Often, you may come across a wine that has a harsh taste in the back of your mouth, and leaves you with a dry feeling like all your saliva was sucked up by cotton balls, or that suction tube the dentist uses. “Ugh, why would I drink this?” you might say. Well, let’s find out what’s causing that, and why it’s there in the first place. You may find yourself seeking out these wines for the right occasion in the future.
The culprit here is a type of acid called tannin. It commonly occurs in different plants: tannic acid is what tea leaves release into hot water to make tea. It also can be found in coffee beans. The tannins found naturally in oak wood are extracted and used to harden animal hides into leather. This process is called tanning and is where tannin gets its name.
Tannins are one of the three acids commonly found in grapes, along with citric acid and malic acid. The tannins are concentrated in the grape skins, as well as the seeds and stems. If the winemaker leaves the skins, seeds, and stems in contact with the grape juice as it ferments, you’ll get a red wine. And the longer they sit in the juice, the darker and more tannic the wine becomes.
Tannins are also absorbed by wine that’s aging in oak barrels, directly from the wood. But this is a much smaller, less significant, source of tannins, and they tend to be smoother and mellower than the ones in the grape skins.
When the tannins come into contact with the salivary glands in the back of your mouth, they dry up the saliva, creating that puckery, bitter feeling. This is because tannin is an astringent; it has a drying effect. Some people think that this is what’s meant by “dry” wine, but that word only means that there’s no sugar in the wine. The effect created by tannin is simply called “tannic.”
So, why in the world do winemakers make wine with tannin? They could avoid it by using grapes with less tannin in the skin, and by reducing the time that the skins are left in the juice. Many wines, including red wines, are made this way. But quite a few wines are made intentionally with a tannic component. There are three principal reasons:
First, the tannins give the wine “structure.” If a wine has a lot of acid, sugar, and/or alcohol, without the tannins the wine may seem unbalanced or flabby. With the addition of tannins, all of these components are balanced out, and none of them sticks out in an unpleasant way. As time goes on, and the wine remains in the bottle, all of these different parts of the wine blend together more completely. A young wine with pronounced tannins, along with healthy acids and alcohol, will mellow out over the years; the tannins will blend with the acid and alcohol, making a mature wine very different from when it was bottled. These wines are meant to sit for one to two years, sometimes up to ten years or more, before being enjoyed, to allow the components to blend together for maximum balance.
Second, some people like tannins. Yes, they are bitter, but plenty of people enjoy the bitterness that tannins lend to tea, coffee, beer, and bourbon. It is an acquired taste, not that different from a fine cigar.
Finally, tannins neutralize, and are neutralized by, fat. Many wines are produced with the intention that they will not be consumed by themselves; rather, they’re meant to be enjoyed with food. A full-bodied, tannic wine will pair exceptionally well with foods that have a significant fat component. Take a creamy cheese, a well-marbled steak, or an alfredo sauce; and get that wonderful, fatty consistency to fully infuse your mouth. Then take a sip of your previously-intolerable tannic wine. You’ll find that the tannins have mysteriously mellowed out and become quite pleasant. That’s the magic of food & wine pairing.
If you’re someone who doesn’t enjoy the acquired taste of tannins in your wine, then you can: avoid those wines; determine if there are enough of the other balancing components of wine present to set aside this wine for a couple of years; or make sure you’re not drinking this wine without a cheese plate or a Texas ribeye steak alongside it.