Biochemical characterization and antioxidant activity of grape (Vitis vinifera L.) seed oils from nine Tunisian varieties

An analytical study of the biochemical composition and antioxidant activity of grape seed oil from nine Tunisian varieties (Merlot, Syrah, Sangiovese, Muscat d'Alexandrie, Razagui, Razaki, Khamri, Marsaoui and Carignan) was conducted. Seed oil yields varied from 6.31% (Khamri) to 12.70% (Merlot). All studied oils were characterized by high proportions of polyunsaturated linoleic acid ranging from 64.77 (Merlot) to 75.37% (Muscat d'Alexandrie). Grape seed oils were also rich in unsaponifiable minor components with the predominance of sterol fraction ranging from 1609.87 (Khamri) to 3814.55 (Carignan) mg/kg oil. Muscat d'Alexandrie seed oil had the highest chelating and reducing abilities while the strongest antiradical activity was obtained in Carignan variety. Antiradical ability was positively correlated with oleic acid but negatively with polyphenols and tocopherols. Multivariate analysis joined Merlot, Carignan, Syrah and Sangiovese in one group, Razagui, Razaki and Marsaoui in a second group and the third group Khamri and Muscat d'Alexandrie. Practical applications Grape seeds are generally known as by-products coming from fruit processing industry. Grape seeds are the subject of many studies due to their richness in natural bioactive substances. The use of these natural bioactive substances has recently increased in food, cosmetic, and pharmaceutical products to replace synthetic antioxidants, which are being restricted because of their harmful health effects. This study aimed to characterize grape seed oils of nine Tunisian varieties through their fatty acids, phenols, sterols, tocopherols, triterpenoids, and antioxidant properties.