Modification And Optimization Of The Physicochemical Properties Of Allanblackia (Allanblackia floribunda), African Walnut (Tetracarpidium conophorum) And Fluted Pumpkin (Telfairia occidentalis) Seed Oil Blend In Bakery Shortening Production
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ABSTRACT
The objective of this work was to modify the physicochemical properties of Allanblackia, African walnut and fluted pumpkin seed oil blend by chemical interesterification, for use in bakery shortening production and to optimize the interesterification temperature, time and catalyst concentration using response surface methodology (RSM) based on central composite design (CCD). Baking performance of the formulated shortenings were evaluated in bread, through physical/morphological and sensory properties. Oils were extracted using solvent (ethanol and hexane) and hot water floatation methods. Hot water floatation method gave oil yield of 43.40, 34.73 and 32.00 % for Allanblackia, African walnut and fluted pumpkin seeds respectively. Melting point and density were respectively 35.43 oC and 0.9145 g/ml, 17.13 oC and 0.9107 g/ml, 18.33 0C and 0.9166 g/ml for Allanblackia, African walnut and fluted pumpkin seed oils. Refractive index (1.4750) of African walnut oil was significantly higher (p<0.05) than those of Allanblackia and fluted pumpkin seed oils. Fluted pumpkin seed oil showed wider plasticity with solid fat content of 44.96 to 0.99 % at 5 to 50 0C. Iodine value, free fatty acid and saponification value ranged from 40.27 to 128.69 g/100g, 0.17 to 0.58 % and 152.03 – 199.98 mgKOH/g respectively. Iodine value of African walnut and fluted pumpkin seed oils were significantly (p<0.05) higher than that of Allanblackia seed oil. Allanblackia seed oil recorded 57.5 % total saturated fatty acids. African walnut oil contained 15.44 % omega-3 fatty acid. The fitted regression model for the response variables from RSM were significant (p<0.05) with C.V value of 0.266, 0.146, 0.502, 0.499, 0.602, 0.448 and 7.830 % and R2 of 96.8, 95.3, 94.2, 90.1, 99.5, 93.2 and 75.7 %, respectively for solid fat content, smoke point, melting point, density, viscosity, Iodine value and free fatty acid. Model lack-of-fit in all cases were desirably not significant (p>0.05). Predicted optimum condition and desirability index of 0.907 was obtained at 74.57 oC, 46.0 min and 0.278 % interesterification temperature, time and catalyst concentration, respectively. Melting point and FFA were reduced significantly after interesterification. Interesterified and non-interesterified margarine containing 60 – 70 % fat base received same overall acceptability with those of the commercial table margarine. Bakery shortenings produced with the optimum interesterified oils, non-interesterified oils, commercial bakery shortenings gave melting point of 32.53, 33.47, 42.70 and 40.10 oC, respectively. Specific gravity and viscosity ranged from 0.9117 to 0.9377 and 21.75 to 38.19 cSt, respectively. Great variation in microstructural morphology were apparent between all the bakery shortenings. Bread baked with interesterified, non-interesterified, local and imported commercial shortenings showed oven spring, loaf weight and specific volume ranging from 0.47 to 1.63 cm, 132.33 to 134.00 g and 3.49 – 3.52 cm3/g, respectively. Loaf from interesterified shortening was scored higher with respect to texture and overall acceptability. All the bread samples however, fell within the like moderately (7) to like very much (8). The interesterified and commercial shortenings showed good shelf stability after 120 days of storage at room temperature. Use of Allanblackia, African walnut and fluted pumpkin seed oils in wide range of domestic and industrial applications, for cooking and food product development is highly recommended, based on their high content of polyunsaturated fatty acids (omega-6 and omega-3) which have cholesterol lowering properties.
