ABSTRACT

The evaluation of microbial succession of Cassava for Garri processing was carried out using grated or homogenized cassava for microbial analysis. The media used were Nutrient agar for total viable count, Violet red bile agar for enumeration of Enterobacteracea, Potatoe dextrose agar for enumeration of yeast and moulds and De, man Rogosa and sharpe agar for enumeration of Lactic acid bacteria. A serial dilution was done and Pour plate method was employed, Gram staining and bio-chemical tests were used for identification of the bacteria.The total aerobic plate count for the fermenting cassava ranged from 5.4 x109 C.F.U/ML to 2.5 x 103 C.F.U/ML, for yeast and mould count 5.2 x 109 C.F.U/ML to 6.5 x 103 C.F.U/ML and Lactic acid bacteria ranged from 9.8 x 109 C.F.U/ML to 4.4 x 103 C.F.U/ML and Enterobacteracea ranged from 5.2 x 109 to 6.5 x 103 C.F.U/ML respectively. The bacteria isolated from the fermenting cassava were Lactobacillus species, Aspergellus niger, Bacillus subtilis, Corynebacterium manihot, Leuconostoc mesenteroides, Geotrichum species, Saccharomyces cerevisea. An evaluation of microbial succession done revealed that Bacillus subtilis and Lactobacillus plantarum showed the highest acid producing ability, Bacillus subtilis and Klebsiella species contributed to the fermenting of the cassava The study concluded that a large number of microorganisms are involved in fermentation of cassava.

TABLE OF CONTENT

Certification i

Dedication ii

Acknowledgement iii

Table of content iv-vi

Abstract vii

CHAPTER ONE

1.0 INTRODUCTION 1

1.1 Justification of the Study 3

1.2 General Objectives 3

1.3 Aims and Objectives of the Study 3

CHAPTER TWO

2.0 LITERATURE REVIEW 

Overview on Cassava (Manihot Esculenta Crantz) 4

2.2 Pest and Diseases 4

2.3 Economic Importance 5

2.4 Composition 5

2.5 Toxic Compounds in Cassava 6

2.6 Toxic Effects and Diseases Associated with Cyanide Exposure 9

2.7 Diseases Related To Cassava Toxicity 11

2.8 Processing into Different Products 12

2.8.1 Garri: 12

2.8.2 Fufu: 13

2.8.3  Chickwangue: 14 

2.9 Cassava Processing Techniques for Garri 14

2.9.1 Peeling 15

2.9.2 Grating and Chopping 15

2.9.3 Drying (Sun- And Oven-Drying) 15

2.9.4 Fermentation 16

2.9.4.1 Physical and Biochemical Changes During Cassava Fermentation. 18

2.9.4.2 Biochemical Changes 19

CHAPTER THREE

3.0 MATERIALS AND METHODS

3.1 Study Area 22

3.2 Sterilization of Materials 22

3.3 Fermenting Procedure 22

3.4 Microbiological Population Studies 24

3.4.1 Media Used 23

3.5 Isolation of Bacteria and Yeast 23

3.6 Isolation Using Pour Plate Method 24

3.6.1 Sub-Culturing:  24

3.6.2 Identification of Bacterial Isolates 24

3.6.3 Identification of Fungal Isolates 24 

3.7 Gram Staining 24

3.8 Biochemical Tests 25

3.8.1 Catalase Test: 26

3.8.2 Indole Test 26

3.8.3 Citrate Test 26

3.8.4 Oxidase Test 27

 3.8.5 Carbohydrate Fermentation Test: 27

3.8.5 Motility Test: 27

3.9 Determination of Physiocochemical Parameters 27

3.9.1 PH 28

3.9.2 Titrable Acidity 28

3.9.3 Cyanide Content 28

3.9.5 Fermentation Modulation 29

3.9.6 Effect of Temperature 29

CHAPTER FOUR

4.0 RESULTS 30

4.1 Microbial Counts 30 

4.2 Microbial Succession during Fermentation of Cassava for Garri Production 30

4.3 Identification of Organisms 31

4.9.2 Effect of PH, Titrable Acidity (%) and Cyanide Content on Cassava Fermentation 39

4.9.3 Fermentation Modulation 39

Discussion 40

CHAPTER FIVE

5.1 Conclusion 44

References 4