MICROBIAL CONTAMINATION OF AFRICAN SALAD SOLD IN MICHAEL OKPARA UNIVERSITY OF AGRICULTURE, UMUDIKE

ABSTRACT

In this study, duplicate African salad samples were collected from ten different vendors in Michael Okpara University of Agriculture Umudike. The samples were determined for their microbial quality. Bacteria isolated from the African salad samples include Staphylococccus aureus, Escherichia coli, Salmonella species and Shigellaspecies, while the fungi isolated include Aspergillus species, Rhizopus species, Fusarium species and Penicillium species.The total viable bacterial count of the samples ranged as low as was 3.3 x 105cfu/g (stadium) to as high as 2.91 x106cfu/g (gate six). The mean fungal count of the samples also ranged as low as 3.1 x 105cfu/g (gate six)to as high as 7.2 x 105cfu/g (male hostel). Staphylococcus aureus had the highest occurrence in all the samples analyzed with 85%, closely followed by Escherichia coli with 80% occurrence, Salmonella species had a total of 75% occurrence and Shigellaspecies had 60% occurrence. In order to reduce the high microbial load of African salad, the preparation should be done in a proper and hygienic way.

TABLEOF CONTENTS

Title page                                                                                                             i

Certification                                                                                               ii

Dedication                                                                                                 iii

Acknowledgement                                                                                    iv

Table of contents                                                                                                       v

List of tables                                                                                    viii

Abstract                                                      ix

CHAPTER ONE

1.0   Introduction                                                                                                                              1

1.1 Aims and Objectives of the study                                                                                              2

CHAPTER TWO

2.0  Literature review                                                                                                                        3

2.1 Cassava                                                                                                                                      3

2.2 How to prepare African salad                                                                                                    4

2.2.1 Flow chart of African salad production                                                                                  6

2.2.2 Nutritional value of African salad                                                                                           6

2.2.3 Health risk associated with African salad                                                                              7

2.2.4 Contamination of African salad                                                                                            11

2.2.4.1 Sources of contamination of African salad                                                                        11

2.2.4.2 Prevention of microbial contamination of African salad                                                   13

CHAPTER THREE

3.0  Materials and methods                                                                                                             15

3.1 Sample collection                                                                                                                     15

3.2 Sterilization of glass wares and media                                                                                     15

3.3 Sample preparation                                                                                                                  16

3.4 Microbiological analysis                                                                                                          16

3.5 Serial dilution                                                                                                                           17

3.5.1 Inoculation                                                                                                                            17

3.5.2 Incubation                                                                                                                             17

3.5.3 Colony counting                                                                                                                    18

3.5.4 Isolation of pure culture                                                                                                        18

3.6 Identification of bacterial isolates                                                                                            18

3.6.1 Macroscopic examination                                                                                                     18

3.6.2 Microscopic examination                                                                                                      19

3.6.3 Gram staining                                                                                                                        19

3.7 Biochemical identification of bacterial isolates                                                                       19

3.7.1Indole test                                                                                                                        19 

3.7.2 Catalase test                                                                                                                          20

3.7.3 Coagulase test                                                                                                                       20

3.7.4 Oxidase test                                                                                                                           20

CHAPTER FOUR

4.0  Results                                                                                                                                      21

CHAPTER FIVE

5.0  Discussion                                                                                                                                27

5.1 Conclusion                                                                                                                               29

REFERENCES                                                                                                                    

LIST OF TABLES

Table 1:Mean viable bacterial counts of the different African salad samples.

Table 2:Mean fungal counts of the different African salad samples.

Table 3:Characterization and identification of bacterial isolates.

Table 4:Morphological characteristics of the fungal isolates.

Table 5:Percentage occurrence of the bacterial isolates from the different African salad samples.

CHAPTER ONE

1.0     INTRODUCTION

African salad popularly called “Abacha, AbachaNcha, Abacha and Ugba” by Igbo tribe of Nigeria, it is an exotic delicacy and a special salad recipe native to Nigeria. The name African salad is thought to have originated from the Igbo’s ideology that salad contains lots of fresh and raw vegetables and some other ingredients consumed without further cooking, therefore it is a salad and of African origin. African salad is widely accessed for its composition of food ingredients known to be rich in protein, carbohydrate, vitamins, and minerals. It can be eaten on its own or in combination with other snacks like coconut, palm kernel and groundnut. Though it can be as filling as any other main course meal. African salad is usually eaten as an in-between meal or as a side dish to the various Nigerian rice recipes. African salad is also regarded as a special delicacy during traditional festivals.(Maky, 2013)

Abacha is processed by harvesting cassava tubers, after which they are peeled, washed and cooked. These are then shredded into fine thin slices, and soaked overnight for fermentation so as to thoroughly reduce the starch and hydrogen cyanide from the cassava. The shredded and fermented cassava is again thoroughly washed the following day before drying it for 2-3 days.

The preparation of African salad takes great efforts and the ingredients needed to prepare African salad vary according to one’s taste and availability. The key to making a good African salad is to make sure that all the ingredients are well incorporated. It can include ingredients such as Ugba (Pentaclethra macrophylla), palm oil, potash, onions, nutmeg, crayfish, salt, pepper, maggi, ogiri (Ricinus communis), garden egg, garden egg leaves, Utazi leaves (Gongronema latifolium), Okazi (Ukazi) leaves (Gnetum africana), Ozeza (Uzeza) leaves (Piper guineense), kpomo (cow skin), meat and stockfish/fish (Osewa, 2013). These ingredients are mixed thoroughly with the shredded cassava (Abacha). The ingredient added is dependent on one’s choice, purchasing power and availability. African salad can be served with fried fish/meat over a cold drink (Palm wine, beer, stout or wine) ( Miriam and Anthonio, 2011)

There is of information on the chemical and microbiological composition of African salad as consumed. Though several works abound on some of the component ingredients, the notion that African salad is nutritionally rich is only but speculative based on its component ingredients

1.1 AIMS AND OBJECTIVES

The aim of this study is to identify the microorganisms of public health importance present in African salad.

The objectives are:

Ø  To carryout microbiological analysis of African salad prepared by food vendors in MOUAU.

Ø  To isolate and identify microorganisms that contaminates African salad.

Ø  To determine the percentage occurrence of the pathogen isolated from the African salad.

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