Colour of Wines: White wines

The stems, skins, and pulp of the light-skinned grapes used for making white wines contain a large and complex mixture of phenolics similar to those found in dark-skinned grapes but not the red/blue-coloured anthocyanins. The absorption of light by these white-wine phenolics occurs mainly in the ultraviolet range, but extends into the visible range sufficiently to cause a light yellow colour in the wines we call ‘white’. After crushing of the grapes, these phenolics are exposed to oxygen and to the acids and other constituents of the grape juice, which causes a number of enzymatic and chemical reactions (including oxidation and polymerization) which result in changes of colour from light yellow to amber and eventually to brown. To minimize extraction of phenolic compounds into the must and subsequent oxidative browning, white wines are usually made with minimum skin contact. Although most white wines are made from light-skinned grapes, white wines may be made from dark-skinned grape varieties (see blanc de noirs) using minimum skin contact and/or charcoal treatments.