When enthusiasts talk about wine, at some point, tannins will come into the discussion. And rightly so because tannins are a major factor for the wine experience. But what are tannins, and what to they do in wine?

What Are Tannins?

Tannins are natural compounds in grape skins, seeds, and stems. They affect the color and age-worthiness of wine. And they also contribute to the balance and structure of a wine. In the mouth, tannins create a drying, puckering sensation.

What Are Tannins Chemically and What Do They Do?

Scientifically speaking, tannins are molecules that belong to the polyphenols. They consist of oxygen, hydrogen, and carbon atoms.

Tannins occur naturally in many plants, including grapes, pomegranates, almonds, walnuts, or red beans. But they also exist in tea, coffee, and tree barks. They function as a natural line of defense in two ways:

  • First, they help keep the plant healthy by protecting it against germs.
  • Second, their flavors reduce the appetite of herbivorous animals and keep them from consuming the plant.

How Are Tannins Added to Wine?

Tannins can get into wine from two different sources:

  • From the grapes’ solids: the skins, seeds, and stems. After the harvest, winemakers crush the grapes either manually or mechanically. Then, they transfer the crushed grapes to a container to start the fermentation process. Typically this container is either a wooden cask or a steel tank. During the fermentation, the wine must absorbs the tannins from the grape solids.
    A technique to fasten this process is “maceration”. Winemakers who use this technique, expose the wine to heat and oxygen in order to cook it. Among other results, this process allows more tannins to get into the wine.
Close Up of Red Wine Must Fermentation

Red Wine Grapes Fermenting with Solids

  • From wooden containers during the aging process. Many vintners store their wines in oak barrels to give them the chance to age and develop more complex aromas. When the wine gets in touch with the wood, it slowly absorbs its tannins. As oak barrels are costly, some winemakers prefer an alternative method to achieve the same goal: They add oak planks or chips to the most.

More Details on Oaking: WHAT IS OAKED WINE AND HOW DOES IT TASTE?

Each varietal has a different level of natural tannins in it. By choosing the right grape and the proper production process, winemakers can impact the tannin level in their wine.

How Do Tannins Affect the Characteristics of Wine?

Winemakers have numerous reasons to manipulate the level of tannins. Among them are the desire to change the wine’s color, its quality, and its age-worthiness.

How Tannins Affect the Color Of Wine

Tannins are the major contributor to wine color. When the crushed grapes ferment, the tannins in their solid parts get into the wine must and change its color. The longer they are in contact with the wine, the deeper will its color become. That means that you can estimate the tannin level by investigating wine color: A pale reddish color is an indicator of a low-tannin wine. In contrast, a dark purple color is a sign of a high-tannin wine.

Vintners typically separate the solids of white grapes from the wine must immediately after crushing them. That means that tannins have no chance to color the wine. Thus, wine from white grapes stays white (or yellowish if you will). There is an exception, though: orange wine. Orange wine is made from white grapes as well, but it ferments together with the grapes’ solid parts. That allows the tannins to color the wine and give it a deep orange tone.

How Tannins Affect Wine Quality

The structure of a wine is a major quality factor. It refers to the interplay of different characteristics: the different aromas, the acidity, and the tannins. A proper level of tannins contributes to a wine’s quality, given it’s in balance with the wine’s acidity, aromas, and mouthfeel.

How Tannins Affect the Aging Ability of Wine

As mentioned before, tannins are a defense mechanism for grapes. And when transferred into the wine, they also function as a preservative. That means that a high-tannin wine will keep significantly longer than a low-tannin wine. So wines with a high level of tannins have a bigger chance to age and develop a more complex structure.

During this aging process, the tannins themselves change too. They become softer and more subtle. The astringent, mouth-drying experience when drinking the wine is less distinct. Typically, wine lovers call wines that provide this improved experience “smooth”.

Aged wines with complex aromas and smooth tannins are the most desired and often the most expensive. In contrast, wines with aggressive tannins tend to create an overwhelmingly astringent and rather unpleasant experience.

How Do Tannins Taste?

Tannin has a bitter taste that you can experience on the back of your tongue. The higher the level of tannins in a wine is, the more distinct will this bitterness be.

Even more important than its taste is the sensation tannin creates. A wine that is high in tannins dries the mouth. It creates an astringent feeling that makes you want to grab a glass of water. You might say that it feels like your gums would stick to your cheeks. Wine experts refer to a wine that provides this experience as “tannic”.

