Recovery of phenolic compounds fromgrape seeds: effect of extraction timeand solid–liquid ratio

The aim of this research was to study the recovery of phenolic compounds from grape seeds, by-products from winemaking industries, using ethanolic solid–liquid extraction. For 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 gdwmL1), were investigated (where dw¼dry waste). Results demonstrated that Pinot Noir seeds had high levels of both total polyphenols (73.66 mgGallic Acid Equivalent gdw1) and flavonoids (30.90 mgCatechin Equivalent gdw1), being the optimum extraction time 19 h approximately. The main phenolic compounds analysed with high performance liquid chromatography were catechin and quercetin with a maximum extraction yield obtained at 29 h (362.23 and 339.35 mg/100 gdw, respectively). Concentration of the polyphenols and their antiradical powers are demonstrated to have a significant linear correlation.