ABSTRACT
The research titled extraction and characterization of watermelon seed oil was carried to investigate the effect that different drying methods, solvents and seed size would have on the quality and quantity of oil from watermelon (Citrilus lanatus) seeds. The watermelon seeds were removed from the pod and washed. The sample was weighed and divided into two equal parts; one part was subjected to sun drying while the other part was subjected to oven drying (at a temperature of 30 oC). Drying by sun as expected was gradual as compared to the oven drying method which was faster and more rapid. The dried seeds (sun-dried or oven-dried) were de-husked, dry-milled into fine crumbs using hand milling machine. The powdered product from the mill was then subjected to oil extraction using hexane and petroleum ether as solvent. Proximate and physico-chemical analysis of water melon seeds were carried out. The results showed that the seeds contained 5.15 ± 0.03 % moisture, 4.90 ± 0.14 % ash, 50.48 ± 0.05 % fat, 32.38 ± 0.02 % protein, 6.10 ± 0.02 % crude fibre and 6.35 ± 0.12 % nitrogen free extract. Physico-chemical characteristics showed that the pale yellow oil had a specific gravity of 0.860 ± 0.003 and a refractive index of 1.471. Saponification value was 184.29 - 187.09 mgKOH/g (for both drying methods). Iodine value was 103.04 – 115.12 mgIodine/g (for both drying methods). Acid value was 10.4 – 12.8 mgKOH/g and free fatty acid was 5.2 – 6.4 mgKOH/g (for both drying methods). The peroxide value was 18.74 meq peroxide/g. The water melon seed can thus be considered a good source of protein with high nutritional value. Many of the physicochemical properties of the seed oil studied compared favourably with other conventional seed oils such as soyabean, cowpea, groundnut etc. The watermelon seed oil therefore has potential for use as domestic and industrial oil.
TABLE OF CONTENTS
Content page
Title Page i
Declaration ii
Certification iii
Acknowledgement iv
Abstract v
Table of Content vi
List of Tables xi
List of Figures xi
List of Plates xi
CHAPTER ONE
1.0 INTRODUCTION 1
1.1 Aims and Objectives 3
1.2 Scope of the Study 3
1.3 Problem Statement 4
1.4 Justification of the Study 4
CHAPTER TWO
2.0 LITERATURE REVIEW 6
2.1 Watermelon Seed Background 6
2.2 Oil 7
2.2.1 Fatty Acids 7
2.2.2 Tocopherols 7
2.2.3 Oxidative Stability 8
2.2.4 Refining 9
2.2.4.1 Degumming 11
2.2.4.2 Caustic Neutralization 12
2.2.4.3 Bleaching 12
2.2.4.4 Deodorization Process 13
2.2.5 General Features of Glycerides Structure in Natural Fats 14
2.3 Nutritional Benefits of Watermelon Seed Oil 15
2.3.1 Application of Watermelon Seed Oil 16
2.3.2 Health Benefits of Watermelon 18
2.4 Leaching 18
2.4.1 Methods of Extraction 19
2.4.1.1 Supercritical Fluid Extraction 19
2.4.1.2 Solvent Extraction 20
2.4.1.3 Mechanical Pressing Extraction 21
2.4.2 Factors Influencing the Rate of Extraction 21
2.4.2.1 Particle Size 21
2.4.2.2 Solvent 22
2.4.2.3 Temperature 22
2.4.2.4 Agitation of Fluid 22
2.4.3 Choice of Solvent 23
2.4.3.1 Selectivity 23
2.4.3.2 Recoverability 23
2.4.3.3 Volatility 23
2.4.3.4 Purity 23
2.4.3.5 Solubility 23
2.4.3.6 Inflammability 24
2.4.3.7 Safety 24
2.5 Physico-Chemical Properties of Oil 24
2.5.1 Acid Value (Free Fatty Acid) 24
2.5.2 Saponification Value 25
2.5.3 Iodine Value 25
2.5.4 Peroxide Value 26
2.5.5 Refractive Index 26
2.5.6 Specific Gravity 27
2.5.7 Viscosity 27
2.6 Proximate Analysis of Oil Bearing Seeds 27
2.6.1 Moisture Content 27
2.6.2 Crude Fiber 28
2.6.3 Ash Content 29
2.6.4 Nitrogen Free Extract 29
2.6.5 Crude Protein 30
2.6.6 Oil Content 30
CHAPTER THREE
3.0 MATERIALS AND METHOD 32
3.1 SAMPLE PREPARATION ANALYSIS 32
3.1.1 Crushing and Grinding 32
3.1.2 Sieving 32
3.1.3 Drying 33
3.1.4 Materials and Apparatus 33
3.1.5 Reagents 34
3.2 Proximate Analysis 34
3.2.1 Oil Content 34
3.2.2 Moisture Content 35
3.2.3 Crude Fiber 36
3.2.4 Ash Content 37
3.2.5 Nitrogen Free Extract 38
3.2.6 Crude Protein 39
3.3 Physico – Chemical Properties of Watermelon Seed Oil 39
3.3.1 pH 39
3.3.2 Refractive Index 40
3.3.3 Viscosity 40
3.3.4 Specific Gravity 40
3.3.5 Acid Value (Free Fatty Acids) 41
3.3.6 Saponification Value 41
3.3.7 Peroxide Value 42
3.3.8 Ester Value 43
3.3.9 Iodine Value 43
CHAPTER FOUR
4.0 RESULTS AND DISCUSSION 45
4.1 Results 45
4.2 Discussion of Results 50
CHAPTER FIVE
5.0 Conclusion and Recommendation 56
5.1 Conclusion 56
5.2 Recommendation 57
REFERENCES 58
APPENDICES 64