ABSTRACT

This study ascertained effects of processing methods on the quality and acceptability of Soybean milk. Three specific on objective and research questions were used for the study. The study adopted an experimental research design. Soybeans were subjected to 3 different processing methods which were the whole soybean seeds and were processed using modified methods of William and Akiko (2000), the soybean were weighed 75 g using 20 capacity weighing scale. Results indicated that the nutrient content of the three soy bean milk samples (SBM A, SBM B and SBM C) were significantly (p≤0.05) different. Sample SBM C ranges from moisture 12.3±0.25  and 41.7a±0.38 more crude protein; 20.3a±0.77 more crude fat ; 21.7a±0.86 more carbohydrates; 5.2±0.76 more total ash; and 5.8a±0.36 more crude fibre than samples SBM A and SBM B respectively. The mean values of the sensory characteristics were equally significantly (p≤0.05) different with the exception of appearance which showed no significant difference. Sample SMC was adjudged most preferable organoleptically, in terms of appearance, taste, aroma and acceptability followed by sample SBM A while sample SBM B received the least nod of organoleptic acceptability. The observed results suggested that steeping before hot extraction might be a better method for processing soymilk in order to improve its wider acceptability. The study recommends that food specialist extension workers should be sent to various towns and regions to continue with the education of rural people on how to process other soybean products such as soybean oil, soybean cake and soybean meal and Government should provide rural people with facilities such as processing machines (like grinding mill, manual bridge press, rain press, decorticators and expellers), at subsidized rates in order to encourage them and to enhance the use of different processing methods of these products that are not available in the rural areas.

TABLE OF CONTENTS 

Title Page i

Declaration ii

Certification iii

Dedication iv

Acknowledgement v

Table of Contents vi

List of tables ix

List of figures x

Abstract xi

CHAPTER ONE: INTRODUCTION

1.1 Background to the study 1

1.2 Problem Statement 3

1.3 Objectives of the Study 4

1.4 Research Question 4

1.5 Significance of the study 5

1.6 Scope of the study 6

CHAPTER TWO: LITERATURE REVIEW

2.1 Conceptual frame work 7

2.1.1 Importance of soybean 7

2.1.2 Food-type Soybeans 11

2.1.3 Constraints in processing and the use of Soybeans products 12

2.1.4 Anti-nutritional factors 13

2.1.4.1 Tannin 13

2.1.4.2 Trypsin inhibitors 13

2.1.4.3 Hemagglutinins (Lectins) 14

2.1.4.4 Lipoxygenase enzymes 14

2.1.4.5 Phytates 15

2.2 Nutritional Quality in soybean 15

2.2.1 Isoflavones and its Content in Soybean and Soybean Related Foods 15

2.2.2 Proteins in Soybeans 17

2.2.3 Carbohydrates in Soybeans and related Foods 18

2.2.4 Lipids in Soybeans and related Foods 19

2.3 Meaning of Processing/General Overview of Processing 21

2.3.1 Handling Stages in Processing 22

2.3.2 Food Processing 23

2.3.3 Methods of food processing 23

2.3.4 Products from Soybean Processing 27

2.3.5 Soybean milk 28

2.3.6 Consumer Perception Studies on Attribute and Benefits of Products 29

2.3.8 Effects of processing methods on soybean products 31

2.3.8.1 Effects of processing on soybean carbohydrates 32

2.3.8.2 Effects of processing methods on soybean minerals 32

2.3.8.3 Effects of processing methods on soybean proteins 33

2.4 Theoretical framework 35

2.4.1 Effects of processing methods on the quality and acceptability of

Soybean 39

2.5 Review of Related Empirical Studies 41

2.6 Summary of literature review 43

CHAPTER THREE: RESEARCH METHODOLOGY

3.0 Introduction 45

3.1 Design of Study 45

3.2 Area of the Study 45

3.4 Materials for the Experiment 45

3.5 Method of Sample preparation 45

3.5.1 Method 1 (Hot Extraction Processing Method) 46

3.5.2 Method 2 (Cold Extraction Processing Method) 46

3.5.3 Method 3 (Steeping before Hot Extraction Processing Method 46

3.6 Proximate composition analysis 52

3.7 Sensory evaluation  55

3.8 Statistical analysis 56

CHAPTER FOUR:  RESULTS AND DISCUSSION

4.1      Proximate composition 57

4.2 Sensory evaluation 59

CHAPTER FIVE: SUMMARY, CONCLUSION AND RECOMMENDATION 

5.1 Summary 62

5.2 Conclusions 62

5.3 Recommendations 63

5.4 Restatement of problem 63

5.5 Description of procedures used 64

5.6 Contribution to knowledge and suggestion for further 64

REFERENCES 65

APPENDIX I 68

LIST OF TABLES

Table 4.1.1: Proximate composition of soybean milk samples 57

Table 4.2.2: Mean sensory scores of soybean milk samples from 3 different

 processing methods of soybean milk 59

LIST OF FIGURES

Figure 1: Hot extraction processing technique  48

Figure 2: Cold  extraction processing technique 49

Figure 3: Steeping before  hot extraction processing technique  50

Figure 4: Samples A, B and C of soybean milk 51