Physico-chemical characterization of bitter apple (Citrullus colosynthis) seed oil and seed residue

Abstract

This reach work was carried out for the characterization of Citrullus colocynthis seed oil and seed residue as an important aspect of nonconventional oils because most of the applications based on their physico-chemical characteristics. Seed oil was extracted using soxhelt extraction assembly with n-hexane and subjected to physicochemical characterization. The proximate analysis showed that the Citrullus colocynthis seed contained 28.50% oil, 6.43% moisture, 13.99% crude protein, 2.23% ash and 46.73% crude fiber. The seed residue was found to be a good sources of minerals containing calcium (130.78 ppm) followed by potassium (123.21 ppm) magnesium (89.53 ppm), Iron (43.32 ppm), zinc (10.05 ppm), and manganese (0.513 ppm). The oil was liquid at room temperature with physico-chemical characteristics like free fatty acid, 1.09 (% as oleic acid); iodine value, 119.53 (g I2/100g); acid value, 3.91(mg KOH/g of oil); totox value, 15.83; saponification value, 196.66%; unsaponifiable matter, 1.44 %; refractive index (20 ˚C), 1.4873; viscosity, 37.9 (cP); and color (1-in. cell) 10R + 70.7Y. The oils revealed a good oxidative stability as indicated by the determinations of p-anisidine value, 1.85, and peroxide value, 6.97 (meq O2/100g). The oil was found to contain high levels of unsaturated fatty acids, especially C 18:2 (54.70%) and C 18:1 (33.66%). The contents of tocopherols (α and δ) in the oil were 1.90 and 0.32 g/100g, respectively. The results of the present study demonstrated that the seeds oil and seed residue of Citrullus colocynthis is a potential source of valuable oil which might be utilized for functional as well as medicinal applications.