Anthocyanin copigmentation and color of wine: The effect of naturally obtained hydroxycinnamic acids as cofactors

•The ability of complex hydroxycinnamates to promote copigmentation was confirmed.•Plant extracts increased color intensity of wine by 15–50%.•The rate of anthocyanins polymerization was not affected by the added cofactors.•The effect of cofactors was minimized after three months of storage. Copigmentation of anthocyanins accounts for over 30% of fresh red wine color, while during storage, the color of polymeric pigments formed between anthocyanins and proanthocyanidins predominates. Rosmarinic acid and natural extracts rich in hydroxycinnamic acids, obtained from aromatic plants (Origanum vulgare and Satureja thymbra), were examined as cofactors to fresh Merlot wine and the effect on anthocyanin copigmentation and wine color was studied during storage for 6months. An increase of the copigmented anthocyanins that enhanced color intensity by 15–50% was observed, confirming the ability of complex hydroxycinnamates to form copigments. The samples with added cofactors retained higher percentages of copigmented anthocyanins and higher color intensity, compared to the control wine, up to 3months. However, the change in the equilibrium between monomeric and copigmented anthocyanins that was induced by added cofactors, did not affect the rate of polymerization reactions during storage.