkey 
but good for 
Porridge.
(Koko)
(i)Quite good but 
strong compared to 
other samples 
(not better than 
others)
Maize dough 
+
20V Full fat 
(FFAF)
(i) Okay and 
acceptable.
(i)Elastic and 
acceptable for 
kenkey.
(i)Okay-but too 
sweet.
(ii) better than 
(BFF)
(i)Acceptable and 
better than all the 
soy-maize samples
Maize dough 
+
20V Extruded 
(EXBF)
(i)Acceptable as 
normal.
(i)Elastic and good (i)Not sweet-very 
low sweet taste.
(i) Okay
Maize dough 
+
20V Defatted 
(DFBF)
(i) Okay (i)Quite acceptable 
and very hard.
(i)Sweet and 
acceptable.
(i) Strong but 
quite acceptable.
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4.7. DIFFERENCE TEST ANALYSIS ON GA-KENKEY
The difference test was performed to determine whether two 
samples of Ga-kenkey could be distinguished from each other by 
sensory analysis. The difference were evaluated based on the 
samples appearance in colour, taste, texture and flavour. The 
analysis of data was done using One-tailed binomial test for 
significance. (Table 36) .
101
TABLE 36. RESULTS OF DIFFERENCE TEST FOR GA-KENKEY
SOY FORTIFIED MAIZE DOUGH SAMPLES
SET NO
SOY
FULL
FAT
(FFAF)
FULL
FAT
(FFBF)
EXTRUDED
(EXBF)
DEFATTED
(DFBF)
COLOUR TEXTURE TASTE FLAVOUR
A X X + + + +
B X X + + + +
C X X + - - +
D X X + - + +
E X X + + -
F X • X - - -
+ =---- =■ Significant difference
- ■ No significant difference
X = TEST SAMPLE
4.7.1. Set A
Analysis of data showed that there were significant 
differences in colour, taste, texture and flavour between. Ga- 
kenkey containing no soy and that containing Full fat (FFBF) Soy. 
For colour; 87% of panellist detected differences 
For texture; 58% of panellist detected differences
For flavour; 70% of panellist detected differences
For taste; 70% of panellist detected differences
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It is therefore apparent that addition of Full-fat soy to 
kenkey before fermentation of the maize dough may contribute to 
change in the colour, texture, flavour and taste of Ga-kenkey.
102
4.7.2. Set B
This evaluation was conducted to ascertain how the method 
of addition of soy affect sensory properties of Ga-kenkey. Test 
for differences indicated significant differences in colour, 
texture, taste and flavour of Ga kenkey containing Full-fat 
(FFBF) and Full-fat soy (FFAF) respectively.
For colour: 71% of panellist detected differences.
For texture: 52% of panellist detected differences 
For taste: 64% of panellist detected differences.
For flavour: 68% of panellist detected differences.
This suggests that the method of addition of soyflour 
produces significant changes in colour, texture, taste and 
flavour of the soy-fortified Ga-kenkey. It appears majority of 
panellists were able to detect differences in colour followed by 
flavour of the products.
4.7.3 Set C
Results of test on Set C was quite different from sets A and
B. Significant differences in colour and flavour were detected 
by the taste panel on Ga-kenkey containing no sov and that 
containing defatted soyflour (FFBF).
For colour: 90% of panellist detected difference 
For flavour: 54% of panellist detected difference 
For texture; 35% of panellist detected difference 
For taste: 38% of panellist detected difference
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Thus no significant differences in texture and taste of the two 
products were detected.
4.7.4 Set D
Results on different test shows that significant difference 
exist between Ga-kenkey containing no soy and that containing 
extruded soyflour on the basis of colour, taste and flavour. No 
significant difference was detected in the texture of the 
products. This indicate that extruded soy imparted textural 
characteristics similar to the maize dough.
For colour: 100% of panellist were able to detect differences
in colour.
For texture, 48% of panellist detected - difference.
For taste, 64% of panellist detected difference.
For Flavour: 84% of panellist detected difference.
The effect of addition of extruded soyflour to Ga-kenkey on 
colour, taste and flavour was very pronounce.
4.7.5 Set E
Difference test results shows that significant difference 
in colour and taste of Ga-kenkey containing Full-fat soy (FFBF), 
and defatted soy (DFBF) . No differences were detected in the 
texture and flavour of the products.
For colour: 77% of panellist detected difference
For texture: 32% of panellist detected difference
For taste: 61% of panellist detected difference
For flavour: 48% of panellist detected difference
With respect of texture it appears Full-fat soy behaves similar
to defatted soy when incorporated into Ga-kenkey.
