ABSTRACT

Salad vegetables are consumed without any heat treatment, sometimes without washing or peeling. Salad vegetables also promote good health but harbor a wide range of microbial contaminants. Vegetables get contaminated with pathogenic microorganisms while growing fields or orchard or during harvesting, post harvesting, handling, processing and distribution. To assess the microbial \quality of salad vegetables sold in Ahia-Eke market, 5 samples of different salad vegetables were purchased from two different vendors. Samples were analyzed to determine the microbial load using MacConkey and Sabouraud agar Microbial load ranged from 9.9 × 105 to 1.2 × 106 Cfu/ml for vendor A and 2.9 × 106 to 9.7 × 106 Cfu/ml for vendor B for the bacteria isolates; the microbial load for the fungal isolates ranged from 3.0 ×105 to 6.3 × 105Cfu/ml for vendor A and 2.6 ×106 to 5.9 ×106Cfu/ml for vendor B. Six bacterial isolates were identified and Staphylococcus aureus was more predominant (24.6%), Bacillus species (11.5%) and Pseudomonas species(11.5%) were the least; four fungal isolates were identified and Aspergillus species were more predominant (29.4%) and Geotrichum was the least predominant (14.9%). The present study revealed the potential hazard of consuming pathogen contaminated salad vegetables; therefore there is need for thorough washing with safe running water before consumption to reduce the number of microorganisms and to safeguard health.

TABLE OF CONTENTS

Title page 

Certification i

Dedication ii

Acknowledgements iii

Table of Contents iv

List of Tables viii

Abstract ix

CHAPTER ONE

INTRODUCTION

1.0 Introduction 1

1.1 Aim 3

CHAPTER TWO

LITERATURE REVIEW

2.0 Overview 4

2.1 Salad vegetables 5

2.1.1 Cabbage 5

2.1.1.1 Green cabbage 6

2.1.1.2 Red cabbage 6

2.1.1.3 White cabbage 7

2.1.1.4 Chinese cabbage 7

2.1.1.5 Nutritional and medical properties of salad cabbage 7

2.1.2 Carrot 8

2.1.2.1 Nutritional importance of salad carrot 9

2.1.3 Cucumber 9

2.1.3.1 Nutritional and medical properties of salad cucumber 10

2.1.4 Green peas 12

2.1.4.1 Nutritional value of green peas 13

2.1.5 Green pepper 13

2.1.5.1 Nutritional value of green pepper 14

2.2 Pathogenic microorganism associated with fresh produce of salad vegetables 14

2.2.1 Pathogens of concern – Bacteria 15

2.2.2 Spore-forming pathogenic bacteria 20

2.2.3 Pathogens of great concern – Viruses 20

2.3 Sources of contamination 21

2.3.1 Pre-harvest 22

2.3.2 Harvest 24

2.3.3 Post- harvest 25

CHAPTER THREE

MATERIALS AND METHODS

3.1 Sample collection 26

3.2 Sample processing 26

3.3 Media preparation 26

3.4 Identification of isolates 27

3.5 Biochemical tests 27

3.5.1 Catalase test 27

3.5.2 Coagulase test 28

3.5.3 Oxidase test 28

3.5.4 Indole test 28

3.5.5 Citrate test 29

3.6 Motility test 29

3.7 Gram staining

CHAPTER FOUR

RESULTS 31

CHAPTER FIVE

5.0 Discussion 39

5.1 Conclusion and Recommendation 40

REFERENCES 42

LIST OF TABLES

Table Title Pages

1 Biochemical characterization of isolates 32

2 Microscopic characterization of fungal isolates 33

3 Total bacterial count (Cfu/ml) of Salad vegetable samples 34

4 Total fungal count (Cfu/ml) of Salad vegetable samples 35

5 Isolated organisms 36

6 Prevalence of bacteria isolated 37

7 Prevalence of fungal isolates 38