TABLE OF CONTENTS
Page
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgement v
Table of Content vi
List of Tables xiii
List of Figures xv
List of Plates xviii
Abstract xxii
CHAPTER 1: INTRODUCTION
1.2 Background to the Study 1
1.3 Statement of the Problem 6
1.4 Justification of Study 6
1.4 Objectives of the Study 7
CHAPTER 2: LITERATURE REVIEW
2.1 Bakery Shortening 9
2.2 Table Margarine 10
2.3 Fats and Oils 11
2.4 Allanblackia as Oil Seed 12
2.5 Fluted Pumpkins as Oil Seed 16
2.6 African Walnut 18
2.7 Oil Extraction and Refining 20
2.7.1 Oil extraction 20
2.7.2 Oil refining 21
2.8 Fat Modification 21
2.8.1 Hydrogenation 21
2.8.2 Blending 22
2.8.3 Fractionation 23
2.8.4 Interesterification 23
2.8.4.1 Chemical interesterification 24
2.8.4.2 Enzymatic interesterification 25
2.8.5 Genetic modification 26
2.9 Physicochemical Properties of Fats and Oils 27
2.9.1 Refractive index 27
2. 9.2 Density 27
2.9.3 Viscosity 27
2.9.4 Smoke point 27
2.9.5 Solid fat content 28
2.9.6 Free fatty acid 28
2.9.7 Saponification value 29
2.9.8 Iodine value (iv) 29
2.9.9 Peroxide value 30
2.9.10 Unsaponifiable matter 30
2.9.11 Lipid composition 30
2.10 Crystallization: Nucleation and
Crystal Growth 31
2.11 Polymorphism of Fat 33
2.12 Response Surface Methodology (RSM) 33
2.12.1 Simultaneous optimization of response variables 36
2.13 Bread 36
2.13.1 Physical and structural changes in bread during baking 37
2.13.2 Chemical transformations in bread during baking 37
CHAPTER 3: MATERIALS AND METHODS
3.1 Materials 39
3.1.1 Allanblackia seeds. 39
3.1.2 Fluted pumpkins seeds 39
3.1.3 African walnut 39
3.1.4 Product control 39
3.1.5 Chemicals and reagents 39
3.2 Oil Extraction and Percentage Fat Content 40
3.2.1 Oil extraction (allanblackia, African walnut and
fluted pumpkin seed oils) 40
3.2.2 Percentage fat content 40
3.3 Oil Analysis (Physical Properties) 41
3.3.1 Density. 41
3.3.2 Refractive index 41
3.3.3 Slip melting point 42
3.3.4 Cloud point 42
3.3.5 Viscosity 42
3.3.6 Colour 43
3.3.7 Smoke point 43
3.4 Oil Analysis (Chemical Properties) 44
3.4.1 Iodine value 44
3.4.2 Free fatty acids 44
3.4.3 Saponification value 45
3.4.4 Peroxide value 45
3.4.5 Unsaponifiable matter 46
3.4.6 Ester value 47
3.5 Fatty Acid Profile 47
3.6 Oil Blending 48
3.7 Chemical Interesterification 48
3.8 Bakery Shortening Production 48
3.9 Physicochemical Properties of Bakery
Shortenings Formulated from Interesterified
Blends of Allanblackia, Fluted Pumpkin And
African Walnut Oils.
3.9.1 Physical properties of bakery shortenings 50
3.9.2 Solid fat content of bakery shortenings 50
3.0.3 Chemical properties of bakery shortenings. 50
3.10 Elemental Composition of Bakery Shortenings 50
3.11 Isothermal Crystallization Behaviour of
Bakery Shortenings 51
3.12 Microstructure Analysis of Bakery Shortenings
Using Scanning Electron Microscope (Sem) 51
3.13 Table (Spreadable) Margarine Production 51
3.14 Physicochemical Properties of Table Margarine 52
3.14.1 Refractive index (pv) of margarine 52
3.14.2 Slip melting point (smp) of Margarine 53
3.14.3 Viscosity of table Margarine 53
3.14.4 Iodine value of margarine 54
3.14.5 Free fatty acid (ffa) of margarine 54
3.14.6 Peroxide value (pv) of margarine 55
3.14.7 pH of margarine 55
3.15 Spreadability of Margarine 56
3.16 Consistency of Margarine 56
3.17 Sensory Evaluation of Table Margarine 57
3.18 Bread Production 57
3.19 Dough Proving Capacity 58
3.20 Physical Properties of Bread 58
3.20.1 Loaf weight and height 58
3.20.2 Loaf volume 58
3.20.3 Specific loaf volume 58
3.20.4 Loaf density 59
3.20.5 Loaf weight loss 59
3.20.6 Oven spring 59
3.20.7 Crumb moisture 59
3.21 Texture Profile Analysis of Bread 60
3.22 Bread Crumb Pore Size Characteristics 60
3.23 Sensory Evaluation of Bread 60
3.24 Changes in Physicochemical Properties of
Shortenings During Storage 61
3.25 Statistical Analysis 61
3.26 Experimental Design 61
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Percentage Oil Yield of Allanblackia, African
Walnut and Fluted Pumpkin Seeds Extracted
With Hexane, Ethanol and Hot Water Floatation. 64
4.2 Physical Properties of Allanblackia, African Walnut And
Fluted Pumpkin Seed Oils 65
4.3 Effect of Temperature on The Solid Fat of Allanblackia,
African Walnut and Fluted Pumpkin Seed Oils. 71
4.4 Chemical Properties of Allanblackia, African Walnut And
Fluted Pumpkin Seed Oils.
