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Dear Dr. Vinny,

I was wondering, since exposing a wine to cold temperatures leads to tartaric acid crystallization, does the overall acid level decrease in the remaining wine? Could we then reduce the acidity level of a wine by putting it in the fridge and then decanting it?

—Yann, Bourgogne

Dear Yann,

The short answer is no, not really. For those trying to follow along, Yann is referring to tartaric acid, one of the natural acids found in grapes. When a wine gets really cold, the tartaric acid can settle out and form shards that look like rock candy. And once tartrate crystals form, they don’t dissolve back into the wine.

So, Yann wonders if you could do a bit of tinkering with this method at home, if a wine is too acidic for your taste and you want to take some acidity out. I see the logic, but not all wines will develop crystals simply by cooling in a refrigerator. The wine may have already been through the process of cold stabilization, for one, or it may not have high enough levels of tartaric acid, which is just one of the several types of acid that might be in your wine.

I checked with professor Roger Boulton at the University of California at Davis, and he notes that if you do chill a wine enough for crystals to form, there will be a loss in the acidity, but it will be very small, not significant enough to be perceived by taste. So, technically the answer might be yes, but you won’t be able to tell.

—Dr. Vinny

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