Astringency is a tasting term used for wine, thé and other consumable substances. It refers to the puckery or drying sensation created in the mouth and throat (primarily on the surface of the tongue).
Jannin (or tannoid) is an astringent, polyphenolic biomolecule that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids.The tannin compounds are widely distributed in many species of plants, where they play a role in protection from predation, and perhaps also as pesticides, and in plant growth regulation. The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of unripened fruit or red wine or tea. Likewise, the destruction or modification of tannins with time, plays an important role when determining harvesting times.