Comparative Determination of Anthocyanins, Low Molecular Weight Phenols, and Flavanol Fractions in Vitis vinifera L. cv Carmenere Skins and Seeds by Differential Solvent Extraction and High-Performance Liquid Chromatography

Although numerous methods have been used to extract polyphenols from vegetal sources, these procedures have been rarely compared directly. Herein, four maceration and extraction methods for phenolics from Carmenere (Vitis vinifera L.) skins and seeds are evaluated. Polyphenols were extracted with mixtures of 4: 1 (v/v) methanol: water, 4: 1 (v/v) acetone: water, 4: 1 (v/v) methanol: water, 4: 1 (v/v) acetone: water, and 1: 9 (v/v) ethanol: water. The extracts were characterized by spectrophotometry for tannins, anthocyanins, total phenols, and color; proanthocyanidin fractionation for monomers, oligomers, and polymers; and high-performance liquid chromatography for anthocyanins and low molecular weight phenols. Seed and skin extracts in methanol/water provided higher polyphenol concentrations compared to the use of acetone/water. Seeds and skins macerated in ethanol/water showed lower concentrations in most polyphenols while seeds and skins that were consecutively macerated in methanol/water and acetone/water showed the highest concentrations of most compounds. In conclusion, solvent polarity, extraction time, and vegetal matrix affected the polyphenol composition of grape seed and skin extracts.