What are tannins?
Tannins are organic compounds found in the roots, seeds and stems of red grape plants and are imparted into the skins of red grapes. Tannins can also be picked up from oak barrels, and therefore can be found in barrel-aged white wines as well. These compounds lend texture, flavor, complexity, and a sometimes astringent tang to red wines. Tannins account for the mouth-pucker experienced when tasting young, full-bodied reds such as Cabernet Sauvignon, and they also provide antioxidants that enable these wines to age for long periods in the bottle.