TABLE OF CONTENTS                                               

Title page    –         –         –         –         –         –         –         –         –         i

Certification          –         –         –         –         –         –         –         –         -ii

Dedication   –         –         –         –         –         –         –         –         –         iii

Acknowledgements         –         –         –         –         –         –         –         iv

Table of Contents  –         –         –         –         –         –         –         –

CHAPTER ONE

1.0     Introduction          –         –         –         –         –         –         –         1-5

CHAPTER TWO

2.0 Meat product   –         –         –         –         –         –         –         –         6-7

2.1 Contamination of meat products    –         –         –         –         –         7-8

2.2 Sources of contamination of meat products       –         –         –         9

2.3 Common microbes of meat products       –         –         –         –         10-11

2.4 Effects of microbes on meat and meat products –         –         –         11-12

2.5 Causes of meat spoilages     –         –         –         –         –         –         12-13

2.5.1  Microbial Spoilage          –         –         –         –         –         –         13-14

2.5.2  Lipid Oxidation     –         –         –         –         –         –         –         15

2.5.3  Autolytic Enzymatic Spoilage   –         –         –         –         –         15-16

2.6 Shelf-life and microbial meat spoilage     –         –         –         –         16-17

2.7 Factors influencing shelf-life and spoilage of

meat and meat Products      –         –         –         –         –         –         17-18

2.7.1  Intrinsic Factors     –         –         –         –         –         –         –         18

2.7.1.1 Composition and Antimicrobial Hurdles      –         –         –         18-19

2.7.1.2 Buffer Capacity and pH –         –         –         –         –         –         20

2.7.1.3 Redox Potential    –         –         –         –         –         –         –         20

2.7.1.4 Water Activity     –         –         –         –         –         –         –         21-22

2.7.2  Extrinsic Factors    –         –         –         –         –         –         –         22

2.7.2.1 Packaging and Gaseous Atmosphere            –         –         –         22-23

2.7.2.2 Storage Temperature                –         –         –         –         –         23-24

2.8 Alteration associated with spoilage          –         –         –         –         24

2.8.1  Off Odours and Off Flavours     –         –         –         –         –         24-25

2.8.2  Colour Alteration   –         –         –         –         –         –         –         26

2.8.3  Gas Production      –         –         –         –         –         –         –         27

2.8.4  Filaments and Ropy Slime         –         –         –         –         –         27-28

2.9   Preservation of meat –         –         –         –         –         –         –         28-29

2.9.1  Low Temperature Methods        –         –         –         –         –         29

2.9.2  Chilling        –         –         –         –         –         –         –         –         29-30

2.9.3  Freezing       –         –         –         –         –         –         –         –         30

2.9.4  Super Chilling        –         –         –         –         –         –         –         31

2.9.5  Controlled Water Activity Methods     –         –         –         –         32

CHAPTER THREE

3.0 Poultry meat    –         –         –         –         –         –         –         –         33-34

3.1 Contamination of poultry     –         –         –         –         –         –         34-35

3.2 Spoilage organisms in poultry meat         –         –         –         –         35-36

3.3 Microbiological risk assessments of poultry products  –         –         33-37

3.4 Microorganisms associated with poultry products       –         –         34

3.4.1  Salmonella and Campylobacter           –         –         –         –         37-38

3.4.2  Clostridium perfringes               –         –         –         –         –         38-39

3.4.3 Escherichia coli      –         –         –         –         –         –         –         40

3.4.4 Listeria monocytogens      –         –         –         –         –         –         40-41

3.5 Control of poultry product contamination          –         –         –         41-44

3.6 Microbial safety of poultry products        –         –         –         –         44-46

3.7     Chemical Methods for Controlling Microbial Spoilage     –         46-52

 CHAPTER FOUR

4.0 Summary         –         –         –         –         –         –         –         –         53-54

4.1 Conclusion       –         –         –         –         –         –         –         –         54

References

CHAPTER ONE

1.0     Introduction

Meat is flesh of animals such as chickens, sheep, pigs and cattle, and it is usually eaten together with other food.  Meat products include all types of meat, poultry and game products in pieces and cuts or comminuted, fresh and processed. Meat is valued as a complete protein food containing all the amino acids necessary for the human body. The fat of meat which varies widely with the species, quality and cut is a valuable source of energy and also influences the flavor, juiciness and tenderness of the lean. Parts such as livers, kidneys, hearts and other portions are excellent sources of vitamins and of essential minerals, easily assimilated by the human system (Heetun et al.,  2015).

