EFFECT OF ROOM TEMPERATURE CURING 
ON MICROBIAL POPULATION OF 
CURED PORK PRODUCTS
RODERICK KWABENA DADDEY-ADJEJ
In Partial Fulfillment of the Requirements 
for the Degree of Master of Philosophy
JUNE 1999
ANIMAL SCIENCE DEPARTMENT 
FACULTY OF AGRICULTURE 
LEGON
380242
TS \H6b ■'&3 3 I2'
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(44t S t £  £2 dC>M
ABSTRACT
A total of 64 fresh bacons of average weight 1.3kg and 64 fresh hams of average weight 
4.6kg were used in the project. The bacons were randomly divided into 2 groups of 32. 
Sixteen 32 bacons were divided equally and dry cured under room temperature (DCRT) 
for 2,4,5 and 6 days respectively. There were 4 replicates in each treatment. The rest 
of the 16 bacons which were also dry cured for 2,4,5 and 6 days but under cold 
temperature (DCCT), served as control. The second group of 32 bacons were similarly 
divided into 2 groups and pickle cured at room temperature (PCRT) and cold 
temperatures (PCCT) respectively for 2, 4, 5 and 6 days. The mean room temperature 
and cold-room temperature for curing were 28°C and 0°C respectively.. All the fresh 
hams were treated in a similar manner. There were four replicates in each treatment.
All products were smoked with hard wood shavings for ten hours at an average 
temperature of 59°C and left intact in the smokehouse for storage under average 
ambient temperature of 31°C and relative humidity of 68°C and relative humidity of 
68%.
Random sampling of deep muscle tissues of fresh hams and bacons for microbiological 
analysis was done before curing. Sampling for microbiological analysis was carried out 
after 1, 4 and 8 days of storage. Standard bacteriological techniques were used to 
enumerate and identify microorganisms.
Staphylococcus sp., Streptococcus sp and Proteus sp were isolated from the dry and 
pickle cure before their use on the fresh bacons and hams. Proteus sp and 
Staphylococcus sp. were isolated from all cured hams and bacons. Streptococcus sp. 
were however isolated from only two DCCT 14 bacons, two DCCT and one PCRT hams 
under ambient storage conditions, With the exception of bacons dry cured for two days, 
all room temperature and cold-room temperature cured bacons and hams carried 
Bacillus sp., Escherichia colI, Serratia sp., Citrobacter ■sp. and Pseudomonas sp.. 
Enterococcus sp. was isolated from only bacons dry cured at cold-room temperature for 
5 and 6 days and hams dry cured at cold room temperature for 4 and 5 days and bacon 
pickle cured under cold room temperature for 2 days. Apart from MoniHa species which 
was isolated from dry cured room temperature bacons after 2 days of curing, no other 
fungus was observed growing on all the products during the curing. Fungi however grew 
on all cured products except the 2-day dry cured bacons under room and coldroom 
temperature conditions.
As the days of curing of dry bacons and hams at room temperature increased, there was 
a corresponding increase in total viable counts (TCVs) of bacteria. The odour of the dry 
cured products also deteriorated leading to the termination of curing on the 6th day. 
Similarly, the TVCs obtained for bacons and hams pickle cured under room temperature 
increased with days of curing leading to worsening of the off-odour. This led to 
termination of the curing on the 5th days.
On the contrary, increasing the days for dry curing or pickie curing under cold-room 
temperatures resulted in decreased TVCs when analysed after smoking and storage for 
one day under ambient conditions.
Comparison of the TVCs of room temperature hams and bacons to their respective 
controls did not usually show very large differences in magnitude during storage. Hams 
that were dry cured under room temperature or cold-room temperature respectively had 
higher TVCs than bacons cured under similar conditions.
iv
ACKNOWLEDGEMENTS
I first want to thank the Almighty God for seeing me through this work right to the very 
end.
With genuine appreciation and thankfulness, I wish to express my heart-felt gratitude to 
my supervisor Mrs. A.R. Barnes, of Animal Science whose guidance, constructive 
criticisms and priceless suggestions helped me to write out this thesis. The author 
wishes further to express his sincere gratitude to Dr. B.D. Akanmori, of Immunology 
Unit of the Noguchi Memorial Institute for Medical Research (N.M.I.M.R.) for his never 
failing help and guidance in the course of this study. Special thanks are due to all 
Senior members of the Department of Animal Science, especially Miss G. Aboagye, Dr. 
IE. Fleisher, Dr. Ofori of Crop Science Department, Legon and Dr. P Akpedonu, Head of 
Bacteriology Unit of N.M.I.M.R.
My list of acknowledgements would be incomplete without mention of Mr. Kwetso, 
Clement Lagbeneku of the Meat Science Laboratory, Mr. M.O. Quartey of the Animal 
Unit (N.M.I.M.R.) and Mrs. Amoachi of the Animal Science Department fo their help in 
laboratory work.
Finally, I wish to greatly acknowledge Miss Grace Quaye of the Disease Control Unit, 
MOH, Korle-Bu who offered to type out the manuscript.
Roderick Kwabena Daddey-Adjei 
June, 1999.
v
DEDICATION
This work is dedicated to my parent Mr. E.F.K. Adjei, Miss F.A. Ofosu, Mrs M.Y. Adjei, 
my brothers, especially Samuel T. Adjei and Literary Club of the University Christian 
Fellowship, in appreciation of their help, guidance and deep concern for my welfare and 
education.
DECLARATION
I do hereby declare, that except for other people's work, which have been quoted and 
acknowledged, this work is my original research, and this thesis has not been presented 
for another degree elsewhere, either in part, or as a whole
SUPERVISORS
Dr. B.D. Akanmori 
Noguchi Memorial Institute for 
Medical Research 
Head of Immunology 
Legon.
Roderick Kwabena Daddey-Adjei
Department of Animal Science 
and Head of Meat Science Unit 
University of Ghana 
Legon.
Head of Department 
of Animal Science ,Legon
Dr. E. K. Awotwi
TABLE OF CONTENTS
Page
Title Page.................................................................................................i
Abstract................................................................................................... ii
Acknowledgement.....................................................................................v
Dedication............................................................................................... vi
Declaration ............................................................................................ vii
Table of Contents................................................................................... viii
List of Tables.................................................  •............... xiii
List of Figures........................................................................................ xiv
List of Appendices...................................................................................xv
CHAPTER
1. INTRODUCTION........................................................................ 1
2. LITERATURE REVIEW................................................................... 5
2.1 Types of Meat............................................................................  5
2.2 Important Microflora of Fresh and cured pork..................................  6
2.2.1 Sources of microorganisms of Meat and Meat products...................  9
2.2.1.1 Exogenous Contamination of Meat and Meat Products........................  10
2.2.1.2 Endogenous Contamination of Meat and Meat Products......................  11
2.3 Spoilage manifestation of Cured Meat Products.............................. 12
2.4 Curing ............................................................................ 14
2.4.1 Types of Cure.......................................................................... 15
2.4.1.1 Dry Cure...........................................................................  15
v ii i
2.4.1.2 Pickle Cure............................................................................
2.4.2 Sodium Chloride.........................................................................  16
2.4.2.1 Diffusion of Sodium Chloride into Meat..........................................  17
2.4.2.2 Role of Sodium Chloride on Microbial species and population................ 18
2.4.2.3 Role of Sodium Chloride and Temperature on Microbial species and
Population...............................................................................  19
2.4.2.4 Role of Sodium Chloride and pH on microbial species and population 20
2.4.3 Effect of Sodium Chloride on Organoleptic Characteristics of meat and
Meat products...................................................     21
2.4.4 Role of Nitrite and Nitrate in meat curing............................  22
2.5 Preservative role of smoke on meat...................................  26
2.5.1 Effect of smoking on microorganism population of meat........  28
3. MATERIALS AND METHODS..............................................  30
3.1 Site and sample allocation............................................... 30
3.2 Curing process..............................................................  30
3.2.1 Dry Cure (DC)............................................................... 31
3.2.2 Pickle Cure (PC)..............................................  31
3.3 Smoking Process.......................................................................  32
3.4 Microbiological Analysis.............................................................  32
3.4.1 Culture media used for bacteriological and mycological analysis  32
3.4.2 Reagents used for biochemical examination....................................  39
3.4.3 Stains used...............................................................................  39
3.4.4 Sampling................................................................................. 39
ix
3.4.4.1. Scheme for bacteriological and mycological examination of samples ... 39
3.4.4.2 Total Viable Counts (TVC) or Plate Counts.....................  41
3.4.4.3 Enterococci/Faecal Streptococci Examination..................  41
3.4.4.4 Fungal and Yeast Identification....................................  41
3.4.4.5 Bacteria Identification................................................. 42
3.5 Statistical Analysis...................................................... 44
4. RESULTS................................................................  45
4.1 Temperature, relative humidity ranges and some muscle physical
Changes during curing and storage...........................................  45
4.2 Changes in microorganism population of hams dry cured for 2, 4, 5
and 6 days............................................................................  49
4.2.1 Changes in microorganism population of bacons dry cured for 2,4,5
and 6 days...........................................................................  51
4.2.2 Changes in microorganism population of hams pickle cured for 2, 4,
and 5 days...........................................................................  53
4.2.3 Changes in microorganism population of bacons pickle cured or 2, 4,
and 5 days...........................................................................  56
4.2.4 Enterococci Enumeration.......................................................... 58
4.3 Bacteria Isolated in Cure and Cured Hams and Bacons..................  59
4.3.1 Mould isolated from hams and bacons during curing.................... 61
4.3.2 Mould isolated stored hams ana bacons...................................... 61
4.3.3 Yeast isolated from stored hams and bacons.............................  61
5 DISCUSSION................................................................................ 64
x
5.1 Changes in microorganism population (TVC) of stored cured hams and 
bacons under ambient conditions..................................................  64
5.1.1 Changes in microbial population as an indicator of spoilage..............  66
5.1.2 Effect of dry cure and pickle cure on microbial growth at room 
temperature...........................................................................  68
5.2 Microorganisms isolated in cure and cured hams and bacons  70
5.2.1 Bacteria in cure......................................................................  70
5.5.2 Fungal Growth during room temperature curing..........................  74
5.5.3 Microbial contaminants in stored cured hams and bacons ,.............. 74
5.5.3.1 Bacteria................................................................................  75
5.5.3.2 Moulds.................................................................................  77
5.5.3.3 Yeasts..................................................................................  79
CONCLUSIONS AND RECOMMENDATIONS ...................................  81
REFERENCES....................................................................... 85
APPENDIX.......................................................................... 99
xi
LIST OF TABLES
Page
Table 1: Changes in microorganism population for 2 day -  dry cured hams  50
Table 2: Changes in microorganism population for 4 day -  dry cured hams  50
Table 3: Changes in microorganism population for 5 day -  dry cured hams 50
Table 4: Changes in microorganism population for 6 day -  dry cured hams 50
Table 5: Changes in microorganism population for 2 day -  dry cured bacons 52
Table 6: Changes in microorganism population for 4 day -  dry cured bacons  52
Table 7: Changes in microorganism population for 5 day -  dry cured bacons .... 52
Table 8: Changes in microorganism population for 6 day -  dry cured bacons.... 52
Table 9: Changes in microorganism population for 2 day -  pickle cured hams.... 55
Table 10: Changes in microorganism population for 4 day -  pickle cured hams ... 55
Table 11: Changes in microorganism population for 5 day - pickle cured hams ....55
Table 12: Changes in microorganism population for 2 day -  pickle cured hams 57
Table 13: Changes in microorganism population for 4 day -  pickle cured hams ....57
Table 14:Changes in microorganism population for 5day -  pickle cured bacons ... 57
Table 15: Enterococci sp. Enumeration.......................................................  58
Table 16: Bacteria isolates from hams and bacons stored under ambient
Conditions in smokehouse..........................................................  60
Table 17: Mould isolates from hams and bacon stored under ambient
Conditions in smokehouse............................................................. 62
x ii
Table 18: Yeast isolate from hams and bacons stored under ambient 
Conditions in smokehouse...........................................
LIST OF FIGURES
Figure 1: 
Figure 2:
Figure 3: 
Figure 4:
Page
Scheme for bacteriological and fungal examination...................  40
Photograph showing hams dry cured for 2 days
and 5 days under room temperature and cold room
temperature smoked at 57°Cand stored in the
smoke house. Notice the separation of muscles
from the rind (rind) of 5-day dry cure ham under
room temperature............................................................  47
Photographs showing bacons dry cured for 5-day
under room temperature and cold room temperature
smoked at 57°C and stored in the smokehouse. No
evidence .of separation of muscles from the skin in
both treatments..............................................................   48
Photographs showing surface of 2-day pickle cured
ham under room temperature (F) and cold room
temperature (E), smoked for 10 continuous hours and
stored in smokehouse for four days. There is profuse
growth of fungus on (F) but less on (E)...............................  63
x iv
11ST OF APPENDICES
Figure a: Temperature and relative humidity variation during storage
under ambient conditions (2- day dry cure hams and 
bacons).............................................................................. 99
Figure b; Temperature and relative humidity variation during storage
under ambient conditions (4 -day dry cure hams and bacons)...  100
Figure c: Temperature and relative humidity variation during storage
under ambient conditions (5- day dry cure hams and bacons)..... 101
Figure d: Temperature and relative humidity variation during
storage under ambient conditions (6- day pickle cure hams
and bacons).......................................................................... 102
Figure e: Temperature and relative humidity variation during storage
under ambient conditions (2- day pickle cure hams and bacons)...
103
Figure f: Temperature and relative humidity variation during storage under
ambient conditions (4 -day pickle cure hams and bacons)............ 104
Figure g: Temperature and relative humidity variation during storage
under ambient conditions (5-day pickle cure hams and bacons).....105
x v
CHAPTER 1 
INTRODUCTION
The pig has presently become the central attraction in the country's bid for quick 
provision of animal protein. This is because it possesses merits such as high prolificacy, 
high dressing out percentage (70% average) and short generation interval. Pork is also 
versatile compared to other meats. Cured and smoked bellies (bacon) and hams 
(thighs) are varieties of processed pork. In Ghana, smoked pork, locally called 
"Domedo"' is common and popular.
It was reported as early as in 1956 by Baker that bacon and ham are excellent 
sources of animal protein, B -  vitamins and inorganic elements. In comparison with 
other meats, pork is also recognised as a major source of thiamine. The thiamine 
content is approximately 1.18mg/100g of pork compared to 0.13mg/100g of beef and
0.21mg/100g of mutton (Kayang, 1987). Pork also contains appreciable amounts of 
riboflavin and niacin, (Ronald and Ronald, 1991). Although pork products could easily 
be the solution to Ghana's animal protein requirement, the problem of their low 
consumption exists. This among other factors, is due to ineffective marketing of pork, 
(Obimpeh, 1986; Andah, 1990; and Barnes, 1990). Fresh pork, is not relished as much 
as processed pork which consumers find tastier. Both religious and non-religious beliefs 
militate against the consumption of pork for a considerable number of people in Ghana. 
However it is of particular interest that such claims and arguments for abstinence, are 
not strictly adhered to by their proponents, more so when they try the products for 
themselves. Considering this and the numerous advantages of pork, it can be concluded
i
that with effective marketing and proper preservative methods, bacon and ham nay be 
widely accepted by the Ghanaian populace.
The flat profile, high fat content and thin thickness are notable attributes that 
greatly contribute to the better preservation of bacon. In general like all meats pork 
spoils rapidly at ambient temperatures with putrid odour, (Wood, Evans and Razvi, 
1972). However bacon spoils less rapidly (1-2 weeks) at ambient temperatures of 
206C, (Spencer, 1969). The advantage of using bacon as a quick and short term 
solution to supply the average Ghanaian with animal protein cannot therefore be reaped 
if the meat product has a short shelflife under ambient conditions as exists in Ghana. 
Cold storage of meat products in the rural setting, where protein deficiency problems 
are most prevalent, is largely hindered by the fact that electric power is not readily 
available due to the high capital investment required in electrification. There is 
therefore the need to evolve a simple but effective processing method for meat which 
could be adopted anywhere in the country. According to Mann, (1963), four general 
processing methods widely used in meat preservation are sun drying, smoking, curing 
with common salt (sodium chloride) and spices, refrigeration and heat sterilization with 
respect to canning. The process used in meat preservation are principally concerned 
with inhibiting microbial spoilage, although modes of preservation are sought which 
minimize concomitant depreciation of the quality of the commodity, (Lawrie, 1985).
