Effect Of Extrusion Process Variables On Quality Attributes Of Extrudates From Blends Of Aerial Yam And Soybean Flours - A Response Surface Analysis
ABSTRACT
This study investigated
the effect of extrusion process variables on quality attributes of extrudates
from blends of aerial yam and soybean flours. Laboratory scale single-screw
extruder was used in extruding blends of aerial yam and soybean flours in the ratio
of 25% aerial yam: 75% soybean. Response surface methodology based on Box-Behnken
design at three factors, five levels of barrel temperature (95, 100, 105, 110,
and115
TABLE OF CONTENTS
CHAPTER TITLE PAGE
Cover Page
i
Title
Page
ii
Declaration iii
Certification
iv
Acknowledgement v
Table
of Contents
vii
List
of Tables xvi
List
of Figures xx
List
of Plates
xxvi
Abstract
xxvii
CHAPTER 1: INTRODUCTION
1.1
Aerial Yam (Dioscoreabulbifera) 1
1.2 Soybean (Glycine max)
3
1.3 Justification of the Study 5
1.4 Aim and Objectives of the Study
6
CHAPTER 2: LITERATURE
REVIEW
2.1
Processing and
Utilization of Aerial Yam 7
2.2 Processing and Utilization
of Soybean
9
2.2.1
Production of Soy
Protein Products 11
2.2.2
Germinated Soy Products
11
2.2.3
Soy Oil
12
2.2.4
Other Traditional Soy
Foods
12
2.2.5
Progress in Soybean
Processing In Nigeria
13
2.3 Food Extrusion
Process 14
2.3.1
Fundamental Principles
of Food Extrusion
16
2.3.2
Single-Screw Extruders
18
2.3.3 Twin-Screw Extruders
21
2.3.4
Comparison of Single-
and Twin-Screw Extruders 22
2.4
Effects of Extrusion Process on Proximate
Composition of
Food Products
24
2.4.1 Dietary Fibre
26
2.4.2 Protein 26
2.4.3
Carbohydrates 28
2.4.4
Reduction of Lipid
Oxidation 30
2.4.5
Product Moisture 31
2.5
Effects of Extrusion
Process on Functional Properties of
Food Products 32
2.5.1 Bulk Density 33
2.5.2
Water Absorption Index
(WAI) and Water Solubility
Index (WSI) 35
2.5.3 Oil Absorption Index 37
2.6
Effects of Extrusion
Process on Anti-nutritional Factors in
Food Products
38
2.6.1 Reduction of Anti-nutritional
factors 38
2.7
Effect of Extrusion
Process on Sensory Properties of
Food Products
43
2.7.1 Flavour Formation and
Retention during Extrusion 43
2.7.2 Aroma 44
2.7.3
Colour
45
2.7.4
Crispness/Hardness/Texture 46
2.7.5 Overall Acceptability
48
2.8
Response Surface
Methodology (RSM)/Analysis
48
CHAPTER 3: MATERIALS
AND METHODS
3.1
Collection of Soybean
Seeds and Aerial Yam Bulbs 51
3.2 Sample Preparation 51
3.2.1
Preparation of Aerial Yam
Flour 51
3.2.2
Preparation of Soybean
Flour 52
3.2.3 Preparation
of Sample Blend 53
3.2.4 Extrusion Cooking
53
3.4
Determination of
Proximate Composition 54
3.4.1
Moisture Content 54
3.4.2
Ash Content 55
3.4.3
Crude Fibre 55
3.4.4
Crude Protein
56
3.4.5
Crude Fat (Lipid)
57
3.4.6
Carbohydrate Content 58
3.4.7 Energy
Value 58
3.5 Determination of Anti-nutritional
Factors
58
3.5.1
Hydrogencyanide
(Cyanogenic Glycosides)
58
3.5.2
Oxalates
59
3.5.3 Phytic acid (Phytates) 60
3.5.4
Tannin 60
3.5.5
Alkaloids
61
3.6
Determination of Functional
Properties 62
3.6.1
Bulk Density 62
3.6.2 Water Absorption Capacity 62
3.6.3
Oil Absorption Capacity 63
3.6.4
Emulsion Capacity 63
3.6.5
Foaming Capacity
64
3.7
Determination of
