Relationship between antiradical activity, polyphenolic antioxidants and free trans-resveratrol in grapes (Vitis vinifera L.)

Abstract

Contents 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 content was determined spectrophotometrically with phenol Folin-Ciocalteau’s reagent, R content by HPLC method, and ARA employing the 1,1-diphenyl-2-picrylhydrazyl stable free radical (DPPH·). Obtained results were evaluated statistically by Statistica programme. TP did not show any statistically significant differences between the analysed varieties (p < 0.05) in grape seeds and skins, but regarding wine-growing regions a significant difference in TP (p < 0.10) in grape skins was found. ARA (p < 0.05) was not significant either for grape seeds or for grape skins in relation to wine-growing regions and varieties. The highest TP contents were found in grape seeds (536.6 mg/g DM), whereas R contents were higher in the skins (av. 1.67 μg/kg DM). Blue grape varieties showed a higher TP content in grape skins and also in must as compared with white grape varieties. The assessment of ARA of extracts of model constituents of grapes tannin (T) and gallic acid (GA) revealed their higher antiradical activity in comparison with ascorbic acid (AA).    

Major factors influencing antioxidant contents and antioxidant activity in grapes and wines

“…54 Free trans-resvetratrol in the musts was contained mainly below the detectable limit. In agreement with Nikfardjam and colleagues, 60 results of Šulc and colleagues 61 show that RES is mainly dependent on variety and vintage year. As expected, signifi cant varietal differences and differences between the blue and white grape varieties were confi rmed.…”

“…Effect of growing locations (altitude, soil) and climatic conditions (temperature, sum of precipitation, vintage years) on major grape and wine antioxidants and antioxidant activity Statistical analysis of variance 61 (Table 4) revealed statistically signifi cant differences among vineyard regions and varieties in total polyphenol content in grape skins (p Ͻ 0.05). Multivariate analysis applied to the phenol compounds revealed both qualitative and quantitative differences in polyphenolic antioxidants of red and white Spanish wines of different geographical origin.…”