ABSTRACT

The effect of chemical preservatives on the shelf life and microbial load of cocoa pulp juice was studied. Cocoa pulp juice was produced and treated with three preservatives, sodium benzoate, potassium sorbate and citric acid and then stored at room temperature alongside an untreated control. Quality parameters of the drink were monitored during the 14 day storage period. Obtained results show that the pH, Total Soluble Solids and sugar contents decreased during storage while Total Titratable Acidity (TTA) increased. The pH decreased in the control sample from 6.23 to 3.13, while the TTA increased from 0.29 to 2.33. The sugar was reduced from 8.82 to 0.00 while the total solids reduced from 21.17 to 17.47. The changes which occured in the sodium benzoate treated juice was from 6.20 to 3.50 in PH, from 0.32 to 2.02 in TTA, from 8.41 to 0.62 in sugar content. The result obtained from those treated with potassium sorbate ranges from 6.20 to 3.33 in PH, from 0.32 to 2.10 in TTA, from 21.28 to 16.99 in TS and from 8.52 to 0.52 in sugar content. The microbial load also increased with time. The fungi Load increased from 4.33cfu/ml to 8.00cfu/ml while the bacteria load increased from 66.0 cfu/ml to 191.33 cfu/ml in the control. The increase in the sodium benzoate treated juice was from 65.67 cfu/ml to 152.00 cfu/ml (bacteria) and from 3.67cfu/ml to 13.00 cfu/ml (fungi). Similar values were recorded for the potassium sorbate and citric acid preservatives. The values of the treated juice samples were lower than the control and was considered to be as a result of their potency as preservatives. Comparatively, the citric acid and the sodium benzoate preservatives performed better than the potassium sorbate preservatives.  

TABLE OF CONTENTS

Title page i

Certification ii

Dedication iii

Acknowledgment iv

Table of Contents v

List of Tables vii

Abstract viii

CHAPTER ONE

1.0 INTRODUCTION 1

1.1 Aim 3

CHAPTER TWO

2.0 LITERATURE REVIEW 4

2.1 Historical Background of Cocoa 4

2.2 Historical Exploitation of Cocoa Industry 11

2.3 Cocoa Production in Nigeria and Farming Method 12

2.4 Harvesting of Cocoa Pod 12

2.5 Cocoa Pulp Juice 13

2.6 Nutritional Composition of Cocoa Pulp Juice 15

2.7 Effects of Microorganism on Cocoa Pulp Juice 16

2.8 Microbial Spoilage of Fruit Juice 16

2.9 Preservatives 18

2.9.1 Sodium Benzoate 19

2.9.2 Potassium Sorbate 20

2.9.3 Citric Acid 21

CHAPTER THREE

3.0 Materials and methods 23

3.1 Source of raw materials 23

3.2 Sample preparation 23

3.3 Treatment with preservatives 23

3.4 Physicochemical Analysis 24

3.4.1 Determination of hydrogen ion concentration (PH) 24

3.4.2 Determination of Total Titratable Acidity 24

3.4.3 Determination of Total Soluble Solids (Brix) 25

3.5 Microbiological Analysis 25

3.6 Sensory Evaluation 26

3.7 Statistical Analysis 27

CHAPTER FOUR

4.0 Result 28

CHAPTER FIVE

5.0 Discussion, conclusion and recommendation 34

5.1 Discussion 34

5.2 Conclusion 35

5.3 Recommendation 36

References 37