Content of phenolic substances in grapes and wine of the Vranec variety (Vitis vilifera L.) grown at different altitude

Introduction.The aim of this study was to determine the content of phenolic substances in grapes and wine of the Vranec variety grown at three different altitudes in the area of Macedonia.Materials and methods.The total phenols content, antocyanins and flavan-3-ols in grape extracts and wines from the control (without application of summer pruning operations) and experimental variants (with application of three different pruning operations) were determined by spectrophotometric analysis.Results and discussion.The highest levels of anthocyanins (10.74 mg/g FW) were found in the berries skin extract when the pruning operation "normation to 6 bunches per vine" was applied in the Veles region (280 m altitude).The concentration of anthocyanins in the other variants from the Veles region were lower and ranged from 7.26 mg/g FW (control) to 8.39 mg/g FW (variant 10 bunches per vine).The highest levels of total phenols were found in the berries skins and seeds of the "6 bunches per vine" variant in the Skopje region (595 m altitude), accumulated in amounts of 22.82 mg GAE/g FW (berries skin) and 101.04 mg GAE/g FW (berry seeds), respectively.The highest content of total flavan-3-ols was found in the berries skins and seeds of the "6 bunches per vine" variant from the Veles region, accumulated in amounts of 2.33 mg CE/g FW (berries skin) and 29.64 mg CE/g FW (berries seeds), respectively.In the wines from the experimental variants, the highest levels of anthocyanins were found in the wine of the variant "6 bunches per vine" from the Veles region (593.56mg/L).In the experimental wines from this variant of the same Veles region, the highest amounts of total phenols were also found (2925.61mg GAE/L).Flavan-3-ols were found in the highest amount (441.46 mg CE/L) in the wine of the variant "6 bunches per vine", but from the Skopje region.Conclusions.The higher altitude showed to increase the amount only of total phenols in the berries skins and seeds.There were no significant differences in the content of phenolic substances -total anthocyanins and total phenols in the wine of the Vranec variety by variants and regions, as their quantities were higher in the variants with normation of grape bunches.