ABSTRACT
The nutrient composition, minerals and anti-nutrient properties of fresh, steamed and baked tofu coagulated with grape juice was studied. The proximate composition, mineral content, anti-nutrient properties and sensory attributes of the fresh, steamed and baked tofu samples were determined using standard laboratory procedures. The data obtained were statistically analyzed using Statistical Product of Service Solution (SPSS) version 23.0. The proximate composition of the tofu showed there was decrease in moisture content of the fresh tofu from 64.83% to 21.79% on baking. Baking also helped to increase the protein of fresh tofu from 16.46% to 18.65%. Fat increased from 2.73% in fresh tofu to 3.45% on steaming. Baking increased the fibre, ash, carbohydrate and energy value of the fresh tofu from 0.32% to 1.21%, 1.18% to 2.29%, 14.45% to 52.68% and 148.19 Kcal/100g to 315.79 Kcal/100g, respectively. The mineral contents of the tofu showed that baking decreased the calcium (110.49 mg/100g to 108.93 mg/100g), magnesium (122.14 mg/100g to 120.48 mg/100g), potassium (58.58 mg/100g to 56.85 mg/100g) and sodium (4.21 mg/110g to 3.40 mg/100g) contents of fresh tofu whereas steaming increased the iron content of fresh tofu from 3.86 mg/100g to 4.03 mg/100g. The antinutrients of the fresh tofu showed that the tannin (1.56 mg/100g), saponin (0.86 mg/100g), phytate (0.95 mg/100g) and oxalate (0.35 mg/100g) contents decreased to 0.64 mg/100g, 0.43 mg/100g, 0.72 mg/100g and 0.72 mg/100g, respectively on baking. Fascinatingly, the anti-nutrients of all the tofu samples were below the lethal dose for humans. The outcome of the sensory evaluation showed that beside the texture of deep-fried chicken (Control) that was liked moderately, its colour, taste, flavour and general acceptability were liked very much compared to the other tofu samples. Tofu can serve as a healthy and nutrient-dense snack or mid-day meal alternative.
TABLE OF CONTENTS
TITLE PAGE i
CERTIFICATION ii
DEDICATION iii
ACKNOWLEDGEMENTS iv
TABLE OF CONTENTS v
LIST OF TABLES viii
LIST OF FIGURES ix
ABSTRACT x
CHAPTER 1
INTRODUCTION1
1.1 Background of the study 3
1.2 Statement of problems 4
1.2 Objectives of the study 5
1.3 Significance of the study 6
CHAPTER 2
LITERATURE REVIEW6
2.1 Tofu 6
2.2 Coagulants 7
2.2.1Salt coagulants7
2.2.2Enzyme coagulant92.2.3Acid coagulant9
2.2.3.1 Grape juice as an acid coagulant10
2.3Soybean 11
2.3.1Nutritional value of soybean seeds12
2.3.2Health benefits of soybean seeds13
2.3.3Anti-nutrients of soybean seeds 14
2.3.4Food uses of soybean seeds 16
2.4Steaming technique 17
2.5Baking technique 18
CHAPTER 3
MATERIALS AND METHODS20
3.1 Study design 20
3.2 Materials 20
3.3 Methods 20
3.3.1 Extraction of grape juice 20
3.3.2Processing of fresh, steamed and baked tofu samples20
3.3.3Proximate analysis24
3.2.3.1Determination of moisture content24
3.2.3.2 Determination of ash content 25
3.2.3.3 Determination of fat content 25
3.2.3.4 Determination of fibre25
3.2.3.5 Determination of protein263.2.3.6 Determination of carbohydrate content 26
3.2.3.7 Determination of energy value26
3.2.4Mineral analysis273.2.4.1 Determination of calcium and magnesium273.2.4.2 Determination of sodium28
3.2.4.3 Determination of iron 29
3.2.4.4 Determination of potassium293.2.5Anti-nutrient analysis 30
3.2.5.1 Determination of phytate30
3.2.5.2 Determination of tannin30
3.2.5.3 Determination of saponin31
3.2.5.4 Determination of oxalate 32
3.2.6 Sensory evaluation33
3.2.7Statistical analysis34
CHAPTER 4
RESULTS AND DISCUSSIONS35
4.1Proximate composition of fresh, steamed and baked tofu35
4.2Mineral contents of fresh, steamed and baked tofu 41
4.3Anti-nutrient properties of fresh, steamed and baked tofu 46
4.4Sensory properties of fresh, steamed and baked tofu50
CHAPTER 5
CONCLUSION AND RECOMMENDATIONS55
5.1 Conclusion 55
5.2 Recommendations 55
References 57
APPENDIX 69
LIST OF TABLES
Table 4.1: Proximate composition and energy value of fresh,
steamed and baked tofu 36
Table 4.2:Mineral content of fresh, steamed and baked tofu42
Table 4.3:Anti-nutrients content of fresh, steamed and baked tofu 47
Table 4.4: Sensory properties of fresh, steamed and baked tofu
and fried chicken used as the control 51
LIST OF FIGURES
Figure 3.1: Flow chart for extraction of grape juice 22
Figure 3.2: Flow chart for tofu production 23
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