International Journal of Waste Resources

Abstract

Characterization of Polyphenolic Phytochemicals in Red Grape Pomace

Dimitris P Makris, Panagiotis Kefalas

Polyphenolic phytochemicals are of particular importance to the food, pharmaceutical and cosmetics industry, because of their unique antioxidant properties. Red grape pomace is a solid waste of the wine manufacturing process and possesses a very high polyphenolic load, hence its significance as a rich and abundant residua source. However, in many instances there is a lack of analytical data regarding its polyphenolic composition. In this study, red grape pomace originating from the Greek native cultivar Vitis vinifera var. Agiorgitiko was efficiently extracted with 57% aqueous ethanol, which is a non-toxic and environmentally benign solvent, with the aim of obtaining a polyphenol-enriched extract. The extract was subsequently analyzed by liquid chromatography-diode array-mass spectrometry analysis, in order to tentatively characterize the major phytochemicals recovered. The compounds identified were a p-coumaric acid derivative, three flavonol conjugates (two glucosides and a glucuronide), along with three anthocyanin pigments that occur in grape berries. Three other major phenolics detected could not be assigned to a tentative formula and their structural elucidation merits further investigation. The data generated from this study could be used in assessing the overall polyphenolic profile of the pomace from this particular Greek, native variety, which could be of value in producing commercial formulations with high antioxidant activity.