MICROBIOLOGICAL ANALYSIS OF COMMERCIALLY PREPARED YOGHURT

ABSTRACT

. Microbial quality of
commercially prepared yoghurt sold in umuahia was evaluated. Ten(10) different
brands of Yoghurt was purchased randomly from hawkers and beverage stores in
Umuahia urban and analyzed in the laboratory. Six (6) of the samples where
registered by NAFDAC [ Sample A, B, C, D, E and F,] while four(4) others were
not registered [ Sample G, H, I, J.]. total viable count (TVC) of the samples
ranged from 3.25x102 (sample B) to 5.0x104 (sample F) for
registered samples (A to F) and 8.2x104 cfu/ml (sample A) to 2.12x105
cfu/ml (sample J). staphylococcal count ranged  from 2.0x102 cfu/ml (sample B and F)
to 9.6x104 cfu/ml (sample J). which is within the acceptable limit
for microbiological quality for readily to eat food samples. Sample B  was negative for taphylococcus aureus. TCC ranges from 1.0x102 cfu/ml
(sample B) to 5.0x104 cfu/ml (sample E) for registered and non-registered
samples, sample C showed no growth of coliform. Total Fungal count ranged from
1.0x102 cfu/ml (sample A and D) to 4.0x104 cfu/ml (sample
G). sample B,  and D showed  no growth of fungi. Organism isolated include

Escherichia coli, Staphylococcus aureus, Salmonella spp,  Citrobacter

spp and Lactobacillus

spp. Aspergillous spp and candida
albicans was also isolated from the samples. Results shows that yoghurt sold
in Umuahia showed  presence of coliforms,
bacteria and fungi which poses great health risk to consumers. 

TABLE OF CONTENTS

Abstract                                                                                                                                       

CHAPTER ONE: INTRODUCTION

1.0  
Introduction                                                                                                                            1

1.1  
Justification of study                                                                                                              2

1.2    Objectives                                                                                                                              2

CHATER TWO: LITERATURE REVIEW

2.1     History                                                                                                                                  3

2.2     Processing of yoghurt                                                                                                           4

2.2.1.   Modifying milk composition                                                                                             4

2.2.2   Pasteurization and Homogenization                                                                                   4

2.2.3   Fermentation                                                                                                                       6

2.2.4   Flavour                                                                                                                                6

2.3.  
Yoghurt preservation                                                                                                             7

2.4.  
Quality control of yoghurt                                                                                                    8

2.5.  
Nutritional health effect                                                                                                      10

2.5.1.    Probiotics                                                                                                                        10

2.6     Spoilage                                                                                                                               11

CHAPTER THREE:  MATERIALS AND
METHOD

3.1   Study Area                                                                                                                             13

3.2    Sample Collection                                                                                                                13

3.3   
preparing of Media                                                                                                              13

3.4   
Isolation and enumeration of microorganism                                                                     14

3.5   
Characterization and Identification of Isolates                                                                   14

3.5.1   Gram Staining                                                                                                                   14

3.5.1   Biochemical test                                                                                                                15

CHAPTER FOUR

4.1     Result                                                                                                                                  18

CHAPTER FIVE: DISCUSSION, CONCLUSION AND RECOMMENDATION

5.1.    Conclusion                                                                                                                         27

5.2.    Recommendation                                                                                                               27

References