Evaluation of antibacterial and antioxidant properties of red (cv Negramaro) and white (cv Fiano) grape pomace extracts.

Grape pomace has attracted the attention of industry, due to its high content in bioactive compounds, and its healthy activities (1-3). In this work, whole and skin pomace from fermented (red) and un-fermented (white) grape by-products were characterized for antioxidant and antimicrobial activities. Antioxidant activity was higher in whole than in skin pomace extracts. The characterization of phenolic composition confirmed the peculiarity of some compounds such as anthocyanins (107.84 ± 10.3 mg/g Total Phenols, TP) in red skin pomace and flavanols (80.73 ±4.04 mg/g TP) in white skin pomace. Fiano and Negroamaro whole and skin pomace extracts were assayed against three pathogenic bacteria. The growth of Staphylococcus aureus DSM 799 and Enterococcus faecalis ATCC 47077 was inhibited by these extracts up to 250 ?g gallic acid equivalents (GAE)/mL whereas Pseudomonas aeruginosa DSM 939 was found to be resistant. The skin pomace extract of cv Fiano showed the lowest Minimum Inhibitory Concentration at 31.25 GAE/mL against Enterococcus faecalis ATCC 47077. Results suggest that differences in antioxidant and antimicrobial activities of different extracts could be ascribed to different phenolic profile (4). Given these results, both red and white pomace extracts could be exploited for future application in food, pharmaceutical and cosmetic industry.