Tannins can be found in the wood, bark, leaves and fruit of plants, such as oak, rhubarb, tea, walnut, cranberry, cacao and grapes. One of their most important functions is protecting the leaves of plants during their growth. However, what are they, really? This blog post aims to answer this question.

Wine tannins: what are they and what they are good for

What do tannins do?

Tannins are primarily a class of polyphenols that prevent plants from being eaten by insects and other predators. They are bitter to the taste, but this property also helps to kill bacteria and fungi. In addition, they are the compounds responsible for the astringent taste that we often notice in the mouth when we eat foods that contain them.

What are the benefits of tannins?

Tannins are antioxidant compounds that also have a range of health benefits. In particular, they are anti-inflammatory, anti-cancer and anti-diabetic. They can also help to prevent sunburn and may help to reduce the risk of skin cancer.

Where can you find tannins?

Tannins can be found in many plants, but particularly in wood, bark, leaves and fruit such as oak, rhubarb, tea, walnut, cranberry, cacao and grapes. Other plants rich in tannins include ivy, tea, artichoke and elder.

Other food stuffs, such as red wine and chocolate, contain tannins, but they contain a type of tannin called procyanidins. These are more complex than the more familiar tannins found in plants, which are known as condensed tannins.

Where do tannins in wine come from?

In the winemaking process, tannins are extracted from the grape skins, stalks, seeds and stems. These tannins account for up to 5% of the weight of the grape and 10% of the weight of the raisin. Tannins possess high molecular weight, so they are not easily absorbed by our bodies.

Do tannins help a wine to age?

Yes, tannins help a wine to age. Tannins are phenolic compounds and are soluble in alcohol. They react with the proteins in our saliva and bind with them. This prevents the proteins from being broken down, and as a result, the proteins form a solid matrix in the mouth. This gives us the feeling of richness and fullness that is associated with a wine that has been matured in oak.

Different grapes, different tannins

Tannins may be found in the skin, seeds and stems of grapes, but they are found in different quantities depending on the grape variety. For example, Pinot Noir has a high concentration of tannins, so the wines it produces will have a long and slow ageing period. On the other hand, Merlot, which is known for producing fruity wines, has fewer tannins, and these don't need to be aged for as long.

Tannins provide a range of health benefits and protect the leaves of plants from being eaten. They are primarily a class of polyphenols that cause many of the physical and sensory properties associated with the mouthfeel of the wine. They are also the compounds responsible for the astringent taste that we often notice in the mouth when we eat foods that contain them.