Wine Tip: Tannins in Wine – How it Feels

Editor’s Note: This is an excerpt from author John Hailman’s book ‘The Search for Good Wine’ which will be available for purchase October 2014 from the University of Mississippi Press. This particular chapter was written on June 24, 1990.
Two readers wrote last week to ask: “What are tannins in wine?” And “Is there such a thing as ‘soft’ tannin, since tannin is an acid?”
Although referred to as “tannic acid” by some writers, tannin is not really an acid at all, but an organic compound called a phenol. If that sounds too complicated, it is the puckery stuffer in strong tea that makes you want to put sugar or milk in it as the English do. Tannin in nuts also makes your mouth puckery if the nuts are too green. The same goes for wine.
Tannin is natural in wines; it’s present in grape skins, grape seeds, and grape stems, and even in the oak barrels, where wine is made and aged. Red wines have much more tannin than white wines because they are left on the skins longer during fermentation to obtain color. The color in red wines also comes from phenols in the skins, unlike “white” wines, which get their light yellow color from the juice rather than skin pigments.
The relation between tannin and color remains with wines as they age – old red wines get lighter as they age. And tannins separate from wines and fall to the bottom of the bottles just like the coloring agents do. In this sense tannins, like colors, do  not do not really soften, they just fall out. Lost tannin is a major reason why an old red wine often tastes better than a young one.
There is some dispute among oenologists and wine chemists, but most agree that some tannins start out softer than others. All plants have tannins, but those in persimmons are a lot more biting than those in grape skins.
More surprising than tannins’ part in the taste of wine is their part in a wine’s smell. Young wines that smell only of fruit are said to have “mere” aroma. Later, after years of bottle-aging, the fruit smell is replaced by something more subtle and mellow, much sought-after by wine lovers: bouquet. Tannins contribute greatly to bouquet, even though scientists cannon explain precisely why, at least not so I can understand it.
In addition to flavor and bouquet, tannin also gives wine stability, preventing oxygen from turning it to vinegar. For this reason, when wine is low in natural tannin, some winemakers add tannin artificially. You can taste this unpleasant addition in cheap jug wines.
Among the worst sources of added tannins are chestnuts and galls from oak trees (fungus among us).
Better winemakers never use foreign tannins in their wines. They simply leave more grape stems in the crusher from the grapes themselves, which are rich in tannins compatible with those naturally in the wine. A bad source of natural tannin is grape seeds, which can be highly bitter. Wine containing seed-juice is usually cheap and called “press-wine”, as opposed to wine from lightly crushed grapes, called “free-run,” which is more expensive and worth it.
If tannin is not acid, what word do you use to distinguish between acid and tannin and how they taste? Acid wine usually is called bitter or sour like lemons; tannic wine on the other hand is called “astringent,” like green nuts or strong tea. Tannin is actually best sensed not as a tasted at all, but by touch, how it feels in your mouth. Highly tannic wines – like young red Bordeaux – actually draw up your mouth. You can even feel tannin on the surface of your tongue when a wine is over-oaked.
Like wines themselves, tannins are good taken in moderation, but rough and harsh if used to excess. When balanced with ripe fruit from good grapes and a light acidity, tannin in wine is refreshing, however chemical it might sound from this brief description.
You did ask me.
John Hailman of Oxford is a regular contributor to HottyToddy.com on two subjects: Law and Wine. Now retired from both his “day job” as a federal prosecutor in Oxford after 33 years and his “night job” of 25 years as a nationally syndicated daily columnist in more than 100 daily papers on wine, food and travel for Gannett News Service and the Washington Post, Hailman will cover both topics under the titles of The Legal Eagle and Wine Tips of the Week. HottyToddy.com will also run periodic excerpts from Hailman’s upcoming book of humorous legal stories, From Midnight to Guntown: True Crime Stories From A Federal Prosecutor in Mississippi. Hailman now teaches Federal Trial Practice and Law and Literature at the University of Mississippi.