Effects Of Chemical Preservatives On The Shelf Life And Microbial Load Of Cocoa Pulp Juice

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