Short answer
Young red wine gets its purple-red from grape-skin anthocyanins. Over time those react with tannins and with fermentation by-products to form new, more stable pigments that are redder-orange and less sensitive to pH, while free anthocyanins decline — so the colour moves from purple through ruby to brick and tawny. White wines deepen from green-gold to gold and amber mainly through slow oxidation of their phenolic compounds. Oxygen exposure speeds both.
Nearly all red grape varieties have colourless juice; the colour is in the skins. During fermentation and maceration, anthocyanins are extracted from the skins into the wine along with tannins. In a young wine many of these anthocyanins are free and behave like the pigments in red cabbage: wine's acidity keeps a share of them in the red flavylium form, and much of the rest is colourless at wine pH. Sulphur dioxide added as a preservative also bleaches free anthocyanins reversibly. The vivid purple of a new red is therefore a fragile colour.
As wine ages, anthocyanins react with yeast metabolites such as pyruvic acid and acetaldehyde, and with tannins, to form new pigments. Pyranoanthocyanins, one family of these, are coloured across the whole pH range, resist bleaching by sulphur dioxide and are more stable in storage than the anthocyanins they come from; their colours sit towards orange-red. Pigmented tannin polymers add brick and brown tones. Meanwhile free anthocyanins are lost. The net effect is a colour that becomes less purple and less intense but more stable — the ruby-to-garnet-to-tawny sequence a taster reads as age.
White wines have little anthocyanin, and their colour comes from much smaller amounts of phenolic compounds. Exposed to oxygen, these oxidise — enzymatically in the juice if it is handled carelessly, and chemically in the wine over years — and form yellow-brown products. A slow, controlled version gives the gold of an aged white; a fast, uncontrolled one is a fault called browning, often with stale, sherry-like aromas. Winemakers prevent it by limiting oxygen, using antioxidants such as sulphur dioxide, and can remove some brown compounds with fining agents.
Rosé and orange wines sit between the two: short skin contact extracts some pigment, and orange wines are white grapes fermented on their skins, extracting phenolics that give amber colour.
Tasters tilt the glass over a white surface and look at depth (how much light gets through the centre) and hue at the rim, where the wine is thinnest. A purple rim suggests youth; an orange or brick rim, age or oxidation. Laboratories measure the same things instrumentally, with absorbance in the yellow-brown, red and sometimes blue regions of the spectrum combined into figures for colour intensity and hue. Lighting matters: warm restaurant light makes every red look browner and older than it would in daylight.
Why: Oxygen exposure during making or storage has oxidised its phenolics.
Fix: Check the closure and storage temperature; smell for stale, bruised-apple notes that often accompany browning.
Why: Warm, dim lighting shifts reds towards brown.
Fix: Judge colour under daylight or a neutral lamp against white.
Each statement is labelled by kind — established fact, a standard’s requirement, observed market data, a convention, or Colourwise’s own interpretation or analysis — with the strength of the evidence behind it.
FactModerate evidence
Pyranoanthocyanins form during winemaking from anthocyanins and yeast metabolites such as pyruvic acid and acetaldehyde; they express colour across all pH values and are more resistant to bleaching and more stable in storage than their parent anthocyanins.
FactStrong evidence
Wine browning results from enzymatic and non-enzymatic oxidation of polyphenols and is prevented mainly by limiting oxygen and using antioxidants; fining agents can remove some brown compounds.
FactModerate evidence
Anthocyanin colour depends on pH, and sulphur dioxide bleaches free anthocyanins, which makes the colour of young red wine less stable than that of aged wine.
Source: Anthocyanins: Factors Affecting Their Stability and Degradation; Influence of the Anthocyanin and Cofactor Structure on the Formation Efficiency of Naturally Derived Pyranoanthocyanins
Colourwise interpretationModerate evidence
The shift of red wine from purple towards brick with age is best read as a change in which pigments dominate rather than simple fading.
Based on: Colourwise's synthesis of the pyranoanthocyanin and oxidation literature cited on this page; the relative contribution of each pigment family varies by wine.
Reviewed 29 September 2026. Colourwise summarises its sources in its own words and does not reproduce standards text or proprietary colour data. Spotted an error? Tell us.