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What Are Tannins In Wine? Why We Pucker: A Guide to Tannins

February 11, 2020
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Scott
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You’ve probably heard of tannins before. Or heard the word tannic thrown around in descriptions and tasting notes of red wine. Especially full-bodied reds. Some people love tannins, some people avoid them, and some people get headaches from them

The presence or amount of tannins in wine doesn’t make that wine good or bad. It’s how those tannins are managed during the winemaking process that’s important. Artfully leveraging tannins can make a good wine soar, and uninspired use of tannins can make a wine flat and one-dimensional.

So let’s look at the meaning of tannin and how and why tannins are used in the winemaking process. Then finally, we’ll go over some words commonly used to describe tannins so you know a tannic wine when you see (and taste) one.

A Tannin Definition: What Is a Tannin?

Tannins are a group of naturally-occurring, bitter-tasting compounds found in many leaves, seeds, stems, wood, bark, and fruit. In fact, up to 50% of the dry weight of leaves is pure tannin.

What Are Tannins in Wine?

Tannins in wine come from two places: the skins, stems, and seeds of grapes and the oak barrels wine is often aged in.

During winemaking, grapes are crushed. When grapes are crushed, all the stems, skins, seeds, and juice form what’s called the must. As the must is allowed to sit, it macerates. That means the color and tannins from the stems, seeds, and skin are leached out into the raw grape juice. And that eventually becomes wine through fermentation.

Then, during the aging process, the oak from aging barrels imparts its own level of tannins into the wine.

Why Do Plants Have Tannins?

According to the U.S. Forest Service, plants developed tannins as a protection mechanism. The bitter taste is meant to dissuade would-be plant eaters from dining on that particular species. The most tannic parts of plants are usually their growth areas, like skin, stems, stalks, and seeds. These are the parts of the plant that are most important to survival and growth, and most in need of defense. It’s an evolutionary strategy that works well for grapes. Until they meet a winemaker.

In the case of tree bark, its purpose is twofold. First, to make the bark inedible. Second, to stop mold and fungi from infecting the tree through the bark. They do this by binding to the enzymes and proteins on the mold or fungi and disabling them.

Tell Me More About This … “Binding of Proteins”

Chemically speaking, tannins are what’s known as polyphenols, a type of biomolecule that binds to proteins. That’s what causes tannins to affect our tongues the way it does. It binds to the proteins on our taste buds to activate a sharp, pungent taste (bitterness). Dark chocolate is a good example of the bitterness of higher tannins. Tannins also bind to the proteins in our saliva, altering their structure and making our mouths feel dry (astringency). Very strong black tea is a great example of astringency. Higher tannins do the same thing to animals’ tongues, and that’s usually enough to discourage them from eating.

What Foods Are High in Tannins?

Foods and plants high in tannins include pomegranates, grapes, most berries, nuts that can be consumed raw, most legumes, the spices clove, tarragon, cumin, thyme, vanilla, and cinnamon, beer, and, of course, red wine.

What Wines Have No Tannins?

Red wines have far more tannins than white. White wines and young, ready-to-drink red wines that haven’t been aged have no or very little tannins. 

White wines aren’t macerated for very long, if at all, and the grape juice absorbs very little of the tannins from the must. Young reds that aren’t aged for long like Pinot Noir, Grenache, Gamay, and Barbera are made with grapes that naturally have less tannins. They also have relatively little contact with oak barrels and so absorb less tannins.

Tannins in Wine: Why Are Tannins Purposefully Put in Wine?

Tannins provide structure so the rest of the material can have form. Without a bitter, astringent character, some wines’ sweet and fruity flavors run rampant. Tannins temper those flavors and provide a fully-balanced, complex profile. Think of them like steel beams are to a skyscraper, bones are to a body, and syllables are to a haiku.

Do High Tannins in Wine Allow for Better Aging?

It depends on the type of wine. Aged wines, like full-bodied reds, which are quite high in tannins, typically age more gracefully than low- or non-tannic wines. This is because, as time passes, the tannins chemically bind into long chains of molecules. As this happens, the length and weight of the chains makes them fall to the bottom as sediment. Sediment should never be part of standard wine pour, by the way. Learn how to decant wine to solve that problem. This removes much of their harsher, bolder characteristics from the wine’s flavor profile. This is referred to as a wine with resolved tannins.

