A group of astringent and bitter compounds found in the seeds and skins of grapes. These compounds slow oxidation and promote aging. Sometimes tannins are found in the barrels that are used to hold the wine. Important to the production of good red wines, because they provide flavor, structure, and texture, tannins have antioxidant traits that contribute to graceful aging. You can detect tannins in the wine you are consuming by the puckery, drying sensation in the back of the mouth and throat.