Phenolic composition and magnitude of copigmentation in young and shortly aged red wines made from the cultivars, Cabernet Sauvignon, Cencibel, and Syrah

Abstract

Young and shortly aged red wines made from single cultivar grapes grown in the warm climate region of La Mancha (Spain), were examined for their phenolic composition and effects of copigmentation on wine colour. In addition to anthocyanins, flavonol and hydroxycinnamic acid profiles allowed the varietal differentiation of these wines. Characteristic flavonols found were principally glycosides, the main ones, being: myricetin 3-glucoside, quercetin 3-glucoside, and quercetin 3-glucuronide. The fraction of red colour due to copigmented anthocyanins ranged from 32% to 43% at the end of the alcoholic fermentation, and this decreased to 20–34% after 3 months of ageing, when a decrease in both monomeric anthocyanin and flavonol concentrations was also observed . Cencibel wines showed the greatest loss in flavonols after 3 months, but these were apparently replaced, in the copigmentation complexes, by other abundant cofactors, such as hydroxycinnamic acids and (−)-epicatechin. Thereafter, Cencibel wines showed proportionally the lowest decrease in this copigmentation effect at this ageing time. After 9 months, the losses of monomeric anthocyanins and cofactors still continued, and only Syrah wines showed a little enhancement of the red colour intensity. At this ageing time, the amounts of monomeric anthocyanins were sufficient for the formation of copigmentation complexes, but the molar ratio of cofactors to anthocyanins was possibly too low for detecting significant effects on colour, especially in Cabernet Sauvignon and Cencibel wines. A second observed effect of copigmentation was the bathochromic shift to bluish hues for Cencibel and Syrah wines, and it only was maintained in the latter wine during all the ageing times checked.