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What’s the difference between Tannins and Acidity?
This one stumped me for a while. When you read about wine-especially red wine–you invariable hear some mention tannins and acid. What’s the difference? I wondered. I thought tannins were acid. At least, that’s what the dictionary says…. (See below) So, I decided to do a little research on the matter.
1. What Are Tannins?
“Tannin: 1. Tannic acid. 2. Any of various chemically different substances capable of promoting tanning.” The American Heritage Dictionary.
“Tannic Acid. A lustrous yellowish to light-brown amorphous, powdered, flaked or spongy mass having the approximate composition C76H52O46, derived from the bark and fruit of many plants and used in tanning, as a mordant, to clarify wine and beer, and as an astringent and styptic.” The American Heritage Dictionary
Okay, so we have a definition. But is it the right one when we’re talking about tannins in wine?
The answer, come to find out, is yes and no. Here’s why.
a. Hydrolyzable and Condensed Tannins
Tannins are a group of phenol compounds found in plants, which create a group of chemicals called “Polyphenols“. These polyphenols are, for the most part, soluble in water.
There are two main types of tannins: Hydrolyzable Tannins and Condensed Tannins.
Tannic acid is a particular type of hydrolyzable (basically means that it is able to be split up and broken down by interacting with water) tannin commonly found in the bark and wood of oaks and other plants. It is used commercially in tanning leather and in certain dying processes. So, what type of tannin comes from the bark of oaks and other plants? Hydrolyzable Tannins.
Another type of tannin, which is a non-hydrolyzable tannin, is called Condensed Tannins (also called “Proanthocyanidins”, but I like “Condensed Tannin” better, don’t you?). Condensed Tannins are often found in other plant sources such as tea, pomegranates and grape seeds and grape skins.
Hydrolyzable tannins and condensed tannins are the two main categories of tannins delineated.
b. Why Tannins tend to be in Red Wine
In general, the reason why red wine has tannins and white wine usually does not, is because red wine is made from red or purple grapes that are fermented with the seeds, skins and often pieces of stems1, which in turn give red wine its condensed tannins. White wine, on the other hand, is usually fermented with just the crushed juice from white grapes or skinless red grapes.
However, if a red or a white wine is later aged in oak (or other type of wooden) barrels, then a secondary source of tannin can be derived from the barrel as well. The type of tannins found in oak or other wood are the hydrolyzable tannins discussed above. It might even pick up some tannin from a cork as well.
3. In Summary: Distinguishing Tannins from Acidity
When distinguishing tannins from acidity, it is easier to start by comparing a white wine that has not been aged in oak (perhaps a Riesling-it is usually quite high in acidity) with a deep red wine (perhaps a Cabernet Sauvignon from California or Australia).
When you try the white wine, you’ll notice the tart, zingy flavor that makes your tongue salivate a little. Kind of like drinking orange juice.
When you try the red wine, you might have that tart, zingy feeling, too (the acid), but what you’ll also notice is that drying, puckery feeling that seems to roll down the middle of your tongue and coat your mouth. The wine feels deep and … complex. That’s the tannins in the red wine.
Just reading about the differences might be helpful, but really, experimenting would be even better. Try a white wine with a red wine. Drink some stepped black tea, too-I bet it will help you more than any description.
You can get an even better feel of the difference by comparing a red wine with high tannins and lower acidity, such as a Cabernet Sauvignon or Shiraz (Yellowtail Shiraz from Australia is a good example–not expensive) with a red wine with lower tannins and higher acidity, such as Valpolicella from Tuscany (Bolla creates an inexpensive version that you should be able to find in your grocery).
When you drink the Shiraz, you’ll notice your tongue feeling gripped with that dry, puckery, steeped tea flavor and the wine will seem very dense and thick. When you drink the Valpolicello, it will feel much lighter and crisper and the flavors will zing your tongue like drinking a glass of orange juice. This will help you sense the difference between tannins and acids in a red wine.
You know, I should really apologize to you. All this testing to discern the difference between tannins and acidity means you’re gonna have to go out and buy wine. And drink it. Lots of it.
Gosh.
Sorry about that.
Wondering if hydrolyzable tannins can be found in the stems of grapes? So am I. The research I’ve seen so far refers to the skins, seeds and stems as condensed tannins, but I have to wonder if the stems might contain hydrolyzable tannins as well since other fibrious materials such as bark or wood contain hydrolyzable tannins. f you find any information on this, please email me: jesse@antiwinesnob.com.
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