103
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4.7.6 Set P
Results indicated no significant differences in colour, 
texture, taste and flavour of Ga-kenkey containing extruded 
soy(EXBF) and defatted soy (DFBF) respectively.
For colour: 29% of panellist detected differences
For texture: 45% of panellist detected differences
For taste: 48% of panellist detected differences
For flavour: 38% of panellist detected differences
The extruded soyflour and defatted soy can therefore be said to
exhibit similarity in colour, flavour, texture and taste when
■added to Ga-kenkey.
4.8 SENSORY EVALUATION OF AKASA PORRIDGE
Akasa is the most common weaning food in Ghana and is also 
common breakfast food. Sensory analysis of the products showed 
differences in consumer preferences for the akasa. samples.
4.8.1 COLOUR:
Mean score results (Table 38) indicated Akasa from maize 
dough containing no soy had the most appealing colour (6.79) 
followed by soy-fortified dough containing extruded soy (6.43) 
Full-fat(FFAF) (5.37), Full-fat (FFBF) and defatted soy (4.64).
Consumer preference for colour differed with the type of 
sample. ANOVA (Table 37) showed that there were significant 
differences in consumer preference for colour of the Akasa 
samples. Further analysis using multiple range tests (LSD), 
showed that the preference for colour of the Akasa samples 
containing soy (whether defatted or fullfat, added before or 
after fermentation) were significantly different from those 
containing extruded soy. There were however, no significant
104
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differences between the colour of unfortified maize dough, and 
that of the maize dough fortified with extruded soy.
Table 37. ANOVA SUMMARY TABLE FOR COLOUR OF AKASA
Source of Variation SS df______m s______F ratio Siq. Level
105
Main Effects 189..4154 18 10.523 1.444 0.1518
Panelist 135..581 14 9 . 678 1.328 0.2242
Sample 59..179 4 14.794 1.031 0.000*
Residual 371,.57 51 7.728
Total corr___________560 . 985_____69
* = significant at p s 0.05
Table 38 MULTIPLE RANGE ANALYSIS FOR COLOUR OF AKASA
SAMPLE MEAN SCORE LSD INTERVALS 
(Homogenous gps)
Maize dough + Defatted 4.643 A
Maize dough + Full fat (FFBF) 4.714 A
Maize dough + Full fat (FFAF) 5.357 A
Maize dough + Extruded (EXBF) 6.428 B
Maize dough + 0% Soy 6 . 785 B
The observations suggest that soybean can impart colour to the 
fermented maize system. Consumer acceptability of the colour 
however depends upon the process treatment given to the soy.
4.8.2 TEXTURE
Akasa containing Full-fat soy (FFAF) indicated the highest 
mean score for texture followed by extruded soy, no soy, Full-fat 
(FFBF) and Defatted soy respectively. Anova showed no difference 
in texture of the samples. (Table 39.& 40)
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Table 39. ANOVA SUMMARY TABLE FOR TEXTURE OF AKASA
Source of Variation ss df MS______F ratio Sia. Level
106
Main Effects 166.299 18 9.238 1.412 0.1665
Panelist 117.499 14 8.392 1.283 0.2504
Sample 48.956 4 12.239 1.371 0 .1293
Residual 333.643 51 6.542
Total corr 499.942 69
Table 40 MULTIPLE RANGE ANALYSIS FOR TEXTURE OF AKASA
SAMPLE MEAN SCORE LSD INTERVALS 
(Homogenous gps)
Maize dough + Defatted (DFBF) 4 . 6-43 A
Maize dough + Full fat (FFBF) 5.214 A
Maize dough + 0% Soy 5.786 A
Maize dough + Extruded (EXBF) 6 . 714 B
Maize dough + Full fat (FFAF) 6 . 786 B
4.8.3 TASTE
Based on mean score Akasa containing no soy had the highest 
score for taste (6.5) followed by that containing Full-fat FFAF 
(6.43), extruded soy (EXBF) (5.14), defatted soy (DFBF) (5.07) 
and Full-fat (FFBF) (4.5).
Anova results (Table 41) indicated no significant 
differences in consumer preference for taste. This implies 
addition of soyflour and method of addition does not 
significantly affect taste of Akasa. This may be of significance 
in weaning food preparation based on Akasa. Full-fat soy flour 
■can be added to the maize dough to enhance nutritional quality 
without change in taste. (Table 42) .
