What Are Tannins?

Tannins are natural compounds found in various plants, including grapes. Tannins bind with proteins, starches, and minerals and help protect plants from bacteria, fungi, and other potentially damaging contaminants. 

Also, tannins impart a bitter flavor, and the unpleasant taste offers another protective measure. Unripe fruits are bitter because they have a high tannin content, but the concentration lessens as the fruit ripens. This process discourages animals from eating the fruit until the seeds are mature and ready to be spread. Animals then eat the fruit and spread the seeds in their droppings

 Tannins can also greatly affect the taste of wine. Grape skins and seeds have high concentrations of the compound. Because winemakers usually use the whole grape when producing wine, the tannic flavors are infused into the liquid and are evident in the finished product. Trees also contain tannins. Wine stored in oak barrels may get additional tannins during the aging process. 

While tannins are often associated with bitter tastes, they can add to the flavor or complexity of wines. Smoky or dry wines often get their characteristics from higher tannin content. 

Here is a look at this unique substance and how it affects the flavor and quality of wines.  

Factors That Impact Tannin Content

All grape skins and seeds have tannins, but the concentration varies depending on the variety. In general, red wines have a higher concentration of tannins than white wines. 

This is because the process of making red wine includes extracting color and flavor characteristics from the skin. However, there are significant differences in tannin content between red wine varieties. 

For instance, Cabernet Sauvignon grapes are famous for their thick skins and high concentration of tannins, which are partly responsible for the wine’s characteristic full-bodied robustness. On the other hand, Pinot Noir grapes have thinner skins and less tannin. This composition results in a lighter, smoother wine. 

The climate and conditions where grapes are grown play a role in tannin levels. Sun, water, and harvest time can affect the thickness of grape skin. Temperature also plays a role. Regions with warmer temperatures generally produce grapes with thicker skins. 

Winemakers can also influence how much tannin is pulled from grape skins. The process of maceration can affect tannin levels. During this step, when seeds and skins soak in freshly squeezed grape juice, the tannins can leach into the liquid. The longer the maceration time, the more tannic the wine. Also, exposing the wine to higher temperatures during fermentation can increase tannin levels. 

How you store and age your wine can also affect its tannin profile. UV light and temperature changes can change the chemical profile of a wine, muting the flavors and qualities imparted by tannins. Proper storage of your bottles can help you avoid this problem and ensure you are getting the full flavor experience the winemaker intended. 

Effects on Wine Flavor

Tannins create a sense of weight and body in the wine. At a wine tasting, you will swirl a glass of wine and see the “legs,” which is the name for the liquid that clings to the sides of the glass. You’re seeing the influence of tannins. They help increase the viscosity of wine, creating thicker legs that seem to cling to the side of your glass.  

Tannins also increase astringency, which is evident in the dry, slightly bitter feeling on the tongue when you taste a red wine. Wine enthusiasts often like this quality because it helps balance the natural sweetness imparted by the grapes. 

Wines with high tannin content often have a noticeable bitterness. This characteristic is especially evident in young wines that were just bottled. As the wine ages in the bottle, the bitterness is replaced by a more balanced flavor. This is why some older vintages that have been stored in the bottle for years are highly valued. 

Wines with lower tannin levels are smoother and emphasize fruit flavors or sweetness. Knowing these basic wine principles can help you make informed choices about which wines you might prefer. They can also help you choose the best bottle for pairing with food. Tannin-rich wines are often good partners for heartier or heavier dishes, such as red meat and hearty pasta dishes. Meanwhile, low-tannin wines properly accent white meat, seafood, or vegetarian fare. 

Wines With the Highest Tannin Content

Certain wines have high tannin content because of their grapes or the length of the maceration process. Luckily, you don’t have to look into the individual winemakers’ grape selection and processes to find out if a wine has high tannin content. Certain varieties are known for the qualities imparted by tannins. 

Here are the wines commonly known for their high tannin content: 

• Cabernet Sauvignon: Cabernet Sauvignon grapes have thick skins packed with tannins that give the wine a full body and intense flavors. Tasting these wines will often reveal slightly bitter qualities, akin to those found in dark chocolate or blackcurrant. Young cabernets are often quite astringent, but they get softer and smoother as they age in the bottle. 
• Chianti: Chianti wines use Sangiovese grapes, which have a high tannin content. These wines have a deep acidity, but they also have sweeter notes of plum and cherry. This quality makes the wine a bit more balanced than Cabernet Sauvignon. 
• Nebbiolo: Nebbiolo grapes are used in several Italian wines, including Barolo and Barbaresco. These wines are known for their complexity and earthy flavors and scents. Some wine enthusiasts do not drink them right after purchasing. Instead, they keep them in the cellar until the flavor softens.  
• Malbec: Though originally from France, Malbec is known as an Argentine wine. They are known for balancing bitter and fruity flavors, making them a good introduction for people who want to try high-tannin wines. 
• Bordeaux blends: Wine-makers in France’s Bordeaux region use Petit Verdot grapes in red wine blends. These grapes create wines with intense but fruity flavors. They are very high in tannins, which soften as the wine ages in the bottle. Petit Verdot fruits are ideal for blends because they give the wine a full body and add to the depth of flavor.  

The best high-tannin wines are a matter of personal taste and depend on food pairings and the quality of the aging process.

Tannin’s Impact on Health

Some people link tannins with headaches, claiming they get headaches after drinking red wine. However, this link remains unproven. One study published in Nature suggested that a compound called quercetin in red wine grapes could be the cause of post-wine headaches. However, Harvard Medical School indicates that tannins can spur the release of neurotransmitters associated with pain, which could lead to headaches. 

People concerned about the headache link can opt for rosé, white, or sweet wines, which have low tannin levels.  

Understanding tannins can help you know what to expect when you try certain wine varieties. This knowledge can also help you decide how long to keep your wines in the cellar and which foods to pair them with once you open them.