Why Does Red Wine Make Your Mouth Feel Dry?

Two reds in your browser tab. A Cabernet a mate swears by, and a Pinot Noir at roughly the same price. You go with the Cabernet, and by the third sip your gums feel like they've been wiped with a tea towel.

Nothing is wrong with the bottle, and nothing is wrong with your palate. Last month's red felt silky because it was built on a different amount of one ingredient.

That ingredient is rarely on the front label, and it explains how a red feels in your mouth: tannin.

The short answer

Tannin latches onto proteins in your saliva, and saliva that can't lubricate leaves your mouth feeling dry, rough and a bit puckered.

That's the whole mystery. The rest is about which bottles do it a lot, which barely do, and how to buy the one you'll enjoy.

What tannin actually is

Tannins are natural compounds in plant bark, leaves, seeds and skins. In wine they come mainly from grape skins and seeds, a little from stems, and from oak barrels. Red wine ferments with the skins and seeds in the juice, so tannin dissolves out as the alcohol builds. Most white wine is pressed off its skins first, which is why it rarely does this to you.

Here's the bit most people have backwards. The dryness isn't a taste. It's a texture. Saliva is your mouth's lubricant, tannin grabs the proteins that make it slippery, and surfaces that were gliding start to rub. Think of it as pouring the oil out of a hinge.

Scientists are still arguing over the full picture, and touch-sensitive receptors in the mouth seem to play a part too, but protein binding is the leading explanation.

It also builds. In lab tests, perceived astringency kept climbing with repeated sips before levelling off. The first sip is the friendly one.

How tannic is your red?

Tannin can be measured in milligrams per litre (mg/L). Here are the average results for five common grapes.

Read that table as a rough guide, not a promise. These are averages from one large study of 1,325 commercial wines, mostly from the United States with some from Bordeaux and Australia, all measured with a single lab method. The spread inside each grape was huge: within Cabernet Sauvignon and within Pinot Noir, the most tannic wine had about 32 times the tannin of the least. Winemaking, vintage and region move the number more than most people expect. And a high number doesn't always mean a harsher mouthfeel: a separate study found Carmenère wines with plenty of tannin that tasters still rated as less astringent than other reds.

Now the trap. "Dry" and "drying" are two different things. In wine, "dry" means not sweet. "Drying" is the tannin. Plenty of people who say they "don't like dry red" are really saying they don't like tannin.

Which one should you actually buy?

• New to red, or you normally drink white: Pinot Noir. Lowest tannin of the five on average.

• Weeknight pasta, pizza or roast chicken: Merlot or Shiraz. Enough structure to hold its own without gripping.

• Steak, lamb or anything off the barbecue: Cabernet Sauvignon. This is where the tannin earns its keep.

• Sipping on its own, no food: lean towards the low end. A big tannic red with nothing on the plate is the classic tea towel scenario.

Grape is only part of it. Skin soak time, stems and new oak all push tannin up or down, and wines from riper grapes tend to feel softer. White wines sit lower still, though skin-contact whites (orange or amber wines) can have noticeable tannin.

Will a steak fix it?

The old rule says red wine with red meat, and there's real science behind the instinct, with a catch.

In a 2012 study from the Monell Chemical Senses Center in Philadelphia, volunteers alternated sips of tea with bites of dried meat. Compared with water, the tea left the meat tasting less fatty, and fatty food reduced the build-up of astringency from the tea. The researchers didn't serve anyone a Cabernet. Tea is astringent for related reasons, so it's a reasonable stand-in, but it's still a stand-in. The study had 21 volunteers, and dried meat carries salt and protein as well as fat, so it can't pin the effect on fat alone.

Treat it as support for the instinct, not proof of any particular pairing. Cheese and red meat tend to soften a tannic red, while something sharp like a green apple does the opposite.

Does age fix it?

Sometimes, and the reason is less settled than you'd think.

The common explanation is that tannins join up into longer chains as a wine ages, the longer chains feel smoother, and some grow big enough to drop out as sediment. But larger tannins are generally more astringent, not less, so chain-building alone shouldn't soften a wine. Research from the Australian Wine Research Institute and elsewhere points to falling tannin levels and structural changes, including colour pigments bonding into tannins, though the details are still being worked out.

What holds up is that red wines generally feel softer with age. If you're buying to drink this week, buy for the style you want now.

The plot twist: tannin is a leather word

The word comes from French, which got it from "tan", the crushed oak bark tanners used to turn hides into leather. Tanning works because tannins bind to proteins, and a hide is mostly protein. So is the film of saliva in your mouth. Your mouth isn't turning into leather, because saliva keeps coming, but it's a small cousin of the same chemistry.

So when someone calls a red "grippy", you can tell them the word started out in a tannery.

The bottom line

Tannin isn't a flaw and it isn't a quality score. It's a texture, and it's about matching it to the moment. Too much with nothing to eat feels like hard work. The right amount with the right plate is what holds the wine up.

To make it stick, order a Pinot Noir and a Cabernet Sauvignon, open them the same night and take three sips of each, no food. Then go back to the Cabernet with a bite of something rich. You'll feel the difference on the first sip and the fix on the third.

Browse our red wine range, with fast delivery Australia wide and free shipping across NSW on orders over $150. Not sure which way to go? Email us at order@whiskywinesake.com and tell us what you're eating. We'll match the tannin to the meal.

FAQs

Why does red wine make my mouth feel dry?

Tannins bind to proteins in your saliva, which reduces its ability to lubricate. The result is a dry, rough, puckering feeling known as astringency.

Is a "dry" wine the same as a drying wine?

No. "Dry" means the wine isn't sweet. "Drying" describes the tannin sensation. A wine can be one without the other.

Which red wines have the least tannin?

Of the five grapes in the largest published comparison, Pinot Noir had the lowest average.

Does white wine have tannin?

Far less, because most white wine is made without skin contact. Oak ageing can add some, and orange wines can have noticeable tannin.

What helps if a red feels too tannic?

Food with some richness, such as red meat or cheese, tends to soften it. Astringency also builds with repeated sips, so alternating sips with food helps.

Does tannin go away as wine ages?

Red wines generally feel softer with age, but the exact reason is still debated, and there's no guarantee a given bottle will improve.