DETERMINATION OF MICROBIAL LOAD ON SOME COMMON SALAD VEGETABLES SOLD IN AHIA EKE MARKET, UMUAHIA

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