PRODUCTION AND PROXIMATE ANALYSIS OF YOGHURT PRODUCED FROM TIGERNUT USING LACTIC ACID BACTERIA (LAB) AS STARTER CULTURE

ABSTRACT

Tiger nut (Cyperus esculentus) is an underutilized tuber of family cyperaceae, which produces rhizomes from the base of the tuber that is somewhat spherical. It grows freely and consumed in Nigeria, parts of Europe particularly Spain as well as the Arabian peninsula. Tiger nut milk is a refreshing drink, prepared mainly with tiger nut and has long being recognized for its health benefits as it contains glucose and oleic acid along with high energy content. In the production and proximate analysis of yoghurt produced from tiger nut using lactic acid bacteria, three lactic acid bacteria were employed; Lactobacillus acidophilus, Lactobacillus bulgaricus and Streptococcus thermophilus.  The proximate analysis of the yoghurt sample gotten from tiger nut produced with commercial starter culture (TGNCOM) were compared with the one produced with laboratory isolates (TGNLAB).  The result of the proximate analysis of both samples showed that that the TGNLAB had the highest fat, fibre and carbohydrate with the values 3.21±0.04, 0.11±0.02 and 6.44±0.18 while the TGNCOM had the highest protein, ash and moisture content with the values 6.91±0.10, 0.53±0.01 and 83.63±0.02 respectively. The fermentation parameters of the various yoghurt samples indicated that at appropriate pH (5.5) at the beginning of the milk fermentation and maintaining such pH to at least 3.6, a palatable product can be produced, this also applies to the temperature which must be kept at a range of at least 30.0oC to 31.5°C. The titrable acidity must fall within the range of 1.30 to 1.39 because anything higher might induce high acidity of the product. The sensory analysis of the yoghurt samples conducted among 11 panelist showed that TGNLAB was the most preferred. This goes a long way to explain that milk from tiger nut fermented with laboratory isolates (LAB) can serve as a source of energy and as functional food and if produced under appropriate stipulated fermentation condition with top notch hygiene can be an alternative to yoghurt produced from other sources.

TABLE OF CONTENTS

Title page ﾿ i

Certification ﾿ ii

Dedication ﾿ iii

Acknowledgements ﾿ iv

Table of Contents ﾿ v

List of Tables ﾿ viii

List of Figures ﾿ ix

Abstract ﾿ x

CHAPTER ONE: INTRODUCTION

1.1 ﾿ Introduction ﾿            1

1.2 ﾿ Aims and Objective ﾿ 5

CHAPTER TWO: ﾿ LITERATURE REVIEW

2.1 ﾿ Origin of Yoghurt ﾿ 6

2.2 ﾿ Starter Culture ﾿ 6

2.3 ﾿ Production of Yoghurt ﾿ 7

2.4 ﾿ Important Metabolic Activities of Yoghurt Technology ﾿ 8

2.4.1 ﾿ Acid Production ﾿ 8

2.4.2 ﾿ Flavour Compounds of Yoghurt ﾿ 9

2.4.3 ﾿ Proteolytic Activity ﾿ 9

2.4.4 ﾿ Urease Activity ﾿ 10

2.5 ﾿ Interaction between Yoghurt Bacteria ﾿ 10

2.6 ﾿ Tiger Nut ﾿ 13

2.6.1 ﾿ Uses and Products ﾿ 14

2.6.2 ﾿ Economic and Nutritional Benefits of Tigernut ﾿ 24

CHAPTER THREE: MATERIAL AND METHODS

3.1 ﾿ ﾿ Source of Materials ﾿ 16

3.2 ﾿ Isolation and Identification of Lactic Acid Bacteria ﾿ 16

3.3 ﾿ Gram Staining ﾿ 18

3.4 ﾿ Motility Test ﾿ 18

3.5 ﾿ Biochemical Tests ﾿ 19

 3.5.1 ﾿ Catalase Test ﾿ 19

3.5.2 ﾿ Coagulase Test ﾿ 19

3.5.3 ﾿ Oxidase Test ﾿ 19

3.5.4 ﾿ Methyl-Red Test ﾿ 19

3.5.5 ﾿ Urease Test ﾿ 20

3.5.6 ﾿ Indole Test ﾿ 20

3.5.7 ﾿ Sugar Fermentation Test ﾿ 21

3.6 ﾿ Milk Extraction ﾿ 22

3.7 ﾿ Production of Tigernut Yoghurt ﾿ 22

3.8 ﾿ Proximate Analysis ﾿ 22

3.8.1 ﾿ Determination of Total Solids/Moisture Content ﾿ 22 ﾿

 3.8.2 ﾿ Determination of Ash Content ﾿ 23

3.8.3 ﾿ Determination of Fat Content ﾿ 24

3.8.4 ﾿ Determination of Protein Content ﾿ 24

3.8.5 ﾿ Determination of Crude Fibre ﾿ 24

3.8.6 ﾿ Determination of Carbohydrate ﾿ 25

3.9 ﾿ Sensory Evaluation ﾿ 25

3.10 ﾿ Statistical Analysis ﾿ 25

CHAPTER FOUR:  RESULTS ﾿ 26

CHAPTER FIVE:  DISCUSSION

5 .1 ﾿ Conclusion ﾿ 33

5.2 ﾿ Recommendation ﾿ 35

References

Appendix