tannins

[Thomas]

As IK said, tannin is extracted during fermentation from the grape skins. The reason red wine contains more tannin than white is that whites are not fremented on the skins--they are pressed before fermentation; red is pressed after fermentation.

Tannin also comes from aging wine in oak.

When there is a lot of tannin in wine your tongue and mouth get to feel like they are being scraped or they have been invaded by cotton. Tannin also gives off a bitter aftertaste. Tea is loaded with tannin too.

The pucker you refer to sounds more like a reaction to tartaric acid in wine than of tannin.