2
Of the four general processes of food preservation methods, the combination of 
cure application (sodium chloride and nitrites) and drying by smoking are easy to apply 
and can give a desirable cumulative effect. Bratzler et at, (1969), reported that wood 
smoke exerted a drying effect as well as a bactericidal and anti-oxidant effect to 
increase the stability of the processed meat. Most important is the ability of smoke to 
delay oxidative rancidity which would otherwise occur as a result of brining and partial 
drying treatments, (Foster and Simpson, 1961; Price and Schweigert, 1971 and Lawrie, 
1985). Smoke also effects the organoleptic characteristics of meat products by 
imparting characteristic smell (odour/flavours) and desirable colour to meat. The art of 
meat preservation by curing is addition of sodium chloride and potassium or sodium 
nitrate and/or nitrite to meat, (Patton, 1971). He stated further that these curing salts 
act in dual capacity as preservatives and tenderisers to improve the palatability and 
acceptance of meat. The combination of smoke and cure would therefore have effect 
on the shelflife of pork products. The shelf life would be indicated by how rapidly the 
organoleptic characteristics, change with time during storage. The degree to which 
these attributes are maintained will be determined by how effective the applied cure can 
combat the activities and effects of microorganisms under ambient conditions.
The objectives of this work are;
1. to determine the maximum number of curing days possible for bacon and ham 
dry cured or pickle cured under room temperature.
3
2. determine the microbial load of the bacons and hams cured under ambient and 
coldroom temperatures.
3. identify microorganisms associated with bacons and hams.
4
CHAPTER 2 
LITERATURE REVIEW
2.1 TYPES OF MEAT
The definition for meat varies and tends to include and exclude certain animal 
species. FAO, (1992) defined meat as the flesh and organs of animals and fowls. 
Potter and Hotchkiss, (1995) expanded this definition to embrace fish. Earlier, Forrest 
et at, (1975) defined meat to be animal tissue, which are suitable for use as food. This 
was modified as the flesh of animals used for food, (Lawrie, 1985). Often it is widened 
to include, as well as the musculature, organs such as liver and kidney, brains and other 
edible tissue. Lawrie, (1985) indicated that, the bulk of meat consumed in the world 
include that from sheep, goats, cattle, pigs and poultry. Ziegler (1966), Price and 
Schweigert, (1971), Lawrie (1974) and Gracey, (1981) have made mention of a wide 
host of animals used as meat.
Meat as an entity can be subdivided into four general categories or types, 
(Forrest et at, 1975). These are "red meat", poultry meat, sea foods and game meat. 
"Red" meat, in terms of consumption, is the largest type and includes beef, pork, 
mutton and veal. However, horse, goat, eland, illama, camel, water buffalo and rabbit 
meats are commonly used. Poultry meat, the flesh of domestic birds, includes that of 
chickens, turkeys, ducks, geese and guinea fowl. Sea foods include the flesh of aquatic 
organs, of which the bulk are fish with the flesh of clams, lobsters, oysters, crabs, and 
many other species. Game meat is the fourth type and according to Krostitz, (1996), it
5
has been one of man's main sources of food in prehistoric times and now piays a 
relatively modest role in total food and meat consumption worldwide. Kordylas, (1990) 
however included game and wildlife along with crustaceans, and moilusces or shellfish in 
this fourth category.
In Ghana both reared and wild animals are considered sources of meat. This 
includes antelopes, wild rodents (rats), rabbits, snakes and birds of various species.
2.2 IMPORTANT MICROFLORA OF FRESH AND CURED PORK
The bacteriology of fresh pork has been investigated by several workers, (Ayres, 
1960; Gardner and Carson, 1967; Gardner et a!, 1967). The flora can be divided into 
five groups. These are the species of the Pseudomonas -  Achromobacter group, 
Enterobacter- Hafnia group, Kurthia group, Lactobacillus group and Microbacterium 
thermosphactum. The first group is numerically the most important and at a storage 
temperature of 2°C, can represent over 95% of the flora. After storage of pork at 
higher temperatures above 15°C, the Pseudomonas- Achromobacter group account for 
perhaps less than 20% of the flora, the remaining organisms being predominantly 
species of Kurthia and Enterobacter -  Hafnia groups. A similar pattern has been 
observed on pork stored in the presence of carbon dioxide, except that under these 
conditions the incidence of species of Enterobacter -  Hafnia group increased and that 
of members of the Pseudomonas- Achromobacter group decreased. Hechelmann and 
Kasprowiak, (1992) found that in the presence of air, Pseudomonadecae are 
predominant in refrigerated raw meat. Earlier, Gill and Newton, (1978); indicated 
that, strains of Pseudomonas, Moraxella, Acinotobacter, Bronchothrix thermosphacta 
were most common on fresh meat with other psychotrophic flora.
6
The microflora of bacon is also well documented, (Hansen, 1960, Ingram, 1960; 
Cavett, 1962; Tonge, Baird-Parker and Cavett, 1964; Spencer, 1967). Both fresh and 
vacuum-packed bacon carry a microflora comprised mainly of micrococci and lactobacilli. 
Under aerobic conditions the microccocci are dominant and putrefactive spoilage results, 
whilst in vacuum packs, lactobacilli are dominant and souring spoilage occurs.
Microflora of fresh pork include the Enterobacteriaceae to which pathogenic 
organisms such as salmonellae, Arizona, and Escherichia coii belong. The Bacillaceae 
which include the genera Bacillus anti Clostridium are also associated with meat. These 
are spore formers and can survive the heat treatment of meat prdoucts. (Hechelmann 
and Kasprowiak, 1992). Schuppel, Salchert and Schippel, (1996), indicated that, cases 
of mastitis can lead to endogenous contamination of meat with Streptoccocci sp; 
{Streptococcus dysgalactaiae; Streptococcus uberis, Streptococcus aga/aciatae. Non 
differentiated streptococci), Escherichia coii, coliform bacteria, staphylococci (coagulase 
-  negative), Clostridium perfringens Actinomyces pyogenes. Shuppel, Salchert and 
Schippel, (1996) in an experiment stressed that, of the E.coii isolated from meat 
samples, nine strains proved to be virulent after allocation to various serotypes. They 
possessed heat-stable enterotoxin II and P-fimbriae.
Gracey, (1981) published a more exhaustive list of microflora of fresh carcasses. 
This included major bacteria or carcass contaminants such as Salmonella sp., Eschericia 
co/i, Staphylococcus aureus, Clostridium perfringens, Clostridium botilinum, Proteus sp’, 
Pseudomonas sp., Providencia sp., Citrobacter sp., Aeromonas hydrophila, Yersina 
enterocoh'tica, Campylobacter sp., and Shigella sp.
i
Important micrflora of cured pork are usually similar to those that contaminate 
fresh pork through improper handling and processing of pork carcasses. These species 
also have the additional ability of surviving the altered conditions in the cured meat. 
Any investigation of this type would be complicated by variations in the properties of the 
meat and of its initial flora and curing procedure, (Riddle, Hibbert and Spencer, 1969). 
Jay, (1978) earlier, made an extensive list of organisms associated with cured and 
uncured meats. He stated that, the flora of fresh and cured meats, including fresh 
poultry and fresh seafood's, included the following genera of bacteria: Alcaligenes, 
Bacterium, Bacteriodes, Brevibacterium, Clostridium, Corynebacterium, Escherichia, 
Flavobacterium, Halobacterium, Lactobacillus, Leuconostoc Micrococcus, Spirillum, 
Photobacterium and Vibrio. Jay, (1978) and Ingram, (1960) reported that, bacteria of 
the genera, Streptococcus, Lactobacillus and Micrococcus are capable of growing well on 
certain types of bacon such as Wiltshire bacon while Streptococcus faecalis is very 
dominant in servai other types of bacon and cured ham.
Vacuum-packed bacon tends to undergo souring due primarily to micrococci and 
lactobacilli. Vacuum-packed, low-salt bacon stored above 20°C may be spoiled by 
Staphylococcus sp., (Tonge, Baird-Parker and Cavett, 1964). Bacteria such as 
Achromobacter, Bacillus-Pseudomonas, Proteus and Microccoccus, have been strongly 
associated with the souring of cured hams, (Jay, 1978). In their study of vacuum- 
packed sliced bacon, Cavett (1962) and Tonge, Baird-Parker and Cavett, (1964) found 
out that," when higher-salt bacon is held at 20°C for 22 days, the catalase positive cocci 
dominated the flora while at 30°C the coagulase negative staphylococci became
dominant. In low salt bacon held at 20°C, the micrococci as well as S. faecalis were 
dominant.
Mould and yeasts are also associated with fresh and cured pork. The mould 
genera of Thamnidium, Penicillium, Sporotrichum, Cladosporium, Mucor, Aspergillus, 
Atiernaria, Oidium, Fusarium, Bot/ytisand Rhizopus were identified while yeasts genera 
such as; Candida, Debaromyces, Saccharomyces, Torulopsis, Rhodotorula, and Torula 
have also been reported, (Jay, 1978). He also indicated that, when spoiled meat 
products are examined, only a few of these yeast and mould are found, and in almost all 
cases, one or more genus is found to be characteristic of the spoilage of a given type of 
meat product. The presence of the more varied flora on non-spoiled meats, then, may 
be taken to represent the organisms that existed in the original environment of the 
products in question or contaminants picked up during processing, handling, packaging 
and storage, (Jay 1978).
2.2.1 SOURCES OF MICROORGANISMS OF MEAT AND MEAT PRODUCTS
Meat is a good medium for microbial growth and susceptible to invasion by them, 
(Cudjoe, 1986). In the healthy and physiologically normal animal, those organs which 
have no direct contact with the exterior may introduce bacteria to the blood, tissues and 
organs, (Gracey, 1981). Effective control of microorganisms by the animal's defence 
mechanisms starts to fail immediately after slaughter or post-mortem. Microorganisms 
gaining access to the meat post-mortem are therefore able to perform their 
physiological functions unhindered. The method of access to the meat is varied.
9
Lawrie, (1985) indicated that, the organisms which spoil meat, gain access though 
infection of the living animal (endogenous disease) or by contamination of the meat 
post-mortem (exogenous disease).
2.2.1.1 Exogenous Contamination of Meat and Meat Products
Majority of microbes associated with meat carcasses are derived from the 
environment, (Cudjoe, 1986). The microbial load of meat is an important factor in 
determining the shelflife and acceptability of all meat products. Initial microbial 
contamination of meat may result from the introduction of microorganisms into the 
vascular system when unsterile knives are used for exsanguination, (Forrest et a!, 1975). 
Since blood continues to circulate for a short period of time following sticking, 
microorganisms introduced through sticking with an unsterile knife, may be 
disseminated throughout much of the animals' body. During slaughtering, hoisting, 
flaying, cutting, processing, storage and distribution of meat, subsequent 
contamination occurs. Contamination of the carcass occurs with contact to hides, feet 
(trotters), manure, dirt and punctured viscera, equipment used for every operation 
performed, the clothing and hands of personnel, washing and scalding water for 
dehairing, brine used in curing, airborne microorganisms in the chilling room, storage 
and aging coolers, in the processing and packaging rooms; (Forrest et a!, 1975; Jay, 
1978; Gracey, 1981; Lawrie, 1985, Hechelman and Kasprowiak, 1992. Woltersdorf and 
Mintzlaff; 1996). Irrespective of the standard of hygiene some surface contamination of 
carcasses are almost impossible to avoid, (Cudjoe, 1986). Non-specific primary 
contamination does not usually contribute to the ultimate microbial deterioration, 
(Mossel, Dijkann and Snijder, 1975). They stated further that, selection occurs, and this 
leads to the proliferation of viable organisms which eventually endanger the health of
10
the consumer or lead to deterioration phenomenon with the upsurge of food 
poisoning by bacteria or fungi, (Lawrie, 1985).
Some bacteria involved in exogenous contamination include, Salmonella sp,, 
Arizona sp., Eschericia coii; Bacillus sp., Clostridium sp., Streptococci sp., Actinomyces 
sp., Listeria monocytogenes, Campylobacter jejuni, Staphylococci sp., Proteus sp., 
Pseudomonas sp., Providencia sp., Citrobacter sp., Aeromonas hydrophi/a, Yersinia 
enterocoiitica, and Shigella sp., (Gracey, 1981; Lawrie, 1985; Hechelmann and 
Kasprowiak, 1992; and Schuppel, Salchert and Schippel, 1996).
2.2.1.2 Endogenous Contamination of Meat and Meat Proudcts
Contamination from infections arise from established disease in the live animal 
and may involved both parasitic worms and bacteria, (Dolman, 1957; Lawrie, 1985) and 
some may be diseases and infections which are naturally transmitted between 
vertebrate animals and man (zoonotic), (Gracey, 1981). These include anthrax, 
brucellosis, contagious pustular dermatitis, erysipelas, leptospirosis, listeriosis, louping- 
ill, ornothosis, psittacosis, Q-fever, ringworm, streptococcal meningitis and tularaemia. 
Most infections arise mainly through contact whiles others are airborne. Some bacteria 
involved in endogenous contamination include, anaerobes like Clostridium sporogenes 
and other Clostridium sp., Bacillus sp., Pseudomonas sp., and coliforms, (Haines, 1941; 
Callow arid Ingram, 1955 and Cosnett et at, 1956).
11
2.3 SPOILAGE MANIFESTATION OF CURED MEAT PRODUCTS
What one individual describes as spoiled might welln be considered edible by 
another, (Forrest et at, 1975). Undesirable changes in flavour, odour and colour may 
also result in stored meat, (Kayang, 1987), and ultimately affect the payability in a 
negative way. Meat spoilage does not necessarily imply decomposition or putrefaction, 
though they may be strongly linked. It is not due to solely microbial action but also to 
such factors as insects, intrinsic enzymatic and oxidative reactions as well, (Forrest et al, 
1975), or involve proteolytic changes, discolorations and slime production, (Ulrich and 
Halvorson, 1951).
Surface slime is a sign of spoilage and it is the superficially obsetvable effect of 
the coalescence of a sufficiently large number of individual colonies of microorganisms 
like Proteus sp and some cocci. The further apart these colonies are apart, the longer 
the time it will take slime to form, (Haines, 1937). Slime growth also results in a greyish 
appearance of the surface, (Kayang, 1987). This adversely affects the aesthetic value of 
the product.
Chemical changes involves the degradation of proteins, lipid, carbohydrates and 
other complex molecules into simpler ones and is accomplished by the action of 
endogenous hydrolytic enzymes that are present in the meat as well as enzymes of 
microbes, (Forrest et at, 1975). Undesirable odours and taste are also evidence of 
spoilage. This is due to gases produced during proteolytic changes by microorganisms,
12
(Price and Schweigert, 1971; Forrest et at, 1975; Lawrie, 1985; Kayang, 1987, Flores 
and Bermell, 1996). Lawrie, (1985), stated further that, free amino adds present are 
attacked by deaminases with the production of hydrogen sulphide, carbon dioxide and 
ammonia. Flores and Bermell, (1996) reported that, acidification also leads to loss of 
typical sensory characteristics because of souring and indicated that, meat proteins lose 
their solubility during acidification and develop a gel texture which affects meat 
consistency. Putrid odours produced during spoilage involve gases such indole, 
methylamine, skatole and hydrogen sulphide. These foul-smelling substances tend to 
be liberated particularly under reducing conditions. For example, Pseudomonas fragi if 
present during the storage of pork at 2 -  10°C, cause proteolysis of myofibrillar proteins 
and this will raise the emulsifying capacity of the meat, (Lawrie, 1985).
Spoilage in meat, may be manifested by colour change. Such change mostly lead 
to a lowering of the aesthetic acceptance of the product. Discoloration may be due to 
the alteration or destruction of meat pigments, (Lawrie, 1985). It was further reported 
that, myoglobin may be oxidazed to brown metmyoglobin, and may combine with 
hydrogen sulphide produced by bacteria, to form sulphmyoglobin or be broken down to 
form yellow or green pigments by microbially produced hydrogen peroxide. Whiteley 
and D'Souza, (1989) reported that Streptococcus faecium subsp. zasse/iflaivus caused a 
yellow discoloration (carotenoid in nature), both under aerobic and anaerobic conditions. 
