Red drupe grapes can produce white wine if they are quickly pressed and the juice not allowed to be in contact with the skins. The color is mainly due to plant pigments, notably phenolic compounds (anthocyanidins, tannins, etc.). The color depends on the presence of acids in the wine. It is altered with wine aging by reactions between different active molecules present in the wine, these reactions generally giving rise to a browning of the wine, leading from red to a more tawny color. The use of a wooden barrel (generally oak barrels) in aging also affects the color of the wine.
The color of a wine can be partly due to co-pigmentation of anthocyanidins with other non-pigmented flavonoids or natural phenols (cofactors or "copigments").[1]
Rosé wine is made by the practice of saignée (exposing wine to red grape skins for only a short period of time in order to give it a lighter feel closer to that of white wine) or by blending a white wine with a red wine.