Updated: Nov 23, 2021
Tannins are a type of bitter and astringent naturally occurring compounds that occur in grape skins, seeds, and stalks they are scientifically known as polyphenols. Polyphenols bind with protein and other molecules causing them to precipitate. When they bind with the protein in human saliva, they give the sensation of drying the mouth out and coating it with a textural component.
Tannins don’t only occur in wine; they occur in many other plants in nature where they act as a deterrent to animals to stop them from eating the fruit or seeds before they’re ripe.
For most people, tea is the most common occurrence you will come in contact with tannins, if you over-brew a cup of black tea then you should be able to notice the tannins pretty easily. They also come across in coffee, dark chocolate, rhubarb, walnuts, and cranberries – in some cases giving a very pleasant sense of bitterness and astringency.
The word tannin itself comes from the Latin word for oak bark, this was what tanners used to use to tan leather. The polyphenols in the oak bark changed the chemistry inside of the leather fibres making it harder for spoilage enzymes to break them down – helping to turn animal skins and hides into leather.
As you can see from the above tannins also come from oak. By ageing your wine in oak, as well as adding flavour you are also adding extra tannins to the wine, these tend to be fairly fine-grained, so some whites will have tannins that come from the oak rather than the grape.
They sound terrible. Are they bad for you?
Not at all – the opposite has been shown to be true, tannins are actually an antioxidant that are constantly touted as being good for you.
Tannins can give some people headaches, but if you are susceptible to them then you would also get headaches from tea, some nuts, cranberries, chocolate, and all of the other delicious foods mentioned above.
Sadly, the most common cause for headaches from wine is from the alcohol.
Some red wines have more tannins than others
Different grape varieties have different levels of tannins.