A review of the current knowledge of red wine colour.

<p><span lang="EN-GB">Anthocyanins are the main compounds present in young red wines, being responsible for their intense red colour. <span>These pigments are mainly located in grape skins and their extractability during winemaking depends on many factors, such as their concentration in vacuoles and interaction with the cell-wall polysaccharides, affecting their stability and concentration in the must.</span> The red colour of anthocyanins at wine pH is explained by the stabilization of the flavylium cation form that displays a red colour; otherwise at this pH the hemiketal colourless is the dominant form, bleaching the wine. <span>Besides the contribution of free anthocyanins, a phenomenon called copigmentation influences the colour of young red wines.</span> Copigmentation can be defined as a</span><span lang="EN-GB"> series of stabilization mechanisms involving van der Walls interactions that occur naturally in red wines and that can explain this unanticipated colour behaviour. </span><span lang="EN-GB">Copigmentation</span><span lang="EN-GB"> is also pointed as the first interaction between anthocyanins and other wine components leading after that to the formation of new coloured compounds </span><span lang="EN-GB">during </span><span lang="EN-GB">red wine </span><span lang="EN-GB">ageing</span><span lang="EN-GB">. Some of these pigments have already been identified and characterized but <span>many are</span> still undiscovered.</span><span lang="EN-GB"> The detection and structural characterization of new pigments, and the knowledge of their chemical formation pathways are crucial <span>to</span> better <span>understand</span> the evolution of the colour of red wine during ageing.</span></p>