What is in a Glass of Wine?: Tannins

What is in a Glass of Wine serves as a foundation for learning about the chemical components of wine: This post is about tannins in wine but there are also acid, alcohol, sugars and aromatic components…Though water remains the most abundant.

These components, called “Structural Components”, help define the taste of wine, and they are very helpful in understanding the wide variety of aromas, flavors, tastes and textures of wine. This series of posts explains how these components appear in wine and how they affect the taste, with special attention on the different aspects that can make them change or evolve.

Here it comes: What is in a Glass of Wine? (III): Tannins

Ready for more about this topic?

Among the 3% of other components of wine, in this video we take a look at tannins.

What are tannins?

Tannins are components responsible for the structure of the wine and belong to a chemical group called phenolic components. Among them, there are other famous substances of wine, like anthocyanins (responsible for the color of wine) and resveratrol (well-known and discussed due to its antioxidant properties).

Biologically, tannins are molecules developed by plants as natural defenses and preservatives… And they affect the taste of the wine. Tannins come from the skins, the seeds or the stems of the grapes and are also present in wood. So, wines fermented in contact with the skins, seeds or stems of the grapes or aged in oak barrel, have tannins. According to the winemaking techniques, red wines and rosé wines always have tannins. White wines can have tannins too if they spend time in oak.

How tannins are perceived?

Tannins in wine are described as structure, as a sensation of dryness and bitterness. The dryness is caused because tannin molecules associate with saliva molecules, “kidnapping” them that makes the mouth feel dry with no saliva. Tannins also have a bitter taste, noticeable in the center and at the back of the tongue.

The taste and intensity of tannins depend on the grape variety. Here is a scale of some varieties ordered by the intensity of their tannins (from less to more tannic):

LESS TANNIC – Gamay – Pinot Noir – Sangiovese – Grenache – Zinfandel – Syrah – Malbec – Merlot – Mourvèdre – Cabernet Franc – Cabernet Sauvignon – Petite Syrah – Nebbiolo – MORE TANNIC

The perception of tannins depends on 2 factors:

– The management of the vineyard: tannins change in the grape during the ripening process. This ripening process can be affected by several agricultural practices as pruning. Unripe tannins taste different than ripe tannins, so the level of ripening or maturation of tannins when the grape is harvested is crucial to the final taste of the wine.

The winemaking process: many techniques in the winery affect intensity of tannins. They can be moderated by aging the wine, increasing their intensity by aging in oak barrels or softening their intensity by aging in the bottle.

Perception of tannins depends not only on the amount of tannins wine has,  but also on the quality and characteristics of these tannins. 

Remember that tannins make a drying sensation in the mouth? Therefore, something you eat and pair with wine can affect the taste of wine. For example, pairing high tannic wine (which dries the mouth) with rich and oily food like lamb, pork chops or cheese softens the impact of the tannins.

In Spanish, there is a curious saying: “do not let them to give it to you with cheese”. This reflects the idea that a harsh, unbalanced wine with unripe tannins can appear better to your palate paired with a rich food such as cheese.

What else about tannins?

Since tannins are natural preservatives of the wine, wines that have a good tannic structure age better that wines that don’t.

⇒ See related posts:

Last note: I’ve separated this post in 4 parts, so they are easy to manage. They are:


What is in a glass of wine: Tannins

Tannins in wine in What VINO Learning about wine


  1. What is in a glass of wine - What VINO LEARNING ABOUT WINE - […] What is in a Glass of Wine? (III):  a short recap of the first video and then a focus…

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