Tannins come from the stems, leaves, skins and seeds of grapes and fruits. Tannins are often described as being astringent and leaving a bitter and unpleasant "leatherary or dry" taste in the mouth. Plants produce tannins naturally to act as a defense mechanism. The bitter flavors ward off birds and other animals from eating the unripe fruit.
Tannins serve three purposes in wine making: it provides structure and color in the aging process: helps clarify wine; and is a natural preservative, preventing oxidation. Over time, tannins soften resulting in a smoother, softer and more complex wine. Tannins are generally found in "red" wines since the wine is made by "pressing" grapes, skin and all. White and rose wines generally do not contain tannins becuase the majority of the skin is discarded.
Fruit wine makers commonly add additional tannin to supplement the natural tannins found in the fruit. The White Silo Winery adds small amounts of tannins to our Raspberry, Blackberry and Black Currant wine. Our Rhubarb wine is acidic enought to not require the addition of tannins.
