EFFECTS OF PROCESSING METHODS ON THE QUALITY AND ACCEPTABILITY OF SOYBEAN MILK (GLYCINE. MAX. L MERRILL)

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