A recent article in Scientific American describes how tannins in wine and teas give the beverage its “characteristic pucker”. Scientists, while able to capture finished tannins inside the plant cells, are still unaware of how tannins have formed there in the first place.
“Tannins are a major way plants have of telling herbivores to graze elsewhere. They are deterrents because they denature — that is, deactivate — proteins. Humans have long taken advantage of this denaturing ability to “tan” animal skins with tannins, producing leather. The denaturation of the hide proteins by tannins renders them impervious to bacterial attack — otherwise known as rotting. In plants, tannins may also dissuade microbes and fungi from attacking and help protect plants from damaging UV.”
Tannins in wine come primarily from the grape (the skins, seeds and stems of a wine grape) and the wood barrels the wine is aged in. When referring to wine, tannin adds bitterness and astringency as well as complexity. Because tannins are polyphenols they tend to cling to proteins. This causes tannins to find protein in saliva which in turn gives the inside of the mouth a rough and dry feeling. Although it may seem primarily negative tannins are important to wine by providing structure and flavor complexity.
One can find tannins in a variety of ways, most commonly woody plants such as ferns or persimmons. It can also be found in the tint of lakes and ponds, as stated by the author Jennifer Frazer, “Though the waters were chestnut brown, they were clear. I could easily see the logs and rocks on the bottoms of the ponds.”
Brillouet J.M., Romieu C., Schoefs B., Solymosi K., Cheynier V., Fulcrand H., Verdeil J.L. & Conejero G. (2013). The tannosome is an organelle forming condensed tannins in the chlorophyllous organs of Tracheophyta, Annals of Botany, 112 (6) 1003-1014. DOI: 10.1093/aob/mct168
Hanna Instruments manufactures several meters for measuring wine including:
To read the entire Scientific American article, click here.
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