Meat products are products resulting from the processing of meat or from further processing of such products, so that the cut surface shows that the product no longer has the characteristics of fresh meat. It can also be said to be any product prepared wholly or partly from fresh meat (which has undergone treatment to ensure a certain degree of preservation) but excluding fresh meat and their examples include bacon, ham, sausages, corned beef, canned meat, etc. Poultry are domesticated avian species that can be raised for eggs, meat and/or feathers. The term poultry covers a wide range of birds, from indigenous and commercial breeds of chickens to mallard ducks, turkeys, guinea fowl, geese, quail, pigeons, ostriches and pheasants (Miller et al. 2002).

Poultry products are poultry which has been slaughtered for human food, from which the blood, feathers, feet, head and viscera have been removed in accordance with rules and regulations. It is any edible part of poultry. Poultry products include meat, eggs and feathers. Consumption of meat is continuously increasing worldwide. The annual per capita consumption increased from 10kg in the 1960’s to 26kg in 2000 and will reach 37kg by the 2030 (Heinz and Haukzinger, 2007).

On the other hand, a significant portion of meat and meat products are spoiled every year. It is reported by Cerveny et al. (2009) that approximately 3.5 billion kg of poultry and meat were wasted at the consumer, retailer and food service levels which have a

substantial economic environmental impact. Significant portion of this loss is due to microbial spoilage. Cerveny et al. (2009) stated that if 5% of this meat loss is preserved, it could satisfy the daily needs of approximately 320,000 people for meat and poultry (Cerveny et al., 2009).

The transformation of animals into meat involves several operations: (a) Handling and loading of animals on the farm (b) Transporting animals to slaughter houses (c) Offloading and holding of animals and (d) Slaughtering of animals. Poor operational techniques and facilities in any of these operations will result in unnecessary suffering and injuries to animals which can lead to loss of meat, reduced meat quality and spoilage of meat (Miller et al.,2002). Therefore, prevention of contamination after slaughtering during meat cutting and processing is essential. Storage time can be extended through hygienic slaughtering and clean handling of the carcasses. Different technical operations are involved in slaughtering: (a) Stunning (b) bleeding (c) skinning (d) evisceration and (e) carcass splitting. Inadequacy at one stage will result in a rigorous negative impact on the product and/or process in the following stage. In addition to the hygiene and storage temperature, the acidity of the meat and the structure of the muscular tissue also affect the rate of the meat spoilage (Heetun et al.,  2015).

For example, liver will spoil faster than the firm muscular tissue of beef (Berkel et al., 2004).  After few hours of slaughtering of animals, muscles become firm and rigid, a condition known as rigor mortis. The process of rigor mortis depends on the stress induced on the animals during the slaughtering process. Raw meat quality is reported to be severely affected by the stress conditions during slaughtering process and the slaughtering methods (Chambers and Grandin, 2001).

Fat, protein, minerals, carbohydrate and water are the constituents of meat (Heinze and Haukzinger, 2007). The quality of meat and meat products degrade as a result of digestive enzymes, microbial spoilage and fat oxidation (Berkel et al., 2004).  Lipid oxidation, protein degradation and the loss of other valuable molecules are the consequences of meat spoilage process. Proteins and lipids can break down resulting in the production of new compounds causing changes in meat flavor, tenderness, juiciness, odor and texture. It is therefore important to understand the causes of spoilage of meat and meat product in order to develop optimum preservation techniques to maintain the freshness of these food products (Berkel et al., 2004).