What Are Tannins?


Oh, tannins. We're sure you've heard a lot about them, particularly concerning red wine like pinot noir or cabernet sauvignon. But have you ever stopped and wondered what the heck tannins are and where they come from? Sure, you know what they taste like, but why? Well, good news. We winemakers know a thing or two about tannins, and today, we're feeling up to sharing all of our winemaking knowledge with you. So, let's begin our lesson, shall we? 

What Are Tannins?

So, let's start with the word "tannin." The word itself is old and reflects a technology that we still use today: the process of tanning. No, not the process of slathering yourself with a self-tanner, but we like where your head is. Tanning, aka waterproof and preserving, is a word used to illustrate changing animal hides into leather utilizing plant extracts from various plant species' components. 

Tannins are naturally occurring plant polyphenols. Alright, we'll pause because, honestly, who knows what polyphenols are? We sure as heck did not know until we started making (and drinking) wine. Polyphenols are a massive family of naturally occurring organic compounds characterized by multiples of phenol units. They are abundant in plants and are structurally diverse. 

So back to tannins, in nature, their main distinction is that they bind and precipitate proteins.  Tannins significantly influence the nutritional value of many foods. They are common in fruits, black tea, chocolate, and fruit. 

Whether you realize it or not, tannins are present in numerous aspects of our daily lives. Plant parts containing tannins include bark, wood, fruit, fruit pods, roots, and plant galls. And while you might not knowingly interact with these elements day to day, they are present. The astringent taste you experience when you have wine and unripe fruits? Thank tannins. The delightful and beautiful colors in flowers and autumn leaves? Another thank you, tannins!

What Do Tannins Do?

What do tannins do when they are in their natural habitat? Well, tannins are a defense mechanism. Similar to your self-deprecating humor, tannins act as a protection against pathogens, herbivores, and hostile environmental conditions. In general, tannins produce an adverse reaction when consumed. These effects of higher tannins can be relatively instantaneous, like the astringency and acidity or bitter taste. 

The reason plans have tannins is to make themselves unpalatable. In nature, they discourage animals from eating a plant's fruit or seeds before the plant is ripe. Nature, how neat is that? If you've ever bitten into an unripe fruit, such as a plum or pear, you know that astringent, mouth-coating feeling you get. Tannins are the responsible culprit! 

Although tannins are known for their less than desirable taste, they can be incredibly delicious when executed well. Moreover, some foods and beverages are cherished for their tannins. We're talking about tea, coffee, dark chocolate, and most importantly, wine. 

In wine, tannins come from four primary origins: grape skins, seeds, stems, and the wood barrels employed during aging. Tannins in wine contribute to the texture and mouthfeel of wine and give wine weight and structure. 

Red wines are better known for having tannins. However, white wines also have tannins, although notably less than their red wine counterparts. This is due to the difference in the way red and white wines are produced. White wine is created mostly from the juice pressed as soon as the grapes get into the winery. In contrast, red wine is created from the entire grape. As red wine ferments, it does so with the grape's skins, seeds, juice, and sometimes even stems. During the fermentation process, both color and tannins are transferred into the wine. 

How Do You Describe Tannins?

When describing tannin content, it is crucial to differentiate between the quality and quantity of tannin molecules. To illustrate the tannins' quality, one usually describes the texture utilizing words like silky or plush. When a wine has a good ratio of noticeable but not overwhelming tannins, one may describe the wine as 'grippy.' If tannins are described as 'green' ripeness, they are often slightly bitter, pucker, and have an unpleasant astringency. Lastly, if a wine is described as polished or elegant, the low tannins are fine-grained in texture, so they are noticeable but simultaneously pleasant. 

Mature wines are often described as having 'resolved' tannin varietals, which means they are soft, smooth, and no longer have an astringent taste. Another element to keep in mind is the difference between bitterness and astringency. Bitterness refers to taste; in contrast, astringency refers to the sensation. 

Here are some tips when you describe a wine: ask questions like, do the tannins immediately coat the mouth, or do they appear slowly? Do they dominate the wine, or do freshness and fruit equally match them? Are they integrated and gentle, or are they assertive and harsh? 

While tannins are a collective term to describe many phenolic compounds, tannins all have one thing in common: they bind and precipitate proteins. In other words, tannins separate them. So what does this mean for the average wine drinker? Human saliva is packed with protein; that is why saliva is so slippery. A red wine heavy in tannins will bind to spit, which is what causes your mouth to feel dry. This protein-binding attribute is the reason why red wine and steak make such a delicious pairing: the way the tannin wine's astringency counteracts the fattiness of the meat. 

Do Tannins Affect Wine Aging?

Here is where a debate kicks in. Some say that tannins help a wine age, but others argue that wines age equally well without tannins. Mouthfeel changes as red wines like Bordeaux, merlot, or syrah mature. While the tannins initially in wine are smaller, tannins start to combine and form more extensive, more advanced chains as time goes on. This process is known as polymerization. 

One argument is that this aging process decreases the tannins' reactive surface, creating a softer mouthfeel. The tannin chains become so long that they fall out of suspension, which sometimes makes a deposit and leads to sediment in bottles. 

All of this to say, it's not clear whether this reaction is the only thing that makes aged wine less astringent. Regardless, mature wines typically are described as having resolved tannins, which are smooth, soft, and not astringent. If a red wine has a bitter and unbalanced tannic structure initially, no amount of aging will ever take them out. 

What Other Foods Are High in Tannins?

As we discussed, there are tons of common human foods that have tannins. These include fruits, vegetables, some grains, chocolate, coffee, tea, and wine. 

White wine also has tannins. However, they are not as prevalent and noticeable as tannins in red wine. Some white wines undergo a short period of maceration, aka skin contact. After grapes are harvested and crushed, they are left with a few hours or longer with their skins before the grape juice begins to ferment. This process pulls flavors out of the grape skin. 

As of late, there has been a rise of "orange wines" or amber-colored wines with white grapes that are vinified with full skin contact, similar to red wines. These orange wines have a tannic element, although they are not as high tannin as red wines. 

Sparkling wines also have a trace amount of tannins. Sparkling wine's bubbles act like little magnifying glasses that highlight each aspect of the wine. Because the bubbles create a textural element, and bottle-fermented wines have a texture that comes from aging on yeast, tannic wines usually come across as bitter and exacerbated by the bubbles. This is why the pressing regimen for high-quality sparkling wines is essential. While very few red sparkling wines exist, those that do counteract the bitterness with sweetness. The wine will still taste dry but have sugar to take the edge off.