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

•Two-step SC-CO2 extraction for polyphenols TPC and proanthocyanidins FI, FII, FIII.•P, CO2 flow rate, % co-solvent studied by Box-Behnken design on the second step.•Optimum extraction conditions: 80 bar, 6 kg/h CO2 flow rate, 20% co-solvent.•7132 mg GAE/100 g DM value of TPC achieved in validation experimental.•Kinetic study of TPC carried out.

Polyphenol extraction from white grape seeds using supercritical carbon dioxide (SC-CO2) containing 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), CO2 flow rate (2, 4 and 6 kg/h) and co-solvent percentages (10, 15, and 20% (w/w)). Total polyphenols (TPC) and fractionation of proanthocyanidins were determined.The statistically generated optimum extraction conditions to obtain the highest total polyphenol concentration were a pressure of 80 bar, CO2 flow rate of 6 kg/h and 20% (w/w) co-solvent. The value achieved in validation experimental was 7132 mg GAE/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.

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