Influence of Two Winemaking Techniques on Polyphenolic Composition and Color of Wines

The influence of two winemaking techniques, delayed extraction of anthocyanins (DE) and separation of the must (SM), on the extraction of polyphenols (anthocyanins and flavonoids) during fermentative maceration and on the polyphenolic composition and color of wines at racking and after 7 months of aging was examined. These techniques consist of reducing the frequency and intensity of mechanical operations on the cap of skins and limiting the oxygen intake to the must during the first days of maceration, working on the recently pressed must (DE) or after a drain (SM). At racking, the wines produced with these two techniques had more color and higher concentrations of anthocyanins (total and monomer) and total polyphenols (total flavonoids, flavans reactive with vanillin, and proanthocyanidins) than the wines produced by a traditional winemaking technique, consisting of several pump-overs in air, starting from the first day of maceration. These differences remained nearly stable after 7 months of aging. The greater extraction of polyphenols was likely due to better conditions for the activity of the pectolytic enzymes naturally present in grapes. The percentage increase in the extraction of anthocyanins was lower than the increase for polyphenols and varied with vintage and with composition of grapes. The evolution of the color was influenced by the extent of the oxygen intake during fermentative maceration.