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 ß-sitosterol amount was detected in the green period of Saurani variety (91.66%), and the lowest ß-sitosterol amount in the spotted period of Halhali variety (86.16%). The highest ∆5-avenasterol amounts were detected in the ripe period of Saurani variety (6.54%), the lowest ∆5-avenasterol amounts were detected in the green period of Halhali variety (2.36%). Total ß-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.

Quality Properties, Fatty Acid and Sterol Compositions of East Mediterranean Region Olive Oils.

In this study, important physicochemical properties, fatty acid and sterol compositions of olive oils from the olives which harvested from Mersin (Buyuk Topak Ulak, Gemlik, Sari Ulak), Adana (Gemlik), Osmaniye (Gemlik) and Hatay (Gemlik, Kargaburun, Hasebi, Halhali) in the Eastern Mediterranean region of Turkey have been investigated. Ripening index and oil yield analysis of the olives and free fatty acids, peroxide value, UV absorbance (K232, K270), fatty acid composition, sterol composition, erythrodiol+uvaol content, and total sterol analysis of the olive oil samples were carried out. The levels of free acidity in the olive oil samples ranged from 0.39% (Hatay Gemlik: HG3) to 2.23% (Mersin Gemlik: MG). Peroxide value ranged from 8.87 to 18.87 meq O2/kg. As K232 values in the oils fluctuated between 1.4370 and 2.3970, K270 values varied between 0.1270 and 0.1990. The results showed that all ΔK values were lower than the maximum legal limit of 0.01. The main fatty acid in all oil samples was oleic acid, ranging from 58.72% (Hatay Hasebi: HHs) to 74.54% (Hatay Gemlik: HG2). Palmitic acid values were within the percentage of 12.83% (Hatay Kargaburun: HK) to 18.50% (HHs). Total sterol content varied from 720.41 mg/kg (Hatay Kargaburun: HK) to 4519.17 mg/kg (Buyuk Topak Ulak: BTU). The ß-sitosterol percentage of olive oils ranged from 76.12% (Adana Gemlik: AG) to 94.23% (Buyuk Topak Ulak: BTU). The results of this study indicated that variety significantly affect the quality indices, fatty acid and sterol compositions of olive oils significantly varied among varieties.

Physicochemical properties of cold pressed sunflower, peanut, rapeseed, mustard and olive oils grown in the Eastern Mediterranean region.

Fatty acid composition and stability of vegetable oils have taken more attention as an essential source of biologically active compounds in a good balanced diet. The purpose of the study was to determine peroxide value, free fatty acids, unsaponifiable matter, total carotenoid content, iodine value and fatty acid composition of sunflower, rapeseed, mustard, peanut and olive oils. Rapeseed and peanut oils had the highest peroxide values, while sunflower oil had the lowest peroxide values. The free fatty acid value of the tested oils varied between 0.43 and 1.36% oleic. The peanut oil had the highest free acid value and the mustard oil had the lowest one. Total carotenoid contents of mustard and rape seed oil were higher than those of the other oils tested. Palmitic acid (C16:0), oleic acid (C18:1) and stearic acid (C18:0) were the common main fatty acid components of the vegetable oils tested. Followed by linoleic acid, the amount of oleic acid was the highest among other fatty acid components. Mustard oil had the highest erucic acid (C22:1) with the amount of 11.38%, indicating that it cannot be used for human consumption. Among the oils investigated, sunflower and mustard oils were more stable than rapeseed, peanut and olive oils.

Antioxidant activity, sterol and fatty acid compositions of Turkish olive oils as an indicator of variety and ripening degree.

This study was carried out to determine the effect of three ripening stages (green, spotted and ripe) on fatty acid, sterol composition and antioxidant activity of olive oils from three olive varieties (Sari Hasebi, Gemlik and Halhali) widely grown in the eastern Mediterranean region of Turkey. The variety had a significant effect on the fatty acids, sterols and total phenolic content. Halhali oil had the lowest oleic acid content (67.28%), while Sari Hasebi oil had the highest (75.61%). Total phenolic content varied between 163.02 mg GAE/kg oil and 749.28 mg GAE/kg oil. Halhali oil showed the highest antioxidant activity (IC50 = 66 µg/ml) whereas Sari Hasebi oil showed the lowest one (IC50 = 2617 µg/ml). The total content of sterols in olive oils ranged from 358 mg/kg in Sari Hasebi to 1092.33 mg/kg in Halhali. The ß-sitosterol content of olive oils varied between 80.72 (Sari Hasebi) and 87.81% (Halhali). ∆-5-avenasterol content ranged between 3.34 (Halhali) and 7.30% (Gemlik). Variety and ripening degree significantly affected the ß-sitosterol, ∆-5-avenasterol and erythrodiol + uvaol contents of oils. Finally, these results showed that sterol and fatty acid compositions can be used as indicators of variety and ripening degree among virgin olive oils.