ABSTRACT

This study determined the effect of local plant preservatives on the microbiology and shelf life stability of palm wine. Fresh palm wine samples collected from traditional palm wine tappers in Umuahia were used for this analysis. The microbiological analysis of the palm wine samples was carried out and this showed high viable counts for both bacteria (TAPC = 6.9 × 106 and 6.4 × 106, TCPC = 5.2 × 106 and 4.6 × 106, TLABC = 3.6 × 106 and 6.1 × 106) for samples A and B respectively fungi (TFPC = 4.0 × 106 and 5.3 × 106) also for samples A and B. Also pathogenic microorganisms were isolated from the palm wine samples. The microorganisms isolated in this study were Bacillus subtilis, Escherichia coli, Enterobacter species, Lactobacillus species, Klebsiella species, Saccharomyces cerevisae, Aspergillus flavus and Rhodotorula species of which Saccharomyces cerevisae was the most predominant. The extracts of local plants such as lime, bitter leaf, scent leaf and black pepper were tested against the bacteria and fungi isolates. The lime juice extracts had the highest inhibitory activity producing a zone of inhibition of 14 mm while the black pepper extract exhibited the lowest inhibitory activity with an inhibition zone of 6 mm. This signified that the plant extracts had inhibitory effects on the microorganisms present in palm wine. Furthermore, the shelf life of the palm wine samples was studied and the results showed a reduction in cell counts when palm wine was treated with different concentrations (0.5, 1.0, 1.5 and 2.0 mL) of the plant extracts. The cell counts were observed to decrease considerably as the concentration of the plant extracts increased. The ethanolic extract of scent leaf and aqueous extract of lime juice had the lowest counts of 40 cfu/ml and 120 cfu/ml after 72 hrs. This showed that scent leaf and lime juice were the best plant preservatives amongst the studied plants to be used for preservation of palm wine. From this study, it can be deduced that these plant extracts studied can be used to prolong the shelf life of palm wine as it significantly reduces the number of microorganisms present in palm wine.    

TABLE OF CONTENTS

Title page i

Certification ii

Dedication iii

Acknowledgments iv

Table of contents v

List of tables viii 

List of Figures ix

Abstract x

CHAPTER ONE

Introduction 1

1.1 Aim and Objectives 3

1.1.1 Objectives

3

CHAPTER TWO

Literature Review 4

2.1 Description of Palm Tree 4

2.2 The African Oil Palm Tree (Elaeis guineensis) 5

2.3 Description of the Palm Sap 6

2.4 Palm Wine 6

2.4.1 Nutritional Content of Palm Wine 7

2.4.2 Tapping of Palm Wine 8

2.4.3 Palm Wine Fermentation 8

2.4.4 Microorganisms Involved in the Fermentation of Palm Wine 9

2.4.5 Uses of Palm Wine 10

2.5 Bitter Leaf Plant (Vernonia amygdalina) 11

2.5.1 Uses 12

2.5.2 Antimicrobial Properties 12

2.6 Basil Plant (Scent leaf) (Ocimum gratissimum) 13

2.6.1 Importance 13

2.6.2 Antimicrobial Properties 13

2.7 Lime (Citrus aurantifolia) 14

2.7.1 Uses 14

2.7.2 Antimicrobial Properties 16

2.8 Black Pepper Plant (Piper nigrum) 17

2.8.1 Importance 18

2.8.2 Antimicrobial Properties 19

2.9 Empirical Studies 19

CHAPTER THREE

Materials and Methods 26

3.1 Sample Collection 26

3.2 Materials 26

3.3 Plant Materials 27

3.3.1 Extraction of Plant Materials 27

3.4 Microbiological Analysis 28

3.4.1 Serial Dilution 28

3.4.2 Inoculation of Samples 28

3.5 Colony Count of Isolates 28

3.6 Characterization and Identification of Isolates 29

3.7 Biochemical Analysis of the Isolates 29

3.7.1 Gram Staining 29

3.7.2 Catalase Test 30

3.7.3 Coagulase test    30

3.7.4 Oxidase Test 31

3.7.5 Citrate Test 31

3.7.6 Motility Test 31

3.7.7 Indole Test 32

3.7.8 Methyl Red Test 32

3.7.9 Vogues Proskauer Test 32

3.7.10 Carbohydrate Fermentation Test 32

3.8 Isolation, Characterization and Identification of Fungi from Fermented 

Palm Wine 33

3.9 Antimicrobial Screening of Plant Extracts 33

3.10 Effects of Plant Extracts on the Shelf Life of Palm Wine 34

CHAPTER FOUR

Results 35

CHAPTER FIVE

Discussion, Conclusion and Recommendation 53

5.1 Discussion 53

5.1 Conclusion and Recommendation 57

References 58