Supercritical fluid extraction of polyphenols from grape seed (Vitis vinifera): Study on process variables and kinetics

Polyphenol extraction from white grape seeds using supercritical carbon dioxide (SC-CO2) contain-ing different percentages of ethanol-water mixture (57% v/v) as co-solvent was carried out at 40◦C.Box–Behnken experimental design was used to optimize the process variables: pressure (80, 100,120 bar), CO2flow rate (2, 4 and 6 kg/h) and co-solvent percentages (10, 15, and 20% (w/w)). Total polyphe-nols (TPC) and fractionation of proanthocyanidins were determined.The statistically generated optimumextraction conditions to obtain the highest total polyphenol concentration were a pressure of 80 bar, CO2flow rate of 6 kg/h and 20% (w/w) co-solvent. The value achieved in validation experimental was 7132 mgGAE/100 g DM. Under these operating conditions a good extraction of FI (>1000 mg catechin/100 g DM)and FII (>800 mg catechin/100 g DM) are obtained