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Table 41. ANOVA SUMMARY TABLE FOR TASTE OF AKASA 
Source of Variation SS df______m s ______F ratio Sig. Level
107
Main Effects 201.345 18 11.185 1. 794 0.0526
Panelist 158.973 14 11.355 1. 821 0.0608
Sample 41.123 4 10.280 1.649 0.1764
Residual 318.026 51 6.235
Total corr 519.371 69
Table 42 MULTIPLE RANGE ANALYSIS FOR TASTE OF AKASA
SAMPLE MEAN SCORE LSD INTERVALS 
(Homogenous gps)
Maize dough + Full fat (FFBF) 4.571 A
Maize dough + Defatted Soy (DFBF) 5.071 A
Maize dough + Extruded Soy >: (EXBF) 5.143 A
Maize dough + Full fat- (FFAF) 6.428 B
Maize dough + 0% Soy 6.500 B
4.8.4 FLAVOUR
With respect to flavour, Akasa containing extruded soy 
(FFBF) appears to have the most appealing flavour (8.428) based 
on the mean score. This was followed by Akasa containing Full-fat 
(FFAF), no soy, Full-fat (FFBF) and defatted (DFBF). (Table 44) 
The low mean score for the product containing defatted soy can 
be attributed to the strong beany flavour as a result of the 
defatting process. Analysis of variance (Table 43) indicates 
no significant difference in flavour of the samples.
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Table 43. ANOVA SUMMARY TABLE FOR FLAVOUR OF AKASA
Source of Variation SS df MS_____F ratio Sig. Level
108
Main Effects 509.031 18 28.279 1.670 0.0774
Panelist 378.089 14 27.006 1.594 0.1130
Sample 31.960 4 32.990 1.948 0.1167
Residual 863.839 51 16.938
Total corr_____ 1372 . 871____ 69  ____
Table 44 MULTIPLE RANGE ANALYSIS FOR FLAVOUR OF AKASA
SAMPLE MEAN SCORE LSD INTERVALS 
(Homogenous gps)
Maize dough + Defatted (DFBF) 4.357 A
Maize dough + Full fat (FFBF) 5.357 A
Maize dough + 0% Soy 6.357 A
Maize dough + Full fat (FFAF) 6.714 B
Maize dough + Extruded (EFAF) 8 .428 B
4.8.5 ACCEPTABILITY
Akasa from maize dough containing no soy was most 
acceptable to consumers from the mean scores. This was also 
followed by Akasa containing Full-fat soy (FFAF) (6.79), 
extruded soy (EFBF) (6.43), Full-fat (FFBF) and defatted soy 
(DFBF) (3.64) . (Table 45 & 46) The Akasa containing the
defatted soy was least accepted perhaps on the basis of the 
strong beany flavour developed during defatting. Anova
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acceptability of the products.
Akasa from the maize dough with no soy was not 
significantly different from that containing Full-fat soy 
(FFAF) and the extruded soy (FFBF) on the basis of 
acceptability. These three sample can thus be said to be the 
most acceptable for preparation of Akasa.
Table 45. ANOVA SUMMARY TABLE FOR ACCEPTABILITY OF AKASA
109
Source of Variation SS df MS F ratio Sicr. Level
Main Effects 218.301 18 12 .127 1.589 0.089
Panelist 71.243 14 5.088 0.667 0.794
Sample 145.965 4 36.491 4.782 0.0024*
Residual 389.184 51 7.631
Total corr 607.485 69
* = significant at p s 0..05
Table 46. MULTIPLE RANGE ANALYSIS FOR ACCEPTABILITY OF AKASA
SAMPLE MEAN SCORE LSD INTERVALS 
(Homogenous gps)
Maize dough + Defatted (DFBF) 3.643 A
Maize dough + Full fat (FFBF) 3.857 A
Maize dough + Extruded (EXBF) 6.428 A
Maize dough + Full fat (FFAF) 6.786 B
Maize dough + 0% Soy 6.857 B
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4.9 DIFFERENCE TEST ON AKASA
Results on the difference test for soy fortified Akasa are 
presented in Table 47.
110
TABLE 47 RESULTS ON DIFFERENCE TEST ON AKASA
SET NO SOY FULL FAT 
(FFAF)
FULL FAT 
(FFBF)
EXTRUDED
(EXBF)
DEFATTED
(DFBF)
COLOUR TEXTURE FLAVOR TASTE
A X X + + + _
B X X + _ + +
C X X + + + -
D X X + _ + -
E X X + + + +
F X X + + - -
+ - SIGNIFICANT DIFFERENCE
NO. SINIFICANT DIFFERENCE 
X = TEST SAMPLE
4.9.1. Set A:
Results indicated there was significant difference in the 
colour, texture and taste of Akasa containing no soy and that 
containing Full-fat soy (BFF).
