Where Does Wine Get
its Tannins and Color?

By Cole Swanson
November 22, 2024

The tannic level and color of a wine derive from the skins of the grape and are known as phenolic flavonoids. The term phenolic flavanoid encompasses four compounds, but we are going to focus on tannin and anthocyanin – the two most important for the grippiness and drying sensations and color of a wine. 

What Are Tannins?

Tannins derive from the skins, seeds, and stems of the harvested wine grapes. They are found in red wine predominantly, and provide a grippy sensation on your teeth and gums that can cause the mouth to feel dry. 

It is also the main component responsible for determining the body of the wine and is the antithesis of acidity, as more tannins means a fuller-bodied wine, while more acidity makes the wine feel less full. 

Tannins are found in many foods besides wine, such as berries, peas, leafy greens, coffee, and tea. Let’s consider tea for a moment to better understand how tannins work. If you were to place a tea bag into water and sip periodically, you’ll experience a grippy sensation on your teeth and gums that intensifies the longer the bag has been submerged. Those are tea tannins that have been extracted – this is also considered maceration. In the case of wine, tannins macerate in their own grape juice during fermentation to be extracted.

Tannin: Phenolic Flavonoid

As a phenolic flavonoid, tannins are responsible for bitter flavors and astringency, a sensation that causes the muscles in your jaw to tighten and mouth to dry by binding with proteins in saliva. These bitter flavors are found mostly in red wine because the skins remain in contact with juice during the entire fermentation process. White wine, however, does not impart tannins or as many bitter flavors because the skins of white grapes are removed before fermentation begins.

The amount of tannin in a wine is due to the amount of tannins in the grape skins – this is evaluated based on the length of the tannic compound inside the skins. Grapes with more tannins, for example, are Cabernet Sauvignon, Syrah, and Nebbiolo, and create wines generally described as “bold” or “big,” and will be more bitter. In contrast, grapes such as Pinot Noir, Gamay, and Cinsaut have less tannin in their skins, and are made into wines typically described as “lighter-bodied,” and will be less bitter.

Wine’s Color: Anthocyanins

Tannins are not where the color of red wine comes from, but the color does also come from the skins of a grape like tannin. Another flavonoid phenolic, called anthocyanin, is responsible for pigmentation. Like tannin, anthocyanins are a compound found in the skins of the grape and are water-soluble, meaning that if you were to squeeze a red grape enough for the juice to escape and place it in water, you’d find the water becomes purple. Such is the case during fermentation.

As the grapes are crushed in a tank, the juice is released and interacts with the skins of the grapes, dying the grape juice purple. This is also why white wine has very little color, because, again, the skins of the grapes are removed before fermentation.

Anthocyanins are found in many plants and fruits, and are known to have powerful antioxidants, which positively affect human health. Examples are strawberries, blueberries, and grapes – essentially many fruits and vegetables with purple-ish skin. This pigmentation is the result of anthocyanins and/or other antioxidants.

Note to Know

Just because a red wine is light in color does not mean it will not have a lot of tannin. In the case of Nebbiolo wine, it is lighter in color than a Cabernet Sauvignon, but is known for its high amounts of tannin. This is because the anthocyanin compound is lesser, but the tannic compound is still great.

References:

Jennifer Angelosante. 2020 Mar 27. Guild Somm: A Guide to Wine Phenolics. Guild Somm. 2024 Nov 20 https://www.guildsomm.com/public_content/features/articles/b/jennifer-angelosante/posts/phenolics

Taghavi T, Patel H, Akande OE, Galam DCA. Total Anthocyanin Content of Strawberry and the Profile Changes by Extraction Methods and Sample Processing. Foods. 2022 Apr 7;11(8)

He F, Liang NN, Mu L, Pan QH, Wang J, Reeves MJ, Duan CQ. Anthocyanins and their variation in red wines I. Monomeric anthocyanins and their color expression. Molecules. 2012 Feb 7;17(2)

Jim Harbertson, Associate Professor of Enology. 2007 Jul 07. Grape and Wine Phenolics: A Primer. Viticulture and Enology: The Study of Grapes and Wine With WSU. 2024 Nov 20. https://wine.wsu.edu/2007/07/07/grape-and-wine-phenolics-a-primer/