Persimmon contains a large number of soluble substances-tannins. In the natural state, some of this substance can be solidified by protein to form insoluble protein salt, or precipitated by alkaloid to form insoluble salt, so the soluble tannins in persimmon can not be completely solidified or precipitated, so the astringency of persimmon is caused by the residual soluble tannins. \ x0d \ x0d \ The phenomenon of "astringency" we mentioned here is due to. As a characteristic that distinguishes persimmon from other fruits, it has a strong astringency, especially the astringent persimmon, that is, its mature fruit, still shows strong convergence. The astringency of persimmon exists in its tannin cells, and Japanese agronomist Saburo Ito and others have conducted a series of studies on its essence. The results show that it is one of leucoanthocyanidin's species, and its main components are substances produced by complex combination of four components, namely epicatechin, catechuic acid-3-citrate, epicatechin and catechin-3-gallate. It is known that its molecular weight is about 14000, and it is a kind of macromolecular polyphenol. \x0d\ Actually, it's not just immature persimmons that have astringency. Usually, most immature fruits have astringency, such as green bananas, green apples and chestnuts, but they are not as "astringent" as persimmons, so people will never taste them if they are immature.