Microbial Species Associated With Openly Hawked Baked Products In Umuahia Metropolis

ABSTRACT

This study evaluated and identified various microorganisms associated with baked products in Umuahia metropolis of which five (5) different baked products comprising of Biscuits, Bread, Cakes, Pie and Eggroll were randomly selected for the purpose of the work. From this study a total of fourteen (14) bacteria strains were isolated and identified using morphological characteristics, pigmentation on media, microscopy, biochemical and sugar fermentation methods. This reveals the major bacterial isolates to belong to Salmonella species, Escherichia coli, Staphylococcus aurues, Proteus species and Pseudomonas aeruginosa respectively, while the microscopic and cultural characteristics revealed three (3) fungal strains to belong to Aspergillus niger, and Aspergilus flavus. The total viable microbial counts evaluated in this study varied from one sample to the other. Amongst the five (5) different baked products investigated however within Umuahia metropolis, Pie had the highest viable bacteria count at 9.1x106, followed by Bread (8.4x106), Eggroll (6.9x106), Cakes (5.7x106), while the least viable bacteria count was recorded on Biscuit (3.3x106) in that order. The total viable fungal plate count investigated on the different baked products, reveals Bread as having the highest viable fungi count at (1.7 x106) and Biscuit having the least viable fungi count at (1.2 x106). The contamination rate and percentage distribution accessed on different baked products revealed that Salmonella species and Staphylococcus aureus are the most frequently occurring isolates with a high percentage occurrence of 4(30%) each, followed by Escherichia coli (17.6%), Proreus spp 2(11.8%) and Pseudomonas aeruginosa 1(5.9%) at respectively. However, there were slight variations in the fungi population, with Aspergillus niger 2(11.8%) being most predominant and occurring isolates, followed by Aspergillus flavus 1(5.8%). Therefore, microorganisms are the common genera of molds generally isolated from the fresh baked products during the present investigation. These molds have been known to produce toxins, which are both acutely and chronically toxic in animal and humans.

TABLE OF CONTENTS

Title Page ﾿   ﾿ i

Certification ﾿ iii

Dedication ﾿ iv

Acknowledgement ﾿ v

Table of Contents ﾿ vi

List of Tables ﾿ vii

Abstract ﾿ ix

CHAPTER ONE

1.0 ﾿ Introduction ﾿ 1

1.1 ﾿ Aim and Objective ﾿ 3

CHAPTER TWO

2.0 ﾿ Literature Review ﾿ 4

2.1 ﾿ Economical Importance of Bakery Products ﾿ 4

2.2 ﾿ Microbial Spoilage of Bakery Products ﾿ 6

2.2.1 ﾿ Bacterial spoilage ﾿ 7

2.2.2 ﾿ Yeast spoilage ﾿ 8

2.2.3 ﾿ Mold spoilage ﾿ 8

2.3 ﾿ Physical Factors Influence the Microbial Growth ﾿ 9

2.3.1 ﾿ Effect of temperature, pH and water activity ﾿ 9

2.3.2 ﾿ Effect of salt tolerance ﾿ 12

2.4 ﾿ Control of Microbial Growth in Bakery Products ﾿ 12

2.4.1 ﾿ Reformulation to reduce product aw ﾿ 13

2.4.2 ﾿ Freezing ﾿ 13

2.4.3 ﾿ Preservatives ﾿ 14

2.5 ﾿ Effect of Chemical Preservatives ﾿ 14

2.5.1 ﾿ Sorbic acid and sorbates ﾿ 15

2.5.2 ﾿ Propionic acids and its salts ﾿ 16

2.6 ﾿ Effect of Bio-preservatives ﾿ 18

CHAPTER THREE

3.0 ﾿ Materials and Methods ﾿ 21

3.1 ﾿ Collection of Samples ﾿ 21

3.2 ﾿ Sterilization of Materials ﾿ 21

3.3 ﾿ Preparation of Culture Media ﾿ 21

3.4 ﾿ Inoculation and Isolation ﾿ 21

3.4.1 ﾿ Method ﾿ 21

3.5 ﾿ Purification of Isolates ﾿ 22

3.6 ﾿ Identification of Bacterial Isolates ﾿ 22

3.7 ﾿ Gram Staining ﾿ 22

3.8 ﾿ Biochemical Test ﾿ 23

3.8.1 ﾿ Catalase Test ﾿ 23

3.8.2 ﾿ Indole Test ﾿ 23

3.8.3 ﾿ Citrate Utilization Test ﾿ 23

3.8.4 ﾿ Hydrogen Sulphide (H2S) Production Test ﾿ 23

3.8.5 ﾿ Starch Hydrolysis ﾿ 24

3.8.6 ﾿ Motility, Indole, Urease (MIU) ﾿ 24

3.8.7 ﾿ Coagulase Test ﾿ 25

3.8.8 ﾿ Oxidase Test ﾿ 25

3.9 ﾿ Identification of Fungi Isolates ﾿ 25

3.9.1 ﾿ Microscopic Features ﾿ 25

CHAPTER FOUR

4.0 ﾿ Results ﾿ 26

CHAPTER FIVE

5.0 ﾿ Discussion, Conclusion and Recommendation ﾿ 33

5.1 ﾿ Discussion ﾿ 33

5.2 ﾿ Conclusion ﾿ 37

5.3 ﾿ Recommendation ﾿ 37

﾿ References