Sensory Characteristics 64
3.7.1
Texture
64
3.7.2
Taste
64
3.7.3
Appearance 64
3.7.4
Aroma
64
3.7.5
Overall
Acceptability 64
3.8
Experimental
Design/Response Surface Analysis
64
3.9
Model Selection for Optimization and
Validation of Extrusion
Process Parameters
65
CHAPTER 4: RESULTS
AND DISCUSSION
4.1 Proximate Composition of Extruded Aerial Yam
and
Soybean Flour Blend
68
4.1.1 Ash
68
4.1.2
Moisture Content 69
4.1.3
Fibre 69
4.1.4
Protein 70
4.1.5
Crude Fat 70
4.1.6
Carbohydrate 71
4.1.7
Energy Value 71
4.2 Model Selection/Equation for Optimization of Extrusion Process
Parameters
of Proximate Composition of Aerial Yam and
Soybean Flour Blends
73
4.2.1 Model Selection/Equation for Optimization of Extrusion Process
Parameters for Ash
73
4.2.2 Model Selection/Equation for Optimization of Extrusion Process
Parameters for Moisture
Content 74
4.2.3 Model Selection/Equation for Optimization of
Extrusion Process
Parameters for Fibre 75
4.2.4 Model Selection/Equation for Optimization of Extrusion Process
Parameters for Protein
76
4.2.5 Model Selection/Equation for Optimization of Extrusion Process
Parameters for Crude Fat 78
4.2.6 Model Selection/Equation for
Optimization of Extrusion Process
Parameters for Carbohydrate 79
4.2.7 Model Selection/ Equation for
Optimization of Extrusion Process
Parameters for Energy Value 80
4.3 Optimization and Validation of Extrusion Process Parameters for
Proximate
Composition of Aerial Yam and Soybean Flour Blends 81
4.4 Response Surface Plots for
the Proximate Composition of
Aerial Yam and Soybean Flour Blends 92
4.4.1 Effect of Extrusion Process
Parameters on Ash 92
4.4.2 Effect of Extrusion Process
Parameters on Moisture Content
95
4.4.3 Effect of Extrusion Process
Parameters on Fibre 98
4.4.4 Effect of Extrusion Process
Parameters on Protein 101
4.4.5 Effect of Extrusion Process
Parameters on Fat 104
4.4.6 Effect of Extrusion Process Parameters
on Carbohydrate 107
4.4.7 Effect of Extrusion Process
Parameters on Energy Value 110
4.5
Antinutritional
Factors of Extruded Aerial Yam and Soybean
Flour Blend
114
4.5.1
Hydrogencyanide (HCN) 114
4.5.2 Phytate 115
4.5.3
Tannin 115
4.5.4
Oxalates 116
4.5.5
Alkaloids
116
4.6 Model
Selection/Equation for Optimization of Extrusion
Parameters
for Anti-nutritional Factors of Aerial Yam and
Soybean Flour Blend
118
4.6.1 Model Selection/Equation
for Optimization of Extrusion Process
Parameters for
HCN 118
4.6.2
Model Selection/Equation
for Optimization of Extrusion Process
Parameters for Phytate 119
4.6.3
Model Selection/Equation
for Optimization of Extrusion Process
Parameters for Tannin 120
4.6.4
Model Selection/Equation
for Optimization of Extrusion Process
Parameters for Oxalates 121
4.6.5 Model Selection/Equation for Optimization of
Extrusion Process
Parameters for Alkaloids 122
4.7. Optimization
and Validation of Extrusion Process Parameters for
Anti-nutritional
Factors of Aerial Yam and Soybean Flour Blends 124
4.7.1 Numerical Optimization of Extrusion Process Parameters for
Anti-nutritional Factors 124
4.8 Response Surface Plots for
the Anti-nutritional Factors of
Aerial Yam and Soybean Flour Blends
131
