Tannins

Tannins are polyphenols that come from grape skins, seeds, stems, tea or wooden barrels. They bind with proteins in saliva and create the dry, puckering feeling in the mouth, called astringency.

In red wine they are important structural elements and contribute to longevity. Young tannins often feel rough, and with ageing they become milder. They are also a feature in tea, cider and cask-aged spirits. They are not the same as bitterness, although the two can overlap in the mouth.