Antioxidant activity of grape bagasse extracts from Regente and Pinot Noir varieties (Vitis vinifera)

Abstract

Grape (Vitis vinifera) bagasse from Pinot Noir and Regente varieties, collected in Videira - Santa Catarina, were evaluated in order to determine the total polyphenol contents and antioxidant capacity. Acidified (HCl 0.1%) aqueous solvent systems of 50% (v/v) methanol, ethanol, and acetone were used. Total polyphenol contents were determined by Folin-Ciocalteu technique, and antioxidant activity was assessed by means of ABTS, DPPH, and β-carotene/linoleic acid techniques. Acetone presented the highest total polyphenol contents, reaching in a dry matter the concentrations of 7.852mg GAE/100g in Pinot Noir variety and 5.334mg GAE/100g in Regente variety. The average antioxidant activity of Pinot Noir and Regente varieties was of 477 and 419μMol TEAC/g by means of ABTS technique, respectively, and 480 and 479μMol TEAC/g, respectively when these samples were analyzed by DPPH technique. From β-carotene/linoleic acid technique analysis, it was observed that the ethanolic extracts showed higher synergism when associated to BHT, presenting 92.6% and 90.9% of oxidation inhibition with 200μL for Regente and Pinot Noir varieties, which were similar to BHT with 200μL, presenting 91.7% of oxidation inhibition. Extracts from grape bagasse demonstrated a potential antioxidant activity, functioning as inhibitors of free-radicals, or in synergism with a synthetic antioxidant.