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Dear Dr. Vinny,
Is it true that tannins are added to wine? And if so, why? Also, what are tannins?
—Aaron, Windham, Maine
Let me start with your last question first: What are tannins? They are a naturally occurring biomolecule that are found in trees and other plants. Wine tannins come from grape skins and seeds, as well as from oak barrels. Tannins don’t have a taste as much as they have a feel, though a wine with a lot of tannins can taste bitter. Tannins are part of a wine’s structure, and they create that puckery sensation that tugs on your cheeks or can make a wine seem drying or even chewy.
Some wines have more tannins than others. For starters, red wines tend to have more tannins than white wines because of the different ways the wines are made: Red winemaking requires more exposure to grape skins, where most wine tannins come from. Certain grape varieties, harvest conditions, enzymes, commercial yeasts and winemaking choices will also affect how tannic a wine is.
Winemakers can also add powdered tannins to make adjustments, particularly to add structure or to counteract sweetness. It’s hard to tell how many producers do so, but my gut is that it’s typically used in more mass-produced wines. A container of tannin powder will cost much less than a barrel or even an oak alternative like wood chips.
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