What are the tannins? 

Tannins are a chemical substance found in fruit plants, seeds, bark, oak, leaves, and skin. Therefore tannins can also be found in grapes.

Usually the extraction of tannins from the grapes is done during the alcoholic fermentation process, which takes place in stainless steel tanks.

Tannins are present in both white and red wines. However, there is a larger concentration of tannins in red wines, because during the red wine alcoholic fermentation the skins of the grape are permanently in contact with the grape juice.


How can we appreciate them?

Tannicity brings bitterness and astringency to the wine, which we can mostly perceive in the front of our mouth and the center of our tongues. Moreover, tannins contribute creating complexity in flavor. They can be also appreciated visually, because they are what gives a wine its color.


Types of tannins and their quality

There are different types of tannins in every bottle of wine, and their quality depends on their origin. The sources of tannins are the following:

  • Skin: Different organisms and substances can be found in the skin of the grape, such as bloom, yeasts and tannins. In order to extract the tannins from the skin, the temperature of the fermentation tanks is raised. These tannins are good and desired by winemakers.

  • Seeds: Tannins can also be found in the seeds of the grapes. They are never extracted directly to avoid breaking the seeds during the process, because certain undesirable oils are found inside them. These tannins are unwanted and considered bad for the wine.

  • Stem: The stem is the woody part of the bunch, which joins all the grapes. Winemakers usually get rid of it with de-stemming, because it brings an undesirable kind of astringency and tannicity. These are also considered to be bad tannins and its extraction is avoided.

  • Barrel: Wood brings tannicity to the wine. The wood strips that form a barrel must be completely dry, or else they will bring green and astringent tannins to the wine. This type of tannins is highly appreciated by winemakers.


So next time you open a bottle of wine, you will already know what tannins are and how to spot them. Now it’s your turn to start classifying them!

By: Adrián Poch

Translated by Anna Carbonell