Tannin is the transliteration of English tannin. It is one of the two phenolic compounds contained in wine. It is especially abundant in red wine and is beneficial to the prevention of cardiovascular diseases. . The tannins in wine are generally obtained by soaking and fermenting grape seeds, skins and stems, or by extracting the tannins in oak due to their storage in oak barrels.

The presence of tannins is one of the most important differences between red wine and white wine. White wine is made by fermenting grape juice after separating the grape juice and skin residue. Therefore, the soul of white wine is acid, not tannin.

Tannin is an acidic substance mainly derived from grape skins and grape seeds. Red wine must retain the grape skins for fermentation. During the fermentation process, the wine will also absorb a certain amount of tannins from the oak. In terms of chemical structure, tannins soaked from grape skins are "condensed tannins" and tannins extracted from oak barrels are "hydrolyzed tannins".

Tannin is the soul of red wine. Its main functions are: to establish a "skeleton" for the wine, making the wine structure stable, solid and plump; to effectively polymerize and stabilize pigment substances, giving the wine perfection and richness. Vibrant color; reacts with other substances in the wine to generate new substances and increase the complexity of the wine. Wines with insufficient tannins will be stunted and usually appear to be light, weak, and tasteless.

Tannin has antioxidant effects and is a natural preservative, which can effectively prevent wine from becoming sour due to oxidation, allowing long-term storage of wine to maintain its best condition. Therefore, tannin is very important for red wine. The aging ability plays a decisive role. A bottle of red wine from a good vintage may only get better after 10 years.

Tannin content is not directly proportional to the quality of red wine. It does not mean that the higher the tannin content, the better the wine. A good glass of wine should be the result of coordination and balance between alcohol, acid and tannin. After experiments, relevant experts came up with a calculation formula for the quality of red wine: alcohol content - (total acid + tannin) = smoothness index.

Wine with a softness index of more than 5 is a wine of better quality. Assume that the alcohol content of a red wine is 12, the total acid is 3.6 g/L, and the tannin is 1.8 g/L. Then, the softness index of this wine is: 12-(3.6 1.8) = 6.6. This wine It should be harmonious, full and mellow.