TABLE OF CONTENTS

Title Page    –         –         –         –         –         –         –         –         –         i

Declaration  –         –         –         –         –         –         –         –         –         ii

Certification –         –         –         –         –         –         –         –         –         iii

Dedication   –         –         –         –         –         –         –         –         –         iv

Acknowledgement –         –         –         –         –         –         –         –         v

Table of Contents   –         –         –         –         –         –         –         –         vi

CHAPTER ONE 

1.0     Introduction –         –         –         –         –         –         –         –         1

CHAPTER TWO

2.0     Overview of Food –         –         –         –         –         –         –         5

2.1     Classification of Food     –         –         –         –         –         –         5

2.1.1  Classification according to shelf-life    –         –         –         –         5

2.1.2  According to Functions   –         –         –         –         –         –         6

2.1.3  According to Nutrients Value     –         –         –         –         –         7

2.1.4  According to Extent and Purpose of Processing      –         –         7

2.2     Purpose of Processing      –         –         –         –         –         –         8

2.3     Food Spillage         –         –         –         –         –         –         –         8

2.3.1  Physical Spoilage of Food         –         –         –         –         –         9

2.3.2  Microbial Spoilage of Food       –         –         –         –         –         9

2.3.3  Chemical Spoilage of Food       –         –         –         –         –         10

2.4     Oxidation     –         –         –         –         –         –         –         –         10

2.4.1  Proteolysis   –         –         –         –         –         –         –         –         11

2.4.2  Putrefaction –         –         –         –         –         –         –         –         12

2.4.3  Pectin Hydrolysis  –         –         –         –         –         –         –         12

2.4.4  Maillard Reaction  –         –         –         –         –         –         –         13

2.4.5  Hydrolytic Rancidity       –         –         –         –         –         –         14

2.5     Factors Influencing Food Spoilage      –         –         –         –         14

2.5.1  pH     –         –         –         –         –         –         –         –         –         15

2.5.2  Water Activity (aw)         –         –         –         –         –         –         15

2.5.3  Nutrient Content    –         –         –         –         –         –         –         16

2.5.4  Oxidation-Reduction Potential   –         –         –         –         –         16

2.5.5  Temperature of Storage   –         –         –         –         –         –         17

2.4.6  Relative Humidity Environment (RH) –         –         –         –         17

2.4.7  Presence and Concentration of Gases in the Environment –         18

2.4.8  Crystal Growth      –         –         –         –         –         –         –         18

2.4.9  Moisture      –         –         –         –         –         –         –         –         18

2.6     Food Preservation Method         –         –         –         –         –         19

CHAPTER THREE

3.0     Heat Treatment of Foods –         –         –         –         –         –         21

3.1     Principal      –         –         –         –         –         –         –         –         21

3.2     Types of Heat Treatment  –         –         –         –         –         –         23

3.2.1  Pasteurization        –         –         –         –         –         –         –         23

3.2.2  Blanching    –         –         –         –         –         –         –         –         23

3.2.3  Grilling        –         –         –         –         –         –         –         –         24

3.2.4  Smoking      –         –         –         –         –         –         –         –         25

3.2.5  Drying         –         –         –         –         –         –         –         –         26

3.2.6  Boiling         –         –         –         –         –         –         –         –         27

3.2.7  Cooking       –         –         –         –         –         –         –         –         27

3.2.8  Frying          –         –         –         –         –         –         –         –         28

3.2.9  Canning       –         –         –         –         –         –         –         –         29

3.2.10 Hot Filling –         –         –         –         –         –         –         –         29

3.2.11 Sterilization –         –         –         –         –         –         –         –         30

3.3     Heat Systems         –         –         –         –         –         –         –         31

3.4     Effects of Heat Treatment on Foods    –         –         –         –         32

3.4.1  Effects of Heat Treatment on Nutrient of Food        –         –         32

3.4.2  Effects of Heat Treatment on Microbial Quality      –         –         34

3.4.3  on Chemical Structure     –         –         –         –         –         –         34

