By Wineland Magazine
Tannins are especially associated with their astringent taste. The perception of astringency is the result of the reaction between tannins and the proteins in saliva. Tannic red wines form a precipitate in the mouth, but due to the lack of tannins in white wines the precipitation will not occur. The tannins occurring in wine, can originate from the grapes or the stems, but they can also be added as exogenous tannins during winemaking.
Tannins are phenolic compounds which occur in many plants. The ability of tannins to react with proteins, is important during winemaking, because enzymatic reactions are inhibited by them and they can also contribute positively to the protein stability of wine. As result of the structural characteristics, they can also contribute to the oxidative and colour stability of wines. They also play an important role in the sensory characteristics of wine. A variety of tannin products became available over recent years and it is important that winemakers are informed about the characteristics of the different products. Available tannins include hydrolysable tannins (ellagic and gallic basis) and condensed tannins (catechinic basis). Ellagic tannins originate from oak and chestnut wood, gallic tannins from oak wood wounds, tara and myrobalan exotic trees, while catechinic tannins originate from grapes and quebracho trees. The traditional tannins for winemaking (exogenous tannins) are extracted from the nutgalls of certain trees ….