Antioxidants from winemaking wastes: A study on extraction parameters using response surface methodology

Abstract

Winemaking by-products present a high environmental impact due to their considerably high biochemical and chemical oxygen demands. This study is focused on the optimization of the traditional solvent extraction technology of phenols from Pinot Noir grape skins (Vitis vinifera). To such a purpose, the combined effects of the extraction time (9, 19 and 29h) and the solid-liquid ratio (0.10, 0.20 and 0.30g DW/mL), were investigated by a 3 2 full factorial design combined with response surface methodology; total polyphenols, flavonoids and trans-resveratrol extraction yields were used as response variables. Results demonstrated that Pinot Noir skins had high levels of both total polyphenols (3.22mg GAE/g DW) and flavonoids (1.01mg CE/g DW), being the optimum extraction time 19h approximately. t-resveratrol was found in a considerable amount (2.24mg/100g DW), while the main phenolic compounds analyzed with Reverse Phase-High Performance Liquid Chromatography were gallic acid, catechin and quercetin. A significant linear correlation was found between polyphenols concentration and their antiradical power. © 2011 Wiley Periodicals, Inc.