Wine 101: Wine terms explained, Tannins

Tannins might sound complicated, but trust me, they really aren’t! Best described by the sensations they cause in your mouth; tannins are a type of molecule called a polyphenol. These molecules bind with proteins in your saliva and the food you’re eating while sipping your glass of wine. Tannins can have a drying effect, along with a whole host of other sensations in your mouth.

Tannin basics

Tannins are bitter tasting so birds and other critters don’t find them delicious. Found in grape skins, seeds, and stems, tannins are a grape’s natural defensive mechanism, protecting them from being gobbled up before they are fully ripe. If you don’t have a glass of wine handy, eat an apple or handful of walnuts or drink a cup of strong black tea– all are rich in tannins too.

Besides being bitter and drying, tannins can also be described as grippy, smooth, or silky. Pay attention to where you feel different tannic sensations in your mouth. How does the top of your tongue feel? What about the sides and tip of your tongue? Do you feel anything in the very back of your mouth?

Since white wines are made with very little skin contact, they contain fewer grape tannins than red wines. But tannins are also found in wood, so winemakers can infuse more tannins in both their white and red wines by aging them in wood barrels. Simply put, no matter where they come from– oak and other types of wood, skins, stems or seeds– tannins give wine structure.

Cat tongue

A newly opened bottle of red wine might give you a sensation I like to call cat tongue. Tannins in the wine can make your tongue’s tastebuds literally stand at attention, similar to the rough tongue of a cat. Sometimes, tannins will feel like they’re wrestling for a championship belt in the back of your mouth. Interestingly, wine tannins have this magical way of mellowing with age and exposure to oxygen!

When you find a bottle that gives you cat tongue, try swirling your glass to aerate the wine. After swirling for 30 seconds, take another sip. Did the prickly sensation decrease as the wine was exposed to oxygen? Does it continue to lose its bite and soften after more swirling? Allowing a wine to breathe actually changes its tannin structure, as the molecules begin to bind together, forming longer chains in a process called polymerization. With more air, the wine becomes silkier and smoother. The change can be quite dramatic, especially in younger bottles of red wine.

Affecting tannins in the vineyard

Along with winemakers and their ability to incorporate more tannins by aging wine in wood barrels, grape growers have developed several ways to manipulate tannins in their vineyards too. Watering the grapevines during specific growing stages can, in a way, dilute the tannins and slow maturation. Grapes exposed to more sunlight tend to have more tannins than those grown in more shade so vineyard managers can choose to do more (or less) leaf-pulling as the grapes ripen, depending on the desired levels of tannins.

Cooler grape growing regions tend to produce more tannic wines than those grown in warmer climates. The same holds true for vintages too. Warmer years produce wines with softer tannins and colder growing seasons create wines with higher levels of tannin.

Altitude also influences tannins so grapes grown at higher elevations have more tannins than those grown closer to sea level. Grapes tend toward more or fewer tannins, depending on the varietal too. For example, thicker-skinned Nebbiolo, Tannat, Cabernet sauvignon, and Syrah have higher degrees of tannins than thinner-skinned Merlot, Zinfandel, and Pinot noir.

Tannins and food

Lastly, polymerization– when the wine tannins bind with themselves, your saliva and the food you’re eating– can make for some memorable food pairings. Cabernet sauvignon and steak, Pinot noir and salmon, Syrah and aged cheese are just a few popular combinations. I encourage you to try your hand at pairing foods with wines of different tannin levels. It’s really fun to experience the many sensations wine tannins can produce in your mouth, especially with prolonged oxygen exposure.