Similarly, hydrogen peroxide -  producing lactic acid bacteria is known to cause green 
discoloration of cooked cured meat products, (Stekelenburg, Zomer and Moulder, 1990). 
Discoloration may also be due to the elaboration of foreign pigments by the micro­
organisms themselves, (Lawrie, 1985). For example, Pseudomonas sp., produce blue- 
green pigments whiles micrococci, sarcinae, and yeast produce pink pigments. B.
13
prodigiosus produce red pigments. Pigments produced by Qadosporium sp., 
Sporotrichum sp. a nd Penicifflum sp. are black, white and blue-green respectively. 
Halophilic pseudomonads produce black or red discolouration in salted meat and meat 
products. Listeria viridescensproduce green cores in sausages.
Jensen, (1949) reported that many types of micro-organisms cause spoilage by 
producing free fatty acids and yellow or green pigments, from the superficial fat in 
meat, and indeed, such changes are frequently the limiting factors in storage.
The sources of' bacteria causing spoilage in cured meat products are evidently 
similar to those implicated in the exogenous and endogenous contamination of meat. 
For example, the spores of aerobic saprophytic Bacillus sp. may easily be carried from 
the soil by wind and settle on uncovered meat product and thrive.
2.4 CURING
Curing has an age-old history, (Mottram and Rhodes, 1973). Curing serves to 
. reduce the growth of microbes, enhances colour and enriches flavour of meat products, 
(Callow, 1956). Forrest et a/, (1975) reported that meat curing involves the application 
of salt, colour fixing ingredients and seasonings to meat in order to impart distinct 
properties to the product. Similarly, Mottram and Rhodes, (1973) reported that, the 
distinctive flavour of cured meat may be due to the salt, sugar, nitrite or smoke or both, 
applied during the curing process. The curing salts act in a dual capacity as 
preservatives and tenderizers, to improve the palatability and acceptance of meat, 
(Patton, 1971). Curing also lowers the moisture content of meat and meat products.
14
The low moisture contents thus becomes a limiting factor for microbial growth and 
hence retards meat spoilage. Nitrite is a bacteriostatic agent for the control of 
Clostridium botu/inum, (Greenberg, 1972).
2.4.1 TYPES OF CURE
Application of cure is achieved either through the rubbing of the curing mixture 
in dry form over the surface of the meat or through the application of a solution of the 
ingredients of the cure. The development of curing technology in the last century has 
concentrated, albeit fortuitously, on two distinct but interrelated objectives; the 
reduction in the curing or maturation period and the increased yield of product from the 
raw material, (Patton, 1971). For any type of curing, the primary function of the 
maturation period is to permit sufficient time for the curing salts to diffuse throughout 
the meat. It follows that the rate of curing is directly related to the method of adding 
the curing salts. The ageing period also allows the developments of characteristic 
flavour, (Patton, 1971).
2.4.1.1 DRY CURE
According to Kitchel I and Ingram, (1965) pork was originally "dry cured". This 
was a slow and laborious process. Sodium nitrate was rubbed by hand into the surface 
of pork legs and boned out "spencers". These cuts were then stacked up and covered 
with dry sodium chloride and left to mature for several months. They were then washed 
in warm water to remove excess salt and dried at a temperature of 80° -  90°F. (22 -  
27.5°C) for 1 -  2 days, incurring a weight loss of 7 -  10%. Curing by this method
15
involved diffusion of curing salts from the surface to the centre of a cut which 
necessitated a long maturation period. Only well rested pigs, produced consistently 
good results, i.e. absence of bone taint. Dry-curing and aging were formerly done using
ambient temperatures, (Kemp et at, 1974). However, most commercial dry-cured hams 
had been cured and aged under conditions of controlled temperature and relative
humidity and with a decreased aging time, (Cecil and Woodroof, 1954: Christian, 1960, 
Skilley, Kemp and Varney 1964 and Varney, 1967).
2.4.12. PICKLE CURE
A modified dry cure still practiced involves the maturation process being 
shortened by injecting pickle into the carcass, particularly the shoulder and leg ( the 
thickest cut) before salting, and this reduces the curing time to three weeks. Tank 
curing or the English Version Wiltshire style cure is the most popular of pickle curing and 
yield can be increased by 10%, (Patton, 1971). The butchered whole side 
is injected with freshly prepared pickle in a strictly controlled system (usually 25 stiches) 
and immersed in a tank of pickle of similar composition. Originally this was for a period 
of five days and it was followed by a period of 2 -  5 weeks maturation. This made a 
total of one month approximately for curing.
2,4.2. SODIUM CHLORIDE
Salt is probably the most widely used of food preservatives, (Ingram and Kitchell 
1967). It dates from antiquity and indeed the use of the salt as a preservative has been 
recorded as early as 300BC., (Patton, 1971). Fundamentally, its success depends on the
16
fact that, it imparts desirable taste in meat and also it inhibits objectionable putrefaction 
and dangerous microorganisms.
2.4.2.1. Diffusion of sodium chloride into meat
The preservation of meat by salt curing depends on salt reaching all parts of the 
meat, including the fatty tissues and the bones, (Wood, 1966). He further indicated 
that, the rate-determining step in salt curing is the diffusion of the salt through the 
tissue. For a given tissue, the rate of diffusion is largely governed by the concentration 
gradient and the temperature. Diffusion of salt in the tissue causes liquid transport due 
to osmosis and changes in the protein structure. Similar changes also occur in the 
drying offish muscles, (Jason, 1958 and 1965). Jason, (1965) stated that, the effect of 
temperature was complex and over the range of temperature (5 -  30°C), usually 
involved in the curing processes, considerable changes are likely to occur in the physical 
properties of the tissue. Diffusion may vary in different directions relative to the 
muscle fibres. (Wood, 1966). Kormendy and Gartner, (1958) Wistriech, Moore and 
Kenyan (1960). worked with leg muscles which were cylindrically cut and found out that 
the salt uptake per unit area of exposed surface correlated with time of immersion by an 
empirical log-log plot of uptake against time. Wood, (1966) worked with tissues which 
were isotropic to salt uptake and recorded that the salt uptake was linear with the 
square root of the time and was also proportional to the concentration. The diffusion 
co-efficient was independent to the brine concentration.
17
2.4.2.2 Role of sodium chloride on microbial species and population
Sodium chloride has many effects on the microbial content of meat, (Yu, Siaw 
and Idris 1982). Solomon, Ekanem and Okubanjo, (19994) noted that, increasing the 
level of sodium chloride in a pork belly product, (unam inung,) decreased the level of 
moisture in the cured meat. The effect of salt is often similar to that of drying, (Wood, 
1966; Ingram and Kitchell, 1967). This is explained by the fact that salt in food imparts 
an osmotic withdrawal of water, which in turn affects the water activity in the food. 
Hence many microbes cannot obtain sufficient water to meet their physiological 
functions. In a salted food, where salt is the main solute, the water activity is often 
expressed as the so-called "brine-concentration", (Hankins etaI, 1950). This is only an 
approximation, since there is an additional contribution by soluble constituents of the 
food itself, (Scott, 1957). There are however, occasions when certain organisms 
tolerate or require high concentrations of sodium chloride which cannot be substituted 
by other salts.
The reason for the specific requirements for sodium chloride is partly accounted 
for by the salt requirements of enzymes extracted from the cells, (Ingram, 1957). For 
example, some forms of cocci are very salt-tolerant and thus thrive in high salt 
concentration. Mohr and Larsen, (1963) also reported that some microbes require a lot 
of sodium chloride to maintain the stability of their cell wall.
The action of salt on micro-organisms is varied. Flores and Bermell, (1996) 
reported that, when salt is used in concentrations of between 2.5 and 3.0% in the
18
manufacture of cured sausages, it inhibits the growth of spoilage organisms but does 
not affect the growth of acidifying organisms unless its concentration rises above 3%. 
Not only does it have an effect upon the ability of growth of microbes, but upon other 
properties of microbes. For example, high concentration of salt depresses certain 
properties of microbes like retention of viability, (Fabian and Winslow, 1929), 
respiration, (Ingram, 1940), fermentation and motility for sporogenesis, (Fabian and 
Bryan, 1933). There are many important differences in detail with respect to the action 
of salt on microbes. For example, by increasing salt concentration, motility may be 
stopped before growth, so that on lightly salted meat, the bacteria are still able to grow 
but these colonies remain isolated instead of spreading to form a continuous slime. This 
is because salting dimishes the amount of free liquid at the meat surface, (Ingram and 
Kitchell, 1967). Salt has more influence on the proteolytic activities of bacteria than on 
their growth, (Rockwell and Ebertz, 1924). They continued that, low concentration of salt 
diminish the production of putrid odours and flavours from meat more than it seeks to be 
explained by the change in the bacteria flora.
2.4.2.3 Role of Sodium Chloride and Temperature on Microbial species and 
population
Temperature plays a critical role in microbial growth. It also has a great 
influence on the action of salt, (Ingram and Kitchell, 1967) and hence microbes. The 
lethal action of salt, like that of other disinfectants is less at low temperatures. Shipp, 
(1958) and Buttiaux and Moriamex, (1958) reported that, Salmonella sp. for example, 
are rapidly destroyed in curing brines at room temperatures but survive for weeks at low 
temperatures. Ingram, (1958) also reported that £  cafbehave similarly. Bardley and 
Taylor, (1960) and Blanche Koelensmid and Van Rhee, (1964), also demonstrated the
19
same effect of temperature on the action of salt on the survival of salmonellae on 
culture media and vacuum packed bacon respectively. The difference of the influence of 
temperature and salt concentration combination as inhibitory to microbial growth is not 
clear, (Ingram and Kitchel, 1967). Dumesh, (1935) reported the growth of E, coh and 
typhoid bacteria at 25°C with concentration of salt at 5 -  8% while the works of Patton, 
(1971) proved the contrary that low temperatures lessened the lethal action of sodium 
chloride. Labrie and Gibbons, (1973) reported that the preservative action of salt on fish 
increased with reduction of temperature. With moulds however, several authors 
agree that the greatest tolerance exists at the optimum temperature for growth, 
(Tomkins, 1929; Heintzeler, 1939) with a much lower tolerance near the temperature 
limits, (Stille, 1948). The maximum salt concentration permitting growth of CL 
botutinum type E\s 5.8% at 30°C and 25°C, 5.1% at 20°C, and 4.3% at 15°C, (Ohye, 
Christian and Scott, 1967). Salt concentrations ineffective at high temperatures may 
become inhibitory or at least, result in markedly delay outgrowth as the temperature 
falls to 10°C or below, (Segner, Schmidt and Boltz, 1966). The optimum and maximum 
temperature for growth are raised when an organism grows in the presence of salt, and 
the rise is large when the organism tolerates high concentration, (Ingram, 1957). It is 
not clear whether the same applies to the minimum growth temperature and more 
research would be needed to indicate this, (Ingram and Kitchell, 1967).
2.4.2.4 Role of Sodium Chloride and pH on microbial species and population
The influence of pH is supplementary to that of salt, (Ingram and Kitchell, 1967). 
They stated that, it is clearly a general rule that, as the acidity rises, less salt is needed 
to prevent growth of individual bacteria and yeasts. Sherman and Holm, (1922) 
reported that with a pure culture of E, coh] small concentration of salt were needed to
20
inhibit cell multiplication at pH values remote from the optimum, and the same is true 
with CL botu/inum, (Ohye, Christian and Scott, 1967), and salmonellae, (Blanche 
Koelensmid and van Rhee, 1964).
Salt and pH may act together in another way. It has been noted that among the 
bacteria from the meats, those which resist salt tend to be unusually sensitive to acidity,
and vice versa, (Ingram, 1958). A combination of acidity and salt, are very generally, 
inhibitory. Unfortunately, exploitation of the principle of more salt application because 
of higher pH of meat as a means of preservation of meat, is hindered by the fact that 
acidity, in meat appears to accentuate the flavour of the salt in it, (Ingram, 1949). The 
action of sodium chloride is synergistic with various inhibitory agents. Benzoic acid, a 
preservative, when used in lower concentration with salt has a synergistic effect, on 
microorganisms, (Von Schelhorn, 1951). The addition of salt, even if it is not itself acid 
in reaction, by raising the ionic strength in solution frequently has the effect of reducing 
the pH, which later is known to increase the effectiveness of weakly acidic presen/atives, 
like benzoic acid, (Ingram, Gttaway and Coppock, 1956). The concentrations of salt 
needed to change the pH appreciably are however, comparatively large, and some 
additional explanation may be necessary. Reports that salt "sensitizes" bacteria to 
carbon dioxide, (Rockwell and Ebertz, 1924) may arise from similar causes.
2.4.3. EFFECT OF SODIUM CHLORIDE ON ORGANOLEPTIC CHARACTERISTICS
OF MEAT AND MEAT PRODUCTS
Sodium chloride has many effects on sensory properties of meat. According to 
(FAO, 1985), it is the main flavouring agent in the manufacture of sausages, bacon and 
ham and also increases the water-holding capacity of the product by aiding swelling of
21
the myofibrillar proteins. Incorporation of salt thus enhances protein extraction and 
therefore the texture of reformed products. Saltiness plays a role in the acceptance or 
rejection of meat products. This implies that it plays more part in the overall 
acceptability of meat and its products, (Mottram and Rhodes. 1973). They reported that 
salt is a major contributor to bacon flavour. The sensory appreciation of the saltiness of 
bacon is much less intense than that of aqueous solution of equal strength, an effect 
due, probably, to fluid binding by the protein or to its slow release during mastication, 
(Ingram, 1949). However, the Canadian National research (1938-39), showed that the 
high salt content (7.5%) of Canadian bacon compared with Danish bacon (6.2%) was 
the major source of dissatisfaction, (Winkler and Cook, 1941). At low concentrations, 
salt helps to improve the flavour and colour of meat, Daun, (1975) and Meyer, (1978), 
but at higher concentrations, especially when used alone, salt gives a dry harsh, dark . 
coloured and unattractive product, (Kramlich , Pearson and Tauber, 1973). According to 
Ellis et al, (1968) and Pearson et at, (1977), high concentration of salt in meat also 
accelerate oxidative rancidity and hereby affecting falvour development. This is because 
salt promotes the activity of lipoxidase in meat. It was further indicated that the 
concentration of sodium chloride alone necessary to confer stability on bacon might be 4 
-  5g/100g water, (Wood, Evans and Razvi, 1972). Bacon is already known to exhibit a 
masking effect on saltiness, (Ingram, 1949) and suggests that salt is bound into the 
cured meat structure more firmly than in untreated pork meat, though whether by a 
chemical or physical mechanisms, is not very clear.
2.4,4 ROLE OF NITRITE AND NITRATE IN MEAT CURING
The art of preserving meat by curing in common salt, with or without smoking
22
has been practiced from remote antiquity , (Kerr et. at, 1926). The use of nitrates also 
dates from ancient times, and has been practiced so long, that its origin is unknown, 
(Hehner, 1910). The curing of meat and comminuted meat products with salt and an 
alkali nitrate salt is an ancient process originally intended as a method of preservation, 
(Wassermann and Talley, 1972). Potassium nitrate has long been used to protect meat 
from spoilage and colouration, (Hoagland, 1908). Hoagland, (1908) stated further that 
the original presen/ing function of meat curing has been changed to one of flavour and 
colour development to satisfy consumer tastes. Since 1929, the inclusion of higher 
sodium or potassium nitrite at the rate of 200 ppm has been approved by the U.S. Meat 
Inspection Division. Changes in the colour and appearance of the product occur in the 
process. It was many years before the mechanism of the curing process was 
understood and in fact, many of the intermediate stages had still to be elucidated, 
(Patton, 1971).
Earlier in 1891, Pollenski demonstrated that the nitrate in the cure was reduced 
as a result of bacterial action. The red colour of the product, which was considered a 
characteristic of cured meat, was found by Kisskalt, (1899) to be formed in the presence 
of nitrite. The use of nitrate or nitrite as a curing agent was reported by Haldane, 
(1901). Kerr et at, (1926) established limits of sodium nitrite concentration in the cure 
that would yield a satisfactory product, and these limits are part of the legal 
requirements for cured meats in use today. The work of Kerr et a!, (1926) however, 
was primarily directed towards the development of the cured colour in the product. It 
was noted that the flavour and quality of the products were equivalent to those 
prepared in the customary fashion, i.e with nitrate only. The relationship of nitrite to 
flavour was first described by Brooks et al, (1940) in a study of use of nitrite in the cure
23
of bacon and ham. Although they presented no taste panel data, the authors stated 
that the panel showed a preference for meat cured with nitrite. At the same time 
parallel work of the Research Association of the British Food Manufacturers, (Mascara, 
1939) reached similar conclusions.
