Extraction and qualitative assessment of African sweet orange seed oil

Abstract

The African sweet orange fruit Citrus Sinensis seeds were obtained from discards of fruits and prepared for use by decoating, sun drying and grinding. By solvent extraction using petroleum ether, a golden yellow coloured oil was obtained and characterized by determining the pH, refractive index, density, solvent miscibility, congealing temperature, flame nature, specific gravity, retention factor on chromatographic plate, heat of combustion, smoke point, flash point, fire point, and the percentage yield. In addition, the spectroscopic analysis was carried out using Genesis FTIR spectrophotometer. The free fatty acid, unsaponifiable matter, saponification, iodine, acid and peroxide values were determined according to the standard method of analysis. Oil yield of 36 % was obtained. The results show a high degree of unsaturation, presence of reasonable amount of free fatty acids, marked level of oiliness, refractive index (1.47 at 25 C), high level of acid value 82 % (0.82)—with the presence of palmitic, stearic, oleic acid, traces of linoleic acid—and interestingly, absence of linolenic, myristic and arachidic acids. The solvent miscibility of the oil was determined by physical observation of the uniform blending of oil sample in acid (HCl), alkali (NaOH), sodium hydrogen carbonate solution, carbonate solution, ether and water at room temperature, 40 o C, 60 o