Evaluation of the antiradical and antioxidant potential of grape extracts

Grape seed and bagasse extract obtained from Narince grape cultivar using different solvent mixtures were assayed for their antioxidant properties. Total phenolic contents of the extracts were determined by the Folin-Ciocalteu method. Antioxidant activities of the extracts at different concentrations were evaluated using the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, hydrogen peroxide scavenging and phosphomolybdenum methods. Also the extracts, as natural antioxidants, were assayed during eight weeks storage of refined poppy oil at 70 degrees C. For this reason peroxide value was used as a criterion to assess the antioxidant activity of grape extracts. The grape seed extracts showed strong antioxidant activity, by measuring their capacity to scavenge DPPH and hydrogen peroxide; to reduce Mo(VI) to Mo (V) and to decrease in the rate of peroxide formation, when compared to bagasse extract. Antioxidant activities of the extracts increased when the extract concentration increased. (c) 2006 Elsevier Ltd. All rights reserved.