Comparative Study of the Physicochemical Properties of Vegetable Oil from Irvigna gabonesis and Citrullus colocynthis Dried Seeds Samples

Abstract

Aim: Extraction and analysis of the physicochemical properties of vegetable oil from Irvigna gabonesis and Citrullus colocynthis were carried out to predict possible applications. Study Design:  It was designed to extract oil from the seeds and investigate the properties to indicate their performance and potentials in industrial applications. Place and Duration of the Study: Department of Biochemistry, Ebonyi State University, Abakaliki, Ebonyi State, Nigeria, between October and December, 2012. Methodology: Fresh seeds were collected, dried and ground to smaller particle size. Soxhlet apparatus method was used in extraction with petroleum ether (40-60ºC) while standard official methods were employed in the analysis. Results: The result revealed that both were oil seeds yielding Irvigna gabonesis 36.43±2.60% and Citrullus colocynthis 28.03±1.20% oil. Physicochemical properties of the oil showed that the total fatty matter in both samples were very high at about 98%. The refractive index was 1.46 and 1.43 for Citrullus colocynthis and Irvigna gabonesis respectively. The acid values of 2.02 and 20.2mgKOH/g were respectively low and high in Citrullus colocynthis and Irvigna gabonesis. The free fatty acid content of 6.97% in Irvigna gabonesis was higher than 2.15% in Citrullus colocynthis. Consequently, the peroxide value of 1.20meq/g was also higher in Irvigna gabonesis than the low amount of 0.45meq/g in Colocynthus. The iodine value of 7.90±1.00 Wij’s was low in Irvigna gabonesis compared to 114.30±1.06 Wij’s in Citrullus colocynthis. The saponification values of 208.10 and 202.90mgKOH/g were high. Conclusion: Irvigna gabonesis oil had high acid value, free fatty acids and peroxide value compared to Citrullus colocynthis. The low iodine number of the Irvigna gabonesis oil indicates high degree of saturation while the high level of iodine value in Citrullus colocynthis was indicative of high unsaturation. The saponification values showed presence of saponifiable lipids. The oils can be useful in nutrition and manufacturing industry.