Grapes and grape products are widely known for health benefits due to their antioxidant content.  In the production of wines and juices, the grape pomace, which includes the peels, stems, and seeds, is often discarded as a low value product even though the pomace has a higher content of antioxidants than the juice. This work evaluates the effectiveness of using an environmentally-friendly solvent, ethanol, as a superheated liquid and supercritical fluid to extract polyphenolic antioxidant compounds from the grape stems of organically grown Crimson Seedless grapes.  The antioxidant content of the extracts was determined by Ferric Reducing Ability of Plasma (FRAP) and Folin-Ciocalteu (F-C) assay.  The optimum extraction temperature was found to be 204 �C with a FRAP value of 22.8 mmole trolox equivalent/g of dry grape stem.  The presentation will compare the results of the FRAP assay with the F-C assay, and discuss the effects of extraction temperature and holding time upon the antioxidant concentrations of the extracts will also be discussed.

Determination of antioxidant activities of superheated ethanol extracts of grape stems

248th National Meeting (2014)

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