Effects of extraction time and solvent on proanthocyanins, hydroxycinnamic acids and flavonols in grape pomace byproducts

Currently, there is a growing interest in the exploitation of the residues generated by the wine industry. Also, the interests of scientists in the potential for specific phytochemicals increased due to their medicinal importance. Grape pomace (a mixture of grape skin and seeds) is one of the most abundant residues of the wine making process. Grape skin residue is a known source of phenolic compounds, thus could be an alternative source for obtaining natural antioxidants (Cobb, 2014). MATERIAL. Grape pomace from red grapes (Vitis vinifera, cv. Merlot) was collected in the winemaking factory of Agrolaguna d.d. (Poreč, Croatia), then freeze-dried. Prior to analysis, skins and seeds were manually separated and grape skins were used for further analysis.