Total Tannin Content

Tannins are high molecular weight phenolic compounds having the ability to precipitate proteins. They are class of secondary metabolites that widely distributed in many plants. Two types of tannins are commonly found in natural products: hydrolysable and condensed tannins. Hydrolysable tannins are complex monomeric or oligomeric polyesters of phenolic acids (gallic or ellagic) with D-glucose or related sugars. Hydrolysable tannins include gallo-, ellagi-tannins and tannic acid. While condensed tannins, also named procyanidins, are dimers to polymers of flava-3-ol (such as catechin). Examples of condensed tannins are procyanidin A2 and B2.