Relationship between antiradical activity, polyphenolic antioxidants and free trans-resveratrol in grapes (Vitis vinifera L.)
Sulc, M.(Ceska Zemedelska Univ., Prague (Czech Republic). Fakulta Agrobiologie, Potravinovych a Prirodnich Zdroju)E-mail:sulc@af.czu.cz | Lachman, J. | Hejtmankova, A. | Orsak, M.
Concentrations of polyphenolic antioxidants as total polyphenols (TP), free trans-resveratrol (R) and their antiradical activity (ARA) in grape skins and seeds of grape varieties and TP in grape musts originating from 5 wine-growing Czech areas from the harvest 2003 were determined. TP conc. was determined spectrophotometrically, R conc. by HPLC, ARA employing the 1,1-diphenyl-2-picrylhydrazyl stable free radical. There were significant differences in TP in grape skins between the regions. The highest TP concentrations were found in grape seeds (536.6 mg/g DM), whereas R concentrations were higher in skins (av. 1.67 microg/kg DM) than in seeds. Blue grape varieties showed higher TP concentrations in grape skins and also in must than did white varieties. The assessment of ARA in extracts of model constituents of grapes tannin and gallic acid revealed their higher ARA in comparison with ascorbic acid.
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