PHYTOCHEMICAL ANALYSIS AND ANTIMICROBIAL PROPERTIES OF CRUDE EXTRACTS OF Vernonia amygdalina Del. ON MICROBIAL ISOLATES IMPLICATED IN TOMATO PASTE SPOILAGE.

ABSTRACT

The antimicrobial activities and preliminary phytochemical screening of crude aqueous extract of Vernonia amygdalina Del. was carried out against isolates obtained from spoilt tomato paste which included Escherichia coli, Pseudomonas aeruginosa, Micrococcus spp, Acinetobacter spp, Lactobacillus spp, Aspergillus spp, Rhizopus spp and Penicillium spp. The extract exhibited antibacterial and antifungal activity against the test organisms. The phytochemical screening of Vernonia amygdalina showed the presence of tannins, cardiac glycosides, saponins, flavonoids, steroids, terpenes, anthraquinones and alkaloids. V. amydalina exhibited antimicrobial action action against test organisms judged by their various zones of inhibition; P. aeruginosa (9.50mm), Micrococcus spp (16.50mm), Escherichia coli. (12.33mm), Acinetobacter spp (10.33mm), Lactobacillus spp (13.50mm), Aspergillus spp (12.50mm), Rhizopus spp (10.33mm) and Penicillium spp (14.50mm). The crude extracts exhibited strong potency against the bacteria and fungi with Penicillium spp and Micrococcus spp being the most susceptible when compared to the control (Chloramphenicol). Since this crude extract was able to inhibit the growth of the organisms associated with tomato paste spoilage, it could as well be used for the preservation of tomato paste.

TABLE OF CONTENTS

Title page ﾿ i

Certification ﾿ ii

Dedication ﾿ iii

Acknowledgement ﾿ iv

Table of Contents ﾿ v-vi

List of Tables ﾿ vii

Abstract ﾿ viii

CHAPTER ONE

1.1 ﾿ Background of Study ﾿ 1

1.2      Aim and Objectives ﾿             4

CHAPTER TWO

2.0 ﾿ LITERATURE REVIEW ﾿ 5

2.1 ﾿ The Nature of Food Spoilage ﾿ 6

2.2 ﾿ Significance  of   Agents  of  Tomato  Spoilage ﾿ 9

2.3 ﾿ Plant antimicrobials in food applications ﾿ 9

2.4 ﾿ Application of Plant Antimicrobials in Shelf-Life Extension 

of Food ﾿ 10

2.5 ﾿ Vernonia amygdalina Del ﾿ 11

2.6 ﾿ Nutrient Composition/Nutritional Uses ﾿ 12

CHAPTER THREE

3.0 ﾿ MATERIALS AND METHODS ﾿ 13

3.1 ﾿ Collection of Plants Materials ﾿ 13

3.2 ﾿ Preparation of Plant Material and Plant Extracts ﾿ 13

3.2.1 ﾿ Cold Aqueous Extract ﾿ 13

3.2.2 ﾿ Preparation of media ﾿ 13

3.2.3 ﾿ Isolation of Bacteria ﾿ 13

3.2.4 ﾿ Isolation of Fungi ﾿ 14

3.2.5 ﾿ Purification (Subculture) of Bacterial Isolates ﾿ 14

3.2.6 ﾿ Purification of Fungal Isolates ﾿ 14

3.3 ﾿ Characterization and Identification of Bacterial Isolates ﾿ 15

3.3.1 ﾿ Antibacterial Assay ﾿ 15

3.4 ﾿ Phytochemical Screening of the Leaves Extracts ﾿ 15

3.4.1 ﾿ Test for Flavonoids ﾿ 16

3.4.2 ﾿ Test for Alkaloids ﾿ 16

3.4.3 ﾿ TestforSaponins ﾿ 16

3.4.4 ﾿ Test for Phenol ﾿ 16

3.4.5 ﾿ Test for Glycosides ﾿ 16

3.4.6 ﾿ TestforTannins ﾿ 17

3.4.7 ﾿ Test for volatile oils ﾿ 17

3.4.8 ﾿ Test for Steroids ﾿ 17

3.4.9 ﾿ Test for Terpenoids ﾿ 17

3.4.10 ﾿ Test for Anthraquinones ﾿ 17

3.4.11 ﾿ Test for Cardenolides Keller-KillianiTest ﾿ 18

CHAPTER FOUR

4.0 ﾿ RESULTS ﾿ 19

CHAPTER FIVE

5.0 ﾿ DISCUSSION ﾿ 25

5.1      CONCLUSION ﾿ 27

5.2 ﾿ RECOMMENDATION ﾿ 28

References ﾿ 29

LIST OF TABLES

Table ﾿ Title ﾿ Page 

1 ﾿ Morphological, biochemical and sugar fermentation profile of 

Bacterial isolates ﾿ 20

2 ﾿ Isolation and identification of fungal isolates ﾿ 21

3 ﾿ Mean Zone of inhibition of crude aqueous 

Extract of V. amygdalina leaves against bacterial isolates ﾿                         22

4 ﾿ Mean Zone of inhibition of crude aqueous 

Extract of V. amygdalina leaves against fungal isolates                              ﾿ 23

5 ﾿ Phytochemical Screening of Vernonia amygdalina (bitter leaves)

Ethanol and Aqueous leaves Extract ﾿ 24