Tannins & Bitterness in Wine
Tannins contribute to two sensations on the palate – astringency (lack of water) and bitterness. (Please note the word: CONTRIBUTE. There are other components in wine that also can enhance one, or both, sensations.)
Tannins are a type of polyphenol. Polyphenols are a small molecule that in wine, come primarily from the skins of the grape and/or from wood contact (wood barrels.) Tannins cause the sensation of astringency …
An astringent substance is one that causes tissues to constrict. The word “tannin” originally comes from the process of using plant extracts to cure hides (remove water) to make leather. Think of the phrase “tanning a hide”.
In wine, the tannins bind with proteins in your saliva. (The next time you spit out a red wine – look into your spit cup – you will see some gross stringy things floating around. These are the tannins forming complex chemical chains with your saliva.) Tannins cause the sensation of all of the water (saliva) being removed from your mouth. In actuality, it is not being removed from your mouth (unless you spit or swallow) it is simply being ‘bound up’ so that it no longer coats the inside of your mouth. A high level of tannins in a wine will leave your mouth feeling rough, with a sandpaper-like texture.
We should describe this as – the sensation of astringency. However, it is commonly described as a drying sensation (a lack of water, not a lack of sweetness.)
We feel the sensation of tannins (astringency) all throughout our mouth. Mostly on the middle of the tongue, the roof of the mouth, the sides of the cheeks – and the gums. Astringency from tannins are felt all over your mouth.
Bitterness is one of the five primary tastes. Bitterness and astringency are often confused on the palate – but they are sensed differently. The receptor sites for bitterness sit at the very back of the tongue and the soft palate.
A good way to perfect your ability to detect bitterness, is with tonic water, which has quinine in it. Add a small amount of it to a neutral beverage until you just get to the point where you can start to detect it. Get the diet version with no sweeteners added. The sensation of bitterness will be localized primarily to this spot in the back of your mouth. (NOT all over your mouth, the way we sense astringency from tannins.)
Another way to focus on bitterness without astringency getting in the way, is to taste a dry (less sweet) wine AFTER a sweet wine. An example in easily found wines: taste something like Kung Fu Girl Riesling before tasting a unoaked Chardonnay like Hendry Estate. The Chardonnay will taste completely bitter.