Bioactive compounds and antioxidant activities of different grape (Vitis vinifera L.) seed oils extracted by supercritical CO2 and organic solvent

This study evaluates and compares the composition in bioactives and the antioxidant activity of six different grape seed oils. In addition, the comparison also concerns two different techniques, namely supercritical carbon dioxide (SC-CO2) extraction and conventional solvent extraction (Soxhlet method with n-hexane as solvent). Tocopherols, tocotrienols, chlorophylls, carotenoids and total phenol contents, as well as lipophilic and hydrophilic antioxidant activities were quantified. Significant differences were noticed among grape cultivars for all the studied bioactives, as well as in the antioxidant activities. As a whole, results demonstrate that grape seed oil is a good source of tocols, and in particular of atocopherol, a-tocotrienol and g-tocotrienol. These three forms constitute between 72.4 and 80.4%, and between 78.5 and 85.1% of the total tocol contents of oils extracted by n-hexane and SC-CO2, respectively. Statistical analysis showed that SC-CO2 extraction allowed for higher total tocols (362e567 mg/kg) and carotenoids (2.7e4.8 mg/kg) levels associated with higher lipophilic antioxidant activity (4.9e8.1 mmol trolox/g oil), in comparison with the extraction with n-hexane. Conversely, total phenolic content, chlorophylls content and hydrophilic antioxidant activity were not affected by the extraction method. Finally, correlations between bioactive lipophilic components and the lipophilic antioxidant activity were established and discussed.