Extraction of oil from grape seeds (Vitis vinifera L.) using recyclable CO2-expanded ethanol

A novel green solvent, CO2-expanded ethanol (CXE), was employed to extract oil from grape seeds, which is one of the main by-products generated by the grape-processing industry. The optimum extraction conditions were obtained by response surface methodology (RSM) coupled with Box-Behnken design (BBD): a pressure of 7.4 MPa, a temperature of 314 K and a CO2 mole fraction of 0.3. The highest oil yield of 13.6 % by CXE extraction was equivalent to or even higher than that obtained with conventional methods, including organic solvent and supercritical CO2 extraction. In terms of reducing solvent consumption and extraction time, the CXE-based process was superior than the conventional methods. CXE oil contained 87.5 % total unsaturated fatty acids, especially linoleic acid was up to 75.5 %, presenting a higher antioxidant capacity.