73
4.5 Fatty Acid Profile of Allanblackia, African Walnut And
Fluted Pumpkin Seed Oils. 79
4.6 Estimated Regression Coefficient and Fit Statistics For
Solid Fat Content of the Samples using Response Surface Methodology. 81
4.7 Effect of Processing Conditions on the Solid Fat
Content of the Samples 84
4.8 Estimated Regression Coefficient and Fit Statistics For
Smoke Point of The Samples 86
4.9 Effect of Processing Conditions on The Smoke Point Of
The Samples 89
4.10 Estimated Regression Coefficient and Fit Statistics For
Melting Point of the Samples 91
4.11 Effect of Processing Conditions on The Melting Point Of
Samples Using RSM. 94
4.12 Estimated Regression Coefficient and Fit Statistics For
Density of The Samples 95
4.13 Effect of Processing Conditions on The Density of the Samples 98
4.14. Estimated Regression Coefficient and Fit Statistics For
Viscosity f The Samples. 99
4.15: Estimated Regression Coefficient and Fit Statistics For
Iodine Value of The Samples. 101
4.16 Effect of Processing Conditions on The Iodine Value of the Samples. 103
4.17 Estimated Regression Coefficient and Fit Statistics for
Free Fatty Acid Value of the Samples 104
4.18 Set Goals and Constraints for Numerical Optimization
Of the Interesterification Variables and Responses,
Based on Response Surface Methodology. 106
4.19 Predicted Optimum Condition and Desirability Index For
The Samples using RSM 108
4.20 Validation of Optimization for The Interesterification Of
Samples using RSM. 111
4.21 Physicochemical Properties of Interesterified Blends Of
Allanblackia, African Walnut and Fluted Pumpkin Seed
Oils at Different Factor Combinations. 112
4.22 Physicochemical Properties of Table Margarine Produced
from Interesterified And Non- Interesterified Blends of Allanblackia,
African Walnut and Fluted Pumpkin Seed Oils. 115
4.23 Sensory Properties of Table Margarine Produced From
Interesterified And Non-Interesterified Blends of Allanblackia,
African Walnut and Fluted Pumpkin Seed Oils. 121
4.24 Physical Properties of Bakery Shortenings Produced
With Optimum Interesterified And Non- Interesterified
Allanblackia, African Walnut and Fluted Pumpkin Seed Oils. 124
4.25 Effect of Temperature on The Solid Fat Of Bakery
Shortening Produced from Interesterified And Non-Interesterified
Allanblackia, African Walnut And
Fluted Pumpkin Seed Oils. 128
4.26 Chemical Properties of Bakery Shortenings Produced
With Optimum Interesterified and Non-Interesterified
Allanblackia, African Walnut and Fluted Pumpkin Seed Oils. 131
4.27 Fatty Acid Profile of Bakery Shortenings Produced from
Interesterified And Non-Interesterified Allanblackia, African Walnut
And Fluted Pumpkin Seed Oils. 135
4.28 Elemental Content (Mg/Kg) Of Interesterified, Non- Interesterified
And Commercial Bakery Shortenings using Energy Dispersive X-Ray
Fluorescence Spectrometry. 138
4.29 Isothermal Crystallization Behaviour of Bakery
Shortenings Produced from Interesterified And
Non- Interesterified Allanblackia, African Walnut and
Fluted Pumpkin Seed Oil Blends. 140
4.30 Morphological Characteristics of Interesterified, Non-
Interesterified and Commercial Bakery Shortenings. 145
4.31 Proving Capacity of Dough Prepared with Interesterified,
Non-Interesterified and Commercial Bakery Shortening. 151
4.32 Physical Properties of Bread Produced from Interesterified,
Non-Interesterified and Commercial, Bakery Shortenings. 153
4.33 Texture Profile of Bread Produced from Interesterified,
Non-Interesterified And Commercial Bakery Shortenings. 158
4.34 Photo Images and Microstructure of Bread Crumb Produced
With Interesterified, Non-Interesterified And
Commercial Bakery Shortenings. 162
4.35 Sensory Properties of Bread Produced with Interesterified,