4.8.1 Effect of Extrusion Process
Parameters on Hydrogencyanide (HCN) 131
4.8.2
Effect of Extrusion Process Parameters on Phytate 134
4.8.3
Effect of Extrusion
Process Parameters on Tannin 136
4.8.4
Effect of Extrusion
Process Parameters on Oxalates 140
4.8.5
Effect of Extrusion
Process Parameters on Alkaloids 143
4.9
Functional
Properties of Extruded Aerial Yam and Soybean
Flour Blends
147
4.9.1
Bulk density 147
4.9.2
Water Absorption
Capacity
148
4.9.3
Oil Absorption
Capacity 149
4.9.4
Emulsion/Foaming
Capacity 149
4.10 Model Selection/Equation for Optimization of Extrusion Process
Parameters
of Functional Properties of Aerial Yam and
Soybean Flour Blends 151
4.10.1 Model Selection/Equation for
Optimization of Extrusion Process
Parameters for Bulk density 151
4.10.2
Model Selection/Equation
for Optimization of Extrusion Process
Parameters for Water
Absorption Capacity 152
4.10.3
Model Selection/Equation
for Optimization of Extrusion Process
Parameters for Oil Absorption Capacity 153
4.10.4
Model Selection/Equation
for Optimization of Extrusion Process
Parameters for Emulsion
Capacity 154
4.10.5
Model Selection/Equation
for Optimization of Extrusion Process
Parameters for Foaming Capacity 155
4.11 Optimization
and Validation of Extrusion Process Parameters for
Functional
Properties of Aerial Yam and Soybean Flour
Blends 157
4.11.1 Numerical Optimization of Extrusion Process Parameters for
Functional Properties 157
4.12 Response
Surface Plots for the Functional Properties of Aerial
Yam and Soybean
Flour Blends
165
4.12.1
Effect of Extrusion Process Parameters on Bulk Density 165
4.12.2
Effect of Extrusion
Process Parameters on Water Absorption Capacity 169
4.12.3
Effect of Extrusion Process Parameters on
Oil Absorption Capacity 172
4.12.4
Effect of Extrusion Process
Parameters on Emulsion Capacity
175
4.12.5
Effect of Extrusion Process
Parameters on Foaming Capacity 178
4.13
Sensory Characteristics
of Extruded Products from
Aerial Yam and Soybean
Flour Blends 182
4.13.1 Texture 182
4.13.2
Taste
183
4.13.3
Appearance 183
4.13.4
Aroma 184
4.13.5
Overall Acceptability
184
4.14 Model
Selection/Equation for Optimization Extrusion Process
Parameters
of Sensory Characteristics of Aerial Yam and
Soybean Flour Blends
187
4.14.1
Model Selection/Equation
for Optimization of Extrusion Process
Parameters for Texture 187
4.14.2
Model Selection/Equation
for Optimization of Extrusion Process
Parameters for Taste 188
4.14.3
Model Selection/Equation
for Optimization of Extrusion Process
Parameters for Appearance 189
4.14.4
Model Selection/Equation
for Optimization of Extrusion Process
Parameters for Aroma 190
4.14.5
Model Selection/Equation
for Optimization of Extrusion Process
Parameters for Overall Acceptability 192
4.15
Optimization and
Validation of Extrusion Parameters for
Sensory
Characteristics
193
4.15.1 Numerical optimization of Extrusion Process
Parameters for
Sensory Characteristics 193
4.16 Response
Surface Plots for the Sensory
Characteristics of Aerial Yam and Soybean Flour Blends 200
4.16.1
Effects of Extrusion Parameters
on Texture 200
4.16.2
Effects of Extrusion Parameters
on Taste 203
4.16.
