The fractionation of red wine grape pomace (RWGP) by subcritical water (SBW) extraction/hydrolysis was studied in a semi-continuous reactor. Different temperature programs were used, comprising ramps and plateaus at different temperatures, with different time lengths. Pressure was kept constant at 100 bar. A program applied to previously defatted RWGP (def-RWGP) featuring plateaus at 50, 100 and 190 °C allowed the recovery of virtually all of the hemicellulose, while leaving in the residue essentially all of the lignin and the cellulose. The latter was readily hydrolyzed enzymatically. When using whole RWGP, it was shown that over 85 % of the lipids remained in the residue. The RWGP extracts had contents of phenolic compounds up to 29 g/100 gextract, and were rich in hemicellulose-derived carbohydrates, mostly in the form of oligomers. The extracts exhibited an antioxidant capacity that compared favorably with that of gallic acid.
- Red wine grape pomace
- Subcritical water