ABSTRACT

Exopolysaccharides were determined from lactic acid bacteria isolated from fermented foods. Foofoo, Ogiri, Ugba, and Yoghurt were the fermented foods used. Five lactic acid bacteria including species of Lactobacillus, Streptococcus, Bacillus, Micrococcus and Leuconostoc. The occurrence of the isolates were Lactobacillus (78%), Leuconostoc (50%), Micrococcus (66.7%), Streptococcus (50%) and Bacillus (66.7%). The distribution of the isolates in the fermented foods vary significantly. Tests on EPS production shsow that the quanitity of EPS produced by the different lactic acid bacteria vary between the organisms. The yield was highest 486.67 mg/l from Lactobacillus, and least 130.0 mg/l in Leuconostoc while Streptococcus, Micrococcus and Bacillus yielded 413.3 mg/l, 133.3mg/l, 320.0 mg/l respectively. Test on optimization of conditions for maximum EPS production show that temperature, pH and fermentation time affected the production of EPS but the optimum conditions show that fermentation at pH 5.0 at 40°C for 96 hours yielded the best results in all the test lactic acid bacteria. Although variations were needed in the preferences of the isolates which includes Bacillus, Streptococcus, and Lactobacillus were used in the optimization test which gave the same result irrespective of the organisms involved. It was recorded that EPS production should be conducted at the above found optimum conditions for maximum yield.   

TABLE OF CONTENTS 

Title page     i

Certification     ii

Dedication     iii

Acknowledgement     iv

Table of Contents     v

List of Tables     vii

List of Figures     viii

Abstract      ix

CHAPTER ONE 

1.1 Introduction      1

1.2 Objective of study      2

CHAPTER TWO

2.0    Literature Review      3

2.1    Exopolysaccharides      3

2.1.1 Exopolysaccharides from Lactic acid bacteria      3

2.1.2 Application of Exopolysaccharides in foods      4

2.2.   Lactic acid bacteria      5

2.2.1 Application  of Lactic acid bacteria      5

2.3    Fermented foods      6

2.3.1 Purpose and benefits of food fermentation      7

2.3.2 Nutritional benefits of food fermentation      7

CHAPTER THREE

3.0   Materials and methods      9

3.1   Sources of materials      9

3.2   Sample preparation and media preparation      9

3.2.1 Preparation of sample      9

3.2.2 Media preparation      9

3.2.3 Preparation of MRS media     10

3.3    Isolation of lactic acid bacteria     10

3.4    Identification of isolates     11

3.5    Screening for exopolysaccharide Production     11

3.6    Extraction of exopolysaccharide                12

3.7    Optimization of EPS production     12

CHAPTER FOUR

Results     14

CHAPTER FIVE

Discussion     24

Conclusion     26

References    26