3 Effects of Extrusion Parameters
on Appearance 207
4.16.4
Effects of Extrusion Parameters
on Aroma 210
4.16.5
Effects of Extrusion
Parameters on Overall Acceptability
214
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1
Conclusion
218
5.2 Recommendations 220
REFERENCES
222
APPENDICES 236
LIST OF TABLES
TABLE TITLE
PAGE
2.1 Extrusion Cooking Applications 16
2.2 Relative Comparison of Single-
and Twin- Screw Extruders
24
2.3 Anti-nutrients and Toxins
affected by Extrusion Cooking 40
3.1 Coded and Actual values of
different Experimental Variables
64
3.2 Experimental Layout for 3
Variables and 5 Levels Response Surface
Experimental Design for the Extrusion of
Aerial Yam and Soybean
Flour Blend 65
3.3
Criteria for numerical
Optimization of Extrusion Process Parameters
for Proximate Composition 66
3.4
Criteria for Numerical
Optimization of Extrusion Process Parameters
for Anti-nutritional Factors 67
3.5
Criteria for Numerical
Optimization of Extrusion Process Parameters
for Functional Properties 67
3.6
Criteria for Numerical
Optimization of Extrusion Process Parameters
for Sensory Characteristics 67
4.1
Proximate Composition
of Extruded Aerial Yam and Soybean
Flour Blends 68
4.2
Coefficient of
Regression/ANOVA for Proximate Compositions
72
4.3 Output for Numerical
Optimization of Extrusion Process
Parameters for Proximate
Composition
81
4.4 Optimal Extrusion Process Parameters with Optimum Predicted
Responses for Validation of the Proximate
Composition 84
4.5 Analysis of Variance (ANOVA) for Ash at 5% Significance Level 94
4.6
Tests of
Between-Subjects Effects of Extrusion Process Parameters
on Ash 94
4.7
Analysis of Variance
(ANOVA) for Moisture Content at
5% Significance Level
97
4.8
Tests of Between-Subjects
Effects of Extrusion Process Parameters on
Moisture Content 97
4.9
Analysis of Variance (ANOVA)
for Fibre at 5% Significance Level
100
4.10
Tests of Between-Subjects
Effects of Extrusion Process Parameters on
Fibre 100
4.11
Analysis of Variance (ANOVA)
for Protein at 5% Significance Level
103
4.12
Tests of Between-Subjects
Effects of Extrusion Process Parameters on
Protein 103
4.13
Analysis of Variance (ANOVA) for
Crude Fat at 5% Significance Level
106
4.14
Tests of Between-Subjects
Effects of Extrusion Process Parameters on
Crude Fat 106
4.15
Analysis of Variance (ANOVA)
for Carbohydrate at 5% Significance Level 109
4.16
Tests of Between-Subjects
effects of Extrusion Process Parameters on
Carbohydrate 110
4.17
Analysis of Variance (ANOVA)
for Energy Value at 5% Significance Level 112
4.18
Tests of Between-Subjects
Effects of Extrusion Process Parameters on
Energy Value 113
4.19
Anti-nutritional Factors of Extruded
Aerial yam and Soybean Flour Blends 114
4.20
Coefficient of Regression/ANOVA
for Anti-nutritional Factors 117
4.21 Output for Numerical Optimization of
Extrusion Process
Parameters for Anti-nutritional
Factors
124
4.22
Optimal Extrusion Process Parameters with Optimum Predicted
Responses for Validation of
the Anti-nutritional Factors 126
4.23
Analysis of Variance (ANOVA)
for HCN at 5% Significance Level 133
4.24
Tests of Between-Subjects
Effects of Extrusion Process Parameters
on HCN
133
4.25
Analysis of Variance (ANOVA)
for Phytate at 5% Significance Level
136
4.26
Tests of Between-Subjects
effects of Extrusion Process Parameters
on Phytate
136
4.27 Analysis of Variance (ANOVA) for Tannin
at 5% Significance Level 139
4.28
Tests of Between-Subjects
Effects of Extrusion Process Parameters
on Tannin
