The influence of storage on the “chemical age” of red wines

Storage conditions and duration have a considerable influence on wine quality. Optimum temperature and humidity conditions may improve wine quality through ageing, while incorrect or excessively long storage leads to negative results. In order to evaluate the global effects of storage on red wine composition, 20 Sangiovese wines were stored in two different conditions (cellar or house) for a period of 2 years and analysed every 6 months. Untargeted LC-MS analysis showed various putative markers for the type and length of conservation (i.e. pigments, flavanols, pantothenic acid etc.), while targeted LC-MS confirmed and expanded these results within specific metabolic groups. The results of multivariate analysis showed that wines stored in the cellar changed little even after 2 years of storage, while wines stored in typical domestic conditions (house) developed approximately four times faster, reaching after just 6 months a composition similar to wines stored in the cellar for 2 years. The formation of several monosulfonated flavanols during the domestic ageing provided the first evidence in wine of a reaction between wine tannins - both catechins and proanthocyanidins - and the exogenous antioxidant bisulfite. Moreover, ageing under domestic conditions appeared to induce an accelerated decrease of wine pigments, while specifically promoting the formation of the pinotin A-like pigments.