Learn About Tannins in Wine: Definition, Origins, and 7 Ways Tannins Affect Wine

Tannins are substances found mainly in plants, bark, and leaves that create a drying, rubbing sensation on your tongue. Wine tannins are extracted from grape skins, seeds, stems-—and, notably, oak barrels.

Tannins are naturally occurring molecules (the technical word for these compounds is polyphenols). When grape skins, seeds and stems soak in juice, they release these tannins. The longer they soak, the more tannins they release.

The word “tannin” is centuries old, and derives from the process of using extracts from plants to cure leather—which is known as tanning. Some of the same plant extracts used for this tanning process are also used in winemaking.

Plants have tannins to make themselves unfriendly to other creatures that might otherwise consume them. From an evolutionary standpoint, they exist to deter animals from consuming a plant’s fruit, leaves or seeds before the plant is ripe. Tannins are the plant equivalent of a porcupine’s quills or a beaver’s tail. The existence of tannins is bad news for non-human animals—it means there is less for them to eat—but it’s wonderful news for wine aficionados.

A warm climate produces hyper-ripe grapes, while a cooler climate contributes to grapes aging slower. The difference influences the types of tannins that are created.

• In warm Australia, for example, Shiraz grapes are plentiful, with smooth, lush, rounded tannins.
• In the cooler climate of Bordeaux, France, meanwhile, cabernet grapes grow more slowly, producing more subtle tannins.

Tannins are added to wine through the processes of maceration and fermentation.

• Fermentation is the process by which yeast produces alcohol from sugar. In winemaking, fruit juice (typically grape juice) is the sugar source. When whole fruits are fermented—which means that their skin is still on—tannins are extracted in the process of fermentation. However, some wine is not made by fermenting the whole fruit. Most notably white wine tends to be made from the fermented flesh of grapes but not from their skin. Therefore such a fermentation process would produce very few tannins in the liquid solution.
• In maceration, wine that has already been fermented is steeped in a barrel of grape skins. The alcohol in the newly-formed wine helps seep additional tannins out of the grape skins and add them to the liquid solution. This process occurs under heat, but cold maceration is also possible (although that traditionally occurs before fermentation).

Understanding tannins isn’t just a matter of comprehending how wine is made. Tannins are deeply connected to the experience of tasting wine, too. Tannins have the following effects on winemaking and wine tasting:

1. 1. Taste. Most liquids aren’t considered “dry.” However, dryness, astringency, and bitterness are common to wine. Tannins are responsible for those unique sensations—tannins, not acidity, are what make wine wine. The drier your mouth is after tasting a wine, the more tannins the drink contains. That instinct to pucker your lips after sipping some red wine—that’s the effect of tannins.
2. 2. Structure. When people talk about structure in a wine, they’re referring to the complete picture a wine builds on your palate. And a lot of the structure has to do with the textural impression the tannins create in your mouth, although the overall harmony between body, tannins, and acidity is also important.
3. 3. Texture. Also called “mouthfeel,” texture is about the way the wine feels in your mouth and throat. The main contributor to texture is tannin. Tannin may be velvety, silky, firm, or astringent.
4. 4. Quality. Ripe, well-judged tannins create a sense of structure and depth. Conversely, an overly tannic finish will dry the mouth out, leaving the consumer reaching for water.
5. 5. Age. Tannins act as a preservative. Winemakers sometimes overload a bottle of wine with tannins so it lasts longer, giving it a longer shelf life. Tannins often become more subtle as they age, which is why aged wines are often coveted—and expensive.
6. 6. Strength. Many fans of wine believe that a little tannin goes a long way. When people speak of letting wine breathe, they mean that air can dilute tannins, making them smoother and understated instead of bold or even overwhelming.
7. 7. Balance. The ideal wine features balance, where acid, tannin, and fruit are all in harmony. An unbalanced wine is one where one element, like tannin, acidity, or alcohol, is higher than the others in a distracting or unpleasant way.

Tannins don’t just protect the plants from animals—they act as a natural antioxidant to protect the wine once the grapes are harvested and produced. This is actually one reason why certain red wines, including Cabernet Sauvignon, age so well.

Some people get headaches from tannins, even in small doses. The best way to determine if you’re susceptible to headaches from tannins is to sample other substances that also contain tannins, such as:

• Dark chocolate
• Apple juice
• Cinnamon
• Walnuts
• Almonds
• Peanuts
• Strong black tea

If you find that chocolate, tea, and red wine all give you headaches, stick to white wine or rosé and put aside the red.

Tannins can be removed from wine through a process called fining. Fining a wine is rarely done, except in these cases:

• If a wine is thought to be too astringent—containing too many or too strong tannins—manufacturers can remove the tannins creating these problems.
• If a wine seems too bitter to a winemaker, the winemaker can balance out the body of the wine by removing certain tannins and leaving others in.
  
• If a wine has too many proteins, a winemaker may choose to remove some of the tannins to reduce or prevent cloudiness.

Most white wines are fermented without their own skins, making them much less tannic—that’s why white wine is less dry than red wine. There are a few exceptions—some white wines might be more strongly tannic if they were kept in wooden barrels. That’s the case with Chardonnay, for instance.

And while red wines usually feature tannins, there are some reds that are more tannic, and others that are less.

The wines that are highest in tannins are all red wines. They include:

• Cabernet Sauvignon
• Monastrell
• Montepulciano
• Nebbiolo
• Petit Verdot
• Petite Sirah
• Sangiovese
• Shiraz

It is possible to drink low-tannin red wine. Such low-tannin varietals include:

• Barbera
• Gamay
• German Riesling
• Grenache
• Zinfandel/Primitivo
• Pinot Noir
• Tempranillo

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