139
4.29
Analysis of Variance (ANOVA)
for Oxalates at 5% Significance Level
142
4.30
Tests of Between-Subjects
Effects of Extrusion Process Parameters
on Oxalates
142
4.31
Analysis of Variance (ANOVA)
for Alkaloids at 5% Significance Level
145
4.32
Tests of Between-Subjects
effects of Extrusion Process Parameters
on Alkaloids
146
4.33
Functional Properties of
Extruded Aerial Yam and Soybean Flour Blends 147
4.34
Coefficient of Regression/ANOVA
for Functional Properties 150
4.35 Output for Numerical Optimization
of Extrusion Process
Parameters for Functional Properties
157
4.36 Optimal Extrusion Process Parameters with Optimum
Predicted
Responses for Validation of Functional Properties 159
4.37 Analysis of Variance (ANOVA) for Bulk
Density at 5% Significance Level 167
4.38 Tests of Between-Subjects Effects
of Extrusion Process Parameters
on Bulk Density
168
4.39 Analysis of Variance (ANOVA) for Water
Absorption Capacity
at 5% Significance
Level
171
4.40 Tests of Between-Subjects Effects
of Extrusion Process Parameters
on Water Absorption Capacity 171
4.41
Analysis of Variance (ANOVA)
for Oil Absorption Capacity at 5%
Significance Level
174
4.42 Tests of Between-Subjects Effects
of Extrusion Process Parameters on
Oil Absorption Capacity 175
4.43
Analysis of Variance (ANOVA)
for Emulsion capacity at 5%
Significance level
177
4.44 Tests of Between-Subjects Effects
of Extrusion Process Parameters on
Emulsion Capacity
178
4.45
Analysis of Variance (ANOVA)
for Foaming Capacity at 5%
Significance Level 180
4.46
Tests of Between-Subjects
Effects of Extrusion Process Parameters
on Foaming Capacity
181
4.47
Sensory Characteristics of
Extruded Aerial Yam and Soybean
Flour Blends 182
4.48 Coefficient
of Regression/ANOVA for Sensory Characteristics 186
4.49 Output for Numerical Optimization
of Extrusion Process
Parameters for Sensory Characteristics
193
4.50 Optimal Extrusion Process Parameters with Optimum Predicted
Responses for Validation of the Sensory
Characteristics
194
4.51
Analysis of Variance (ANOVA)
for Texture at 5% Significance Level
202
4.52
Tests of Between-Subjects
Effects of Extrusion Process Parameters
on Texture
203
4.53
Analysis of Variance (ANOVA)
for Taste at 5% Significance Level
205
4.54
Tests of Between-Subjects
Effects of Extrusion Process Parameters
on Taste
206
4.55
Analysis of Variance
(ANOVA) for Appearance at 5%
Significance Level 209
4.56
Tests of Between-Subjects
Effects of Extrusion Process Parameters
on Appearance
210
4.57
Analysis of Variance
(ANOVA) for Aroma at 5% Significance Level 212
4.58 Tests of Between-Subjects effects
of Extrusion Process Parameters
on Aroma
213
4.59 Analysis of Variance (ANOVA) for Overall Acceptability
at 5%
Significance Level 216
4.60
Tests of Between-Subjects
Effects of Extrusion Process Parameters
on Overall Acceptability
216
LIST OF FIGURES
FIGURE TITLE
PAGE
2.1
A Flow Chart for the Production
of Flour from Aerial Yam
9
2.2
Conventional Processes
for Producing Full-fat and Defatted
Soybean Flour/Grits 14
2.3
A Cross-section of a Single-Screw
Extruder 19
4.1 Ramp
for Optimization of Extrusion Process Conditions for
Proximate Compositions of Aerial
Yam and Soybean Flour Blend 82
4.2 Comparison of the Predicted
and Experimental Values for Ash 86
4.3 Comparison of the Predicted and Experimental Values
for
Moisture Content 86
4.4 Comparison of the Predicted
and Experimental Values for Fibre 88
4.5 Comparison
of the Predicted and Experimental Values for Protein 88