For colour; 80% of panellist detected difference
For texture; 67% of panellist detected difference
For taste; 67% of panellist detected difference
For flavour; 53% of panellist detected difference
No significance difference in flavour was detected by the
panellist.
4.9.2. Set B
Results indicated significant difference in colour, taste 
and flavour of Akasa containing Full-fat (AFF) and Full-fat soy 
(BFF) respectively. No significant differences was observed in 
the texture of the products.
93.3% of panellist detected difference in colour
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For taste; 73% of panellist detected difference 
For flavour; 50% of panellist detected difference 
For texture; 53% of panellist detected difference
4.9.3 Set C
Results showed significant difference in the colour, taste 
and texture of Akasa containing no soyflour and that containing 
defatted soy (BFF).
For colour; 93% of panellist detected difference
For texture; 73% of panellist detected difference
For taste; 53% of panellist detected difference
For flavour; 73% of panellist detected difference
Thus the ability of panellist to detect difference between
samples was greater for colour, flavour and taste.
4.9.4 Set D
Significant difference was found- in only the colour and 
flavour of Akasa containing no soy and that containing defatted 
soy respectively.
No significant differences were detected in the texture and taste 
of the Akasa samples.
The panellist scores were:
For colour; 67% detected difference 
For texture; 40% detected difference 
For taste: 47% detected difference 
For flavour; 67% detected difference
4.9.5 Set E
Resulting difference test indicated significant differences 
in colour, texture, flavour and taste of the Akasa containing
Ill
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Full-fat(FFBF) and defatted soy (DFBF)
73% of panellist detected difference in colour 
For texture 66% of panellist detected difference 
For flavour 80% of panellist detected difference 
For taste 73% of panellist detect difference
4.9.6 Set F
Akasa containing extruded and defatted soy showed difference 
in colour and texture. No significant .differences was observed 
in the flavour and taste of the two products.
In order of panellist ability to detect differences 
80% of panellist detected difference in texture 
60% of " " " in colour
46% of " " " in flavour
40% of 1 " " in taste
Thus panellist could easily detect difference in texture of the 
products.
4.10. Summary of Comment by Taste Panellists
A) Ga- Kenkey
1. Ga-kenkey containing no soy is the best because the colour,
texture, and flavour is good. This comment was passed by
majority of the panellist.
2. Ga-kenkey containing Full-fat (FFAF) is also good for its
taste and flavour.
3. Some of products are not comparable to 'original' kenkey 
because of their flavour and colour.
4. Some of the soybean products have strong flavour
5. Ga-kenkey containing Full-fat (FFBF) should b e  improved.
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B) AKASA
1. Akasa containing no soy was most acceptable
2. Most of the soy-fortified Akasa were found to be good 
except for some which had 'bad' taste and flavour.
113
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114
5.0 CONCLUSION
A. The processing of Soybean and its incorporation into 
fermented maize dough not only enhanced the nutritional 
quality but also influenced the characteristics of the dough 
and therefore the product quality of the intended food uses.
B. The method of addition of the soyflour affected 
physicochemical characteristics such as pH, total acidity, 
water absorption and pasting properties of the dough.
C. Sourness of dough is an important taste index for 
consumers , and it is measured by the pH and acidity. It 
changed as fermentation proceeded as was indicated by the 
increase in acidity and lowering of pH of the fermenting dough 
system. Addition of soyflours to the maize dough further 
lowered pH and increased acidity of the dough. Addition of 
Full fat soy to maize dough before fermentation of the maize 
dough enhanced the development of sourness in the soy- 
fortified maize dough. This was indicated by high titratable 
acidity values. Lower pH and higher acidity in soy fortified 
maize dough can therefore be achieved when soyflour was added 
before fermentation than after fermentation of the maize 
dough.
D. Temperature and fermentation influence water absorption of 
soy-fortified maize- dough significantly. Water absorption at 
70°C was generally higher than at 2 9°C. Water absorption
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affect dough formation.
115
E. Addition of soyflour to maize dough also affected cooking 
properties significantly. Viscosity indices (Peak viscosity, 
vis 95°C, vis 95°C Hold Vis 50°C and Vis 50°C Hold) decreased 
on the addition of soyflour to the maize dough. The viscosity 
indices increased with fermentation time irrespective of 
method of addition. The full fat soy product (Soy fortified 
dough) showed the lowest viscosity characteristics. Maize 
dough with no sov showed better cooking properties than the 
soy-fortified samples.
Soy-fortified maize dough in which the soy was added after 
fermentation had better cooking properties than those in which 
the soy was added before fermentation of the maize dough. 
Increasing the soy level also decreased the ease of cooking 
of the soy-fortified maize dough. Among the soy-fortified 
maize dough samples, the doughs containing Full-fat soy flour 
showed more difficulty in cooking.
