ABSTRACT
The microbiological quality of ready-to-eat food products sold in a federal medical center was assessed. A total of forty eight food samples, including beans, fried rice, jollof rice and moi-moi were collected from two food vending sites which serves as the major ready to eat food vending centres in the hospital premises. A total of nine species of microorganisms including Bacillus spp, Escherichia coli, Klebsiella spp, Proteus spp, Staphylococcus aureus, Aspergillus niger, Aspergillus fumigatus, Penicillium spp and Mucor spp were isolated from the food samples. The mean total aerobic plate count, coliform count and fungal count from Site I range from 2.5 × 103 to 9.1 × 106 cfu/g, 3.2 × 103 to 3.4 × 104 cfu/g, and 6.0 × 102 to 7.3 × 104 cfu/g respectively. Site II had aerobic plate count, coliform count and fungal plate count ranging from 2.7 × 103 to 9.8 × 106, 5.2× 103 to 7.8 × 104 cfu/g, and 9.0 × 103 to 9.3 × 106 cfu/g respectively. Based on the specifications by International Commission for Microbiological Specification for Foods (ICMSF), the level of contaminations was within acceptable microbiological limits except for beans; this could be attributed to extensive handling, mixing and to the fact that it is consumed as raw food. It is recommended that a closer and stringent supervision of ready-to-eat foods sold in hospital areas should be carried out by relevant authorities to prevent possible outbreak food borne illness.
TABLE
OF CONTENTS
Title page i
Certification ii
Dedication iii
Acknowledgements iv
Table of Contents v
List of Tables vii
Abstract viii
CHAPTER ONE:
INTTRODUCTION 1
1.1 Types of food 2
1.1.1 Fast
food 2
1.1.2 Junk
food 3
1.1.3 Whole
foods 3
1.1.4 Organic foods 4
1.2 Sources
of food 4
1.3 Aims and objectives 5
CHAPTER TWO: LITERATURE
REVIEW 6
2.1 Microbial
contamination 6
2.2 Microbial food contamination 7
2.3 Mechanism of microbial food contamination 18
2.3.0 Pre-Harvest/Harvest Contamination of Food 19
2.3.1 Pre-harvest
Factors 19
2.3.2 Harvest factors 21
2.3.4 Pre-Slaughter
and Slaughter Contamination 21
2.4 Microbiological
food contamination at post harvest/post-slaughter 23
2.4.1 Food
processing/ food preparation factors 23
2.4.2 Distribution,
marketing and storage factors 26
2.5 Food
contamination mechanism in some selected foods 27
CHAPTER THREE: MATERIALS AND METHODS 30
3.1 Study area 30
3.2 Media used 30
3.3 Sterilization 30
3.4 Sample
processing 31
3.5 Physicochemical
analysis 31
3.6 Identification of bacteria 31
3.7 Gram
staining 32
3.8 Catalase
test 32
3.8.0 Coagulase
Test 33
3.8.1 Citrate
Test 33
3.8.2 Motility
test 33
3.8.3 Urease
test 33
3.8.4 Indole
test 34
3.8.5 Triple Sugar Iron Test 34
3.8.6 Oxidase Test 34
3.9 Identification
of fungal isolates 34
CHAPTER FOUR: RESULTS 35
CHAPTER FIVE:
DISCUSSION, RECOMMENDATION AND CONCLUSION
5.1 Discussion 40
5.2 Recommendation 41
5.3 Conclusion 42
References 43
LIST OF TABLES
Table Title Page
1:
Mean microbial load of food
samples in site 1 from 36
Federal
Medical Center Umuahia (cfu/ml)
2:
Mean microbial load of food
samples in site 2 from Federal
Medical Center Umuahia (cfu/ml) 37
3:
Fungal loads of food samples from
site 1 and site 2 from
federal medical center 38
4: Food
samples and microorganisms isolated 39
CHAPTER
ONE
INTTRODUCTION
Food is any substance or material eaten or drunk to
provide nutritional support for the body or for pleasure (Francis, 2000). It
usually consists of plant or animal origin, which contains essential nutrients,
such as carbohydrates, fats, proteins, vitamins, or minerals, and is ingested
and assimilated by an organism to produce energy, stimulate growth and maintain
life. Food chemistry is the study of chemical processes and interactions of all
biological and non-biological components of foods. The biological substances
include meat, poultry, lettuce, beer, and milk as examples. It is similar to
biochemistry in its main components such as carbohydrates, lipids, and protein,
but it also includes areas such as water, vitamins, minerals, enzymes, food
additives, flavors, and colors.
This discipline also encompasses how products change
under certain food processing techniques and ways either to enhance or to
prevent them from happening. An example of enhancing a process would be to
encourage fermentation of dairy products with microorganisms that convert
lactose to lactic acid; an example of preventing a process would be stopping
the browning on the surface of freshly cut Red Delicious apples using lemon
juice or other acidulated water (Francis, 2000). Food meets a basic physical
need. To this effect, food has been defined as edible or portable substances
(usually of plant or animal origin) consisting of nourishing and nutritive
components such as carbohydrates, fats, proteins, essential minerals and
vitamins which (when ingested and assimilated through digestion) sustains life,
generates energy and provides growth, maintenance and health of the body (David
et
al., 2012). Besides, food also meets emotional, social and psychological
needs. Regrettably, foods despite their beneficial roles in the body, can also
serve as vehicles for disease transmission and cause of death if contaminated
with harmful microorganisms, microbial toxins or environmental contaminants
(chemical allergens and Microphysical particles).