Non-Interesterified And Commercial Bakery Shortenings. 168
4.36 Changes in Physicochemical Properties of Bakery
Shortenings Produced from Interesterified and
Non-Interesterified Allanblackia, African Walnut
And Fluted Pumpkin Seed Oils During Storage. 171
CHAPTER 5: CONCLUSSION AND RECOMMENDATIONS
5.1 Conclusion 181
5.2 Recommendations 183
5.3. Contributions to Knowledge 184
References 185
Appendices 208
LIST OF TABLES
Page
3.1 CCD Design matrix for chemical interesterification of
Allanblackia, African walnut and fluted pumpkin seed oils 62
3.2 Experimental range and levels of the independent variables
for chemical interesterification 63
4.1 percentage (%) oil yield of Allanblackia, African walnut
and fluted pumpkin seeds 64
4.2 Physical properties of Allanblackia, African walnut and
fluted pumpkin seed oils 66
4.3 Chemical properties of allanblackia, African walnut and
fluted pumpkin seed oils 74
4.4 Fatty acid profile of Allanblackia, African walnut
and fluted pumpkin seed oils 79
4.5 Estimated regression coefficient for solid fat content (SFC)
of the samples using rsm 82
4.6 Estimated regression coefficient for smoke point of the samples using rsm 86
4.7 Estimated regression coefficient for melting point (MP) of the samples using rsm 92
4.8 Estimated regression coefficient for density (Dn) of the samples using rsm 96
4.9 Estimated regression coefficient for viscosity (Vs) of the samples using rsm 100
4.10 Estimated regression coefficient for iodine value of the samples using rsm 102
4.11 Estimated regression coefficient for percentage free fatty acid of
the samples using rsm 105
4.12 Set goals and constraints for numerical optimization of
variables and responses for the interesterification of Allanblackia,
African walnut and fluted pumpkin seed oils based on
response surface methodology 107
4.13 Predicted optimum condition and desirability index for the interesterification of Allanblackia, African walnut and fluted pumpkin
seed oils based on response surface methodology 109
4.14 Validation of optimization for the interesterification of Allanblackia, African walnut and fluted pumpkin seed oils based on response surface methodology 111
4.15 Physicochemical properties of interesterified blends of Allanblackia, African walnut and fluted pumpkin seed oils at different factor combinations 113
4.16 Physicochemical properties of table margarine produced from interesterified and non-interesterified blend
of Allanblackia, African walnut and fluted pumpkin seed oils 118
4.17 Sensory properties of table margarine produced from interesterified and non-interesterified blend of Allanblackia, African walnut and fluted pumpkin seed oils 122
4.18 Physical properties of bakery shortenings produced with optimum interesterified sample, non-interesterified sample and commercial shortening 126
4.19 Chemical properties of bakery shortenings produced with optimum interesterified and non- interesterified Allanblackia,
African walnut and fluted pumpkin seed oils. 132
4.20 Fatty acid profile of bakery shortenings produced with optimum interesterified and non- interesterified Allanblackia, African walnut
and fluted pumpkin seed oils. 136
4.21 Elemental content (mg/kg) of interesterified, non-interesterified and commercial bakery shortening using energy dispersive x-ray fluorescence spectrometry 139
4.22 Proving capacity (cm3) of dough prepared with interesterified,
non-interesterified and commercial bakery shortenings 152
4.23 Physical properties of bread produced from interesterified
and non-interesterified bakery shortening 155
4.24 Texture profile of bread produced from interesterified, non- interesterified and commercial bakery shortenings. 159
