Interactive effect of pre-fermentative grape freezing and malolactic fermentation on the anthocyanins profile in red wines prone to colour instability

Abstract

The effects of pre-fermentative freezing of red grapes from Schiava variety and co-inoculation with lactic bacteria were evaluated on the profile of anthocyans of the musts and the finished wine. Peonidin-3-glucoside is the main anthocyanin in Schiava grape musts, but it was overcome by malvidin-3-glucoside at bottling. Grape freezing increased the extraction of all anthocyanins in the musts. However, the amount of all anthocyanins except peonidin-3-glucoside and malvidin-3-glucoside was lower in wines from frozen grapes than in control wines. Wines obtained with co-inoculation showed higher anthocyanin content than their respective controls. Petunidin-3-(6′′-p-coumaroyl)-glucoside, peonidin-3-(6′′-cis-p-coumaroyl)-glucoside and malvidin-3-(6′′-trans-p-coumaroyl)-glucoside were dramatically affected by the interaction of the two applied factors. Colorimetric hue (H*) was strongly correlated with peonidin-3-glucoside, and spectrophotometric tint (N) with malvidin-3-glucoside. Tint also showed a positive correlation with malolactic fermentation. Graphical abstract: [Figure not available: see fulltext.]