4.6 Comparison of the Predicted
and Experimental Values for Fat 89
4.7 Comparison
of the Predicted and Experimental Values for
Carbohydrate
90
4.8 Comparison
of the Predicted and Experimental Values for
Energy Value
91
4.9 Response Surface Plot showing the Effect of Barrel
Temperature and
Screw
Speed on Ash
92
4.10
Response surface plot showing the effect of Barrel
temperature
and Feed moisture on Ash 92
4.11
Response Surface Plot showing the Effect of Screw
Speed and
Feed Moisture on Ash 93
4.12 Response Surface Plot showing
the Effect of Barrel Temperature
and
Screw Speed on Moisture Content
95
4.13
Response Surface Plot
showing the Effect of Barrel Temperature
and Feed Moisture on Moisture Content 95
4.14
Response Surface Plot
showing the Effect of Screw Speed
and Feed Moisture on Moisture Content 96
4.15
Response Surface Plots
showing the Effect of Barrel Temperature
and Screw Speed on Fibre
98
4.16
Response Surface Plot
showing the Effect of Barrel Temperature
and Feed Moisture on Fibre 99
4.17
Response Surface Plot
showing the Effect of Screw Speed
and Feed Moisture on Fibre 99
4.18
Response Surface Plots
showing the Effect of Barrel Temperature and
Screw Speed on Protein 101
4.19
Response Surface Plot
showing the Effect of Barrel Temperature
and
Feed Moisture on Protein 101
4.20 Response Surface Plot showing
the Effect of Screw Speed and
Feed Moisture on Protein 102
4.21 Response Surface Plot showing
the Effect of Barrel Temperature
and Screw Speed on Crude Fat
(Lipid) 104
4.22 Response Surface Plot showing
the Effect of Barrel Temperature
and Feed Moisture on Crude Fat (Lipid) 104
4.23 Response Surface Plot showing the Effect of Screw Speed
and Feed
Moisture on Crude Fat (Lipid) 105
4.24 Response Surface Plots showing the Effect of Barrel
Temperature
and Screw Speed on Carbohydrates 107
4.25 Response Surface Plot showing the Effect of Barrel Temperature and
Feed Moisture
on Carbohydrate 107
4.26 Response Surface Plot showing the Effect of Screw Speed
and
Feed Moisture on Carbohydrate
108
4.27 Response Surface Plot showing the Effect of Barrel Temperature
and
Screw Speed on Energy Value 111
4.28 Response Surface Plot showing
the Effect of Barrel Temperature and
Feed Moisture on Energy Value
111
4.29 Response Surface Plot showing
the Effect of Screw Speed and
Feed
Moisture on EnergyValue
112
4.30 Ramp for Optimization of Extrusion Process Parameters for
Anti-nutritional Factors of Aerial
Yam-Soybean Flour Blends 125
4.31 Comparison of the Predicted and
Experimental Values for HCN
127
4.32 Comparison of the Predicted
and Experimental Values for Phytate
127
4.33 Comparison of the Predicted
and Experimental Values for Tannin
128
4.34 Comparison of the Predicted
and Experimental Values for Oxalate
128
4.35 Comparison of the Predicted and Experimental
Values for Alkaloid 129
4.36 Response Surface
Plots showing the Effect of Barrel Temperature
and Screw Speed on HCN 131
4.37
Response Surface Plot
showing the Effect of Barrel Temperature
and Feed Moisture on HCN 132
4.38
Response Surface Plot
showing the Effect of Screw Speed and
Feed Moisture on HCN 132
4.39
Response Surface Plot
showing the Effect of Barrel Temperature
and Screw Speed on Phytate 134
4.40
Response Surface Plot
showing the Effect of Barrel Temperature
and Feed Moisture on Phytate 134
4.41
Response Surface Plot
showing the Effect of Screw Speed and
Feed Moisture on Phytate 135
4.42
Response Surface Plot
showing the Effect of Barrel Temperature
