Tannin

Tannin is a group of natural compounds (a kind of phenol) found in grapes, located especially in the skins, seeds and stems. When grapes are pressed and red wine ferments in contact with the skins, the tannins are drawn out into the wine. That is why you find the most tannin in red wine, while white wine rarely has very much, because it is typically made with little or no contact with the skins. Tannin can also come from oak barrels during ageing.

What tannin does for your experience is, first and foremost, a dry, astringent sensation. It feels as if the mucous membranes in your mouth, your cheeks and your gums contract and become a little rough, much the same way as after a cup of very strong tea. The more tannin, the stronger this astringent effect. At the same time, tannin helps give the wine structure and body and is a big part of the reason why many red wines can develop nicely over the years, because the tannins gradually become softer and more rounded with ageing.

A classic misunderstanding is to confuse tannin with bitterness or with acidity. Try to notice the rough, dry feeling itself rather than the taste. A good trick at the table: tannin is softened by rich food. A piece of juicy beef or a well-marbled dish makes a young, tannic red wine more supple and harmonious.