Barnett et a!, (1935) reported on an extensive study of the factors affecting 
cured ham flavour which established the relationship between the amount of nitrite in 
the cure and amount of cured favour. In the study on the concentration of nitrite in the 
pumping pickle, they found that the panel had an equal preference for hams pumped 
with pickle containing nitrite concentration of 1.5g sodium nitrite/ 1 litre of brine and 
those in which pickle with O.lg sodium nitrite/ 1 litre of brine has been used. Cho and 
Bratzler, (1970) studied the effect of nitrite and smoke on the flavour of cured pork 
roasts, reaching the conclusion that more cured flavour was present in the roasts cured 
with nitrite. Nitrite-containing and nitrite-free samples could also be distinguished when 
the samples were smoked and when sodium chloride was omitted from the cure. 
However, the result also revealed that on 116 occasions involving 288 individual tasting, 
no differentiation was made between salted pork and cured meat. A similar conclusion 
regarding the role of nitrite in flavour formation in frankfurters was obtained by 
Wassermann and Talley, (1972). Sausages prepared with and without nitrite were 
examined by Skjelkvale, Valland and Russwurm, (1973). They found out that, the 
quality of 4500mg/kg, of nitrite as used by Barnet et a!, (1965) caused a bitter flavour 
with decreased acceptability but no significant differences were observed between 
frankfurters cured with 150 or 75mg nitrite/kg, Wassermann and Talley, (197’2) or 
sausages with 80 or 40mg nitrite/kg meat Skjelkvale, Valland and Russwurm, (1973). 
Saltiness of cure plays some part in the overall acceptability of meat products, (Mottram
24
and Rhodes, 1973). A comprehensive study of the acceptability of Canadian and 
Danish bacon was carried out by the Canadian National Research Council in 1938 -  
1939. The work revealed that the high salt of Canadian bacon (7.5%) compared with 
Danish bacon (6.2%) was the major source of dissatisfaction, (Winkler and Cook, 1941). 
These observations were followed by a laboratory taste panel study in which bacon 
containing, salt in the range 4.5 -  9.0% was evaluated, (Hopkins, 1947). A preference 
for bacon with 4.7% salt was obseived as best with reference to nitrite free bacon while 
bacon containing 0.25% nitrate and 4% salt level was preferred in the nitrate-salt bacon 
group. Nitrate at levels of 50mg/kg did not apparently contribute to saltiness. Mottram 
and Rhodes, (1973) investigated the effect of varying the concentration of sodium nitrite 
used in curing pork upon the flavour of bacon. The taste panel used identified the 
various flavour characteristics and examined products cured under different conditions. 
As the nitrite concentration was increased from zero to lOOOmg/kg, an almost linear 
increase in the intensity of bacon flavour was found but above 1500mg/kg, further 
increase in flavour was small. Salt was shown to make a major contribution to bacon 
flavour but sodium nitrite; had no detectable taste at concentrations similar to those 
found in bacon. The differentiation between salted pork and bacon in blind comparisons 
by flavour or odour was remarkably uncertain. Wolf and Wassermann, (1972) 
suggested a re-appraisal of the curing process because the nitrite may under some 
conditions react with amino compounds present to give small concentrations 
nitrosamines. They concluded that, without the use of nitrite, the characteristic cured 
flavour is not developed in meat products. Simon et a! (1972) reported meat 
frankfurters made with beef and pork, scored low in a hedonic taste panel evaluation 
when they contained no nitrite. Wassermann and Talley, (1972) found the role of nitrite 
in frankfurter flavour to be complex and depended on the type of evaluation panel used.
25
They reported that, both smoked and unsmoked frankfurters, showed significant 
differences between products prepared with or without 156 mg nitrite/kg. However, in 
tests in which "Frankfurter" flavour was scored, the smoked, non-nitrite-treated sample 
was rated as highly as the cured sample. Analysis of variance showed an interaction 
between smoke and nitrite. Komarik, (1951) stated that, the processing and curing of 
unchilled pork, was reported in the U.S.A. It was claimed that this process called the 
"Thermocure", could produce satisfactory cured bellies in ten hours from slaughter. 
Patton, (1971) noted that, the main advantages of this cured unchilled carcasses were 
that, the hot processing allowed for more rapid production and turnover and lower 
weight losses. Some researchers obtained increased yields, lower cooking and drip 
losses, improved colour and tenderness and most reported favourably. However the 
findings were somehow equivocal and it may be said that few detrimental characteristics 
were found with hot processed cured meats, and the main advantage must be the 
saving in time and space in production. Smith, Messier and Tittiger, (1989) reported on 
the effect ''dry cured" products, proscuitto, proscuittini and Genoasalami had on 
Trichinella spiralis. They reported that, curing of the various productions was shown to 
destroy the Trichinella larvae. Pepsin digestion revealed that larvae progressively 
became lossely coiled, uncoiled and subject to digestion during the curing process.
2.5 PRESERVATIVE ROLE OF SMOKE ON MEAT
Smoking is often combined with curing., (Adjekum, 1997). Smoke is generally 
produced 'by the slow combustion of saw-dust derived from hard woods, which 
averagely consists of about 40 -  60% cellulose, 20 -  30% hemicellulose, and 10 -  30% 
lignin; and it inhibits microbial growth, retards fat oxidation and imparts flavour to cured
26
meat, (Lawrie, 1985). The saw-dust or hard wood shavings may include oak and 
mahogany, (Kayang, 1987). The preservative action of wood smoke on meat has been 
attributed to some of the numerous complex chemical compounds in the smoke, 
(Lawrie, 1985). According to Foster and Simpson, (1961) wood smoke consists of two 
phases which are:- a disperse, liquid phase containing smoke particles and a dispersing 
gas phase. There are over 200 compounds present in wood smoke, (Wilson, 1963). It 
is believed that formaldehyde accounts for most of the preservative action of wood 
smoke, although most of the compound include phenols, organic acids, alcohols, 
carbonyl compounds and polycyclic hydrocarbons, aldehydes, ketones and cresols, 
(Forrest et a/, 1975); formic, acetic, butyric, caprylic, vanillic and syringic acids, 
dimethoxyphenol, methylglyoxal, furfural, methanol, ethanol, acetaldehyde, diacetyl, 
acetone and 3, 4 -  benzopyrene, (Lawrie, 1985). Some of these compounds exhibit 
either bacteriostatic or bactericidal properties. (Forrest et at, 1975). In addition, 
phenols also have an antioxidant activity that retards the onset of oxidative rancidity, 
(Forrest et a/1975). They also indicated that the compounds listed above probably 
contribute to the characteristic flavour of smoked meat. The idea of the presen/ative 
role of smoke is also towards the lowering of water activity of the product. The 
dehydration effects of the smoke on the meat together with its antioxidant and anti­
bacterial properties all contribute to the preservative action of the smoke and this is 
crucial in augmenting the keeping quality of the product, (Bratzler eta/, 1969).
During smoking, smoke components are absorbed by surface and interstitial 
water in the product, (Forrest et a/, 1975). They reported further that in products that 
have their surface remaining intact, a preservative effect will persist and the reverse is 
true with respect to a loss in bacteriostatic effect. In most present day processed
27
meats, smoking contributes little if any preservative action; since the smoke components 
in no case, penetrate more than a few millimeters. The rate and amount of smoke 
deposition are affected by factors such as temperature, relative humidity, duration of 
smoking, smoke concentration, smoke composition, method of smoke production, 
product composition and air velocity in the smoke house, (Foster and Simpson, 1961 
and Ziegler, 1966). Ziegler, (1966) reported further that, the change in colour of the 
outside surface of smoked meat is hastened by high temperatures and that meat, which 
have been subjected to four to six days of smoke or until they become brown in colour, 
have some added keeping qualities. The outside surface of such smoked meat and 
meat products must be trimmed off before cooking or the meat is likely to cause 
digestive disorders. This is due to the poisonous effect of too large a quantity of the 
pyroligneous acid. During high temperatures in the smokehouse, deposited phenols on 
the meat may volatilize; thus causing them to be reversely absorbed into the gaseous 
phase, (Forster and Simpson, 1961).
Electrostatic smoking processes have been developed in an attempt to speed 
smoke deposition, but these processes have not achieved widespread commercial 
application, (Forrest et at, 1975). A second type of smoking involves liquid smoke 
preparations that have been developed as an attempt to eliminate the smoking process. 
Liquid smoke preparations are free of carcinogenic compounds, such as 3, 4 -  
benzopyrene, that have been discovered in low levels in natural wood smoke.
2.5.1 EFFECT OF SMOKING ON MICROORGANISM POPULATION OF MEAT
Moisture content of meat is reduced by smoke components. The bacteriostatic and
28
bactericidal effects of smoke components serve to decrease microbial numbers 
especially on the surface of meat/products. Smoking to an internal temperature of 58°C 
is capable of destroying all surviving staphylococcion meat. Smoking is often combined 
with curing and this increases the storage life of products, (Adjekum, 1997). 
Apparently, this combined effect decreases microbial load especially on the meat 
surface. The combined effect of time and temperature of smoking on microbes of 
sausages (frankfurters) showed an inverse relationship between time and temperature 
of smoking with bacterial counts from the product immediately after smoking and 
storage, (Heiszler et at, 1972). The combination of heat and smoke is usually effective 
in reducing significantly the surface bacterial population of the product, (Price and 
Schweigert, 1971). They stated further that, in addition, surface dehydration, protein 
coagulation, and the deposition of a resinous material resulting from the condensation 
and formaldehyde and phenol, produce a reasonably effective chemical and physical 
barrier against microbial growth and penetration of the finished product. Today, few 
meat foods are however produced, in urban settlements in which smoke constituents 
play an important role in preserving the product against microbial spoilage. This is 
because, cold storage (refrigeration) is very effective in minimizing microbial growth and 
thus spoilage.
29
CHAPTER 3
MATERIALS AND METHODS
3.1 SITE AND SAMPLE ALLOCATION
The experiment was conducted at the Animal Science Department of the 
University of Ghana, Legon.
A total of 64 fresh bacons and 64 hams of average weight 1.3kg and 4.6kg 
respectively were used in the study. These were from Large Whites, which had been 
slaughtered on a clean slaughter slab after resting them. The bacons were randomly 
divided into two groups of 32 each. Each group was further divided into 2 equal groups 
of 16 bacons each. The 16 bacons was further sub-divided into 4 groups of 4 bacons 
each and dry cured under coldroom temperature (DCCT)and room temperature (DCRT) 
for 2,4,5 and 6 days. The coldroom temperature cured products served as control. 
The second group of 32 bacons were similarly divided and pickle cured under room 
temperature (PCRT) and coldroom temperature (PCCT) for 2, 4, 5 and 6 days 
respectively. The hams were similarly divided and subjected to the same treatments. 
The mean room temperature and cold room temperature for curing were 28.0°C and 0°C 
respectively.
3.2 dURING PROCESS
The curing mixture was according to Ziegler's 8-3-  ^ m ixture o f  8 pounds
30
C3 .6kg) sodium ch lo r id e , 3 pounds (1.4kg) sugar and M ounces 
(7gm) sodium n i t r i t e  fo r  45kg. meat.
3.2.1 DRY CURE fOO
The 8-3-1A. dry cure mixture was made up of 70.8% finely ground sodium chloride,, 
27.5% sugar and 1.7% sodium nitrite and was used at a ratio of 60g of the 8-3-1A cure 
mixture per kilogram of meat. The cure mixture was rubbed onto the meat surface. 
Four replicates of each treated meat type were prepared and laid in a plastic container 
and covered with a plastic sheet and left at average room temperature (28°C) or 
average coldroom temperature of 0°C for 2, 4, 5 or 6 days of curing. The hams and 
bacons being cured under room temperature were covered with a mesh to prevent flies 
settling on the meat. The relative humidity and corresponding temperature during 
curing were recorded every three hours.
3.2.2 PICKLE CURE (PC)
The pickle cure was made up of 66.13% water, 24% sodium chloride, 9.3% sugar and
0.57% sodium nitrite. Pickle equivalent to 10% of green weight of ham or bacon was 
introduced into them through stitch pumping. The rest of the solution wass used as a 
cover pickle for the hams and bacons. Four replicates each of ham and bacon were 
prepared and left to cure for 2,4,5, and 6 days under average room temperature. 
(28°C) and 0°C coldroom temperature. The hams and bacons being cured under room
31
temperature were covered with mesh to prevent flies settling, on the meat. The relative 
humidity and corresponding temperature during curing were recorded.
3.3 SMOKING PROCESS
The smokehouse, which was built of blocks and concrete was preheated to a 
temperature of 30°C for thirty minutes. Cured hams and bacons were hung randomly in 
the smokehouse for an hour for excess liquid on the meat to drip off. Smoking was 
done at an average temperature of 59°C for ten continuous hours. Smoke was 
generated by combusting hardwood firewood and shavings. The hardwood included 
sapele (redwood) and shedua.
At the end of smoking, the meat were left intact in the smokehouse to cool to 
ambient temperature overnight.
3.4 MICROBIOLOGICAL ANALYSIS
Sampling was aseptically done on the fresh hams and bacons before curing. 
Samples were also aseptically taken from the interior of each smoked ham and bacon 
after storage in the smokehouse for 1, 4 and 8 days.
3.4.1. CULTURE MEDIA USED FOR BACTERIOLOGICAL AND MYCOLOGICAL 
ANALYSIS
The culture media for bacteriological and mycological analysis included Blood
32
Agarm, MacConkey Agar, Nutrient Agar, Selenite Faecal Broth, Sabouraud Dextrose 
Agar, Plate Count Agar, Oxidative -  Fermentative Agar, Triple Sugar Agar, Enterococcus 
Agar and Petrifilms. The compositions and preparations of these media were as follows:
COMPOSITION OF BLOOD AGAR
1. Blood Agar Bases -  Special from Difco Laboratories 
Detroit Michigan U.S.A.
Formula in grams per litre
Please arrange in straight line
Beef Heart Infusion 500g
Racto -Tryptose 10g
Sodium Chloride 5g
Selected Peptone mixture 20.Og
Defibrinated Sheep Blood (Sterile) to be added
PREPARATION OF BLOOD AGAR
40gms of Bacto blood agar base (dehydrated) was suspended in 1000ml cold 
distilled water and heated to boiling to dissolved the medium completely.
Solution was sterilized in the autoclave for 15 minutes at 121°C. 5% freshly 
obtained sheep blood was added to the cooled and sterilized medium at 
approximately 45°C. Medium was well mixed and dispensed into sterile petri 
dishes.
33
COMPOSITION OF MACCONKEY AGAR BASE
2. MacConkey Agar Base -  Special from Difco Laboratories 
Detroit Michigan U.S.A.
Formula in grams per litre 
Bacto -  Peptone, Difco 17g
Protease Peptone, Difco 3g
Bacto-Lactose lOg
Bacto-Bile Salts No3 1.5g
Sodium Chloride 5g
Bacto-Agar 13.5g
Bacto-Neutral Red 0.03g
Bacto-Crystal Violet 0.001
PREPARATION OF MACCONKEY AGAR
To rehydrate the medium, 50g of the agar was suspended in 1000ml cold 
distilled water and heated to boiling point to dissolve the medium completely. The 
medium was sterilized in the autoclave for 15 minutes at 121°C and dispensed into 
sterile petri -  dishes to solidify.
3. COMPOSITION OF NUTRIENT AGAR
Formula and Preparation
Oxide dehydrated medium formula (CM3)
Lab-Lemco powder l.Ogms/Lt.
Yeast extract 2.0 "
34
Peptone
Sodium Chloride 
Agar
5.0 "
5.0 "
15.0 "
PREPARATION OF NUTRIENT AGAR
To rehydrate the medium, 28gms of the dehydrated nutrient agar base was 
suspended in 1000ml cold freshly distilled water and heated to dissolve the medium 
completely. The medium was sterilized in an autoclave for 15 minutes at 121°C and 15 
pounds pressure. It was dispensed aseptically into sterile petri dishes and test tubes.
