Content of polyphenolic antioxidants and trans-resveratrol in grapes of different varieties of grapevine (Vitis vinifera L.)

Abstract

Contents of polyphenolic antioxidants as total polyphenols and trans-resveratrol in grape musts, grape skins and seeds of twelve vine varieties from the harvests 2001 and 2002 were determined. Polyphenolic antioxidants of grapes are very effective in preventing cancer and cardiovascular diseases. Total polyphenolic content was determined spectrophotometrically with phenol Folin-Ciocalteau's reagent and trans-resveratrol content by the HPLC method. The average annual total polyphenol contents in the years 2001 and 2002 were 171 mg/land 324 mg/lin the must, 7, 470 mg/l and 15, 600 mg/kg DM in grape skins and 91, 450 and 107, 440 mg/kg DM in the seeds. The average annual trans-resveratrol values in the years 2001 and 2002 reached 0.817.10-2 mg/kg DM and 4.97.10-2 mg/kg DM in grape skins and 52.7.10-2 mg/kg DM and 4.63.10-2 mg/kg DM in the seeds and there was hardly any trans-resveratrol presence in the must. The results were evaluated statistically by Statgraphic and Anova programmes. Statistically significant differences in total polyphenols were found between analysed vintages, varieties and contents in seeds and grape skins. Regarding the trans-resveratrol content, statistically significant differences between vintages were found.