Influence of Different Phenolic Copigments on the Color of Malvidin 3-Glucoside

Abstract

[EN]The effectiveness of seven phenolic compounds (catechin, epicatechin, procyanidin B2, caffeic acid, p-coumaric acid, myricitrin, and quercitrin) as copigments of malvidin 3-glucoside, the major anthocyanin in red wines from Vitis vinifera, using a copigment/pigment molar ratio of 1:1 was assayed ) in model wine solutions under the same conditions (pH 3.6, 12% ethanol). The stability of the copigment- ° pigment complexes formed was studied during a storage period of 60 days at 25 °C. Tristimulus colorimetry was applied for color characterization of the copigmentation process, and HPLC-DAD- MS was used to monitor changes in the composition of the samples. Copigmentation has been found to occur in all cases despite the low copigment/pigment molar ratio used, although the effect was different depending on the compound. Flavan-3-ols appeared as the less effective copigments, procyanidin B2 being even worse than monomeric flavanols, whereas flavonols behaved as the best ones. These latter copigments also induced the most statistically significant bathochromic shift in ìmax. In the colorimetric analysis, it was observed that the lightness L* of the copigmented solutions increased with time, chroma C*ab decreased, and the hue hab increased. The copigments *ab ab that produced a greater increase in the hue angle were the monomeric flavan-3-ols, which therefore showed to be the least protective cofactors against browning of the anthocyanin solution during the storage. With the time of storage, the formation of new pigments was observed in the solutions containing flavanols (xanthylium structures) and hydroxycinnamic acids (pyranoanthocyanins), which