and Screw Speed on Tannin 137
4.43
Response Surface Plot
showing the Effect of Barrel Temperature
and Feed Moisture on Tannin 137
4.44
Response Surface Plot
showing the Effect of Screw Speed and
Feed Moisture on Tannin 138
4.45 Response Surface Plot showing the Effect of Barrel Temperature
and Screw Speed on Oxalate 140
4.46 Response Surface Plot showing the Effect of Barrel Temperature
and Feed Moisture on Oxalate 140
4.47 Response Surface Plot showing the Effect of Screw Speed
and
Feed Moisture on Oxalate 141
4.48 Response Surface Plot showing the Effect of Barrel Temperature
and Screw Speed on Alkaloids
143
4.49 Response Surface Plot showing the Effect of Barrel Temperature
and Feed Moisture on Alkaloids 144
4.50 Response Surface Plot showing the Effect of Screw Speed
and
Feed Moisture on Alkaloids
144
4.51 Ramp for Optimization of Extrusion Process Parameters
for
Functional Properties of Aerial
Yam and Soybean Flour Blends 158
4.52
Comparison of the Predicted and Experimental
Values for
Bulk Density 160
4.53 Comparison of the Predicted
and Experimental Values for Water
Absorption Capacity 161
4.54 Comparison of the Predicted
and Experimental Values for Oil
Absorption Capacity 162
4.55 Comparison of the Predicted
and Experimental Values for
Emulsion Capacity 163
4.56 Comparison of the Predicted
and Experimental Values for
Foaming Capacity
164
4.57
Response Surface Plot
showing the Effect of Barrel Temperature
and Screw Speed on Bulk Density 165
4.58
Response Surface Plot
showing the Effect of Barrel Temperature
and Feed Moisture
on Bulk Density 165
4.59
Response Surface Plot
showing the Effect of Screw Speed and
Feed Moisture on Bulk Density 166
4.60
Response Surface Plot
showing the Effect of Barrel Temperature
and Screw Speed on Water Absorption Capacity 168
4.61 Response Surface Plot
showing the Effect of Barrel Temperature
and Feed Moisture on Water Absorption Capacity 169
4.62
Response Surface Plot
showing the Effect of Screw Speed and
Feed Moisture on Water Absorption
169
4.63
Response Surface Plots
showing the Effect of Barrel Temperature
and Screw Speed on Oil Absorption Capacity 172
4.64
Response Surface Plot
showing the Effect of Barrel Temperature
and Feed Moisture on Oil Absorption Capacity 172
4.65
Response Surface Plot
showing the Effect of Screw Speed and
Feed Moisture on Oil Absorption Capacity
173
4.66 Response Surface Plot showing
the Effect of Barrel Temperature
and Screw Speed on Emulsion
Capacity 175
4.67 Response Surface Plot showing
the Effect of Barrel Temperature
and Feed Moisture on Emulsion
Capacity 176
4.68 Response Surface Plot
showing the Effect of Screw Speed and
Feed Moisture on Emulsion Capacity 176
4.69 Response
Surface Plot showing the Effect of Barrel Temperature
and Screw Speed on Foaming Capacity 170
4.70 Response Surface Plot
showing the Effect of Barrel Temperature
and Feed Moisture on Foaming Capacity 179
4.71 Response Surface Plot
showing the Effect of Screw Speed
Feed Moisture on Foaming
Capacity 179
4.72 Ramp for Optimization of Extrusion
Process Conditions for
Sensory Characteristics of
Aerial Yam and Soybean Flour Blends 194
4.73 Comparison of the Predicted
and Experimental Values for Texture
195
4.74 Comparison of the Predicted
and Evalues for Taste 197
4.75 Comparison of the Predicted
and Experimental Values for
Appearance 198
4.76 Comparison of the Predicted and Experimental Values for Aroma 299
4.77 Comparison of
the Predicted and Experimental Values for
Overall Acceptability 200
