In viticulture, colour plays an important role in various areas. It starts with the vineyard soil with an influence on the growth of the vines, continues with the colour of the foliage and the colour of the grapes with a direct influence on the colour of the wine, which is also of great importance in a wine evaluation.
The soil colour provides information about its composition with a considerable influence on growth and wine quality. For example, a reddish soil indicates iron content. This soil, known as Rotliegend or Terra Rossa, is particularly suitable for red wines. See a complete list under soil type.
The ripening phase of the grapes during the annual vegetation cycle is called véraison. It begins with the discoloration of the berries, which take on their final colour until they are fully ripe. In the case of wine grapes, a distinction is usually only made between white and red varieties. The criterion is whether the grapes are suitable or used to make red wine or rosé (red variety) or white wine (white variety). However, there is a wide range of colours, from white, through yellow, green, grey, brownish, pink, red, violet, blue and black. Table grapes or ornamental vines are divided into white, red and blue (black) varieties. For the purely optical determination of grape varieties on the basis of morphological characteristics, the berry colour, among other things, plays a role; see Molecular genetics and DNA.
Many grape varieties include the berry colour in their name, for example blanc = white, bleu = blue, gris = grey (actually reddish, i.e. wine grey), noir = black, rosé = pink, rouge = red and vert = green.
The red colouring substances are removed from the skins of the berries by the mash fermentation which is common in the production of red wine. There are several methods to enhance this effect. See autovinification, electroporation, extraction, pomace mashing, mash heating, rot fermenters and overpumping
Regarding the stabilization of the wine colour or a colour correction during vinification, see under Beautification (especially the two paragraphs on gelatine beautification and colour stabilization).
The standard wine types, which differ in colour, are white wine, rosé or red wine and, more recently, Orange Wine. The colour intensity or the colour shading can be quite different, therefore the determination of the wine type is not always possible with the colour alone. There is hardly any difference in colour between a light red wine and a dark rosé wine. In any case, the method of winemaking for the individual wine types is very different. The colour of the wine is determined by various colouring agents contained in the grapes from the large groups of carotenoids and flavonoids. The red and blue colourings of the anthocyanins belonging to the flavonoids are mainly contained in the skins of the berries. They are dissolved out or extracted during the mash fermentation which is common in red wine and give the red wine its colour.
At first glance, red and white wine grapes differ mainly in the colour of the berry skin, which ranges from blue to black for red wine grapes. Even dark red white wine grapes cannot normally produce red wine. The flesh of the berries, on the other hand, is grey to white even on most red wine grapes; especially light-coloured on the varieties Blauer Portugieser, Gamay, Pinot Noir and Pinot Meunier (black Riesling). Such grapes can produce an almost colourless grape must when pressed. This is used in the production of white wine from dark grapes for Blanc de noirs. The so-called Teinturier varieties (dyer's grapes), on the other hand, have red (dark) pulp, which produces particularly dark-coloured red wines. These are preferably used for blending, in order to give dark red wines with a weak colour a dark colour. Small quantities of around 5% are sufficient to achieve this (see under Cuvée).
In a wine evaluation, the colour of the wine is not given too much weight because there are more important quality criteria. However, it must be very pure and the wine must be free of residues and turbidity. Especially with red wines, the depth of colour plays a role (the darker the "more beautiful"). During bottle aging, the colour can change considerably in connection with polymerisation (caking and precipitation of colouring agents). As a rule, red wines first become lighter and then darker again over the years, while white wines become continuously darker. However, this also depends on various criteria such as grape variety, vegetation development (see below), type of vinification or ageing, closure and storage.
Colour designations for red wines are blue-red, bordeaux-red (wine-red), blackberry-red, fire-red, garnet-red, cardinal-red, carmine (crimson), cherry-red, copper-red, mahogany (red-brown), ochre, opaque (opaque), orange, purple, robe, rosé, ruby red, scarlet red, black, tawny (tawny), violet, brick red and vermilion, for white wines amber, pale yellow, brown, yellow-brown, yellow-green, golden, golden yellow, greenish, straw yellow, white and lemon yellow.
Some wine faults are expressed by an unusual colour or cloudiness. Oxidative processes are often responsible. See brown fracture, protein haze, yeast haze, high colour, madeirised, lactic acid cast, oxidation and black fracture (white fracture).