pigmented tannins, also called polymeric pigments, are responsible for the colour of red wines, together with anthocyanins, which are the phenolic red pigments of dark-skinned grapes. Pigmented tannins comprise a great diversity of molecular species formed by the reactions of anthocyanins with non-pigmented catechins, proanthocyanidins (i.e. condensed tannins from grapes), and ellagitannins (i.e. hydrolysable tannins extracted from barrels or added as components of some oenological tannins), under the influence of acids and oxygen. Their formation begins in the course of maceration, and then progresses throughout the ageing of a red wine, so that the grape anthocyanins as individual molecular species make only a transitory and ever-diminishing contribution to the colour of a red wine.