Viscosity at 50°C indicates increasing the soy flour level in 
the dough from 0% to 20% reduces the thickness of the cooked 
paste on cooling. This is important in foods such as Ga 
kenkey in which acceptability is partly determined by texture 
after cooking.
F. As far as sensory analysis of the soy fortified dough 
prepared into Ga kenkey and Akasa (Porridge) is concerned, the 
products from maize dough with no soy and Full fat soy 
fortified maize dough in which ■ the soy was added after
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fermentation were most acceptable to consumers. The full fat 
soy product (soy added after fermentation of maize dough had 
preference for colour, texture, taste and flavour similar to 
the unfortified maize dough. The defatted soy fortified 
product was least prefered for its 'hard' texture and flavour.
G. The full fat soy fortified product (soy added before 
fermentation) was also the least prefered for its strong and 
objectionable flavour and increased sourness in the product. 
Thus on adding soyflour to maize dough before fermentation, 
the duration of fermentation and the development of sourness 
should be considered.
H. On the diference test on Ga kenkey panelist were able to 
detect differences in colour, texture, taste and flavour 
between Ga kenkey from maize dough (no soy) and full fat soy 
products (FFBF). For texture and taste no difference were 
detected between Ga kenkey product from maize dough (no soy) 
and the defatted soy product.
I. The method of addition of full-fat soyflour to maize dough 
also affected responses. Differences, were detected by 
panelists in colour, texture taste and flavour between the 
products (Ga kenkey) containing full fat soy flour added 
before fermentation and after fermentation respectively. 
Difference test also showed no significant differnces in 
responses between the product containing Extruded soy and 
Defatted soy respectively. Difference test on Akasa showed
116
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that panelists detected differences in the colour between 
samples presented. For Akasa samples containing full-fat 
soyflour added before and after fermentation differences in 
colour flavour and taste were noticed.
J. The method of addition of soyflour to maize dough is 
therefore an important factor to be considered in fortifying 
maize dough with soyflour. Hence 20% Full-fat soyflour added 
to maize dough fermented for 48 hours may be convenient for 
Ga-kenkey and Akasa preparation.
117
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118
Adeyemi, I.A.; Oluwamukorai, M.O. (1989) . An investigation into 
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128
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pH Characteristics of Soy-maize dough
_______ (Soy-flour added before fermentation of Maize dough)
APPENDIX I
FERMENTATION TIME 
(HOUR)
Soy-Maize Sample 0 6 24 48
Maize dough (No soyflour)
5 . 90 4 . 85 4 .42 4.10
Maize dough + 10 Full fat Soy
6.21 4 . 75 4 . 09 3 . 68
Maize dough + 20% Full fat
6.60 4 .51 3 . 81 3 .76
Maize dough + 10% Extruded Soy
