Ultra- and nanofiltration of aqueous extracts from distilled fermented grape pomace

Aqueous extracts from pressed distilled grape pomace were processed using ultrafiltration (UF) and nanofiltration (NF) membranes to obtain fractions enriched in compounds with antioxidant activity. The properties of concentrates (composition, phenolic content and antioxidant activity) were determined for different commercial UF and NF membranes as a function of the volume reduction factor. Membrane concentrates obtained under selected conditions were extracted with ethyl acetate to yield fractions with enhanced antioxidant activity. The radical scavenging capacities of ethyl acetate extracts were in the range reported for synthetic antioxidants. Cleaning resulted in the recovery of 92–100% of the initial permeability.