4. COMPOSITION OF SELENITE FAECAL BROTH
Formula and Preparation Special from [
Sodium hydrogen selenite 8g
Peptone l.Og
Mannitol 0.8g
Di-Sodium hydrogen phosphate
anhydrous (Na2HP04) 2.0g
PREPARATION OF SELENITE FAECAL BROTH
With care, the medium was mixed with water and heated to 80°C to dissolve. 
The medium was dispensed in 5ml amounts into test tubes with caps. With caps 
of test tubes loosened the dispensed medium was sterilised for 20 minutes. Test 
tubes were tightened after sterilization to cool.
35
5. COMPOSITION OF SABOURAUD DEXTROSE AGAR (LAB.M. 
SABOURAUD DEXTROSE AGAR)
(A selective medium for the isolation of yeasts and fungi). 
Formulation g/h'tre
Balanced Peptone NO.l 10.0
Dextrose 40.0
Agar 12.0
PREPARATION OF SABOURAUD DEXTROSE AGAR
62g of the medium was dispersed in lOOOmls of deionised water and soaked for 
10 minutes. It was swirled to mix and sterilized at 121°C for 15 minutes. Care 
was taken not overheat the preparation. At 30°C, the medium was dispensed in 
15 mis portions into sterile petri dishes.
6. COMPOSITION AND PREPARATION OF PLATE COUNT AGAR
Fluka Biochemika -  Plate Count Agar.
Composition g/litre
Tryptone 9
Yeast Extract 2.5
Dextrose 1.0
Agar 9.0
17.5g of medium was dissolved in lOOOmls of deionised water and sterilized at 
121°C for 15 minutes. It was then dispensed (15mls) into sterile petri dishes to cool and 
solidify for use.
36
7. COMPOSITION AND PREPARATION OF m ENTEROCOCCUS AGAR
Composition: (Difco Laboratories)
q/litre
Bacto tryptose 20
Bacto Yeast Extract 5
Bacto Dextrose 2
Dipotassium Phosphate 4
Sodium Axide 0.4
Bacto Agar lOg
2,3,5 -  Triphenyl Tetrazolium Chloride - 0.1
42g medium was dissolved in lOOOmls of sterile deionised water and boiled in a 
water bath till boiling was initiated. The dissolved medium was poured (15mls) 
into sterilized petri dishes and allowed to solidify for use.
8. COMPOSITION AND PREPARATION OF OXIDATIVE- FERMENTATIVE 
AGAR
(Hugh and Leifson)
Peptone
Sodium Chloride 
Sodium Phosphate 
Thymol Blue
q/litre
2.0
5.0
0.3
0.03
37
9.8g of the dry medium was suspended in lOOOmls of purified water and heated 
with agitation till a solution occurred. The solution was then sterilized at 121°C 
for 15 minutes.
COMPOSITION AND PREPARATION OF TRIPLE SUGAR AGAR
(Difco Laboratories) g/litre
Bacto -  Beef Extract 3
Bacto -  Yeast Extract 3
BactoPeptone 15
Protease-Peptone, Difco 5
Bacto -  Dextrose 1
Bacto -  Lactose 10
Saacharose -  Difco 10
Ferrous Sulphate 0.2
Sodium Chloride 5
Sodium Thiosulphate 0.3
Bacto Agar 12
Bacto-phenol red 0.024
65g of the medium was suspended in lOOOmls of distilled water and boiled to 
dissolve. The solution was poured (15mls) into test tubes with caps and 
sterilized at 121°C for 15 minutes and slanted.
38
10 PETRIFILMS -  These are already prepared and sterilized medium for 
identification of E. co/iand other coliforms.
3.4.2 REAGENTS USED FOR BIOCHEMICAL EXAMINATION
Biochemical examination reagents used included Urea Broth, Gelatin, Kovac's 
reagent, Catalase, Indole, Mannitol, Oxidase and Peptone water (motility determination).
3.4.3 STAINS USED
Stains used included Lactophenol cotton blue, Lugol's iodine, Safranine Crystal 
violet and Methylene blue.
3.4.4 SAMPLING
A sample of meat (lOg) was taken asceptically from muscle tissues 2cm below 
the surface of the bacon and butt end of ham of every replicate of raw and cured 
products (to include deep tissue microbial contaminants) and put into 90mls of 0.1% 
sterile peptone water and homogenized by shaking vigorously at an acute angle, thirty 
(30) times. This dilution was a 1 in 10.
3.4.4.1 SCHEME FOR BACTERIOLOGICAL AND MYCOLOGICAL 
EXAMINATION OF SAMPLES
Figure 1, illustrates the scheme that was used for bacterial and fungal 
enumeration, identification and characterization.
39
S C H E M E  F O R  B  A C  T E R ; O L O G  I r A ' *. M D F U N  <'. A 1 E X A  M  I N A  T I O  U
A  B  «' D
Yeast  and Fungi En te ro cocc i/Faeca I *Stre p l u t o u  i f ' l - i 1.? if11*./ i - j 'm i  Count I s o l a t i o n  and I d e n t i f i c a t i o n
T
B i o c h e m i c a l  T e s t s
1 Ox dase l Indo1e Test
2 Calalasp ? Urea
Hydrolysis
M k •mo 1 y :» i •. 1 i; i men tali on 
of sugars
V U
o<r
3.4 4.2 TOTAL VIABLE COUNTS fTVC ) OR PLATE COUNTS
A volume of 0,1ml of the homogenized solution with lOg of meat and 90mls 
medium was serially diluted with sterile pipettes before dispensing onto Plate Count 
Agar. A sterile glass rod bent at its tip at 90° ("hockey stick") was used to spread the 
diluted inoculum evenly over the Plate Count Agar and incubated at 37°C, Colonies were 
counted 18 -  24 hours later. Total viable counts (TVCs) of plates that showed counts 
not exceeding 300 colonies were made using a hand lens and hand tally counter.
3 4.4.3 ENTERCOCOCCI/FAECAL STREPTOCOCCO ENUMERATION
Samples were treated as in the case of Plate Count Agar, except it was 
dispensed onm Enterococcus Agar.
3.4 4.4 FUNGAL AND YEAST IDENTIFICATION
A volume of 0.1ml of the 1 in 10 ratio mixture in section 3.4.4. was dispensed 
onto Sabouraud Dextrose Agar with a sterile pipettte and spread with a sterile "Hockey 
stick", (glass rod), incubated at 25°C and examined for 24 -  72 hours for fungal frowth. 
Lactophenol cotton blue stain was used to examine yeast, fungal mycelia, hyphae and 
spores. Fungi and yeast were identified according to Smith, (1969). The staining 
technique involved the picking of part of a pure colony with a sterile metal pin, teasing 
the picked colony over a drop of sterile distilled water on a clean glass slide and fixing it 
over a gentle flame. After drying, a drop of Lactophenol cotton blue stain was poured 
onto the sample, a minute allowed to elapse and the stain examined under the 
microscope.
41
3.4.4.5 Bacteria Identification
lOg of meat sample was taken aseptically from deep muscles, 2cm below the 
surface of the bacon and butt end of ham to include deep tissue microbial 
contaminants. This was put into 90mls of Selenite Faecal Broth and homogenized and 
left for 24 hours, after which an inoculum was picked with a sterile inoculation loop and 
streaked unto MacConkey medium for discrete colonies. MacConkey Agar differentiated 
non-lactose fermentors (pale colonies) and lactose fermentors (pink colonies).
The mixture from section 3.4.4. was also subcultured on Biood Agar to note the 
colonial morphology at 37°C in 24 hours.
Colonies from the subcultures of Blood and MacConkey Agars were then Gram 
stained to note the shape and Gram's reaction. Gram's staining method was as follows:
1. A sterilized metal inoculation loop was used to pick inoculum form a test tube, 
smear it on a glass slide and air dried.
2. Air dried slides were fixed by slowly passing the slide three times through a spirit 
flame and allowed to cool.
3. The smear was flooded with crystal violet for three minutes.
4. The smear was then washed with Gram's iodine.
5. The smear was flooded with Gram's iodine for a minute and washed with tap
water.
6. The smear was decolourised with methylated spirit till not more crystal violet 
came out.
42
7. Tap water was used in washing the smear till the stain was clear.
8. Carbol-fuchsin was washed with tap water, blotted and examined under oil
immersion.
Various biochemical tests (section 3:4:2) were employed to ascertain the identity 
of the bacteria which had been isolated and kept on Nutrient agar.
An already prepared media identification kit (petrifilm) was employed to identify 
coliforms and other members of the Enterobacteriaceae. Esherichia co liwas identified 
on the petrifilm medium as blue colonies surrounded by gas bubbles whiles other 
coliforms appeared as black colonies with or without gas bubbles. Faecal streptococci 
were identified with a selective medium called m Enterococcus Agar.
Indole production tests was used to determine the ability of other coliforms apart 
from £  co/ito decompose amino acid and tryptophan to indole.
The method employed was as described by Cruickshank, (1970).
Triple Sugar Iron (T.S.I.) Agar was used in the identification of Gram-negative 
enteric pathogens, particularly members of the Salmonella -  Shigella group, (Difco 
Manual, 1965). These microorganisms have the ability of fermenting lactose, 
saccharose, dextrose with the formation of acid and gas and also produce hydrogen 
sulphide.
43
Further reactions with mannitol, urea, gelatin, catalase, Kovac’s reagent, oxidase, 
peptone water (for motility determination) were employed to differentiate closely related 
bacteria.
Serological tests could not be performed, due to unavailability of reagents.
3.5 STATISTICAL ANALYSIS
Total viable count (TVC) or bacteria counts obtained from the microbial analysis 
were corrected using the log transformation. This gave standard values for comparisons. 
Each TVC presented for every cured pork product (C.P.P.) on the different days of 
storage was the average of the minimum and maximum TVC obtained out of the four 
replicates from plate counts. The magnitude of the log transformed values (standard 
values) then showed the rate of bacteria growth with increase in days of storage.
44
CHAPTER 4
RESULTS
4.1 TEMPERATURE. RELATIVE HUMIDITY RANGES AND SOME MUSCLE
PHYSICAL CHANGES DURING CURING AND STROAGE
Temperature and relative humidity ranges during curing under room temperature 
and coldroom temperature were variable. The maximum and minimum room 
temperatures during curing were 31.0°C and 26.5°C respectively, while the maximum 
and minimum relative humidities were 85.0% and 53.0% respectively. The maximum 
and minimum coldroom temperatures during curing were +4.0°C and -4.0°C 
respectively, whiles the maximum and minimum relative humidities were 99.0% and 
93.0% respectively. Smoking temperatures ranged between 57 -  62°C.
The maximum and minimum temperatures recorded during storage were 
+46.0°C and +23.0°C respectively, while the maximum and minimum relative humidities 
under ambient conditions were 85.0% and 34.4% respectively. Figures a -  g of the 
appendix show the relationship of temperature and relative humidity during storage of 
the products. The graphs showed in all cases that, as the temperature of curing 
increased the relative humidity decreased.
Off-odour from all dry and pickle cured hams was observed after two days of 
curing under room temperature conditions and worsened with increase in days of 
curing. Curing under room temperature conditions was curtailed after five days for
45
pickle cured hams and bacons whiles curing was curtailed after six days for dry cured 
hams and bacons due to intense off-dour of the products at those times.
There was no off-odour detected in all hams and bacons cured under cold room 
temperature conditions. However the coldroom temperature curing was also ended on 
the fifth and sixth days for pickle curing and dry curing respectively.
Curing under room temperature conditions, resulted in separation of the muscles 
of the hams than their controls as the days of curing increased, (figure 2). The increase 
in separation of the room temperature cured hams was more pronounced over five days 
than two days. Curing under coldroom temperature resulted in hams and bacons with 
muscles less separated, (figures 2 and 3). This separation in muscles was more 
pronounced in hams than bacons.
Observation of 2 day DCRT ham stored over four days showed less turgidity of 
its muscle when compared to its control. The same was true of 5 day DCRT ham stored 
over one day against its control.
46
J a
/ n
(vOOWv [<ZK\fx\
(S»«t>k<2^  10 W j} 
S U r t J  L| dcjjj.
f Co Rot)**n Tlkyp ) 
(S^Okza> tOkrs) 
S-fore^ g  c /q y j
D * y s  t>*>  C — e H ? !  
I  * —^  f O  V**# I
| d a y .  |
Figure 2 4 Photographs showing hams dry cured for 2 daysoarid 5 days 
under room temperature and cold room temperature,smofced-u 
at 57®C and stored in the smokehouse. Notice the separation 
of muscles from the rind (skin) of 5-day dry cure ham under 
room temperature.
Figure ,3: Photographs showing bacons dry cured for 5 days under room
temperature and cold room temperature,smoked at 57°C and 
stored in the smokehouse. No evidence of separation of 
& muscles from the skin in both treatments.
4.2 CHANGES IN MICROORGANISM POPULATION OF HAMS PRY
CUREP FOR 2.4.5 AND DAYS
Tables 1 -4, present the TVCs for hams dry cured for 2,4,5 and 6 days. In 
general, increasing days of room temperature curing, showed an increase in TVCs on 
the first day of storage of the hams in the smokehouse. However, increase in days of 
curing under coldroom temperature showed a decrease in TVCs on the first day of 
storage. Comparison of TVCs of hams dry cured under room temperature and hams dry 
cured under coldroom temperature on the first day of storage, showed that the former 
products had higher TVCs. For example, table 1 shows TVC for DCRT ham on the first 
day of storage as 4.403 ad 3.952 for its corresponding DCCT control ham.
The TVCs for both DCRT hams and their corresponding DCCT hams, increased 
with increase in days of storage under ambient temperatures and relative humidities. 
Their TVC/day (gradient) were usually positive. The only exception was 5 days DCRT 
ham (table 3) which decreased in TVC from 5,300 (first day of storage) to 3,190 (fourth 
day).
49
Table 1 CHANGES IN MICROORGANISM POPULATION FOR
2-DAY DRY CURED HAMS ,
Mean 
Temo. °C
Mean Rel 
Humiditv/%
Days of
Storaae TVC
DCRT
TVC/Dav
DCCT 
TVC TVC/Dav
27.9 58.6 1 4.403
+0.516
3.952
+0.802
28.9 60.0 4 5.950
+0.511
6.358
+0.413
29.0 61.4 8 7.994 6.008
Table 2 CHANGES IN MICROORGANISM POPULATION FOR
4-DAY DRY CURED HAMS
Mean 
TemD. °C
Mean Rel 
Humiditv/%
Days of
Storaae TVC
DCRT
TVC/Dav
DCCT 
TVC TVC/Dav
34,3 46.6 1 4.809
+0.266
2.960
+0.012
31.0 60.3 4 5.608
+0.322
5.966
+0.061
30.1 62.7 8 6.896 6.239
Table 3 CHANGES IN MICROORGANISM POPULATION FOR
5-DAY DRY CURED HAMS
Mean 
Temo. °C
Mean Rel 
Humiditv/%
Days of
Storaae TVC
DCRT
TVC/Dav
DCCT 
TVC TVC/Dav
31.4 64.6 1 5.330
-0.713
2.452
+0.590
31.3 59.3 4 3.160
+0.725
4.223
+0.325
29.4 73.9 8 ' 6.088 5.521
Table 4 CHANGES IN MICROORGANISM POPULATION FOR
* “6-DAY DRY CURED HAMS
Mean 
TemD. °C
Mean Rel 
Humiditv/%
Days of DCRT 
Storaae TVC TVC/Dav
DCCT 
TVC TVC/Dav
25.7__________733____________ 1___________ 5J09________________ 2.236
50
Increase in TVCs of DCCT hams on the fourth day of storage was much higher 
than the TVCs of DCRT hams, all of which were stored under ambient temperature 
conditions in the smokehouse.
4.2.1 CHANGES IN MICROORGANISM POPULATION OF BACONS DRY CURED
FOR 2.4.5 AND 6 DAYS
Tables 5,6,7 and 8 generally showed that, increasing days of room temperature 
curing, showed an increase on TVCs on the first day of storage of the bacons in the 
smokehouse. Increase in days of coldroom temperature curing, however, resulted in a 
decease of TVC on the first day of storage of the bacons. The only exception was the 
relatively high TVC of bacons cured under coldroom temperature for six days (tables 7 
and 8). The TVC (2.099) for 6 days DCCT bacon was expected to have been lower than 
TVC (2.069) for 5 days DCCT bacon by the first day of storage.