Light-bodied reds that don’t have extended maceration processes or oak-barrel aging, and consequently have low tannins, don’t need aging. That's because the amount of tannins isn’t high enough to require softening. That’s why they’re ready to drink young. These young wines can benefit from a quick decant. If you're wondering what does a wine aerator do, there's your answer, they can help soften some of the tannins.

Because some aeration methods are better for different types of wines and their tannins, here's some information about wine decanters vs wine aerators.

What Affects the Level of Tannins in Wine?

Tannin management in the winemaking process is a useful lever winemakers have to control the flavor and character of their wines. There are four primary ways tannins are managed. They are the ripeness of grapes chosen, the type of grape, the maceration process, and the aging process.

Ripeness of Grapes

You’ve experienced this before when you’ve eaten fruit. Young fruit is typically harder and more bitter. Ripe fruit is softer and sweeter. That’s the depletion of tannins in action. The riper the grapes, the more tannins have broken down. That results in a weaker physical structure and less tannin molecules to bind to taste receptors and create a bitter flavor.

Grape Varieties

Some grapes are just more tannic than others. This has everything to do with how that particular grape evolved to ensure its survival and thrive in its environment. Which the presence of tannins helps it do. Consider the soil and climate it grows in (warmer weather produces less tannic grapes), the irrigation and water it receives (the less water the grape gets, the more tannins), and the natural predators it has (exposure to natural predators increases tannins in grapes).

All of these factors play a role in how much natural tannin a grape has. Some of the most tannic wines out there are from Nebbiolo, Cabernet Sauvignon, Syrah, Sangiovese, and Malbec.

Maceration

While a grape may be naturally tannic, its tannins can be tempered or enhanced through different types of maceration. Two commonly used maceration strategies to increase tannins in wine are cold-soaking and extended maceration. 

Cold-soaking is when the maceration process is done in a temperature-regulated vat to keep the raw grape juice from fermenting. This allows the maceration process to continue as usual, and the grape juice to keep absorbing tannins from the must.

Extended maceration is done after the wine is fermented. The fermented wine is returned to the must to soak in the grape skins, seeds, and stems for up to 100 days. This increases the tannin level in the wine, but in a different way. Because the fermented wine is now alcoholic, the tannins it extracts have increased molecule sizes. That usually makes them a bit softer and less bitter than tannins derived from cold-soaking.

Wine Tannins and Aging 

We know wood and bark—especially oak—have tannins, and if wine is kept in constant contact with oak, it absorbs them. The longer a wine is aged in an oak barrel, the more tannins it will absorb from the oak barrel. But keep in mind that, as wines age, some tannin chains grow and resolve. The resulting wine can be varied combinations of tannins from different sources. That’s why aged red wines are considered the most complex. Optimal wine storage temperature and wine cellar lighting both have ramifications on tannin levels, too.

Tannins and Wine Tasting

Will tannins always be described as bitter and astringent? No. There are whole wine lingo dictionaries out there. And they have lots of words the wine community uses to describe the effect of tannins on the senses. Here are some them:

Aggressive: Wines with bold tannins and sharp flavors

Big: While big can refer to big fruit flavors, it can also refer to big tannins

Brawny: Big, sharp wines with raw, woody characteristics

Chewy: Wines with a thicker mouthfeel, often because of a firm tannic structure

Coarse: Robust and raw tannins; like brawny but without the woody bits

Dry: Another word for astringent, a tightening, puckering feeling in the mouth and tongue

Firm: Solid, bold tannic structure

Grippy: Like dry and astringent, these speaks to the constricting feel on the tongue

Harsh: Noticeable, strong tannins

Plush: The firm texture of tannins can make it feel thick and smooth in the mouth

Silky: Like plush, but with enhanced smoothness

Not only will these help you identify a tannic wine, but it can help you describe them, too. And that's a hand tool to have to upsell cocktails.

Tannins and Wine: A Love Story

We’ve defined tannins and given them some meaning within the context of wine and winemaking. We've also equipped you to recognize when tannic wines are being described. Higher tannins are an acquired taste, and because they’re not sweet or fruity they sometimes get a bad reputation. But wine wouldn’t be wine without tannins. They’re made for each other. And some of the biggest, most complex and impressive wines in the world are that way because of their expertly-managed tannin profiles. There should always be a spot in your wine inventory or wine cellar for some firm and complex tannic wines. They often fetch the highest wine bottle prices or wine by the glass prices and can boost your restaurant or bar profitability in a big way.

If you’re anything like me, this article is just one of many steps in your quest for how to become a sommelier. So go forth, pucker up, and enjoy the plush, brawny grip of tannins.