5.99 4.77 4 .39 4.17
Maize dough 20% Extruded Soy
6.63 4.99 4 .42 4 .12
Maize dough + 10% Defatted Soy
5.98 4 . 65 4 .25 4 . 03
Maize dough + 20% Defatted Soy
5.87 5.07 4.38 4.23
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pH Characteristics of Soy-maize dough
(Soy flour added after fermentation of maize dough)
APPENDIX II
Soy-Maize sample 0 6 24 48
Maize dough (No Soy) 5 . 90 4.85 4 .42 4.10
Maize dough + 10% Full fat Soy 6.51 4 . 74 4 .53 4 .44
Maize dough + 2  0% Full fat Soy 6 . 04 4 . 72 4.49 4 .46
Maize dough + 10% Extruded Soy 5 . 50 4 . 92 4 . 87 4.71
Maize dough + 2  0% Extruded Soy 6 . 04 4 . 90 4.85 4 .75
Maize dough + 10% Defatted Soy 5 . 62 4 . 92 4 .52 4 . 51
Maize dough + 20% Defatted Soy 5 . 98 4.96 4 .74 4 . 68
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APPENDIX III
Acidity Characteristics of Soy-maize dough
(Soyflour added after fermentation of Maize dough)____
Soy-Maize Sample 0 6 24 48
Maize dough (No Soy) 0 . 0440 0 . 0980 0.1064 0.1842
Maize dough+10% Full fat Soy 0 . 0420 0 . 0748 0.1120 0.1568
Maize dough+20% Full fat Soy 0.0521 0.0732 0.1049 0.1504
Maize dough+10% Extruded Soy 0 . 0411 0.0726 0.1008 0.1043
Maize dough+20% Extruded Soy 0 . 0392 0.0643 0.0952 0.1036
Maize dough+10% Defatted Soy 0.0420 0.0542 0.0991 0.1260
Maize dough+20% Defatted Soy 0.0580 0 . 0621 0.0941 0.1092
APPENDIX IV
Acidity Characteristics of Soy-maize dough
(Soyflour added before fermentation of Maize dough)
Soy-Maize Sample 0 6 24 48
Maize dough (No Soy) 0 . 0440 0.0980 0.1064 0 .1842
Maize dough+10% Full fat Soy 0 . 0420 0.0980 0.1848 0 . 2352
Maize dough+2 0% Full fat Soy 0.0532 0.1232 0.2394 0 .3500
Maize dough+10% Extruded Soy 0 . 0336 0.0896 0.1232 0.1204
Maize dough+20% Extruded Soy 0.0420 0.1008 0.1260 0.1988
Maize dough+10% Defatted Soy 0 . 0420 0.0896 0.1512 0.1652
Maize dough+20% Defatted Soy 0.0580 0.1038 0.1652 0.2296
TOTAL TITRABLE ACIDITY (g per lOOg sample (dry matter basis)
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APPEND IX  V SENSORY EVALUATION OF AKASA "PORR IDGE "
C O L O U R T E X T U R E T A S T E
075 238 313 675 790 075 238 313 675 790 075 238 313 675 790
1 5 10 7 9 8 5 9 6 8 7 4 9 5 6 7
2 5 2 4 1 3 5 1 4 2 3 5 4 1 3 2
3 1 10 3 2 7 8 1 2 6 9 5 4 1 3 2
4 3 9 2 7 6 2 7 3 5 6 2 7 3 4 5 ._.
5 3 8 2 9 7 2 9 6 10 8 8 7 4 10 9 !
6 9 3 5 1 7 8 2 6 3 5 7 3 10 2 ,  I5 _j
7 10 3 7 1 5 10 1 7 3 5 3 10 5 1 7
8 2 10 6 9 _ 7 _
r
9 10 8 6 9 4 10 7  i
9 3 10 6 9 j 8 3 9 8 10 6 3 10 5 9 7 1
10 1 3 2 6
I
5 j 1 6 2 7 8 4 2 3 10 1 !
11 2 10 4 6 8 j 2 10 7 8 6 7 10 4 10 e i
12 10 2 6 5 9 ! 5 3 8 6 9 8 3 6 5 s_____i
13 7 9 6 8 5 5 8 6 9 7 5 8 j 9
14 4 6 6 2 5 5 6 1 3 7 4 \ 6 5 8 i  !
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SENSORY EVALUATION OF AKASA •'PORRIDGE” (ContcJ.)
F L A V O U R A  ^ C  E  P  T  A B I  L  I T Y i
0 7 5 2 38 3 1 3 5 7 5 7 9 0 0 7 5 2 3 8 3 1 3 6 7 5 7 9 0  '
;
1 6 10 8 3 7 3 9 4 7 5 !
2 5 1 4 2 3 5 4 2 1 3  . i
3 2 8 7 9 1 5 4 2 1 9 j
4 6 8 2 7 i 5 2 7 3 8 7 )
5 8 3 7 5 5 2 6 4 9 8 '
6 3 6 9 4 8 9 5 7 2 3
| 7 5 1 3 7 10 5 7 3 10 1
8 3 10 8 9 5 2 10 6 4 8 !
9 3 10 6 9 8 1 10 3 8 5 !
