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.