Tables 5,6,7 and 8 also showed further that, the TVCs for dry cured room 
temperature bacons and their controls, increased with increase in days of storage. Their 
associated gradients (TVCs/day) were positive. The only exceptions were TVCs for 5 
days DCRT bacons and 5 day DCCT bacons (table 7), which decreased from 3.224 on 
the fourth day of the storage to 3.001 on the eighth day of storage; and 3,389 on the 
fourth day of storage to 2.901 by the eighth day of storage respectively. Their gradients 
reflected negatively as -0.056 and -0.r22 respectively.
51
Table 5 CHANGES IN MICROORGANISM POPULATION FOR 
2-DAY DRY CURED BACONS
Mean 
TemD. °C
Mean Rel 
Humiditv/%
Days of 
Storaae TVC
DCRT
TVC/Dav
DCCT '
TVC TVC/Dav
27.9 58.6 1 2.801
+0.399
2.798
+0.408
28.9 60.0 4 3.997
+0.499
4.023
+0.411
29.0 61.4 8 5.994 5.667
Table 6 CHANGES IN MICROORGANISM POPULATION FOR
4-DAY DRY CURED BACONS
Mean 
TemD. °C
Mean Rel 
Humiditv/%
Days of 
Storaae TVC
DCRT
TVC/Dav
DCCT 
TVC TVC/Dav
34.3 46.6 1 3.160
+0.256
2.628
+0.428
31.0 60.3 4 3.224
+0.069
3.911
+0.020
30.1 62.7 8 3.001 3.989
Table 7 CHANGES IN MICROORGANISM POPULATION FOR
5-DAYS DRY CURED BACONS
Mean 
TemD. °C
Mean Rel 
Humiditv/%
Days of 
Storaae TVC
DCRT
TVC/Dav
DCCT 
TVC TVC/Dav
31.4 61.6 1 3.160
+0.358
2.069
+0.440
31.3 59.3 4 3.224
-0.056
3.389
-0.122
29.4 73.9 8 3.001 2.901
Table 8
•
CHANGES IN MICROORGANISM POPULATION FOR
6-DAYS DRY CURED BACONS
Mean 
Temo. °C
Mean Rel 
Humiditv/%
Days of
....Storage...
DCRT
TVC TVC/Dav
DCCT 
TVC TVC/Dav
25.7 73.3 1
4.626
2.099
52
Comparision of TVCs of DCRT bacons and DCCT bacons on the first day of 
storage, showed that DCRT bacons (table 5) had higher TVC (2.802) than the TVC for 
DCCT bacon (2.798).
In general however, the TVCs of DCCT bacons increased higher from the first 
day of storage to the fourth day of storage than their corresponding DCRT bacons in all 
the respective days of curing (tables 6,7 and 8).
Hams that were dry cured under room temperature or coldroom temperature 
had higher TVCs than the bacons cured under similar conditions.
4.2.2 CHANGES IN MICROORGANISM POPULATION OF HAMS PICKLE CURED
FOR 2.4 AND 5 DAYS
Tables 9, 10 and 11 present the TVCs of pickle cured room temperature hams 
and their corresponding controls. Similar changes as observed in dry cured hams and 
bacons were evident. The TVC for both room temperature and coldroom temperature 
cured hams increased with increase in days of storage. Their associated TVCs/day 
(gradient) were positive. Some of products were extensively spoiled and gave very 
offensive odour. These were therefore discarded before the eighth day of storage as 
indicated in tables, 9, 10 and 11.
Generally, increasing days of room temperature curing, showed an increase in 
TVCs on first 3ay of storage for PCRT hams while increase in days of curing, decreased 
TVCs of PCCT products on the first day of storage.
53
Comparison of TVCs of PCRT ham to PCCT ham on the first day of storage, 
showed that PCRT hams, usually had higher TVCs than their corresponding PCCT ham. 
The only exception was 4 days PCRT ham (table 10) which had a lower TVC (2.700) on 
the first day of storage as against 4 days PCCT ham, which had a higher TVC (2.835) on 
the same day of storage.
The TVCs of PCCT hams also increased from the first day of storage to higher 
counts by the fourth day of storage than their corresponding PCRT hams, (tables 9, 10 
and 11).
54
Table 9 CHANGES IN MICROORGANISM POPULATION FOR 
2-DAY PICKLE CURED HAMS
Mean 
TemD. °C
Mean Rel 
Humiditv/%
Days of 
Storaae TVC
DCRT
TVC/Dav
DCCT 
TVC TVC/Dav
31.6 66.5 1 2.801
+0.495
2.272
+0.701
27.2 81.7 4 4.287 4.376
28.9 77.1 8
TablelO CHANGES IN MICROORGANISM POPULATION FOR
4-DAY PICKLE CURED HAMS
. Mean 
TemD. °C
Mean Rel 
Humiditv/%
Days of 
Storaae TVC
DCRT
TVC/Dav
DCCT
TVC TVC/Dav
30.6 67.0 1 2.700
+0.484
2.835
+1.931
29.1 75.0 4 4.151
+0.528
4.766
26.7 80.0 8 6.263
Table 11 CHANGES IN MICROORGANISM POPULATION FOR
5-DAY PICKLE CURED HAMS
Mean 
Terno. °C
Mean Rel 
Humiditv/%
Days of 
Storaae TVC .
DCRT
TVC/Dav
DCCT 
TVC TVC/Dav
35.1 61.8 1 4.053
+0.599
2.869
+1.105
29.4 74.4 4 5.849
+0.038
6.185
25.8 79.9 8 6.001
55
4.2.3 CHANGES IN MICROORGANISM POPULATION OF BACONS PICKLE
CURED AFTER 2.4. AND 5 DAYS
Tables 12, 13 and 14 present changes in TVCs for PCRT bacons and their 
corresponding PCCT bacons.
The tables also showed similar trends as already seen with earlier treatments. 
The TVCs for PCRT bacon and the corresponding PCCT bacon, increased with increase in 
days of storage. Their associated gradients were positive. The only exception was 4 
days PCRT bacon, (table 13), where the gradient was negative. (-0.072).
Increasing days at room temperature curing increased the TVCs on the first day 
of storage for PCRT bacons. Increase in days for coldroom temperature curing, 
decreased TVCs on the first day of storage for PCCT bacons.
Comparison of TVCs of PCRT bacons to their corresponding PCCT bacons, 
showed higher TVCs for PCRT bacons when observed on the first day of storage.
The TCVs of PCCT bacon increased in every comparison from the first day of 
storage of higher counts by the fouth day of storage than their corresponding 
PCRTbacon. The only exception was 5 days PCCT bacon which had no viable count 
compared with TVC of 3.469 for 5 days PCRT bacon on the fourth day of storage (Table 
14).
Mostly, comparison of PCRT ham to the same-number-of-days-cured PCRT bacon 
and comparison of PCRTham to the same-number-of-days-cured PCCTbacon showed the 
bacons with lower TVCs than hams.
56
Table 12 CHANGES IN MICROORGANISM POPULATION FOR
2-DAY PICKLE CURED BACONS
Mean 
TemD. °C
Mean Rel 
Humiditv/%
Days of 
Storaae TVC
DCRT
TVC/Dav
DCCT 
TVC TVC/Dav
31.6 66,5 1 2.040 2.290
+0,450 +0.387
27.2 81.7 4 3.389 3.452
+0.603 +0.416
28,9 77.1 8 5.801 5.117
Table 13 CHANGES IN MICROORGANISM POPULATION FOR
4-DAYS PICKLE CURED BACONS
Mean Mean Rel Days of DCRT DCCT
TemD. °C Humiditv/% Storaae TVC TVC/Dav TVC TVC/Dav
30.6 67.0 1 2.602 1.370
-0,072 + 1.157
26.1 75.0 4 2.386 4.842
+0.691 +0.980
26.7 80,8 8 5.151 5.233
Table 14 CHANGES IN MICROORGANISM POPULATION FOR
5-DAY PICKLE CURED BACONS
Mean Mean Rel Days of DCRT DCCT .
TemD, °C Humiditv/% Storaae TVC TVC/Dav TVC TVC/Dav
35.1 61-.8 1 3.009 0.000'
+0.153
29.4 74.4 4 3.469 0.000
* +0.071
25.8 79.9 8 3.753 _ _
57
4.2.4 ENTEROCOCCI SP. ENUMERATION
Five different products were found to be contaminated after curing, smoking and 
storage in the smokehouse with Enterococci sp. (Faecal Streptococci). Their log 
transformed numbers in the different products are as shown in table 15. The highest 
population (2.813) and lowest population (1.063) of Enterococci sp. were found in 5 
days DCCT ham and 4 days DCCT ham respectively. From the results, it appears that 
low temperature (coldroom temperature) selected for Enterococci sp. gorwth. Other 
products had no enterococci.
Table 15: ENTEROCOCCI SP. ENUMERATION
PRODUCT LOG TRANSFORMED MEAN COUNTS
5 days DCCT Ham 2.813
5 days DCCT Bacon 1.903
2 days PCCT Ham 1.699
6 days DCCT Bacon 1.297
4 days DCCT Ham 1.063
58
4.3 BACTERIA ISOLATED IN CURE AND CURED HAMS AND BACONS
Isolates identified in both dry and pickle cures included Staphylococcus sp., 
Streptococcus sp. and Proteus sp.
Isolates from the cured hams and bacons during storage under ambient 
conditions in the smokehouse are as shown in table 16 in descending order of frequency 
of occurrence on the 28 cured hams and bacons in the experiment. Staphylococcus sp. 
and Proteus sp. were found on all 28 differently cured hams and bacons. Bacillus sp. 
were found on 27 cured products, Escherichia coii (7), Streptococcus sp. (5), 
Enterococcus sp. (5), Serratia sp., (4), Citrobacter sp. (3), Klebsiella sp. (2), 
Pseudomonas sp. (2) and Arizona sp. (1).
Bacteria isolates found in both dry and pickle cured hams and bacons were 
similar. These are Staphylococcus sp., Streptococcus sp. and Proteus sp.
59
TABLE 16: BACTERIA ISOLATES FROM HAMS AND BACONS
STORED UNDER AMBIENT CONDITIONS IN  SMOKEHOUSE
ISOLATE* CURED HAMS AND 
BACONS
--------- -------  <
FREQUENCY
1. Staphylococcus sp. All samples 28
2. Proteus sp. All Samples 28
3. Bacillus sp. All Samples except 2 days 
DCCT Bacon
27
4. Eschericia coli 4 days DCCT Ham 
4 days DCCT Bacon 
4 days DCRT Ham 
4days DCRT Bacon 
2 days PCCT Bacon 
4 days PCRT Bacon 
4 days PCCT Bacon
7
5. Streptococcus sp. 4 days DCCT Ham 
6 days DCCT Ham 
& days DCCT Bacon 
6 days DCRT Ham 
6 days PCRT Bacon
5
6. Enterococcus sp. 4 days DCCT Ham
5 days DCCT Ham
5 days DCCT Bacon
6 days DCCT Bacon 
2 days PCRT Ham
5
7. Serratia sp. 2 days PCCT Ham 
2 days PCCT Bacon 
2 days PCRT Ham 
2 days PCRT Bacon
4
8. Citrobactersp. 4 days DCCT Ham 
4 days DCCT Bacon 
4 days DCRT Ham
3
9. Klebsiella sp. 2 days DCCT Ham 
2 days DCRT Ham
2
10. Pseudomonas sp. 4 days PCRT Bacon 2
m -  — 5 days PCCT Ham -
11. Arizona sp. 4 days PCCT Ham 1
*Many bacteria were not speciated due to the lack of biochemical reagents
60
4.3.1 MOULD ISOLATED FROM HAMS AND BACONS DURING CURING
Moni/ia spwere identified growing on all room temperature cured hams and 
bacons after the second day of curing. None was observed on any of the hams and 
bacons being cured under coldroom temperature.
4.3.2 MOULD ISOLATED FROM STORED HAMS AND BACONS
Table 17 presents mould isolated from cured hams and bacons 
under ambient conditions in the smokehouse.
Mould identified and their frequency of occurrence on the cured hams and 
bacons were Moni/ia sp. (26), Rhizopus sp., (24), PeniciHium sp. (3), Cladosporium sp. 
(2) and Aspergillus sp. (2). For example, figures 6 and 7 show fungal growth on 2-day 
pickle cured room temperature (F) and 2 day -  pickle cured coldroom temperature (E) 
hams stored for four days. The fungal growth was more profuse on the room 
temperature ham than the coldroom temperature ham, stored over a similar period.
4.3.3 YEAST ISOLATED FROM STORED HAMS AND BACONS
Yeast isolated originated from the family Saccharomycetaceae. They were 
isolated on five cured pork products. (Table 18).
61
TABLE 17: MOULD ISOLATES FROM HAMS AND BACONS STORED
AMBIENT CONDITIONS IN SMOKEHOUSE
ISOLATES CURED HAMS AND BACON FREQUENCY
1. Monilia sp. All products except 2 days 
DCRT and DCCT Bacon
26
2. Rhizopus sp. All products except 2 days 
DCRT and DCCT Bacon, 2 
Days PCRT and PCCT Bacon
24
3. Penicillium sp. 2 days PCCT Bacon, 4 days 
PCCT Ham 
4 days PCRT Bacon
3
4. Cladosporium sp. 4 days PCCT Bacon 
4 days PCCT Ham
2
5. Aspergillus sp.. 6 days DCCT Bacon . 6 days PDCRT Bacon 2
TABLE 13: YEAST ISOLATE FROM HAMS AND BACONS STORED 
UNDER AMBIENT CONDITIONS IN SMOKEHOUSE
ISOLATE* CURED HAMS AND 
BACON
FREQUENCY
1. Saccharomycetaceae
6 days DCCT Ham 
2 days PCCT Ham 
2 days PCCT Bacon 
4 days PCCT Bacon 
4 days PCRT Ham
5
62
Figure 4s Photographs showing surface of 2 day^pickle cured ham under 
room temperature (F) and coldroom temperature (E),smoked for 
10 continuous hours and stored in smokehouse for four days.
2 There is profuse growth of fungus on (F)but less on (E)
CHAPTER 5
DISCUSSION
5.1 CHANGES IN MICROORGANISM POPULATION fTVC) OF STORED CURED 
HAMS AND BACONS UNDER AMBIENT CONDITIONS
The increase in TVCs during storage under ambient conditions conforms to the work of
Kemp et at, (1974), Kayang, (1987) and Anang, (1995). In their work, Kemp et at,
(1974) reported that, microbial counts increased as storage temperature and time
increased. Likewise Kayang, (1987) reported that, increasing the length of storage
outside the refrigerator under ambient temperature condition, permitted the proliferation
of microorganisms. Most of the TVC/day or gradient of bacteria growth were positive
and represent part or parts of the logarithmic phase of the growth curve of bacteria.
The positive gradient indicates where bacteria cells had adequate nutrients to meet their
physiological needs. However, the results obtained on a few occasions showed negative
gradients. This represented the death phase of bacteria growth, where the
accumulation of toxic materials from the bacteria pushed survival conditions to a
minimum or there could have been incubation of some invading organisms.
Increase .in bacteria population during curing and even more so with increasing days of
curing under room temperature conditions, resulted in subsequent increase in toxic
material build up. It could also be due to the depletion of nutrients with increase in
days of storage. Low levels of necessary nutrients essential for fastidious and exacting
%
bacteria imply the dying off of those microbes, (Hechelmann and Kasprowiak, 1992). 
These reasons could possibly have led to the observed negative TVC/day.
64
The usually higher TVC seen in the coldroom temperature products over their 
corresponding room temperature products after 4 days of storage, was probably due to 
the earlier depletion of nutrients in room temperature products during curing. This is 
explained more by the fact that microbial spoilage was initiated in room temperature 
products during room temperature curing whiles their corresponding coldroom 
temperature products were intact and protected to a large extent against microbial 
attack by the low temperature environment except for psychrophiles. Hence, during 
storage under ambient conditions in the smokehouse, microorganisms in cold room 
temperature cured hams and bacons had the opportunity of proliferating in the hams 
and bacons during storage under ambient conditions.
