Impact of grape dehydration process on the phenolic composition of wines during bottle ageing

The effect of grapes dehydration on, phenolic profile was evaluated in wines during bottle ageing. Wines produced with Cabernet Sauvignon and Merlot grapes, dehydrated in different percentages (30 and 40%) under controlled conditions, were analyzed by spectrophotometric and chromatographic assays during 22 months of storage. The phenolic profile of the wines and their evolution during bottle ageing was different according to the grape variety and the percentage of dehydration applied. An increase in the concentration of phenolic acids (gallic, protocateic, coumaric) and flavonols (quercetin, campferol, and myricetin) was observed in all samples during bottle ageing, along with a reduction of anthocyanin (delphinidin, malvidin, peonidine, and cyanidin 3-O-glucoside) and flavanols (+)-catechin and (−)-epicatechin). Main changes in the phenolic composition of all wines occurred during the 10th and 13th month, but the changes in wines produced from dried grapes were softer than control wines, indicating that dehydration process improve the wine phenolic stability and permit long periods of ageing for this kind of wines. Practical applications Different wine regions utilize the grape dehydration to produce differentiated and high value-added wines. This study provides an overview on the effect of grape dehydration process under controlled conditions on wine phenolic evolution during bottle ageing. The results provide relevant information about the storage time required for this kind of wine to improve its commercialization and consumption.