TABLE OF CONTENTS

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

Certification –         –         –         –         –         –         –         –         –         ii

Dedication   –         –         –         –         –         –         –         –         –         iii

Acknowledgements         –         –         –         –         –         –         –         vi

Table of Contents  –         –         –         –         –         –         –         –         v

CHAPTER ONE

1.0     Introduction –         –         –         –         –         –         –         –         1

CHAPTER TWO                              

2.0     Starter Culture       –         –         –         –         –         –         –         3

2.1     Types of Starter Culture   –         –         –         –         –         –         3

2.2     Sources of Starter Cultures        –         –         –         –         –         5

2.3     Characteristics of Good Starter Cultures        –         –         –         6

2.4     Factors Affecting Fermentation Process        –         –         –         8

2.5     Preparation of Starters     –         –         –         –         –         –         18

CHAPTER THREE

3.1     Benefit of Starter Cultures in Yoghurt Production   –         –         23

3.2     Roles of Starter in Fermented Foods   –         –         –         –         26

3.3     Maintenance and Preservation of Starter Cultures-  –         –         27

CHAPTER FOUR

4.0     Summary and Conclusion-        –         –         –         –         –         35

4.1     Summary     –         –         –         –         –         –         –         –         35

4.2     Conclusion  –         –         –         –         –         –         –         –         36

References

CHAPTER ONE

1.0     INTRODUCTION

Yoghurt, a ferment milk product has become more popular worldwide for its important properties such as high soluble protein, rich nutrients, high calcium content, low-sugar and fat (Cappuccino and Natalie, 2008). For its preparation, the milk is allowed to ferment with the microbial inoculums called lactic acid bacteria (LAB) which are used as a starter under controlled environment condition (Aswal et al., 2012). These bacteria ferment milk sugar lactose to lactic acid thus lowering the pH and inhabiting the growth of pathogenic bacteria (Zacharof and Lovitt, 2012). These bacteria also produce acetone which is the main flavouring agent of yoghurt (Guzet Seydim et al., 2005). Various types of factor influence yoghurt quality which may be nutritional (quality of raw milk), environmental temperature. pH, time of incubation and size of starter (Temitayo et al., 2016).

Amount of active starter culture is an important factor which influences the quality of yoghurt. To activate the starter, suitable amount of inoculum, the time and the temperature of incubation are the important considerations. Aroma, flavor, stability, texture of final product that the rate of acidification of raw milk at the primary selection criteria of suitable starter culture (Obi et al., 2010). In some country, the manufacturers usually follow the traditional method for making yoghurt without understanding the importance of above factors, and they have no knowledge about the microbiology of starter culture. Therefore, manufacturers cannot control the quality of yoghurt, and hence quality varies from one batch to another as well as from one region to another.