MICROBIAL FOOD SPOILAGE DISORDERS (DISEASES) AND ITS CONTROL

ABSTRACT

Foods and microorganisms have long and interesting associations which developed long before the beginning of recorded history. Foods are not only nutritious to consumers, but are also excellent sources of nutrients for microbial growth. Depending on the microorganisms present, foods may spoil or be preserved by fermentation. Foods can act as a reservoir for disease transmission, and thus detection and control of pathogens and spoilage organisms are important areas of food microbiology. During the entire sequence of food handling from the producer to the final consumer, microorganisms can affect food quality and develop potential health effects for humans. Food spoilage is a metabolic process that causes foods to be undesirable or unacceptable for human consumption due to changes in sensory characteristics (tactile, visual, olfactory or flavour). Chemical reactions that cause offensive sensory changes in foods are mediated by a variety of microbes that use food as a carbon and energy source. These organisms include bacteria, fungi, protozoa and viruses. Many physical and chemical methods are employed to control the growth of certain microbes on foods thereby preventing their spoilage.

TABLE OF CONTENTS

Title Page i

Table of Content ii

Abstract iii

CHAPTER ONE

1.0 INTRODUCTION 1

1.1 Principles Underlying Spoilage of Food 2

1.2 Factors Affecting the Development of

Micro-organisms in Foods 6

1.2.1 Intrinsic Parameters 12

1.2.2 Extrinsic Parameters

1.3 Foods and Their Microbial Spoilage 15

1.3.1 Dairy Products 15

1.3.2 Vegetables 16

1.3.3 Raw Meat 16

1.3.4 Fish 17

1.3.5 Fruits and Juices 18

CHAPTER TWO

2.0 DISEASE OF MICROBIAL FOOD SPOILAGE 20

2.1 Types of Microbial Food Borne Disease 20

2.2 Description of Selected Diseases 22

2.2.1 Staphylococcal Food Poisoning 22

2.2.2 Botulism 23

2.2.3 Salmonella Gastroenteritis 24

2.2.4 Shigellosis (Bacillary Dysentery) 26

2.2.5 Escherichia Coli Enteritis 27

2.2.6 Bacillus Cereus Gastroenteritis 29

2.2.7 Yersinia Enterocolitica Gastroenteritis 30

2.2.8 Listeriosis by Listeria Monocytogenes 31

CHAPTER THREE

3.0 CONTROL OF MICROBIAL FOOD SPOILAGE 33

3.1 Applications of Heat 33

3.1.1 Boiling 34

3.1.2 Pasteurization 34

3.2 Low Temperature (Refrigeration and Freezing) 36

3.3 Drying (Removal of H2O) 36

3.4 Irradiation (Uv, X-ray, Gamma Radiation) 37

3.5 Control of Microbial Growth by Chemical Agents 38

3.5.1 Antiseptics 38

3.5.2 Disinfectants 39

3.5.3 Preservatives 39

3.6 Intermittent Boiling (Tyndalization) 40

3.7 Sterilization 40

CHAPTER FOUR

4.0 CONCLUSION AND RECOMMENDATION 42

4.1 Conclusion 42

4.2 Recommendations 43