Effect of extraction solvent, waste fraction and grape variety on the antimicrobial and antioxidant activities of extracts from wine residue from cool climate

Wine residue (seeds, skin and pomace) from New Zealand were subjected to extraction process using three different solvents [50% aqueous acetone (Ace/w), 50% aqueous ethanol (Eth/w) or 50% aqueous methanol (Meth/w)] in order to study the effect of extraction solvent, fraction and variety on the phenolic profile, antioxidant and antimicrobial activity of the obtained extracts. Ace/w extracts resulted in the highest antioxidant activities (P < 0.05) of the extracts compared to other solvents. Extracts from Pinot noir (PN) were more effective against Staphylococcus aureus and Candida albicans than extracts from Pinot meunier, PM, (P < 0.05). Mixed effects were found for the extraction solvent and the residue fraction on the antimicrobial activities. Compounds that exhibited the highest antimicrobial activity are those reported in literature to be of low or modest antioxidant activity.