Tannins are water soluble oligomers rich in phenolic groups that give plants containing them a bitter taste. There are two main types of tannins: condensed tannins, which are formed by the condensation of flavanols into polymeric networks; and hydrolysable tannins, which are esters of sugars like glucose bonded to gallic acid molecules. Examples of plants containing these tannins include the bark and heartwood of Eucaliptus wandooo and the pods of Caesalpenia spinosa.

1. Biosynthesis and Crude
Extraction of Tannins

2. Tannins
• Tannins are water soluble oligomers that are rich in phenolic groups.
• Plants rich in tannins are bitter in taste.
TYPES
• Condensed tannins
• Hydrolysable tannins

3. Biosynthesis of Tannins:
• Condensed Tannins
Condensed tannins are formed biosynthetically by the condensation of
flavanols to form polymeric networks. Examples of condensed tannins
(proanthocyanidins)
E.g. Eucaliptus wandooo (Bark & Heartwood)
• Hydrolysable Tannins
Hydrolysable tannins are esters of a sugar (usually glucose) with one or
more gallic acid molecules.
E.g. Caesalpenia spinosa (Pods)