Chemical evaluation of citrus seeds, an agro-industrial waste, as a new potential source of vegetable oils

The seed oils from seven Turkish and ten Vietnamese varieties of Citrus fruits were examined for their fatty acid composition, tocopherols and sterol contents. The oil contents of the samples varied between 32.1 g/100 g and 58.8 g/100 g. The major fatty acid of the extracted seed oils was oleic (12.8-70.1%), followed by linoleic (19.5-58.8%) and palmitic (5.1-28.3%). Stearic, vaccenic, linolenic and arachidic acids were found at low levels. The total content of vitamin E active compounds in the oils ranged between 0.8 and 21.0 mg/100 g. The predominant isomers were alpha- and gamma-tocopherol, with approximate equal amounts between about 0.4 and 17.5 mg/100 g. The total sterol contents of the oils were found between 1310.54 and 3986.58 mg/kg, with beta-sitosterol as the predominant sterol that accounted for more than 70% of the total amount of sterols. Other sterols, campesterol (8.03-15.26%), stigmasterol (2.55-7.69%), Delta 5-avenasterol (1.80-5.67%), cholesterol (0.83-2.70%) and chlerosterol (0.93-1.78%) were detected in most of the oils. The results of the present study indicate that the seed oils of Citrus fruits are considered to be a potential oil source due to their fatty acid composition and important tocopherol and sterol, and might be used for edible applications as well as the production of potential value-added products.