Effect of copigments and grape cultivar on the color of red wines fermented after the addition of copigments.J Agric Food Chem. 2005 Oct 19; 53(21):8372-81.JA
The prefermentation addition of copigments led to significantly different red wines according to the copigment structure (flavonol or hydroxycinnamic acid) and the grape cultivar [Tempranillo (= Cencibel) or Cabernet Sauvignon]. The flavonol rutin enhanced copigmentation and anthocyanin extraction, improving the red color, but the hydroxycinnamic acids (especially caffeic acid) had converse results. The above effects were higher in Cabernet Sauvignon wines, particularly if rutin or p-coumaric acid was used. These wines showed the highest copigmentation as they contained more anthocyanins and flavonols, whereas the coumaroylated anthocyanins of Tempranillo wines could have prevented the action of the added copigments. After 21 months, the main pyranoanthocyanins found were the malvidin-3-glucoside 4-vinylphenol and the malvidin-3-glucoside 4-vinylcatechol (pinotin A) adducts. The results suggested that the former adduct was primarily generated following enzymatic decarboxylation of p-coumaric acid during fermentation, whereas pinotin A was formed through a pure chemical reaction, which depended on the concentration of free caffeic acid during aging.