Unhindered microbial build up under ropm temperature curing (where growth 
conditions were optimal) as compared to a hindered and limited microbial growth under 
coldroom temperature curing (where low temperature was a limiting factor) may have 
been the main reason why TVCs of room temperature products were higher by day 1 of 
storage than their corresponding coldroom temperature products. Although smoking 
reduces microbial count, (Ulrich and Halvorson, 1951), its effect is known to be more on 
the surface of the meat product. The deeper tissue of hams especially might have 
needed more than 10 hours of smoking at 59°C for the heat to be transferred into deep 
muscles and temperature raised to a over 50°C to reduce the internal microorganism 
population effectively. This probably" was not attained in the experiment. Hence the 
higher TVCs observed in room temperature cured products over their corresponding 
coldroom temperature cured products by day 1 of storage. Occasionally coldroom 
temperature cured products had TVCs that were higher than their corresponding room 
temperature TVCs. This may be due to contamination of the coldroom temperature
65
products or carcasses or colonisation of the products by cold storage flora. This includes 
Pseudomonas sp. and Achromobactor guttatus, (Price and Schweigert, 1971). The 
growth of putrefactive spoilage microorganisms, and most enzyme activities are greatly 
reduced at low temperatures, (Forrest et a/, 1975). This also explains why TVCs of 
coldroom products were relatively lower than their corresponding room temperature 
products. The initial microbial load has a profound effect upon the spoilage life of fresh 
and processed meat products. However the minimization of further contamination 
during all subsequent handling, processing, packaging and storage is essential in order 
to maintain optimum qualitative properties and also prolong shelf-life, (Forrest et at, 
1975). '
Comparing any bacon to its similarly treated ham, showed lower counts for the 
bacon than the ham. This observation conforms to that of Kayang, (1987). He 
attributed it to the thinness of the bacon which permits a more effective penetration of 
smoke and heat, which controlled the growth of microorganisms. An additional reason 
suggested by Frazier, (1958) is that, the higher fat content of bacon than ham protects 
it from microbial degradation. This is because fatty acids are antinutritional factors for 
many microbes.
5.1.1 CHANGES IN MICROBIAL POPULATION AS AN INDICATOR OF
SPOILAGE
The definition of spoiled meat is variable among different societies. What one 
individual describes as spoiled might be considered edible by another, (Forrest et at, 
1975). They commented further that, spoilage in its usual connotation, is frequently
66
adequate with the decomposition and putrefaction that results from microorganism
activity. Some authors like Jay, (1978) believe that, the build up of microbial population
<
causing the spoilage in the meat products may go along with visible spoilage signs like 
colour change, softening of meat texture, putrefaction, slime formation and 
decomposition. For this experiment, very acute off-odour of the cured and stored hams 
and bacons was the first criteria used to determine the shelflife. With experience, this 
method is one of the best, (Forrest et at, 1975). However it is subjective and there is 
still a lack of scientific consensus regarding standardization of measurements methods 
for odour and the method is cumbersome, laborious and costly, (Baker, 1998).
Undesirable changes in colour of the cured hams and bacons as was observed in 
present experiment with increase in days of storage may have been oxidation of 
myoglobin to metmyoglobin, Lawrie (1985) or pigments produced by microbes like 
streptococci, (Whitely and D'souza, 1989)
Other authors have suggested the use of critical TVCs above which meat 
products may not be consumed. Bacteria counts equal to and above 107 represent a 
food product of terrible and unacceptable microbial count with very low nutrient content 
and necessary to cause illness, (Smith, 1969). In fact, Anang, (1995) supported this 
assertion that bacteria counts of the magnitude 107C.F.U./cm2 is unacceptable. 
However, Hechelmann and Kasprowiak, (1992), reported that, TVCs are guide values 
and recommendations and are not legally binding. They continued that, these values 
may b i usefuTindicators of the history on the storage of the meat and possible health 
implications when consumed. These values vary from country to country. For example 
the recommended maximum level of TVC for heat --processed and smoked meats in
67
Oregon, U.S.A. is 105C.F.U/lgm of meat, Powers, (1976); while Jay, (1978) proposed 
limits of a low maximum 106 and high maximum of 1Q7C.F.U. for a gramme of fresh and 
frozen fish, frozen raw and comminuted meat, and non-frozen ground beef. The 
maximum TVC values in the present experiment were reasonably within the ranges 
stated by the various authors above. (Tables 1 -  14) These limits could thus have also 
being the reference values. Presently in Ghana, no such limits of recommended or 
proposed microbiological limits have been set. It is however anticipated that, the Food 
and Drugs Board (Ghana), Standards Board (Ghana), the Universities and Research 
Stations in Ghana will collaborate and come out with some form of recommendations.
5.1.2 EFFECT OF DRY CURE AND PICKLE CURE ON MICROBIAL GROWTH AT
ROOM TEMPERATURE
In the majority of the products cured over different lengths of days, the higher 
TVCs of room temperature products over the cold room temperature products, indicates 
how less effective room temperature curing was in keeping down bacterial population. 
Frazier, (1958), Forrest et al, (1975), Jay, (1978) and Anang (1995) reported that, no 
type of cure of any strength is capable of resisting total microbial growth and spoilage 
for a long time when extrinsic factors like storage temperature, moisture level (relative 
humidity) and oxygen levels are optimum. Temperature, especially is a critical factor 
that will determine the stability and shelflife of any cured hams and bacons. It was 
clearly realised from the experiment that, no cold room temperature cured hams and 
bacons emitted any off-odour during'curing. This was because, low temperatures, are 
even lethal to many microbes. No matter the level of hygiene maintained, the 
processing (curing) of any meat cannot be devoid of microorganisms. The sources of 
bacteria during room temperature curing were numerous. Literature by Frazier, (1958) 
Forrest et a (1975), Jay; (1978) and Anang (1995), suggests that, room temperature
68
(28°C) is high enough to permit spoilage of cured hams and bacons. Very pungent off- 
odour by curing day two was the result of microbial degradation of the meat. Although 
no plate counts were done during room temperature curing, off-odour production was 
enough assessment of the increasing microbial population with increase in days of room 
temperature. Five days was the maximum number of days possible for both ham and 
bacon during pickle curing at room temperature. The high moisture content of the 
injected pickle (66.13%) as well as the total immersion in pickle solution, greatly 
increased the water activity for microbial spoilage. This fact coupled with the relatively 
high room temperature (26.5 -  28°C) during curing, high internal moisture content of 
ham and less fat content, rendered ham greatly vulnerable to bacterial attack and 
spoilage. Therefore microbial counts from hams were usually higher than their 
corresponding similarly cured bacons group which had higher fat content, lower 
moisture content and were thin in thickness and very broad in surface area. The width 
and broadness of bacon, presented a very wide surface area which led to the quick and 
effective drying up of the surface of the bacon. This in turn probably lowered the water 
activity and favoured less microbial growth.
Six days was the maximum number of days possible for room temperature 
curing. The difference of one day between the maximum of six curing days for dry 
cured room temperature products and the maximum of five curing days of pickle cured 
room temperature products was probably due to the lower moisture content in dry cure. 
The 8-3-1/4 sugar mixture in the dry cure represented 70.8% sodium chloride, 27.5% 
sugar Snd 1.7% sodium nitrite. The only fluid available for microbial usage were the 
extracellular and cell fluid of the hams and bacons. This fluid would be far lower in the 
dry cured products due to exosmosis. The higher moisture content (66.13%) in pickle
69
cured products (especially ham) plus that of the extracellular and cell fluid, enhanced 
bacteria to cause spoilage quicker than it would be in dry cured products. Another 
explanation, by Forrestt et al, (1975) suggests that, increasing the salt content of meat 
lowers the isoelectric point and thus the pH. It seems that, the magnitude of the pH 
shift depends on the amount of sodium chloride added and leads to water oozing out of 
the meat products. It is therefore not surprising that, dry cured products with 70.8% 
sodium chloride appeared drier than pickle cured (24%) products.
On the whole, it may be summarized that any type of room temperature curing 
has a limited effect in controlling microorganism population. This control is within the 
first few days of the curing, after which spoilage is complete.
5.2 MICROORGANISMS ISOLATED IN CURE AND CURED HAMS AND 
BACONS
Many of the bacteria isolated are of great public health importance to man. This 
is because they cause illness by the ingestion of the bacteria or their toxins which results 
in food contamination. Many of the microbes cause gastroenteritis. The illness caused 
render their victims a liability to their dependants. Secondly, the bacterial activities in m 
any of the food cause spoilage amounting to huge financial losses in the food industry. 
Some can lead to death.
5.2.1 BACTERIA IN CURE
The three microorganisms isolated in the cure were Staphylococcus sp. 
Streptococcus sp. and Proteus sp. Their physiological activities initiated off-odour. 
Random sampling of microbial contaminants in the deep tissues of ham and bacons
70
mostly revealed no microbes before curing. Identification of microbes in deep muscle 
tissues with petrifilms on the few occasions bacteria were isolated showed them to 
belong to the family Enterobacteriaceae but excluded Eschericia coii. This implies that, 
the likely source of Staphylococcus sp. and Streptococcus sp. is the cure.
The isolation of staphylococci in the cured hams and bacons, conforms with the 
works of Kemp et a!, (1974); Jay, (1978); Kayang, (1987); and Hechelmann and 
Kasprowiak, (1992). Earlier, Castellani and Niven, (1954) and Kemp, (1974) had 
confirmed that many varieties of staphylococci, grow quite readily on cured meats. 
Some were coagulate positive others were negative. Debruyne, (1998) indicated that, 
the prevalence of staphylococci in any food is an indication of contamination from the 
skin, nose, arms, throat, hands, fingers, hair, face and eyes of personnel working with 
the cure or meat samples. These bacteria are associated with mucous membrane and 
skin. Inadequately cleaned equipment, like knives and axes, may also be sources of 
staphylococci, (Thatcher and Clark, 1975) as well as the curing ingredients (salt and 
sugar) which were purchased from the open market for this project.
Kayang, (1987) reported that, the presence of large numbers of staphylococci 
generally indicate that, sanitation and temperature control have somewhere been 
inadequate. This means that, storage of the cured products under ambient conditions, 
provided the necessary atmosphere for the survival of mesophilic bacteria (of which 
staphylococci are part) in the cure and cured hams and bacons. The ability of 
staphylbcocci to survive in salt medium is due to their high tolerance to salt under warm 
temperatures, (Gradwohl, 1973). Some of the toxigenic cocci are very salt tolerant and 
grow in sodium chloride solutions that approach saturation, while some species also
71
tolerate nitrite fairly well and therefore can grow in curing solutions and cured meat if 
other environmental conditions are favourable, (Frazier, 1958). They are fairly tolerant 
to dissolved sugars. Though the staphylococci isolated was not speciated, it must be 
noted that, there are grave implications if any of the isolated species are among the 
pathogenic types. This is because, they contribute to the stability and safety of the 
meat product, (Hechelmann and Kaksprowiak, 1992). Pathogenic staphylococci produce 
heat stable enterotoxins that can cause food-poisoning with diarrhoea, nausea, 
vomiting, severe abdominal cramps and weakness, (Jay, 1978). He stated further that, 
the pathogen, Staphylococcus aureus, also produces boils and carbuncles in man while 
their enterotoxin cause gastroenteritis or inflammation of the lining of the stomach and 
intestines. To avoid any such illnesses, cured hams and bacons should be adequately 
and properly cooked before eating. Unfortunately the toxin of S. aureus is heat stable; 
so cooking will only eliminate the vegetative cells but not the toxin.
Streptococcus sp. has wide temperature range of growth (10 -  45°C) with some 
degree of salt tolerance. The presence of this species still goes to emphasize the 
probable lack of proper hygiene on handling of carcasses during slaughter and 
processing. Some species are associated with the upper respiratory tract infection of 
man and other animals. The presence of this bacteria may therefore not be due only to 
the cure but also the carcasses. Ingestion of meat with this contaminant may cause 
diseases such as scarlet fever and septic sore throat. They are also associated with 
mastitis.
72
Proteus sp. may be found in the intestinal tract of man and animals and the 
presence of some species in foods in large numbers, may indicate faecal contamination. 
This raises a big question about the hygiene standards of the persons who were selling 
the common salt and sugar used as cure on the open market. Education about personal 
hygiene and some basic teaching of food microbiology is strongly recommended for 
those who deal in food items. There was a low frequency of occurrence of Proteus sp in 
the cured hams and bacons after curing and smoking. This means that, certain factors 
in the cured hams and bacons might have discouraged their growth. This may be due 
to their low degree of tolerance to salt and the effect of smoking which decreased with 
the water activity of the cured products. The presence of Proteus sp. signifies 
contamination of the carcass with the gut content and offals during evisceration perhaps 
by inexperienced or careless butchers in the slaughted house, (Gracey, 1981). Animals 
for the present experiment were slaughter on a slaughter slab. Cross-contamination 
may have taken place from the slab to the carcass or the spilling of the gut content with 
the meat. This could have been the probable source of Proteus sp. to the meat. 
Another source of this bacteria may be from a decaying material of plant or animal 
origin which may have found its way onto the meat or salt used. (Jay, 1978). 
Inefficient disinfection after slaughtering and deboning, results in pieces of left over 
animal tissue to become the sites of multiplication for Proteus sp. Another probable 
reason, though quite remote with respect to the present experiment, is the issue of 
"miss-cured" hams. Hams that are not properly cured, may sometimes be the suitable 
substrates for Proteus sp. (Gracey, 1981). Others are of the opinion, that, the presence 
of Prdteus Sp. may be an indication of a probable wound infection, pus from abscesses, 
urinary tract infection, otitis, dysentery and diarrhoea before slaughter.
73
Although starter cultures are used in curing meat in the meat industry, care 
needs to be taken to use desirable microorganisms that impart desirable flavours during 
curing. All cure before application should be sterilized before the desired microbes are 
introduced into the cure for the curing process. With reference to the three proteolytic 
bacteria {Staphylococcus sp., Streptococcus sp. and Proteus sp.) isolated in the cure 
before curing, sufficient heat must be applied to destroy them before cure application as 
dry or pickle cure is made.
5.5.2 FUNGAL GROWTH DURING ROOM TEMPERATURE CURING
The results showed no fungal growth during coldroom temperature curing.
Monilia sp. and sometimes its perfect stage of growth, Neurospora sp. was found 
growing on dry cured room temperature hams and bacons. Their growth was much 
prominent on dry cured room temperature bacons. No fungal growth was however 
observed on 2 days DCRT products. Smith, (1969) reported that Monilia sp is able to 
grow on the products because it is osmophilic and therefore can tolerate high salt 
temperatures on the surface of the products. It can also grow between warm 
temperatures and even very low temperature as -40°C. Growth was more profuse on 
bacon because Monilia sp. possesses lipase enzyme and is a saprophyte. It is easy for 
the spores of the fungus to fall on the flat broad bacon surface whenever it wasexposed 
during room temperature curing. The presence of Monilia sp. indicates that, the curing 
room and surrounding areas have a 'high concentration of the organisms which may 
initiate spoilage of meat products cured and prepared in the vicinity. Its presence is also 
indicative that'bacterial growth is taking place in the product and is far advanced. This 
inference is made because the growth of bacteria, paves the way to a sharp lowering of 
the pH of meat to limits unsuitable for the growth of many other bacteria except for
74
some fungi like MonHia sp.. MonHia sp. was absent on 2 days DCRT products probably 
because the pH, was relatively too high to allow for its growth.
The absence of MonHia sp. on pickle cured products at room temperature was 
due to the fact that, products were submerged in the pickle cure. It therefore had no 
organic substrate to grow on.
5.5.3 MICROBIAL CONTAMINANTS IN STORED CURED HAMS AND BACONS
5.5.3.1 BACTERIA
Apart from Staphylococcus sp, Streptococcus sp, and Proteus sp. which were 
found in the majority in the hams and bacons prior to smoking, other bacteria were 
isolated from the products during storage in the smoke house after smoking. These 
were Bacillus sp. Escherichia coii, Streptococcus sp; Enterococcus sp. Serratia sp. 
Citrobacter sp; Klebsiella sp, Pseudomonas sp and Arizona sp.
