Effect of oxidation on color parameters, tannins, and sensory characteristics of Sangiovese wines

The oxidation of two premium wines, Chianti Classico and Brunello di Montalcino, obtained from Sangiovese grapes in 2017 and 2018 vintages, is simulated through oxygen exposure by applying three consecutive saturation/consumption cycles. After each oxidation cycle, wines are analyzed for color intensity, hue, CIElab coordinates, polymeric pigments, monomeric anthocyanins, acetaldehyde, tannins, and flavans and compared to control wines. By increasing the oxygen supply, monomeric anthocyanins decrease faster in the younger wines, acetaldehyde is highly produced in the older ones, while the formation of polymeric pigments depends on the wine type. The color intensity, the yellow and blue tint increase in all wines. The effect of oxidation on main phenolic compounds is more affected by the wine age than the type. Oxidation also significantly affects wine sensory characteristics: the astringency intensity decreases, whereas the subqualities of silk and velvet increase. The percentage increase of the silky sensation is from four to sevenfold higher in young wines. The silkiness is correlated with some anthocyanins decrease [malvidin 3-(6II-acetyl)-monoglucoside, delphinidin 3-monoglucoside, petunidin 3-monoglucoside, malvidin 3-monoglucoside]; the velvet sensation with polymeric pigments formation, acetaldehyde production, and malvidin 3-(6II-acetyl)-monoglucoside decrease. Moreover, after oxidation, aged wines are characterized by an enhanced balsamic odor and aroma.