Supercritical antisolvent extraction of antioxidants from grape seeds after vinification

The objective of this study is the extraction and concentration of antioxidants (catechin, epicatechin, gallic acid and resveratrol) from grape seeds vinification wastes using supercritical antisolvent extraction (SAE). The grape seeds (Vitis vinifera, Syrah variety) were defatted, and, then extracted with ethanol. The antioxidants extracted in the resulting solution were concentrated using the SAE technique, in which supercritical CO2 is used to precipitate selected, non soluble compounds. Several experiments were carried out using pressures ranging from 8 to 15 MPa and temperatures ranging from 35 to 60 °C. The content of the antioxidants in the different extracts was determined using high performance liquid chromatography (HPLC). The determination of the total polyphenols content (TPC) by the method of Folin-Ciocalteau was also accomplished. Operating at 15 MPa and 40 °C, the extracts after SAE processing were enriched in antioxidants of more than 150% with respect to the starting extracts.