10 3 5 1 2 8 2 3 1 10 9
11 7 10 4 3 6 1 10 3 10 7 1
12 2 3 5 6 8 8 3 8 5 9
13 4 9 5 8 7 3 9 5 10 8
14 4 5 6 8 7 3 9 5 10 8  '
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APPENDIX VI DATA ON DIFFERENCE TEST FOR AKASA
SET A
PANELLIST COLOUR TEXTURE FLAVOUR TASTE
1 + + + +
2 + + + +
3 _ + _ + Colour
4 + + + + x = 12
5 + + + -
6 + + _ + Texture
7 - _ + _ x = 10
8 + _ - -
9 + + + + Flavour
10 - _ _ _ 00nX
11 + + _ _
12 + _ + + Taste
13 + + + + x = 10
14 + + _ +
15 + - - +
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SET B
PANELLIST COLOUR TEXTURE FLAVOUR TASTE
1 + + + +
2 + + + +
3 + _ +
4 + + + +
5 + _ _ +
6 + + + _
7 - _ _ _
8 + _ - -
9 + + + +
10 + _ _ +
11 + + + +
12 + _ + +
13 + + + +
14 + + + _
15 + _ _ _
14 8 9 11
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SET C
PANELLIST COLOUR TEXTURE FLAVOUR TASTE
1 + + + +
1 2 + + + +
3 _ _ + + Colour
4 + + + +
HII+
. 5 + + + -
6 + _ +• - Texture
7 + _ _ _ (+) = 11
8 + + _ _
9 + + + + Flavour
10 + + _ - (+) = 11
11 + + _ -
12 + + + - Taste
13 + + + +
00n+
14 + + + +
15 + - + +
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SET D
PANELLIST COLOUR TEXTURE FLAVOR TASTE
1 + + + -
2 + + + + Colour
3 . . + - (+) = 10
4 + + + +
5 + + + Texture
6 + . + _ VOn+
7 _ + -
8 + _ _ - Flavour
9 + + + + (+) = 10
10 _ _ _
11 + _ + - Taste
12 + _ + + ( + ) = 7
13 + + + +
14 _ _ +
15 - - - -
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SET E
Panellist Colour Texture Flavour Taste
1 + + + -
2 + + + +
3 + + _ Colour
4 + + + + (+) = 11
5 + + + _
6 + + + + Texture
7 _ + + (+) = 10
8 + + +
9 + + + + Flavour
10 - _ + + ( + ) = 12
11 + _ + +
12 + + _ _ Taste
13 + + + + (+) = 11
14 + +
15 + + - + •
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PANELLIST COLOUR TEXTURE FLAVOR TASTE
1 + + + -
2 + + + +
3 + _ - Colour
4 _ - - ( + ) = 9
5 + + +
6 + + + - Texture
7 _ + _ + ( + ) = 12
8 _ + - +
9 _ _ - - Flavour
10 + + + _
r**n
11 + + _ _
12 + + - + Taste
13 + + + +
V
OII*+
14 + + + -
15 - - + -
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SENSORY EVALUATION OF GA KENTEY
1. DIFFERENCE TEST
APPENDIX VII
SET A  - MZ + 0% SOY
MZ + FULL FAT (FFBF)
MZ + FULL FAT (FFBF)
SET B - MZ + FULL FAT (FFBF)
MZ + FULL FAT (FFBF)
MZ + FULL FAT (FFBF)
SET C - MZ + 0% SOY
MZ + DEFATTED (DFBF)
MZ + DEFATTED (DFBF)
SET D MZ + EXTRUDED (EXBF)
MZ + EXTRUDED (EXBF)
MZ + 0% SOY
SET E MZ + FULL-FAT(FFBF)
MZ + DEFATTED (DFBF)
MZ + DEFATTED (DFBF)
SET F MZ + EXTRUDED(EXBF)
MZ + EXTRUDED (EXBF)
MZ + DEFATTED (DFBF)
MZ = Maize dough.
Q2 Preference tests
1. MZ + 0% SOY - 015
2. MZ + FULL-FAT(FFBF) 020
3. MZ + EXTRUDED(EXBF) Oil
4. MZ + DEFATTED (DFBF) 023
5. MZ + FULL-FAT (FFAF) 012
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SENSORY EVALUATION QUESTIONNAIRE 
DEPARTMENT OF NUTRITION AND FOOD SCIENCE 
SENSORY -EVALUATION OF GA KENKEY AND AKASA PORRIDGE
NAME: .......................  SEX:   DATE: ........
X. You have been provided with three (3) samples of Ga Kenkey.
For each set please write the code number of the odd sample w i t h
respect to the following chateristics.
Set A  Set B Set C Set D Set E Set f
Colour
Texture
Flavour
Taste
2. Please indicate your preference for the quality attribute by ranking the
coded sample.
Indicate your rank by making a vertical line on the scale.
Colour
1 2 3 4  5 6 7 8 9  10
Texture
1 2 3 4  5 6 7 8 9  10
Flavour _____________________________________________________________________
1 2 3 4  5 6 7 8 9  10
Taste _____________________________________________________________________
1 2 3 4  5 6 7 8 9  10
Acceptability -------------------------------------------------------------
1 2 3 4 5 6 7  8 9 10
Comments: ...................................................................
a p p e n d i x VIII
1
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APPENDIX IX
SENSORY EVALUATION & GA KENKEY 
CODE SAMPLES
1020 - MAIZE DOUGH + 20% FULLFAT (FFBF)
2023 - MAIZE DOUGH + 20% DEFATTED SOYFLOUR (DFBF)
3011 - MAIZE DOUGH + 20% EXTRUDED SOYFLOUR 20% (EXBF)
4012 - MAIZE DOUGH + 20% FULL-FAT (FFAF)
5015 - MAIZE DOUGH + 0% SOY
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APPENDIX X RESULT ON DIFFERENCE TEST (6A KENKEY)
___________________________________ S E T A __________________
PANELLIST COLOUR TEXTURE FLAVOUR TASTE
1 + + +
2 + + .
