When tasting red wines , we often refer to the tannins they contain. But these molecules, which give a very particular taste to wine, are often little known. So let's see what tannins really are , and their role in the production and characteristics of a wine.
What are wine tannins?
For once, the etymology of the word "tannin" won't really help you understand its meaning. Indeed, “tannin” comes from the Gallic word “tann”, which means “oak”. We are no further ahead!
In reality, tannins are chemical molecules, or phenolic compounds , which are found in the skin of the grapes, the seeds and the stems, but also in the wood of the oak barrel. On contact with saliva proteins, they create a reaction which gives a rough appearance in the mouth , or a more or less marked feeling of dryness.
The tannins of a wine can then be silky, we are talking about soft tannins, but they can also be much more imposing, even rough on the palate. To measure the tannin levels of wines, one can use the permanganate index .
What are the origins of tannins?
Tannins are naturally present in wines, and come from different elements of nature. They then evolve throughout the winemaking process, but also during the aging of the wine.
In the grape film
The amount of tannins in the skin of the fruit varies depending on the grape varieties . The thicker the skin, the richer it is in tannins. Those who have already tried the experience of tasting a grape picked from a vine intended for wine production will better understand this sensation of dryness in the mouth. In fact, table grapes have thinner skin and are much more pleasant in the mouth.
For winemaking, the thicker the skin of the grape, the more marked the tannin structure will be . We then see that Cabernet Sauvignon or Malbec produce wines with powerful tannins, while Gamay produces softer wines.
Furthermore, the more ripe the grapes are picked, the more supple and pleasant the tannins are on the palate.
In the grape seeds
Tannins are also present in grape seeds , and more particularly in their oily part. This is also why when biting into a grape seed, you can feel a strong acidity in the mouth, or even an unpleasant astringency.
In the stalk of the bunch of grapes
Tannins are also present throughout the plant part of the grape bunch . Some winegrowers then choose to keep this part during winemaking, and in particular during fermentation, in order to give the grape juice the antioxidant properties and the taste of tannins.
In the wood of oak barrels
Finally, tannins are chemical compounds that are also found in the wood of oak barrels used to age wine. The longer the wine is placed in barrels, the more the tannin characteristics will be marked on the palate.
Note that the younger the barrel, the higher the tannin content.
The characteristics of wine tannins
If you want to learn wine tasting, you will have to learn to put words to the sensations felt in the mouth. To describe tannins, several qualifiers are possible.
- Wines with powerful or hard tannins : in wine with hard tannins, the tannin content is such that an imbalance is formed, giving an unpleasant harsh taste;
- Wines with firm tannins : firm wine has a high tannin content, but not excessively. The wine is structured, without astringency;
- Wines with soft tannins : the tannins present in supple wine are balanced, letting the fruit aromas stand out with a slight roughness;
- Wines with soft or round tannins : wines with round tannins have a low tannin content, which allows the roundness and softness of the wine to stand out;
- Silky wines : silky wines are even lighter in tannins;
- Melted wines : more rarely, it can happen that the structure of the wine becomes homogeneous over time, and offers a very surprising and pleasant balance.
Tannins are naturally present in wine, and contribute to the more or less pleasant sensations that we can perceive in the mouth. To learn to distinguish the different types of tannins in wines, do not hesitate to take part in a tasting workshop in the cellars of the Berne estate.