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
11 Background of the study 3
12 Statement of problems 4
12 Objectives of the study 5
13 Significance of the study 6
CHAPTER 2
LITERATURE REVIEW6
21 Tofu 6
22 Coagulants 7
221Salt coagulants7
222Enzyme coagulant9223Acid coagulant9
2231 Grape juice as an acid coagulant10
23Soybean 11
231Nutritional value of soybean seeds12
232Health benefits of soybean seeds13
233Anti-nutrients of soybean seeds 14
234Food uses of soybean seeds 16
24Steaming technique 17
25Baking technique 18
CHAPTER 3
MATERIALS AND METHODS20
31 Study design 20
32 Materials 20
33 Methods 20
331 Extraction of grape juice 20
332Processing of fresh, steamed and baked tofu samples20
333Proximate analysis24
3231Determination of moisture content24
3232 Determination of ash content 25
3233 Determination of fat content 25
3234 Determination of fibre25
3235 Determination of protein263 236 Determination of carbohydrate content 26
3237 Determination of energy value26
324Mineral analysis273241 Determination of calcium and magnesium273242 Determination of sodium28
3243 Determination of iron 29
3244 Determination of potassium29325Anti-nutrient analysis 30
3251 Determination of phytate30
3252 Determination of tannin30
3253 Determination of saponin31
3254 Determination of oxalate 32
326 Sensory evaluation33
327Statistical analysis34
CHAPTER 4
RESULTS AND DISCUSSIONS35
41Proximate composition of fresh, steamed and baked tofu35
42Mineral contents of fresh, steamed and baked tofu 41
43Anti-nutrient properties of fresh, steamed and baked tofu 46
44Sensory properties of fresh, steamed and baked tofu50
CHAPTER 5
CONCLUSION AND RECOMMENDATIONS55
51 Conclusion 55
52 Recommendations 55
References 57
APPENDIX 69
LIST OF TABLES
Table 41: Proximate composition and energy value of fresh,
steamed and baked tofu 36
Table 42:Mineral content of fresh, steamed and baked tofu42
Table 43:Anti-nutrients content of fresh, steamed and baked tofu 47
Table 44: Sensory properties of fresh, steamed and baked tofu
and fried chicken used as the control 51
LIST OF FIGURES
Figure 31: Flow chart for extraction of grape juice 22
Figure 32: Flow chart for tofu production 23