Take a bite of the skin of the grape, and chew it for a minute. Taste that puckery, bitter taste? What you are tasting fellow wine drinkers, are the tannins in the grape skin. Tannins are also found in the stems and seeds of the grape. These types of tannins are the least preferred type of tannin by wine drinkers and sometimes referred to as “the bad tannin”. Tannins are more noticeable in red wine, because it is macerated (soaked with skins and seeds) and sometimes fermented while in contact with the skins and seeds to extract the color from the skins.
Tannins are found in a lot of plants, like tea. They also have been used to aide in tanning animal skin. (uhm disgusting) But the type of tannins we care about are in the grape. But there is another type of tannin found in wine (these are referred to sometimes as the “good” tannins) are called “Hydrolyzable tannins”. Hydrolyzable tannins are extracted from the barrel of the wood. As your wine ages in it’s bottle, the “good” tannins will eventually go away. The “bad” tannins will be just as prominent in your wine, regardless of how long it ages.
Modern winemakers try to minimize the taste of the amount of the “bad” tannins by gently crushing the grapes while extracting their juice to avoid crushing the seeds. Tannins also play an important role in preventing oxidation of the wine. Un-aged wines with high tannin content can be less palatable than wines with a lower level of tannins
You probably have heard red wine is good for your heart? That is because of the, you guessed it, tannins. Tannins, in the form of proanthocyanidins (a class of flavinols) have been shown to have a positive effect of vascular health. The study showed that tannins suppressed production of the peptide responsible for hardening arteries.
So what does “mouthfeel” mean, anyways? Well I am glad you asked. Remember that puckery feeling when you bit into that grape skin? When you bite into the skin (or sip the wine) the tannins constrict your tongue and (this is kind of gross) the mucous membranes of your mouth. This cause the “furring” of the mouth, or puckering of the gums, a sensation very similar to what happens when you drink tea (which also has tannins) that has been steeped to long.. But the good news is, that all this “gross” talk creates the impression of a full-bodied liquid. Which for a wine, is a desirable effect.
There you have it, now you are an expert on tannins. Go out and get your mouthfeel on.....