4.25 Sensory properties of bread produced from interesterified,
non-interesterified and commercial bakery shortenings 169
LIST OF FIGURES
Page
3.1 Flow diagram for bakery shortening production 49
4.1 Effect of temperature on the solid fat of Allanblackia,
African walnut and fluted pumpkin seed oils 72
4.2 Effect of interesterification time (x2) and catalyst
concentration (x3) on percentage solid fat content
of Allanblackia, African walnut and fluted pumpkin
seed oil blend. 84
4.3 Effect of interesterification temperature (x1) and time (x2)
on the smoke point of Allanblackia, African walnut and
fluted pumpkin seed oil blend 88
4.4 effect of interesterification temperature (x1) and catalyst
concentration (x3) on the smoke point of Allanblackia,
African walnut and fluted pumpkin seed oil blend 89
4.5 Effect of interesterification time (x2) and catalyst
concentration (x3) on the smoke point of Allanblackia,
African walnut and fluted pumpkin seed oil blend 90
4.6 Effect of interesterification temperature (x1) and time (x2)
on the melting point of Allanblackia, African walnut and
fluted pumpkin seed oil blend 94
4.7 Effect of interesterification time (x2) and catalyst
concentration (x3) on the density of Allanblackia,
African walnut and fluted pumpkin seed oil blend 98
4.8 Effect of interesterification temperature (x1) and time (x2)
on the iodine value (iv) of Allanblackia, African walnut
and fluted pumpkin seed oil blend 103
4.9 Effect of interesterification time (x2) and catalyst
concentration (x2) on the iodine value (IV) of Allanblackia,
African walnut and fluted pumpkin seed oil blend 104
4.10 Effect of temperature on the solid fat of bakery shortening produced from interesterified and non-interesterified Allanblackia,
African walnut and fluted pumpkin seed oils. 129
4.11 Isothermal crystallization behaviour of interesterified bakery
shortening at 5, 10, 15, 20, 25, 30 and 35 oc. 141
4.12 Isothermal crystallization behaviour of non-interesterified
bakery shortening at 5, 10, 15, 20, 25, 30 and 35 oc. 142
4.13 Isothermal crystallization behaviour of commercial bakery shortening (local) at 5, 10, 15, 20, 25, 30 and 35 oc. 143
4.14: Isothermal crystallization behaviour of imported commercial bakery shortening (imported) at 5, 10, 15, 20, 25, 30 and 35 oc. 144
4.15: Changes in solid fat content during storage at room temperature (28±20c) 172
4.16 Changes in slip melting point during storage at room temperature (28±2 oc) 173
4.17 Changes in smoke point during storage at room temperature (28±2 oc) 174
4.18 Changes in free fatty acid content during
storage at room temperature (28±2 oc) 175
4.19 Changes in peroxide value during storage at room temperature (28±2 oc) 176
4.20 Changes in iodine value during storage at room temperature (28±2 oc) 177
LIST OF PLATES
Page
2.1 Fruit, seeds and tree of Allanblackia floribunda 16
2.2 Fluted pumpkin fruit and seeds. 17
2.3 African walnuts 20
4.1 Table margarine produced from interesterified Allanblackia,
African walnut and fluted pumpkin seed oils 116
4.2 Table margarine produced from non-interesterified Allanblackia, African walnut and fluted pumpkin seed oils 117
4.3 Bakery shortenings produced from Allanblackia, African walnut and fluted pumpkin seed oil blends (interesterified
and non-interesterified) and the commercial bakery shortenings
(local and imported) 125
4.4 Microstructure of bakery shortening produced from interesterified Allanblackia, African walnut and fluted pumpkin seed oil blend 146
4.5 Microstructure of bakery shortening produced from
non-interesterified Allanblackia, African walnut and
fluted pumpkin seed oil blend 147
