Tannin

Tannin is an astringent ingredient contained in grape skins and seeds, and is a kind of polyphenol.
Tannin itself is a water-soluble compound that exists not only in grapes but also in other plants, and generally has the function of coagulating proteins.
Tannin is an important element that is indispensable for red wine of long-term aging type. Generally speaking, the intensity of tannin and the shade of color are proportional.
Among the peels and seeds, it is especially found in grape seeds, so it is often found in wines that are made with “Koshi”.
The tannins of polyphenols are mainly derived from grape seeds and pericarps and from barrel components. Grape-derived catechin tannins have a smoother astringency. The
White wine also has tannins, which are tannins derived from barrels.
The action of tannin is widely known to prevent wine oxidation by oxidizing itself, and when tannin is contained in the mouth, it binds to proteins in the mucous membrane of the mouth and feels strong astringency and bitterness I will let you. This is called astringent action, and it is this tannin that accumulates on the bottom of the container as starch over time.