Tannins in tea and wine - why cheese works with red wine!:

Interesting report from Univ of Minnesota:

Tannins are found throughout the plant world, and at least one of their properties has been known for some time. The word ‘tannin’ is derived from the process of using plant extracts to cure leather (tanning). This highlights one of the principal chemical aspects of tannins – they are highly reactive with proteins. Tannins play an important role in both grapes and wines. In wine, the perception of astringency on the palate is attributed to tannins.  In your mouth they bind with salivary proteins and cause the proteins to precipitate. The end result is that your mouth will lack the lubrication that saliva provides. Thus, astringency caused by tannins are very much a tactile sensation in your mouth. This is why we often will describe the sensation of tannins as silky or rough.

The British learned long-ago that a splash of milk in their black tea can make it more palatable. This works because instead of reacting with the salivary proteins in the mouth, the tannin extracted from the tea leaves reacts with milk protein (casein), resulting in a beverage that is less astringent. The same thing occurs when one consumes red wine with cheese. The proteins in the cheese react with the tannins in the wine, making the wine seem less harsh. Tannins are what make drinking red wine with a high-protein food like steak such an enjoyable experience.