4.6 Microstructure of local commercial bakery shortening 148
4.7 Microstructure of imported commercial bakery shortening 149
4.8 Dough samples before proving 154
4.9 Dough samples after proving 154
4.10 Bread samples after baking 154
4.11 Photo image of bread crumb produced from interesterified bakery shortening. 163
4.12 Microstructure of bread crumb produced from interesterified
bakery shortening 163
4.13 Photo image of bread crumb produced from non-interesterified
bakery shortening. 164
4.14 Microstructure of bread crumb produced from non-interesterified bakery shortening 164
4.15 Photo image of bread crumb produced from local
commercial bakery shortening. 165
4.16 Microstructure of bread crumb produced from local
commercial bakery shortening. 165
4.17 Photo image of bread crumb produced from imported commercial bakery shortening. 166
4.18 Microstructure of bread crumb produced from imported commercial bakery shortening. 166
LIST OF EQUATIONS
Page
2.1 Fatty acid 11
3.1 Fat content 41
3.2 Density of oil 41
3.3 Refractometer reading 41
3.4 Kinematic viscosity 43
3.5 Iodine value 44
3.6 Free fatty acid 45
3.7 Saponification value 45
3.8 Peroxide value 46
3.9 Unsaponifiable matter 47
3.10 Ester value 47
3,11 Solid fat content 50
3.12 Refractive index 52
3.13 Viscosity 54
3.14 Iodine value 54
3.15 Free fatty acid 55
3.16 Peroxide value 55
3.17 Spreadability 56
3.18 Consistency 57
3.19 Specific loaf volume 58
3.20 Loaf density 59
3.21 Loaf weight loss 59
3.22 Crumb moisture 59
3.23 CCD regression model 62
4.1 Solid fat content regression model 83
4.2 Smoke point regression model 87
4.3 Melting point regression model 94
4.4 Density regression model 99
4.5 Viscosity regression model 104
4.6 Iodine value regression model 106
4.7 Free
fatty acid regression model
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APA
SAMUEL, B., & CHIBOR (2023). Modification And Optimization Of The Physicochemical Properties Of Allanblackia (Allanblackia floribunda), African Walnut (Tetracarpidium conophorum) And Fluted Pumpkin (Telfairia occidentalis) Seed Oil Blend In Bakery Shortening Production . Michael Okpara University of Agriculture. Retrieved June 7, 2026, from http://repository.mouau.edu.ng/works/modification-and-optimization-of-the-physicochemical-properties-of-allanblackia-allanblackia-floribunda-african-walnut-tetracarpidium-conophorum-and-fluted-pumpkin-telfairia-occidentalis-seed-oil-blend-in-bakery-shortening-production-7-2
MLA
SAMUEL, BARIWERE, and CHIBOR. "Modification And Optimization Of The Physicochemical Properties Of Allanblackia (Allanblackia floribunda), African Walnut (Tetracarpidium conophorum) And Fluted Pumpkin (Telfairia occidentalis) Seed Oil Blend In Bakery Shortening Production ." Michael Okpara University of Agriculture, 27 Jul. 2023, http://repository.mouau.edu.ng/works/modification-and-optimization-of-the-physicochemical-properties-of-allanblackia-allanblackia-floribunda-african-walnut-tetracarpidium-conophorum-and-fluted-pumpkin-telfairia-occidentalis-seed-oil-blend-in-bakery-shortening-production-7-2. Accessed June 7, 2026.
Chicago
SAMUEL, BARIWERE, and CHIBOR. "Modification And Optimization Of The Physicochemical Properties Of Allanblackia (Allanblackia floribunda), African Walnut (Tetracarpidium conophorum) And Fluted Pumpkin (Telfairia occidentalis) Seed Oil Blend In Bakery Shortening Production ." Michael Okpara University of Agriculture (2023). Accessed June 7, 2026. http://repository.mouau.edu.ng/works/modification-and-optimization-of-the-physicochemical-properties-of-allanblackia-allanblackia-floribunda-african-walnut-tetracarpidium-conophorum-and-fluted-pumpkin-telfairia-occidentalis-seed-oil-blend-in-bakery-shortening-production-7-2