MICROBIAL QUALITY OF POWDERED SOY MILK SOLD IN ABA

ABSTRACT

The present study was conducted to assess the microbial quality of powdered soymilk samples sold in Aba, Abia state. A total of 10 samples were randomly purchased from local markets within the metropolis. The study samples were differentiated into two categories, branded and unbranded powdered soymilk samples. The branded soymilk samples were labeled TE, BC, and UCD to reflect their brand names while the unbranded samples were labeled N1 to N4 .The total viable count of the soymilk samples ranged from 2.0×105-8.7×105 (cfu/g) with a branded powdered soymilk sample (TE2) giving the lowest count, while the highest count was recorded in an unbranded sample (N2). The Total coliform count ranged from 4.5×104-9.0×104 (cfu/g), with a branded sample (UCD2) giving the lowest count while the highest count was recorded in an unbranded powdered soymilk (N2). The total fungal count ranged from 1.1×104 in a branded sample (TE1) to 3.3×104 (cfu/g) in an unbranded sample (N1). The isolates were four (4) bacteria (Staphylococcus aureus, Bacillus spp., Streptococcus spp., and E. coli) and two moulds (Aspergillus spp. and Penicillium spp.). Bacillus spp. recorded the highest incidence (8) and percentage occurrence (80%) while Aspergillus spp. and E. coli recorded the least incidence (4) and percentage occurrence (40%). Comparing the general counts, the study suggested the need for implementing regulatory measures like good manufacturing and management practices, hygienic distribution and retail storage practices for ensuring microbiological safety of powdered soymilk offered for public consumption in Aba, since both the branded and unbranded powdered soy milk samples gave results above the acceptable limits.

TABLE OF CONTENTS

Title page ﾿ i

Certification ﾿ ii

Dedication ﾿ iii

Acknowledgement ﾿ iv

Table of Contents ﾿ v

List of Tables ﾿ x

List of Figures ﾿ xi

Abstract ﾿ xii

CHAPTER ONE

INTRODUCTION

1.1 ﾿ INTRODUCTION ﾿ 1

1.2 ﾿ AIMS AND OBJECTIVES ﾿ 3

CHAPTER TWO

LITERATURE REVIEW  

2.1 ﾿ SOYBEAN ﾿ 4

2.1.1 ﾿ ORIGIN OF SOYMILK ﾿ 4

2.1.2 ﾿ AGRONOMIC CHARACTERISTICS ﾿ 4

2.1.3 ﾿ COMPOSITION OF SOYBEAN ﾿ 5

2.2 ﾿ SOYMILK ﾿ 7

2.2.1 ﾿ DEFINITION OF SOYMILK ﾿ 7

2.2.2 ﾿ HISTORY OF SOYMILK ﾿ 8

2.2.3 ﾿ COMPOSITION OF SOY MILK ﾿ 8

2.2.3.1 ﾿ CHEMICAL COMPOSITION OF SOY MILK ﾿ 8

2.2.3.2 ﾿ PHYTOCHEMICALS IN SOY MILK ﾿ 10

2.2.4 ﾿ CLASSIFICATION OF SOY MILK ﾿ 12

2.2.5 ﾿ SOYMILK PREPARATION METHODS ﾿ 12

2.2.6 ﾿ NUTRIONAL VALUES OF SOY MILK ﾿ 18

2.2.6.1 ﾿ SOYMILK INTAKE AND HEART DISEASE ﾿ 18

2.2.6.2 ﾿ SOYMILK AND MENOPAUSE ﾿ 19

2.2.6.3 ﾿ SOYMILK INTAKE AND BONE HEALTH ﾿ 20

2.2.6.4 ﾿ SOYMILK INTAKE AND BREAST HEALTH ﾿ 21

2.2.7 ﾿ MAJOR CONCERNS ABOUT SOY SUPPLEMENTS AND HEALTH PRODUCTS

2.2.8 ﾿ MICROORGANISMS ASSOCIATED WITH SPOILAGE OF MILK AND MILK PRODUCTS

2.2.8.1 ﾿ PSYCHROTROPHS ﾿   22

2.2.8.2 ﾿ COLIFORMS ﾿   23 ﾿

2.2.8.3 ﾿ LACTIC ACID BACTERIA ﾿    23

2.2.8.4 FUNGI ﾿     24 ﾿

2.2.8.5 ﾿ SPORE-FORMING BACTERIA ﾿     25

2.2.8.6  OTHER MICROOGANISMS ﾿     26 ﾿

2.2.9 ﾿ PRESERVATION AND STORAGE OF MILK AND PRODUCTS ﾿     26 ﾿

CHAPTER THREE

MATERIALS AND METHODS

3.1 ﾿ SOYMILK SAMPLES ﾿    28

3.2 ﾿ STERILIZATION OF MATERIALS ﾿     28

3.3 ﾿ MEDIA USED AND THEIR PREPARATION ﾿     28

3.4 ﾿ MICROBIOLOGICALANALYSIS OF SAMPLES ﾿     29

3.4.1 ﾿ SERIAL DILUTION ﾿      29

3.4.2 ﾿ ISOLATION AND ENUMERATION ﾿       29 

3.5 ﾿ CHARACTERIZATION AND IDENTIFICATION ﾿ OF THE BACTERIAL ISOLATES ﾿ 30

3.5.1 ﾿ PURIFICATION AND STORAGE OF THE ISOLATES ﾿ 30

3.5.2 ﾿ COLONIAL MORPHOLOGY ﾿ 30 ﾿

3.5.3 ﾿ GRAM STAINING ﾿   30

3.5.4 ﾿ BIOCHEMICAL TESTS ﾿   31

3.5.4.1 ﾿ CATALASE TEST ﾿    31 ﾿

3.5.4.2 ﾿ COAGULASE TEST ﾿    32

3.5.4.3 INDOLE TEST ﾿     32

3.5.4.4 ﾿ METHYL RED TEST ﾿      32

3.5.4.5 ﾿ VOGES PROSKAUER TEST ﾿       33

3.5.4.6 ﾿ CITRATE UTILIZATION TEST ﾿       33 ﾿

3.5.4.7 ﾿ OXIDASE TEST ﾿        34

3.5.4.8 ﾿ SUGAR FERMENTATION TEST ﾿       34

3.6 ﾿ IDENTIFICATION AND CHARACTERIZATION OF THE FUNGAL ISOLATES ﾿

CHAPTER FOUR

RESULTS ﾿        36

4.1 ﾿ RESULTS ﾿ 36

CHAPTER FIVE

DISCUSSION, CONCLUSION AND RECOMMENDATIONS

5.1 ﾿ DISCUSSION ﾿ 42

5.2 ﾿ CONCLUSION ﾿   45

5.3 ﾿ RECOMMENDATIONS ﾿ 45

REFERENCE ﾿   47