The Biochemical Changes Associated With Sorghum Bicolor (Guinea Corn) Fermentation By Saccharomyces Cerevisiae And Other Associated Microorganisms

ABSTRACT  

This study was to determine the microbiological and biochemical changes during fermentation of sorghum bicolor using Saccharomyces cerevisiae. The bacteria species isolated from the fermented sorghum samples, were identified based on their morphological characteristics, pigmentation on media, microscopy, biochemical and sugar fermentation methods while the yeast (Saccharomyces cerevisiae) used for the fermentation of sorghum was isolated using pour plate technique on Sabouraud Dextrose Agar (SDA). This study revealed that mean viable microbial counts varied as the time of fermentation increased. However the viable counts on the fermented sorghum sample were seen to decrease from the fermentation period of 0 hours to fermentation period of 72 hours. The total viable counts on Lactic acid bacteria revealed more counts (6.4x108) at the end of fermentation period (72hours) compared with single cultures. The physical analysis of the fermented sorghum samples in this study also revealed that pH, Temperature and Titratable acid slightly increased by fermentation interval from 0 hour to 72 hours of fermentation respectively. The proximate composition of the fermented sorghum samples revealed that the moisture content, crude fiber, crude protein and crude fat of the samples were high, and This study also revealed Lactobacillus spp as being the most widely distributed and frequently occurring isolates with a high percentage occurrence of 7(42.27%) while Saccharomyces cerevisiae 4(24.26%) was the most widely distributed among fungal species. this could improve the nutritional quality of sorghum. Therefore, the results reported could serve as a starting point to understand the microbiological and biochemical processes in the fermentation of sorghum using Saccharomyces cerevisiae with the aim of improving the efficiency of the process.

TABLE OF CONTENTS

Title Page ﾿ i

Certification ﾿ iii

Dedication ﾿ iv

Acknowledgement ﾿ v

Table of Contents ﾿ vi

List of Tables ﾿ viii

Abstract ﾿ ix

CHAPTER ONE

1.0 ﾿ Introduction ﾿ 1

1.1 ﾿ Aim and Objectives ﾿ 3

CHAPTER TWO

2.0 ﾿ Literature Review ﾿ 4

2.1 ﾿ Sorghum ﾿ 4

2.2 ﾿ History of Fermented Foods ﾿ 4

2.3 ﾿ Fermentation of Foods ﾿ 5

2.4 ﾿ Fermentation Process ﾿ 6

2.4.1 ﾿ Natural Fermentation ﾿ 6

2.4.2 ﾿ Back Slopping ﾿ 7

2.4.3 ﾿ Controlled Fermentation ﾿ 7

2.5 ﾿ Alcoholic Fermentation ﾿ 7

2.5.1 ﾿ Traditional Alcoholic Beverages ﾿ 8

2.6 ﾿ Types of Fermented Cereal Foods ﾿ 9

2.6.1 ﾿ Tarhana ﾿ 9

2.6.2 ﾿ Togwa ﾿ 9

2.6.3 ﾿ Ogi ﾿ 9

2.6.4 ﾿ Yosa ﾿ 10

2.6.5 ﾿ Balao balao ﾿ 10

2.6.6    Burukutu ﾿ 10

2.7 ﾿ Microorganisms Involved In Fermentation Process ﾿ 11

2.1 ﾿ Lactic Acid Bacteria ﾿ 12

2.2 ﾿ Fermentation by Lactic Acid Bacteria Homofermentation and Heterofermentation 12

2.3 ﾿ Taxonomical Classification of Lactic Acid Bacteria ﾿ 13

2.4 ﾿ General Position of Specific Lactic Acid Bacteria ﾿ 13

2.4.1 ﾿ Lactobacillus ﾿ 13

2.4.2 ﾿ Streptococcus ﾿ 14

2.4.3 ﾿ Pediococcus ﾿ 14

2.5 ﾿ Occurrence of Lactic Acid Bacteria in Nature ﾿ 14 

2.6 ﾿ Saccharomyces cerevisiae ﾿ 15

CHAPTER THREE

3.0 ﾿ Materials and Methods ﾿ 16

3.1 ﾿ Sample Collection and Sources of Commercial Yeast ﾿ 16

3.2 ﾿ Isolation of Yeast from Palm Wine ﾿ 16

3.3 ﾿ Characterization of Yeast Isolates ﾿ 16

3.4 ﾿ Laboratory Preparation of Burukutu (Fermentation of Sorghum) ﾿ 16

3.5 ﾿ Microorganism Used As Starter Culture ﾿ 17

3.5.1 ﾿ Preparation and Inoculation ﾿ 17

3.5.2 ﾿ Assessment of Fermentation ﾿ 17 

3.6 ﾿ Biochemical Analysis ﾿ 17

3.6.1 ﾿ pH ﾿ 17

3.6.2 ﾿ Total Titratable Acidity (TTA) ﾿ 17

3.6.3     Temperature                                                                                                               17

3.7 ﾿ Proximate Analysis ﾿ 18

3.7.1 ﾿ Mineral Content Determination ﾿ 18

3.8 ﾿ Microbiological Analysis  ﾿ 18

CHAPTER FOUR

4.0 ﾿ Results ﾿ 19

CHAPTER FIVE

5.0 ﾿ Discussion and Conclusion

5.1 ﾿ Discussion ﾿ 28

5.2 ﾿ Conclusion ﾿ 33

References