By the way, if you want to test a very straight tannin experience, try this: Brew a cup of black tea. Let it steep longer than it should so that it becomes really strong. Now take a sip. The initial sensation when drinking this tea is almost pure tannin.

Which Wines Are High in Tannins?

The most tannic wines are produced from red varietals. Among them are:

  • Cabernet Sauvignon is a varietal that vintners grow all around the world. No matter where they do it, the resulting wines are always very tannic. Some Bordeaux wines (that typically are blends of Cabernet Sauvignon and Merlot) are almost undrinkable when young. That’s true in particular for wines with Cabernet Sauvignon as the dominant grape. But after a long aging phase, the softened tannins make them very enjoyable. Besides, wines from the Napa Valley tend to contain a high level of tannin.
  • Sangiovese grapes originate from Italy. But vintners in the United States, Argentina, Corsica, and other countries cultivate it too. Sangiovese grapes are the basis for numerous Italian blends, including Chianti, Brunello, Tignanello, and also Super Tuscans. Most of them are high in tannins, and especially Brunello wines are very age-worthy.
  • Syrah (or Shiraz as Australians call it) is a versatile varietal that can produce many different styles of wine. Many of them are on the tannic side. In particular, wines from the new world (Australia, California) tend to be high in tannins. But the same is true for Syrah that comes from the Northern Rhone region in France.
  • Another Italian varietal that produces high-tannin wines is Nebbiolo. It’s the dominant grape in the region of Piedmont. Winemakers use it to make high-quality wines with great aging abilities. The most popular examples are Barbaresco and Barolo.
  • Tempranillo grapes are tannic as well. They originate from Spain. Vintners grow it in the regions of Navarra and Rioja in Northern Spain. In some cases, they take measures to add even more tannins to their wines. Rioja Reserva, for instance, ages for two years in oak barrels before bottling. Besides Spain, you can find Tempranillo wines from Portugal and New World regions like California, Texas, Mexico, and Argentina.
  • Tannat comes from a region in the Southwest of France, close to the Spanish border. In the last years, many winemakers in the new world started growing it too. You can find it in Uruguay, Argentina, Brazil, and the United States. While wines from Latin America are rather soft and approachable, Tannat wines from France typically are very tannic.
  • Other tannic red wines are Argentinian Malbec, French Mourvèdre, and Italian Montepulciano.
Bottle and Glass filled with Rioja Wine

Bottle of Rioja Reserva

Tannic white wines are rare. Only oaked wines might have a significant level of tannins, especially Chardonnay from New World countries. Nevertheless, they are still less tannic than the red wines mentioned above.

More Details on New World Wines: COMPARING OLD WORLD WINE VS. NEW WORLD WINE

Which Wines Are Low in Tannins?

Most white wines contain only little tannin that is barely detectable when drinking them. But you can also find red wines that contain low levels of tannin:

  • Pinot Noir wines belong to the most famous wines in the world. They are light and approachable. Their low tannin levels are one reason for that. Pinot Noir is widespread in Central France, where it’s the only component of red Burgundy wines. Beside, winemakers in Germany, Switzerland, Austria, United States, Canada, and Australia grow it.
  • Barbera is an Italian varietal. Just like Nebbiolo, it originates from the Piedmont region. But nowadays it is grown all over the country, and it also made its way to California and other New World wine regions. Barbera wines like Barbera d’Asti are low in tannins, but high in acidity, making them a great match for rich dishes.
  • Frappato comes from the Italian island Sicily. It’s an important ingredient in fruity Cerasuolo di Vittoria blends. You can also find pure Frappato wines of excellent quality.
  • Gamay is popular in Beaujolais, a French region adjacent to Burgundy. Gamay wines such as Moulin à Vent or Morgon taste similar to Pinot Noir. Actually, there is a tradition of blending Pinot Noir and Gamay in Switzerland, where vintners cultivate these grapes as well.
  • Other low-tannin varietals are Schiava (also called Vernatsch), Dolcetto, and Etna Rosso. All of them are from Italy.

Final Words

As you have read, tannins are an essential component of wine and contribute significantly to the drinking experience. With the information in this article, you are not only able to understand the effect of tannins. You are also capable of finding new wines that match your personal preferences in terms of astringency.