Red wine gets its color from pigments called anthocyanins, which are concentrated in grape skins. The juice inside most red grapes is actually clear or pale green. It’s only when that juice sits in contact with the skins during winemaking that the deep red, purple, or violet hues transfer into the liquid. No skin contact, no red wine.
Anthocyanins: The Pigments in Grape Skins
Grape skins contain five main types of anthocyanin pigments: malvidin, peonidin, delphinidin, petunidin, and cyanidin. The specific mix of these pigments, and their concentration, determines whether a grape variety produces wine that leans ruby red, deep violet, or almost black. Malvidin is the dominant pigment in most wine grapes, while peonidin tends to be more prominent in table grapes.
The amount of pigment varies dramatically between grape varieties. Teinturier grapes like Gros noir pack roughly 214 mg of free anthocyanins per kilogram of berries, while a variety like Cardinal contains only about 17 mg per kilogram. That’s more than a twelvefold difference. Thick-skinned grapes like Cabernet Sauvignon and Syrah naturally produce darker wines because there’s simply more pigment available to extract. Thin-skinned varieties like Pinot Noir yield lighter, more translucent reds.
How Skin Contact Transfers Color
The process of soaking grape skins in juice is called maceration, and it’s the single most important factor in determining how deeply colored a red wine becomes. When red grapes are crushed, the winemaker leaves the skins (and often seeds and stems) in the juice throughout fermentation. As alcohol develops, it acts as a solvent, pulling anthocyanins and other compounds out of the skins and into the liquid.
The length of this skin contact varies widely. Some lighter-style reds might macerate for just a few days, while bold, deeply colored wines can sit on their skins for weeks or even months. A 2018 trial on Cabernet Sauvignon tested extended maceration periods of 21 and 60 days to study how prolonged contact affects the final wine’s color and texture. There’s no single “right” duration. Winemakers adjust it based on grape variety, desired style, and how the wine tastes along the way.
This is also why rosé exists. Rosé wines get their pink color from very brief skin contact, sometimes just a few hours. And it’s why you can make white wine from red grapes: if you press the grapes immediately and separate the clear juice from the skins before any color transfers, the result is a white (or very faintly pink) wine. Champagne, for instance, is often made partly from Pinot Noir, a red grape, using exactly this technique. The key is working with whole, fresh grape clusters and avoiding any maceration.
Why Acidity Matters for Color
Anthocyanins are shape-shifters. Their color changes depending on the acidity of the liquid they’re dissolved in. At very low pH levels (below 3.0, meaning higher acidity), anthocyanins take on a vivid red form. As pH climbs toward the 3.0 to 4.0 range typical of most wines, more of those pigment molecules flip into a colorless form. Push the pH above 3.7, and the pigments increasingly shift toward yellowish tones.
This is why crisp, high-acid red wines often appear brighter and more intensely red, while lower-acid reds can look duller or more purple. Winemakers sometimes adjust acidity partly for this reason. Other compounds in the wine, called co-pigments, can amplify the color by interacting with anthocyanins, creating blue-purple tints and making the wine appear deeper and more saturated than the anthocyanins alone would produce.
How Tannins Lock Color In
Young red wines contain a high concentration of free, unbound anthocyanin pigments floating in solution. These free pigments are unstable. They’re sensitive to changes in pH, temperature, and oxygen exposure, which means the color of a very young wine is somewhat fragile.
Over time, tannins (another group of compounds extracted from grape skins and seeds) begin bonding with anthocyanins to form larger, more stable molecules. This process, called polymerization, essentially chains tannin molecules together until an anthocyanin caps the end of the chain, locking it in place. Once anthocyanins are incorporated into these polymer chains, the color becomes far more resistant to fading. This is one reason winemakers value tannin structure: it’s not just about mouthfeel, it’s about long-term color stability.
Why Red Wine Changes Color With Age
If you’ve ever compared a young red wine to one that’s been aging for a decade, the color difference is striking. A young wine is typically deep purple or ruby. Over years, it gradually shifts toward garnet, brick red, and eventually brownish-orange at the rim.
This happens because anthocyanins slowly break down through oxidation. As tiny amounts of oxygen interact with the wine over time, the pigments responsible for red and purple hues degrade, and yellow-brown compounds take their place. Lab measurements confirm this clearly: a 2018 Syrah shows peak absorbance in the red spectrum, while the same wine from 2010 and 2014 shows a pronounced shift toward yellow-brown wavelengths. Enzymatic oxidation, which can be accelerated by fungi-derived enzymes, pushes the browning process even faster.
The tannin-anthocyanin polymers formed during aging do resist this breakdown better than free anthocyanins, which is why well-structured wines with good tannin content tend to hold their color longer. But all red wines eventually lose their youthful purple intensity. That faded, tawny-edged appearance in an older wine isn’t a flaw. It’s the natural end point of the same chemistry that made the wine red in the first place.
Anthocyanins and Health
The same pigments that color red wine also function as antioxidants. Epidemiological research has linked moderate anthocyanin consumption with reduced risk of coronary heart disease. One study found that red wine anthocyanins are rapidly absorbed into the bloodstream after drinking and, even at low concentrations in plasma, increased antioxidant capacity while reducing a protein involved in inflammatory signaling. These pigments are also found in blueberries, blackberries, and other deeply colored fruits, so red wine isn’t the only source.