Why is wine the colour that it is?

Aren’t red wines red because they are made from red grapes? And white wines white because their grapes are white? That is usually sort-of correct as far as it goes. At least if you take red to be sufficiently loosely defined to include various shades of purple; and white to mean straw, green and golden colours. But it is far from the full story. And it does not explain how, for example, the red grape Pinot Noir can be used to make a white Champagne. And what about rosé, and the small but growing number of orange wines?

To explain all this, we need to take a step back and look at grapes in more detail. Remove the skin from the vast majority of grape varieties, red or white, and you will find they have a white flesh – again I use the term white loosely. What you think of as the colour of the grape is literally only skin deep. And the extent to which wine takes on the colour of the grape depends on the degree of contact with its skins. There are a number of factors involved, but critical is the length of time that contact is maintained.

Leaching of skin colour will start immediately after crushing, which is when the grapes are squeezed to break their skins and release the juice. And the step in winemaking that ends all skin contact is called pressing. Here, after letting most liquid run off the skins and other solid matter, the solids are pressed to extract even more, some of which will be added back to the liquid that ran off freely. Thus the colour of the wine mainly depends not only on the colour of the grape skins, but when pressing takes place, as summarised in this table. (Actually it occurs to me that in some cases the actual pressing after fermentation might not take place, and the wine is just removed from the skins. But for the sake of this table, let’s call that pressing nonetheless, otherwise things get even more complicated.)

Press immediately after crushing Press after fermentation
White skins White wine Orange wine
Red skins White wine Red wine

So, Pinot Noir yields white Champagne because its grapes are pressed so soon after crushing that there is no time for the skin colour to leach out. It is not clear to me why orange wines are such a marked shade of orange, rather than its something closer to the colour of the grape skins, but it must be something to do with how easily the various grape skin pigments can be extracted.

For simplicity, I omitted rosé wine from this table, but it is often obtained by using red grapes, and pressing at some time between the extremes that would yield white or red wine. It can also be made by crushing red grapes and letting some slightly pink juice slowly run out after crushing. With this method the pink juice is used to make rosé wine, while the remainder of the solids and juice is used for red. Either way, the point is that red grapes are used, but with a very limited degree of skin contact. Alternatively rosé wines can be made by adding a touch of red wine to white, a method typically used for rosé sparkling wines, and at the cheaper end of the market also for still rosé wines.

Arguably there is also an intermediate category of white grape wine that is equivalent to rosé, where the skins are removed well after crushing but before fermentation is complete. These wines could be referred to as orange wines with limited skin contact, and in colour they would be a lighter shade of orange. But unlike rosés, the colour of these wines is not so important, and one suspects that the main point of doing this is to tone down the astringency and distinctive phenolic aromatics of full-blown orange wines. Traditionally this is the style of wine in Western regions of Georgia, though it can also be found in other parts. Also wines that are certainly white can be created from a very limited degree of skin maceration that helps to extract aromatic compounds.

After all this you might be wondering why wines from white grapes are generally pressed before fermentation, and red grapes wines afterwards – which is the only reason wines finish up with their typical red and white colours. That is a very good question, and one that I have often pondered.

About Steve Slatcher

Wine enthusiast
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