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 29 h) and the solid-liquid ratio (0.10, 0.20 and 0.30 gDW/mL), were investigated by a 32 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 (3.22 mgGAE/gDW) and flavonoids (1.01 mgCE/gDW), being the optimum extraction time 19 h approximately. t-resveratrol was found in a considerable amount (2.24 mg/100 gDW), 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. PRACTICAL APPLICATIONS Winery by-products (grape marc) are a possible font of antioxidants and their extracts can represent a significant economic and social benefit. The research of the efficient methods for phenolics compound extraction is one of great interest. Collected experimental data could be used in further studies as a comparison with those of other innovative technologies, such as supercritical fluid, ultrasound and/or microwave-assisted extraction.
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