An adequate supply of Safe, wholesome and healthy food
is essential to the health and wellbeing of humans. This is in keeping with the
phenomenon of food security, defined by Food and Agricultural Organization
(FAO) of the United Nations (UN) as Food security exists when all people, at
all times, have physical, social and economic access to sufficient, safe and
nutritious food which meets their dietary needs and food preferences for an active
and healthy life. Thus, besides assuring that all people have access to enough
food to lead productive lives, food security also has the challenge of assuring
that the food is safe from a chemical, physical and biological aspect. This
aspect of food security is called food safety (an umbrella term that
encompasses many facets of handling, preparation and storage of food to prevent
illness and injury) including chemical, microphysical and microbiological
aspects of food quality (Hyman et al.,
1993). Microbiological aspect of food safety involves exclusion from food, of
pathogenic microorganisms or microbial toxins which presence in food could
constitute potential health hazards.
1.2
TYPES OF FOOD
1.1.1 Fast
Food
Fast food is the term given to food that can be prepared and served
very quickly. While any meal with low preparation time can be considered to be
fast food, typically the term refers to food sold in a restaurant or stored
with preheated or precooked ingredients and served to the customer in a packaged
form for take-out/take-away. Outlets may be stands or kiosks, which may provide
no shelter or seating (Jakel, 1999) or fast food restaurants (also known as quick
service restaurants). Franchise operations which are part of restaurant
chains have standardized foodstuffs shipped to each restaurant from central
locations (Talwar, 2003).
1.1.2 Junk Food
Junk food is
an informal term applied to some foods which are perceived to have little or no
nutritional value, or to products with nutritional value but which also have
ingredients considered unhealthy when regularly eaten, or to those considered
unhealthy to consume at all. The term was coined by Michael Jacobson, Director
of the Center for Science in the Public Interest, in 1972 (Brendon, 2006). Junk
foods are typically ready to eat convenience foods containing high levels of saturated
fats, salt, or sugar; and little or no fruit, vegetables, or dietary fibre, and
do not provide any health benefits. Junk food includes foods such as soft
drinks, hamburgers, hot dogs, ice cream, cake, French fries, chocolate,
confectionery, pizza, cookies, fried chicken, onion rings and doughnuts.
1.1.3 Whole Foods
Whole foods are foods that are unprocessed and unrefined, or processed and
refined as little as possible before being consumed. Whole foods typically do
not contain added ingredients, such as sugar, salt, or fat. Examples of whole
foods include unpolished grains; fruits and vegetables; unprocessed meat,
poultry, and fish; and non-homogenised milk. The term is often confused with
organic food, but whole foods are not necessarily organic, nor are organic
foods necessarily whole. Because of the lack of basic processing, some whole
foods have a very short shelf life (Behall, 2000).
1.1.4 Organic
Foods
Organic foods are made in a way that complies with
organic standards set by national governments and international organizations.
For the vast majority of human history, agriculture can be described as
organic; only during the 20th century was a large supply of new synthetic
chemicals introduced to the food supply. This more recent style of production
is referred to as “conventional.” Under organic production, the use of
conventional non-organic pesticide (including insecticides, fungicides, and
herbicides) is precluded.
1.2 SOURCES OF FOOD
Historically,
people obtained food from hunting, farming, ranching, and fishing, known as
agriculture. Today, most of the food energy consumed by the world population is
supplied by the food industry operated by multinational corporations using
intensive farming and industrial agriculture methods. Almost all foods are of
plant or animal origin.
Cereal
grain is a staple food that provides more food energy worldwide than any other
type of crop. Maize, wheat and rice together account for 87% of all grain production
worldwide. Other foods not from animal or plant sources include various edible
fungi, especially mushrooms: Fungi and ambient bacteria are used in the
preparation of fermented and pickled foods such as leavened bread, alcoholic
drinks, cheese, pickles, kombucha and yoghurt, Blue-green algae such as
Spirulina. Inorganic substances, baking soda, cream of tartar are also used to
chemically alter an ingredient (McGee, 2004).
Many
plants or plant parts are eaten as food. There are around 2,000 plant species
which are cultivated for food, and many have several distinct cultivars. Seeds
of plants are good sources of food for animals, including humans because they
contain nutrients necessary for the plant’s initial growth, including many
healthy fats, such as Omega fats. In fact, the majority of foods consumed by
human beings are seed-based foods. Edible seeds include cereals (such as maize,
wheat, and rice), legumes (such as beans, peas, and lentils), and nuts.
Oilseeds are often pressed to produce rich oils, such as sunflower, flaxseed,
rapeseed (including canola oil), and sesame (McGee, 2004). One of the earliest
food recipes made from ground chickpeas is called hummus, which can be traced
back to Ancient Egypt times.
Seeds are
typically high in unsaturated fats and, in moderation, are considered a healthy
food, although not all seeds are edible. Large seeds, such as those from a
lemon pose a choking hazard, whereas seeds from apples and cherries contain
poison cyanide. Fruits are the ripened ovaries of plants, including the seeds
within. Many plants have evolved fruits that are attractive as a food source to
animals, so that animals will eat the fruits and excrete the seeds some
distance away. Fruits, therefore, make up a significant part of the diets of most
cultures. Some botanical fruits, such as tomatoes, pumpkins and eggplants, are
eaten as vegetables. Vegetables are second types of plant matter that are
commonly eaten as food. These include root vegetables (such as potatoes and
carrots), leaf vegetables (such as spinach and lettuce), stem vegetables (such
as bamboo shoots and asparagus), and inflorescence vegetables (such as globe
artichokes and broccoli). Many herbs and spices are highly flavorsome
vegetables (McGee, 2004).
1.3 AIMS
AND OBJECTIVES
The aim of this research work is to
examine the microbial load of pathogenic organisms associated with food.
Objectives
1.
To isolate and identify
resident microorganisms present in the food.
2.
To determine pathogenic
microorganism in the food sample.
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