3.4.4  Problems Associated with Food Heat Treatment      –         –         35

3.5     Benefits of Food Heat Treatment         –         –         –         –         36

3.5.1  Eliminations of Food Heat Treatment  –         –         –         –         36

3.5.2  Increase palatability of food      –         –         –         –         –         37

3.5.3  Increase shelf-life  –         –         –         –         –         –         –         38

CHAPTER FOUR

4.0     Summary and Conclusion

4.1     Summary     –         –         –         –         –         –         –         –         39

4.2     Conclusion  –         –         –         –         –         –         –         –         40

References

CHAPTER ONE

1.0     INTRODUCTION

The term food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal or fungal origin and contains essentials nutrient such as carbohydrate, fat, proteins, vitamins or minerals (Steele, 2004).

Food can broadly classified according to the shelf life, functions and nutrient value, and processing mechanism. Shelf life is the length of time that a commodity may be stored without becoming unfit for use, consumption or sale. Consumption of spoiled food can lead to illness and in the extreme situation to death (Steele, 2004).

The purpose of processing food is to use different techniques by the food industries to turn fresh food into food products. Unprocessed or minimally process food, process culinary or food industry ingredients, and ultra processed food products are the three major groups base on the extent and purpose of food processing (Carbs, 2010).

Food can be spoiled by different physical, microbial or chemical activities which reduces food edibility and it can be detected by color, smell, texture, and flavor of food.  Food spoilage is related to food safely (Steele,2010).

Food are said to be spoiled due to physical changes or instability.  Moisture loss or gain, moisture migration between different components, and physical spoilage (Rahman,1995).  Other factors of food spoilage are microbial spoilage which occurs due to the action of microorganism.  It is also the most common cause of airborne disease.  The growth of most microorganism can be prevented or hindered by adjusting storage temperature, reducing waste activity, towering pH, using preservatives, and using proper packaging (Tianli et al., 2010).

Chemical spoilage occurs naturally in foods and leads to unpleasant sensory results in food products. In oxidation, Oxygen, amino acids Converts into organic acid and ammonia. This is the elementary spoilage reaction in refrigerated fresh meat and fish (Jay, 2000). In proteolysis, the entire phenomina require the presence of miscellaneous protease enzymes (Rogers and Overall, 2013). Putrefaction are the series of anaerobic reactions through which amino acids detour to a mixture of amines such as mercaptans and hydrogen sulfide.  Pectin hydrolysis, this process cause the color changes in fruits jams or jellies (Walter and Taylor,1991).  Others are Maillard reaction and hydrolytic rancidity.

There are also factors that influencing food spoilage which are moisture, temperature, crystal growth and food preservation method.

Heat treatment is used in a general sense and relates to the determination of heating condition required to produced microbiologically safe products of acceptable eating quality.  Heat treatment generally involve heating of food for a specific period at a predetermined temperature to kill microorganisms of public health concern and deactivate enzymes that cause deterioration of the food during storage.  A range of different heat treatment is now employed in the food industry.  A variety of packaging materials are used, not just tin-plate aluminium and glass, but also rigid and semi-rigid plastic materials formed into the shape of cans, pouches, laminated packages, and bottles.  The food environment consist of intrinsic and extrinsic factors.

Food preservation can be achieved by manipulating these factors which limits the microbial growth and avoids enzymatic degradation (Roding et al., 2015).  Heat treatment is the widely used methods for preserving food by the application of heat to preserve food quality and extend shelf life (Teixeira, 2014).  It is a worldwide practiced and economically viable system that can be adopted to almost any foodstuffs and package (Rodrigo et al., 2015).  The preservation is done by destroying pathogenic or spoilage type microorganisms, and inactivating the enzymes and toxins present in the food (Storforos, 2015).

Nicolas Appert first presented a combined method in addition to heat treatment for preserving food by sealing the container in 1810 (Tucker and Featherstone, 2015). After that time a series of important research works have been done on heat treatment and today we have several developed methods of heat treatment, pasteurization, hot filling, and sterilization (Kumar and Sadeep, 2014).