The presence of these microorganisms indicate the type of handling and 
contamination that might have taken place after curing of the hams and bacons. The 
presence of these microbes were also similar to microorganisms normally found on 
cured meat as indicated by Jay, (1978), Hechelmann and Kasprowiak, (1992), Muller 
and Fehihaber, (1995) and Schuppel, Salchert and Schippel, (1996). The source of 
many microbes is the soil, (Jay, 1978).’ Spores of bacilli may be easily conveyed in the 
air from the soil on to cured hams and bacons after the opening of the smokehouse 
door for*the taking of samples or go through the chimney of the smokehouse. It is not 
easy controlling bacilli because there are many varieties ranging from aerobic to 
facultative types and can hydrolyze meat proteins, (Muller and Fehihaber, 1995). The
75
same authors reported that, Bacillus sp. are saprophytic and belong to the group of 
microbes with the highest proteolytic activity. In some cases, enzyme activities of 
Bacillus sp. are still detectable even after the longest heat exposure times of 20 minutes 
at 71°C and 10 minutes at 75°C. These residual exoprotease activities can survive a 
wide range of heat treatments used in the food processing industry and can, in certain 
milleius lead to undesirable changes in the stored products, (Muller and Fehlhaber, 
1995). Deterioration of the cured hams and bacons and the effect on sensory properties 
are partly attributed to these exoprotease activities. During the experiment, smoking 
temperature was below 63°C and therefore implies that, the bacilli exoproteases present 
were not inactivated. In order to minimize the incidence of bacilli, it would be expedient 
to keep the cured hams and bacons in an environment that has a minimum access to air 
blowing from outside.
The incidence of Escherichia co liis a clear indication of exposure of the meat to 
animal and human gut contents or faecal matter. The presence of the other gram 
negative species Serratia sp., Pseudomonas sp. Proteus sp. and other members of the 
group Enterobacteriaceae, is also strongly indicative of cross-contamination of the meat 
with gut contents of mammals and birds. In the present experiment this may have been 
during exsanguination or "sticking" of the animal with an unclean knife which had been 
used earlier to enviscerate an aminal. Gram negative bacteria were in the majority of 
the microorganisms isolated Board, (1968), reported that, the predominance of gram- 
negative rods in products, is an indication of abundance of supply, of relatively simple 
nutrients in the product. Many of the gram negative bacteria have a relatively simple 
nutritional need. Autolysis or preliminary hydrolysis of proteins by the meat enzymes 
undoubtedly helps microorganisms start growing and cause spoilage with off-odour in
76
the meat by furnishing the simple nitrogen compounds needed by many microorganisms 
that cannot attack complete and complex native protein. After the use of simpler 
nutrients, only microbes with advanced form of nutrition can survive, (Frazier, 1958). 
According to Gracey, (1981) some of the organisms with advanced form of nutrition 
included E. coii, Proteus sp. and Pseudomonas sp. as one group and the second group 
are those with simple form of nutrition including Serratia sp. and Klebsiella sp. These 
two groups of organisms were encountered on the cured products between the first and 
fourth and eighth days of storage. Sapong, (1990) reported that, Serratia sp. and 
Klebesiella sp. represent possible aerobic contaminants, and may have found their way 
into the cured meat whenever they were occasionally blown unto the meat from the 
ground or during washing of the carcasses with contaminated water. The variable mode 
of cross-contamination may explain why the bacteria occurrence on the various cured 
meat products was without pattern.
The incidence of Arizona sp, a closely related species of Salmonella sp. and 
causal agent of bacillary dysentry, typhoid and enteric fevers, (Gradwohl, 1963), 
indicated cross-contamination of the products, (Table 16) by the personnel working with 
the meat, and insects such as flies and cockroaches. Some houseflies (Musca 
domestica) were occasionally observed around the smokehouse. Some of the flies may 
have entered the smokehouse through the chimney and transmitted bacteria and 
even possibly, Streptococcus faecaiisfmm  a gut source or contaminated matter to the 
products in storage. The chances of this type of contamination occuring more 
frequently was lessened by placing a wire mesh around the chimney during storage in 
the smokehouse. The low frequency of of occurrence of these two pathogens over the 
duration of the whole experiment goes to indicate the little role Musca domestica played
77
as a vector during spoilage. Streptococcus faecalis, is known to be very resistant to 
curing and is only destroyed at temperatures above 72°C. This probably assured their 
survival since the maximum temperature during smoking was 62°C.
Pseudomonas sp. frequency of occurrence was lower than normally expected on 
meat products. Most of the species that occur in this genus, are cold storage microflora 
and do not thrive well in warm conditions. Few have the ability to thrive successfully 
under a wide range of temperatures ranging from room temperatures to temperatures 
lower than room temperature, (Saviour and Board, 1972). Pseudomonas sp. is able to 
utilize extensively the native proteins of the cured hams and bacons for satisfying it's 
nutritional requirement, (Board, 1965) and is highly suspected as one of the species 
contributing to the foul odour produced during the experiment, (Gracey, 1981).
5.5.3.2 MOULDS
The contamination of a food product by an agent of food-borne diseases 
constitute a hazard to the health of consumers, (Saudi and Mansour, 1990). The 
presence of the five fungi isolated is in agreement with authors like Jay, (1978), 
Kiermier, (1981), Leistner and Eckardt, (1981), Orth, (1981), Gracey (1981) and 
Mansour, (1986).
Most of the moulds isolated from the cured hams and bacons are very important, 
(table 17). They included Aspergillus sp and Penidllium  sp. which can produce 
mycotoxins in meat and milk products, Kiermeir, (1981) and Leistner and Eckardt, 
(1981) or even carcinogenic mycotoxins by Aspergillus sp, (Jay, 1978); Cladosporium sp. 
which is responsible for the development of black spots on preserved meat at low
78
temperatures (-6°C) or temperatures just below freezing point, Smith, (1969) and 
Mansour, (1986), Some strains of Penicfflium sp. which produce toxins at iow 
temperatures, (Orth, 1981). The rest of the fungi, isolated in the experiment, were 
Moni/ia sp. and Rhizopus sp. which are noted largely for food spoilage, (Jay, 1978).
Gracey, (1981) reported that, Aspergillus sp. Penicillium  sp. and Rhizopus sp. 
have a wide limit of growth conditions and are also saprophytic and mesophilic. This 
accounts for their ability to grow on the cured hams and bacons. They grow at 
temperatures ranging from 20-30°C with water activity ranging from 0.88 to 0.80,
Gracey (1981). Possession of such wide growth capabilities accounts for the 
development of their spores on any cured ham or bacon. Their capabilities favour moist 
osmophilic conditions similar to those that existed (especially) on pickle cured products 
and dry cured ham. These cured products had high moisture and salt levels. The 
existing relative humidites and temperatures, ranging from 46.6 -  80.1% and 25.5 -  
35.1°C respectively, provided adequate growth conditions for these mesophilic fungi. 
The moisture level in the cured hams (especially room temperature cured products), 
decreased with increase in days of storage in the smokehouse. This affected the water 
activity of the cured products by decreasing it and thus favoured fungal growth, (Frazier, 
1958). Such factors account for the almost frequent presence of Rhizopus sp. and 
Moni/ia sp. on the cured hams and bacons.
5.5.3.3 YEASTS
No yeast cells were found in any of the cures but only in a few of the cured
79
products, (table 18). Their source is likely to be through spores floating in the 
atmosphere or picked from the curing table. Organisms may also have contaminated 
the cured hams and bacons during storage, as well as the slicing of the products for 
samples. Taking of samples for microbiological examination involved cutting a cross- 
section of the smoked hams or bacons, which exposed a new fresh muscle surface. A 
floating spore could therefore, easily settle on it from the atmosphere. Smoking of cut 
meat products surfaces after slicing is therefore highly recommended.
The growth of the isolated yeast cells (Saccharomycetaceae) were in only five 
products out of the twenty-eight products employed in the experiment. This low 
frequency of occurrence is in accordance with literature. Infact, studies carried out on 
yeast developed inside cured meat products are few and this probably may be due to 
the fact that some authors like Francisco et al, (1981) Jociles et al, (1983), Hugas et at, 
(1987), had not detected their presence or because, as in other cases, Giolitti et a l 
(1971) and Carrascosa et al, (1988), had recorded very low levels. They may thus not 
play an important role in the curing process, (Molina, Silla and Flores, 1990). From the 
results, the yeasts isolated thrived well on pickle cured products, irrespective of the 
temperature of curing. This implies that, coldroom or room temperature curing was not 
capable of preventing the yeast from utilizing the available nutrients in the cured 
products. Yeasts are normally found on or in food products with a low water activity. 
However, it is still in accordance with Smith, (1969), Mansour, (1986) and Saudi and 
Mansour, (1990) that, they grew well in moist filled pickle cured products. The yeast
isolated belong to the group of yeasts with physiological characteristics that permit 
generalizations fitting many habitats. Firstly Saccharomyceteae grow best with plentiful
so
supply of available moisture, (Frazier, 1958). He further indicated that, they are 
osmophilic, where they grow well in high concentration of sugar as was used in the 
pickle. In any case, osmophilic yeasts have a very limited growth, if at all with a water 
activity of 0.78 in both brine and sugar syrup. Possibly growth of yeasts in the cured 
products was not realised because of temperature variations which might have 
influenced the movement and distribution of cure solutes in a manner that could not 
support yeast growth.
It must be noted that the water activity values of the cured products vary with 
the nitrite properties, pH, temperature, availability of oxygen and presence of inhibitory 
substances, (Frazier, 1958). Very little is however, known about the effect they may 
exert on meat products when they develop in the interior of ham, (Molina, Silas and 
Flores, 1990). Certainly, their development, on the surface of cured products have an 
evident influence on their sensory quality. This is because they improve the 
organoleptic characteristics on flavour.
81
CHAPTER 6
CONCLUSION AND RECOMMENDATIONS
No type of cure (dry or pickle) was strong enough to prevent microbial growth 
under room temperature curing. Increase in days of room temperature curing, resulted 
in a corresponding off-odour particularly noticeable after 2 days curing with 
corresponding changes in muscle structure and colour in all cured hams and bacons. 
The maximum number of days of curing for both dry cured hams and bacons was 6 
days. It was 5 days for pickle cured hams- and bacons at room temperature. The 
corresponding coldroom curing did not cause any noticeable off-odour with increase in 
days of curing. Increase in days of coldroom temperature curing resulted in decreased 
TVCs after storage in the smokehouse for a day.
Storage of all dry pickle and cured products under ambient conditions in the 
smokehouse saw a progressive deterioration with increase in days of storage. The 
deterioration was particularly greater and more acute for room temperature cured hams 
and bacons than their corresponding controls.
Randomly sampling of all fresh hams and bacons usually showed no microbes 
in deep muscle tissues. Bacteria isolated from the cure (dry and pickle), were the same 
in the deep muscle tissues of cured hams and bacons. These included Staphylococcus 
sp. and Proteus sp. The source from which the cure was purchased was highly 
suspicious and brought into question the level of hygiene that is maintained by some
82
open air market sellers. Other contaminants during storage of the cured pork products 
included pathogenic and non-pathogenic bacteria of various implications. Gram 
negative enteric bacteria were in the majority and comprised Arizona sp., Pseudomonas 
sp., Klebsiella sp., Serratia sp. and E, coll. Others were the spore forming Bacillus sp. 
and the problematic Streptococcus faecalis, which is noted for its extreme resistance to 
extermination in salt cure even at high temperatures (70°C) during curing.
Fungi isolated on the hams and bacons during room temperature curing and 
storage belonged to the genera Peniciliium sp., Cladosporium sp. and Monilia sp. Yeast 
present belonged to the family Saccharomycetaceae,
Due to decreased TVCs, and less likelihood of the growth of pathogens under 
cold room temperature, it is recommended that curing should be done under low 
temperatures rather than high temperatures.
Comparison of the TVCs of room temperature hams and bacons to their 
respective controls did not usually show very large differences in magnitude during 
storage. Hams that were dry cured or pickle cured under room temperature or 
coldroom temperature respectively had higher TVCs than bacons cured under similar 
conditions. Bacons are thus less likely to carry bacteria load high enough to cause 
diseases.
83
Curing under room temperature conditions is recommended only for bacons. 
The recommended or safest length of time for room temperature pickle curing is two 
days and that for room temperature dry curing is four days. Hams should not be dry or 
pickle cured under room temperature conditions due to high possibility of the growth of 
pathogens which can lead to illness.
There was not specific association of any microorganism to any particular cured 
product. The source of contaminants were from the cure and the environment. Cross­
contamination was evident. The presence of Staphylococcus sp. implies contaminations 
from humans (working personnel) or animals. It indicated the possible presence of heat 
stable and exterotoxins which can be the source of gastro intestinal diseases. Eschericia 
co ii implies faecai contamination. Arizona sp., Klebsiella sp., Proteus sp. and 
Enterococcus sp. have public health significance.
It is highly recommended that food handlers and dealers on the education on the 
handling of food and the maintenance of proper hygiene. Legislation should be 
enforced to insist that these personalities have a regular health check up. It is highly 
recommended that all cure be heat treated before application.
Knives and surfaces should be cleaned well before use and some amount of 
smoking should be done after the slicing off of a piece of the cured pork hams and 
bacons for use. Cooking of meat to be eaten must be adequately cooked before 
sen/ing.
As much as possible, smokehouses used should be made from material (such as 
clay) to allow effective cooling. This would ensure low storage temperatures. The 
smokehouse should not be in the direct path of sun rays or near a heat emitting source, 
strong wind paths and must be as far as possible from unhygienic sources like a rubbish 
dump. Its door must be tight fitting to prevent entry of pests like cockroaches, flies and 
rodents.
Animals should also be thoroughly examined or inspected by qualified personnel 
and slaughtered under hygienic conditions. Proper disinfection of slaughtered houses 
and equipment should be a must.
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1 e
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re
FIGURE a
Temperature & Relative Hum idity variation during storage under ambient conditions.
(2 days dry cure ham and bacon- Experiment 1)
• ‘v i i r v  >>f • s lo r . i i ) -
FIGURE b
Temperature & Rclntivu Hum id ity variation during storage under ambient conditions.
(4 clays dry euro ham and bacon- Experiment 2)
Hours of storage
te
m
pe
ra
tu
re
 
(c
el
ci
us
)
F IGURE c
Tem p e ra tu re  and re la t ive  h um id i t y  v a r ia t io n  du r ing  s to rage  u nd e r  am b ien t  cond i t io n :
(5 days  d ry  cu re  ham  and  bacon- E x p e r im e n t  4)
hours nfter storage
-a—  •" Mi' HI!
re
lat
ive
 
hu
m
id
ity
! 7
,.) 
T
01
te
m
p
e
ra
tu
re
FIGURE d
tem pe ra tu re  and re la t ive  h um id i t y  v a r ia t io n  d u r in g  s to rage  u nd e r  am b ie n t  cond it ions
(6 da ys  d ry  cu re  ham  and bacon- E x p e r im e n t  3)
csjoM
hours of storage
—s — f EfvlP —•— R H
re
la
tiv
e 
h
u
m
id
it
y
te
m
pe
ra
tu
re
(c
el
ci
us
)
COO
(2 days p ick le cure ham and bacon- Experim ent 5)
FIGURE ' e
T em pe ra tu re  and re la t ive  h um id i t y  v a r ia t io n  du r ing  s to rage  u nd e r  am b ie n t  cond it ions .  " H
hours after storage 
-a— TEMP —*— RH
re
lat
ive
 
hu
m
id
ity
 
(%
)
te
rn
pe
ra
Ui
re
(c
el
ci
us
)
o
rH
(4 days p ick le  cure ham and bacon- Experim ent 6)
FIGURE - f
Tem pe ra tu re  and re la t ive  h um id i t y  va r ia t ion  du r ing  s to rage  u n d e r  am b ien t  cond i t ions .
hours after storage
- a - T E M P  — RH
re
lat
ive
 
hu
m
id
ity
(%
)
te
m
pe
ra
tu
re
 
(c
el
ck
is
)
O
( 5 days p ickle cure ham and bacon-,Experim ent 7)
f ig u r e  -g::-.
T em p e ra tu re  and re la t ive  h um id i t y  v a r ia t io n  du r ing  s to rage  u n d e r  am b ie n t  cond i t ions .  rH
hours of storage
-B-TEM P  —*-RH
re
lat
ive
 
hu
m
id
ity
 
(%
)