3 + + + +
4 + + + +
5 + .
6 + + + +
7 + .
8 + + + .
9 + +
10 + + +
11 + . COLOUR
12 + . + + =  87%
13 + + + +
14 + + + + TEXTURE
15 + + + =  582
16 + +
17 + . + FLAVER
18 + . + “ 70%
19 + + + +
20 + . + + TASTE
21 + + + + =  702
22 _ + . +
23 _ + _ .
24 + + . +
25 + _ + .
26 + _ + +
27 + . + .
28 + + + +
29 + +
30 + . .
31 - + + +
2/ lb 22 22
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RESULTS ON DIFFERENCE TEST (GA KENKEY)
SET B
PANELLIST COLOUR TEXTURE TASTE FLAVOUR
1 _ + . .
2 . + .
3 + + +
4 + + . +
5 + . .
6 + + + +
7 + .
8 „ + + .
9 . + + _
10 + + +
11 + + _
12 _ . _
13 + + + +
14 _ + _ +
15 + . _ +
16 + _ + +
17 + + + +
18 + . + +
19 + . + +
20 . _ + +
21 + + + +
22 + _ +
23 + + . +
24 + + _ +
25 + _ + _
26 + . + +
27 _ + +
28 + + + +
29 + + + +
30 + + +
31 + - + +
~7T “ 2 T
==»
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RESULT ON DIFFERENCE TEST (GA KENKEY)
PANELLIST COLOUR TEXTURE TASTE FLAVOUR
1 + + +
2 + + +
3 + +
4 + + + .
5 + . _
6 + - .
7 + _
8 + + . _
9 + + +
10 + + +
11 + _ .
12 + . _
13 _ . . _
14 + + . _
15 + + + _
16 + . + +
17 + _ +
18 + . • . +
19 + . . _
20 + _ + +
21 + + _ +
22 _ + . .
23 _ _ +
24 + + + +
25 + + +
26 + . . .
27 + + + +
28 + + + +
29 + + _ +
30 + . . • +
31 + . + +
28 T T - “12™ T T
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RESULT ON DIFFERENCE TEST (GA KENKEY)
SET D --------------------------
PANELLIST COLOUR TEXTURE TASTE FLAVOUR
1 + • * + +
2 + + +
3 + + + +
4 + + +
5 + + +
6 + -
7 + + «■
8 + + _ +
9 + + •' _ -
10 + . - +
11 + + . +
12 + + + +
13 . + + +
14 * + _ +
15 + 1 ■_ i _ +
16 + ■ + +
17 + ■ _ + +
18 + . +
19 + * I + +
20 + * + +
21 + . + +
22 . + _ _
23 _ + +
24 + _ _ +
25 + _ + +
26 + + + _
27 + _ _ +
28 + + + +
29 + + + +
30 + . +
31 + + + +
31 “ IB- ~W "25"
aancu* “““ = = «
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SET E
RESULT ON DIFFERENCE TEST (GA KENKEY)
PANELLIST COLOUR TEXTURE TASTE FLAVOUR
1 + + +
2 + + + +
3 + + _ .
'4 + . .
5 . .
6 + ’ + +
7 + + +
8 + + + +
9 + + _
10 + + +
11 _ . _
12 . . _
13 + + + +
14 + . _ .
15 + . . _
16 + . . _
17 + + + +
18 . _ + .
19 + _ _
20 + _ _ _
21 + + + +
22 _ _ + _
23 + + + +
24 + + _
25 . + .
26 + _ + +
27 + . + +
28 + + + +
29 + + + +
30 . . + .
31 + - - +
“ 2T“ 10 ~W " i r
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RESULT ON DIFFERENCE TEST C6A KENKEY)
SET F --------------------------
PANELLIST COLOUR TEXTURE TASTE FLAVOUR
1 + . .
2 + + .
3 + .
4 . + .
5 + + + +
6 + . +
7 _
8 . +
9 + + +
10 . + _
11 . _
12 . + + .
13 . . . _
14 _ + . +
15 . _ + .
16 + . + +
17 . . _ _
18 . + _
19 + . ■f
20 _ + + +
21 + + + +
22 . . +
23 _ _ _ _
24 + . . +
25 . . _
26 + + + +
27 + . . _
28 + + + +
29 _ . . _
30 . _ +
31 + + + -
9 ‘ 14 ' 15 "12"
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