Abstract
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 α-tocopherol, α-tocotrienol and γ-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 (362–567 mg/kg) and carotenoids (2.7–4.8 mg/kg) levels associated with higher lipophilic antioxidant activity (4.9–8.1 μmol 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.
•Grape seed oil content in bioactives varies considerably among grape cultivars.•Supercritical CO2 extracted oils exhibit high lipophilic antioxidant activity.•Vitamin E and carotenoids levels correlated with lipophilic antioxidant activity.•Phenolics and chlorophylls content not affected by the extraction method.