4.78 Response Surface Plot showing the Effect of Barrel Temperature
and Screw Speed on Texture 200
4.79
Response Surface Plot
showing the Effect of Barrel Temperature and
Feed Moisture on Texture 200
4.80
Response Surface Plot
showing the Effect of Screw Speed and
Feed Moisture on Texture 201
4.81
Response Surface plot
showing the Effect of Barrel Temperature and
Screw Speed on Taste 203
4.82
Response Surface Plot
showing the Effect of Barrel Temperature and
Feed Moisture on Taste 204
4.83
Response Surface Plot
showing the Effect of Screw Speed and
Feed Moisture on Taste 204
4.84
Response Surface Plot
showing the Effect of Barrel Temperature and
Screw Speed on Appearance 207
4.85
Response Surface Plot
showing the Effect of Barrel Temperature and
Feed Moisture on Appearance 207
4.86
Response Surface Plot
showing the Effect of Screw Speed and
Feed Moisture on Appearance 208
4.87 Response Surface Plot showing
the Effect of Barrel Temperature and
Screw Speed on Aroma
210
4.88 Response Surface Plot showing
the Effect of Barrel Temperature
and Feed Moisture on Aroma 211
4.89 Response Surface Plot showing
the Effect of Screw Speed and
Feed Moisture on Aroma
211
4.90 Response Surface Plot showing
the Effect of Barrel Temperature
and Screw Speed on Overall Acceptability 214
4.91 Response Surface Plot showing
the Effect of Barrel Temperature
and Feed Moisture on Overall
Acceptability 214
4.92 Response Surface Plot showing the Effect
of Screw Speed and
Feed Moisture on Overall Acceptability 215
LIST OF PLATES
PLATE TITLE PAGE
1 Aerial Yam Plant (Dioscorea bulbifera) 1
2 Aerial Yam (Dioscorea bulbifera) bulbs 52
3 Processed Aerial Yam Flour 52
4 Processed Soybeans Flour 53
5 Extrudate Sample of Aerial Yam
and Soybean Flour Blend 54
0.0
ENOBONG, O (2023). Effect Of Extrusion Process Variables On Quality Attributes Of Extrudates From Blends Of Aerial Yam And Soybean Flours - A Response Surface Analysis. Repository.mouau.edu.ng: Retrieved Apr 27, 2024, from https://repository.mouau.edu.ng/work/view/effect-of-extrusion-process-variables-on-quality-attributes-of-extrudates-from-blends-of-aerial-yam-and-soybean-flours-a-response-surface-analysis-7-2
OKON, ENOBONG. "Effect Of Extrusion Process Variables On Quality Attributes Of Extrudates From Blends Of Aerial Yam And Soybean Flours - A Response Surface Analysis" Repository.mouau.edu.ng. Repository.mouau.edu.ng, 20 Jul. 2023, https://repository.mouau.edu.ng/work/view/effect-of-extrusion-process-variables-on-quality-attributes-of-extrudates-from-blends-of-aerial-yam-and-soybean-flours-a-response-surface-analysis-7-2. Accessed 27 Apr. 2024.
OKON, ENOBONG. "Effect Of Extrusion Process Variables On Quality Attributes Of Extrudates From Blends Of Aerial Yam And Soybean Flours - A Response Surface Analysis". Repository.mouau.edu.ng, Repository.mouau.edu.ng, 20 Jul. 2023. Web. 27 Apr. 2024. < https://repository.mouau.edu.ng/work/view/effect-of-extrusion-process-variables-on-quality-attributes-of-extrudates-from-blends-of-aerial-yam-and-soybean-flours-a-response-surface-analysis-7-2 >.
OKON, ENOBONG. "Effect Of Extrusion Process Variables On Quality Attributes Of Extrudates From Blends Of Aerial Yam And Soybean Flours - A Response Surface Analysis" Repository.mouau.edu.ng (2023). Accessed 27 Apr. 2024. https://repository.mouau.edu.ng/work/view/effect-of-extrusion-process-variables-on-quality-attributes-of-extrudates-from-blends-of-aerial-yam-and-soybean-flours-a-response-surface-analysis-7-2