Supercritical fluid extraction of grape seed (Vitis vinifera L.) oil. Effect of the operating conditions upon oil composition and antioxidant capacity

In this work, the supercritical fluid extraction of grape seed oil has been studied at 180,200 and 220 bar, and 313.15 and 323.15K to analyse their influence upon oil quality. The extraction curves exhibit an initial linear extraction period followed by a smooth asymptotic plateau at 11.5%. The extraction rate increases with increasing pressure and decreasing temperature, due to the influence of pressure and temperature upon the oil solubility; the convective mass transfer coefficient played a minor role on the process. The triacylglycerides content and the fatty acids profile have been determined, being roughly unaffected by the operating conditions adopted. The antioxidant activity of the oil has been assessed by the DPPH center dot spectrophotometric method, and showed to increase with pressure and noticeably with temperature. Along extraction curves, the antioxidant activity is more pronounced on the oil collected during the first stages of the process, where 35-40% of total oil is extracted. (c) 2010 Elsevier B.V. All rights reserved.