Extraction of proanthocyanidins from grape marc by supercritical fluid extraction using CO2 as solvent and ethanol–water mixture as co-solvent

Abstract

The extraction of phenolic compounds from grape marc using supercritical CO2 containing 15% ethanol–water mixture (57%, v/v) (EtW) as co-solvent, at 8, 10, 20 and 30MPa/313.15K suggested 8MPa as the most suitable pressure. At 8MPa/313.15K, different co-solvent percentages (15, 10, 7.5%) at CO2 flow rate of 6 and 4kg/h were investigated for proanthocyanidins (PAs) the extraction. The highest extraction yields were obtained at 4kg/h CO2–7.5% EtW flow rate (2600 mgGAE 100 gDM−1) and 6kg/h CO2–10% EtW (2527 mgGAE 100 gDM−1). At 6kg/h CO2–10% EtW flow rate the amounts of monomeric (188 mgcatechin 100 gDM−1) and oligomeric (154 mgcatechin 100 gDM−1) fractions of PAs, as well as their antioxidant activity (809 and 546 mgα-tocopheroll 100 gDM−1) were higher than at 4kg/h CO2–7.5% EtW-flow rate. SC-CO2 methods were compared with conventional methanol extraction.