Fatty Acid and Sterol Compositions of Turkish Monovarietal Olive Oils with Regard to Olive Ripening

This study was conducted in crop season of 2018 and the olive fruits from three Turkish varieties Saurani, Karamani and Halhali under the same pedoclimatic conditions (with no irrigation and no fertilization) were assessed. Oil content, fatty acid, and sterol compositions of three monovarietal 'Halhali', 'Karamani', and 'Saurani' virgin olive oils were examined at green, spotted and ripe olives. The oil content of olives ranges between 23.77-34.77% and the highest oil yield was observed in the ripe Karamani variety. In terms of fatty acids, the lowest oleic acid values were found in the ripe period of Karamani variety (59.78%), and the highest oleic acid values in the green period of Halhali variety (69.97%). The oleic and palmitic acid contents decreased, while linoleic and stearic acid contents increased with olive ripening. Total sterol amounts of olive oils varied between 946-1782 mg/kg and showed a significant increase with ripening (p < 0.05). The highest beta-sitosterol amount was detected in the green period of Saurani variety (91.66%), and the lowest beta-sitosterol amount in the spotted period of Halhali variety (86.16% ). The highest increment 5-avenasterol amounts were detected in the ripe period of Saurani variety (6.54%), the lowest increment 5-avenasterol amounts were detected in the green period of Halhali variety (2.36%). Total beta-sitosterol, stigmasterol and erythrodiol+uvaol contents of olive oils are changed with ripening. Accordingly, these results showed that fatty acid and sterol compositions can be used as indicators of variety and ripening degree among monovarietal virgin olive oils.