DEVELOPMENT OF MICROBIAL QUALITY OF SOY MILK BASED YOGHURT-LIKE BEVERAGE

ABSTRACT

Research efforts in the developing countries have been geared towards the towards the improvement of protein quality foods using blends of legume and cereal which is considered a nutritionally balanced product. Therefore, this present study is aimed at finding local substitute for milk based product with high protein content of a well balancing amino acid composition and high digestibility; determining the proximate composition and microbial analysis with a view of knowing the consumer acceptability of the product. Yoghurt samples were produced from blends of soymilk using Streptococcusthermophilus and Lactobacillusbulgaricus as starter cultures (probiotics). Yoghurt samples produced were coded A, B and C representing yoghurt containing 2g of sugar, yoghurt containing 2g of pineapple and yoghurt only as control respectively. Yoghurt samples were subjected to chemical and microbiological assessment. The results of chemical analysis after final fermentation revealed protein contents of A, B and C as 4.10, 4.20 and 4.30% respectively for the samples. Fat contents varied between 2.25, 2.18 and 2.07%, ash content 1.52, 1.01 and 1.04 were obtained for the samples respectively. The carbohydrate contents of the samples ranged from 3.51 to 7.93 after incubation, while all the samples showed fairly acidic levels. Water contents of between 88.0 to 89.08% were obtained. The microbiological examination revealed a tolerable level for all the samples.

TABLE OF CONTENT

Certification ﾿ i

Dedication ﾿ ii

Acknowledgement ﾿ iii

Table of content ﾿ iv

List of table ﾿ v

List of figure ﾿ vii

Abstract ﾿ viii

CHAPTER ONE ﾿ 1

INTRODUCTION ﾿ 1

1.1 ﾿ Background of study ﾿ 1

1.2 ﾿ Problem statement ﾿ 3

1.3 ﾿ General objective ﾿ 3

CHAPTER TWO ﾿ 4

LITERATURE REVIEW ﾿ 4 ﾿

2.1The nature of soy milk ﾿ 4

2.2 Production processes ﾿ 5

2.3 Constituents of soymilk ﾿ 6

2.3.1 Protesaeinhibitor ﾿ 6

2.3.2 Ligmans ﾿ 6

2.3.3 Phytosterols ﾿ 7

2.3.4 Coumestans ﾿ 7

2.3.5 Saponins ﾿ 7

2.4. Problems associated with soymilk production and consumption. ﾿ 8

2.5Spoilage of soy milk ﾿ 8

2.6 Lactic Acid Bacteria ﾿ 9

2.7 Conditions that favors the Growth of Lactic Acid Bacteria (LAB) ﾿ 11

2.8 Classification and uses of lactic acid bacteria ﾿ 13

2. 8.1 Uses of lactic acid bacteria ﾿ 13

2.9 Yoghurt and its components ﾿ 14

2.9.1 Yoghurt starter cultures ﾿ 15

2.9.2 Other component of yoghurts ﾿ 16

2.10 Nutritional quality of yoghurt ﾿ 16

2.11 Uses of yoghurt ﾿ 17

CHAPTER THREE ﾿ 18

MATERIALS AND METHODS ﾿ 18

3.1 ﾿ Collection of samples ﾿ 18

3.1.1 ﾿ Sterilization of materials ﾿ 18

3.1.2 ﾿ Preparation of soy milk ﾿ 19

3.1.3 ﾿ Preparation of yoghurt from soymilk ﾿ 19

3.2 ﾿ Methodology for total viable count ﾿ 19

3.3 ﾿ Proximate analysis ﾿ 27

3.3.1 ﾿ Moisture content determination ﾿ 27

3.3.2 ﾿ Ash content determination ﾿ 28

3.3.3  ﾿ Crude protein determination ﾿ 28

3.3.4 ﾿ Fat determination ﾿ 30

3.3.4 ﾿ Carbohydrate determination ﾿ 31

3.3.5 ﾿ Determination of total titratable acidity ﾿ 31

3.3.6 ﾿ Determination of pH ﾿ 31

CHAPTER FOUR ﾿ 32

4.0 Results ﾿ 32

CHAPTER FIVE ﾿ 38

DISCUSSION, CONCLUSION AND RECOMMENDATION ﾿ 38

5.0 ﾿ Discussion ﾿ 38

5.1    ﾿ Conclusion ﾿ 39

5.2    ﾿ Recommendation ﾿ 40

Reference ﾿