Wine color

Since pigments are localized in the center of the grape drupe, not in the juice, the color of the wine depends on the method of vinification and the time the must is in contact with those skins, a process called maceration.

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 of a wine can be partly due to co-pigmentation of anthocyanidins with other non-pigmented flavonoids or natural phenols (cofactors or "copigments").

[8] Flavanol-anthocyanin adducts are formed during wine ageing through reactions between anthocyanins and tannins present in grape, with yeast metabolites such as acetaldehyde.

The first step is the formation of colorless dimeric compounds consisting of two flavanol units linked by carboxy-methine bridge.

This is followed by the formation of xanthylium salt yellowish pigments and their ethylesters, resulting from the dehydration of the colorless dimers, followed by an oxidation process.