Comprehensive Evaluation of the Relationships Between Grape Skin Color/Ripening Time and Antioxidative Capacity, Some Phytochemicals, and Fatty Acid Compositions of Their Seeds

It has been proven that grapes, which are widely cultivated around the world, have positive health effects. However, the phytochemical composition of lesser-known local varieties of Vitis vinifera L., which has a very wide range of varieties, is still being studied. The aim of this study was to determine the effects of skin color and ripening time on the phytochemical compositions of grape seeds. As a plant material local grape varieties cultivated in Southeastern Anatolia (Turkey) were used. The results showed that grape skin color has an effect on vitamin K1, vitamin K2, vitamin D3, δ‑tocopherol, stigmasterol, ergosterol, myristic acid, oleic acid, trans-elaidic acid, and the monounsaturated fatty acid (MUFA) and saturated fatty acid (SFA) contents of seeds. The seeds of grape varieties with colored skins were richer in K2, D3, stigmasterol, oleic acid, trans-elaidic acid, and MUFAs, while the seeds of grape varieties with white skins were richer in K1, δ‑tocopherol, ergosterol, and SFAs. The ripening time of the grapes was found to have a partial effect on the fatty acid compositions of the seeds, but without any effect on linoleic acid contents. As the ripening time was delayed, there was an increase in oleic acid and MUFA contents of the seeds, while there was a decrease in SFA contents. In general, increased vitamin K1 contents of the seeds were parallel to decreases in vitamins K2, D2, and D3, as well as α‑tocopherol content and antioxidant activity. The seeds of grape varieties that have colored skins were found to have more suitable compound compositions for use in the production of functional foods that support human and animal health. In addition, it was concluded that grape berries that ripen late may be more favorable for grapeseed oil production.