Fermentative Production And Microbiological Analyses Of Cassava (Manihot Esculenta) Flour

ABSTRACTS

The fermentative production of cassava (Manihot esculenta crantz) flour was done in two different methods, which were the fixed and unfixed fermentation method. The cassava tubers were harvested from the N.R.C.R.I, Umudike, peeled, washed, sliced into big bits of about 5 to 8cm in length and allowed to ferment. The microbial load, succession, pH and cyanide content of the cassava were determined during retting and after production. The results showed the presence of E.coli and Lactobacillus spp, Bacillus spp, Staphylococcus spp, Aspergillus spp, Penicillum spp, yeast, and Geotichum spp  after the first day of fermentation. The dominant organisms after fermentation were Lactobacillus spp and Yeast. The Bacteria load was 1.59x105 to 0.61x105 cfu/g,  fungi load of 1.10x103 to 0.40x 103 cfu/g for fixed fermented cassava flour. The unfixed had the Bacteria load of 1.64 to 0.61x 105 cfu/g and fungi load of 1.10x103 and 0.45x103 cfu/g. On the other hand, the Hydrogen cyanide content and pH decreases as the fermentation period increases in both flour. It is therefore recommended that cassava tubers should be fermented at a minimum of 48 hours as its cyanide content decreases with increase fermentation period.    

TABLE OF CONTENTS

Title page ﾿ i 

Certification ﾿ ii

Dedication ﾿ iii

Acknowledgement ﾿ iv

Table of Contents ﾿ v

List of Figures ﾿ vii

List of Tables ﾿ viii

Abstract ﾿ x

CHAPTER ONE

INTRODUCTION ﾿ 1

1.1 ﾿ Background of Study ﾿ 1

1.2 ﾿ Aims and Objectives ﾿ 2

CHAPTER TWO

LITERATURE REVIEW ﾿ 3

2.1 ﾿ Description of Cassava ﾿ 3

2.2 ﾿ Habitat ﾿ 3

2.3 ﾿ History of Cassava ﾿ 3

2.4 ﾿ Physiology and Morphology of Cassava Plant ﾿ 5

2.4.1 ﾿ Toxicity ﾿ 5

2.4.2 ﾿ Varieties ﾿ 8

2.5 ﾿ Cassava Processing and Utilization ﾿ 8

2.6 ﾿ Nutritional Composition of Cassava ﾿ 13

2.7 ﾿ Fermentation Technology ﾿ 15

2.7.1 ﾿ Methods of Fermenting Cassava to Flour ﾿ 16

2.8 ﾿ Health and Benefits ﾿ 18

2.9 ﾿ Acute and Chronic Effects of Cyanide ﾿ 19

CHAPTER THREE

MATERIALS AND METHOD ﾿ 21

3.1 ﾿ Cassava Roots Used ﾿ 21

3.2 ﾿ Sample and Media Preparation ﾿ 21

3.2.1 ﾿ Fixed Fermentation Method ﾿ 21

3.2.2 ﾿ Unfixed Fermentation Method ﾿ 22

3.3 ﾿ Media Preparation ﾿ 24

3.4 ﾿ Microbial Analysis ﾿ 24 

3.4.1 ﾿ Determination of Microbial Load ﾿ 24

3.4.2 ﾿ Determination of Microbial Flora ﾿ 25

3.4.3 ﾿ Determination of Hydrogen Cyanide ﾿ 26

3.4.4 ﾿ Determination of pH ﾿ 26

3.4.5 ﾿ Characterization of Bacteria Isolates ﾿ 27

3.5 ﾿ Cultural Examination ﾿ 27

3.5.1 ﾿ Gram Reaction ﾿ 27

3.5.2 ﾿ Microscopic Features ﾿ 27

3.6 ﾿ Characterization of Fungi Isolates ﾿ 28

3.6.1 ﾿ Viable Counting of the Fungi Growth ﾿ 28

3.6.2 ﾿ Identification of Fungi ﾿ 28

3.6.3 ﾿ Colony Features of Fungi Isolates ﾿ 28

3.6.4 ﾿ Microscopic Features ﾿ 28

3.6.5 ﾿ Identification of Isolates ﾿ 29

3.7 ﾿ Biochemical Tests ﾿ 29

3.7.1 ﾿ Oxidase Test ﾿ 29

3.7.2 ﾿ Coagulase Test ﾿ 29

3.7.3 ﾿ Citrate Test ﾿ 29

3.7.4 ﾿ Indole ﾿ 30

3.7.5 ﾿ Test for Carbohydrate ﾿ 30

CHAPTER FOUR

RESULTS ﾿ 31

CHAPTER FIVE

DISCUSSION, CONCLUSION AND RECOMMEMDATON ﾿ 38

5.1 ﾿ Discussion ﾿ 38

5.2 ﾿ Conclusion ﾿ 39

5.3 ﾿ Recommendation ﾿ 39

References ﾿ 40