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

•CO2 flow rates modified with 15% EtOH-W (57%, v/v).•Effect of pressure on phenols extraction studied at 8–30 MPa/313.15 K.•Effect of co-solvent percentage studied at 7.5, 10 and 15%.•High phenols yield and antioxidant activity at low co-solvent percentage.•High selectivity for proanthocyanidins fractions at 6 kg/h CO2–10% EtOH-W.

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 30 MPa/313.15 K suggested 8 MPa as the most suitable pressure. At 8 MPa/313.15 K, different co-solvent percentages (15, 10, 7.5%) at CO2 flow rate of 6 and 4 kg/h were investigated for proanthocyanidins (PAs) the extraction. The highest extraction yields were obtained at 4 kg/h CO2–7.5% EtW flow rate (2600 mgGAE 100 gDM−1) and 6 kg/h CO2–10% EtW (2527 mgGAE 100 gDM−1). At 6 kg/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 4 kg/h CO2–7.5% EtW-flow rate. SC-CO2 methods were compared with conventional methanol extraction.

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