MICROBIOLOGICAL EXAMINATION OF FOODS SOLD WITHIN FEDERAL MEDICAL CENTRE, UMUAHIA

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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