Anthocyanin molecular interactions: the first step in the formation of new pigments during wine aging?

The changes in red wine colour on aging are still a challenge. From recent work involving model experiments, it has been concluded that high quality red wine storage conditions (long period of time, permanent contact with wood, low pH values, low temperature and aqueous environment), are all in favour of good molecular associations between the wine anthocyanins and the aromatic planar colourless molecules present in such a medium. In this article, factors which affect anthocyanin non-covalent interactions will be reviewed. They include pigment and copigment concentrations and structures, pH, solvent and temperature. The complex of a pigment with one of its copigments may be the starting point of a covalent linkage between the molecules. This could explain changes in colour and in anthocyanin reactivity observed during the aging of red wines, for instance.