Q: What is wine sediment made of, and is it safe to consume?—Leonard, Spokane, Wash.
A: Many wine lovers have had a run-in with sediment, a natural byproduct of winemaking and the aging process. While most people agree that consuming sediment isn’t all that pleasant, it makes sense to wonder if the grit at the bottom of your glass presents any health risks.
In white wines (and occasionally rosés and sparkling wines), sediment most often takes the form of small crystals that fall to the bottom of the bottle or stick to the underside of the cork. These crystals may look like sugar, glass or even “wine diamonds,” but they’re actually a harmless acid salt called potassium bitartrate (also called potassium acid tartrate, potassium hydrogen tartrate or even just “tartrate”). These crystals form during winemaking from tartaric acid, the principal acid in wine. They can have a slightly acidic, generally pleasant taste, though they’re tasteless to many people. They form at low temperatures, which is why they’re especially common in white wines that have been refrigerated. On the other hand, cold stabilization during winemaking makes the finished wine unlikely to contain tartrate crystals.
The most common name for potassium bitartrate is cream of tartar, which you probably have in your kitchen next to the baking soda (it’s also a common component of baking powder). The Food and Drug Administration classes potassium bitartrate as “generally recognized as safe,” meaning it can be freely used as a food additive. Most people have probably consumed cream of tartar in meringue, cookies and other foods. Some studies have linked consuming massive quantities of potassium bitartrate—usually to achieve a laxative effect—with dangerously high blood potassium levels, which can lead to heart problems. However, the small amount in wine shouldn’t pose any risks.
In red wines, sediment is a complex mixture that includes spent yeast cells, leftover bits of grape matter, and polymers—long molecular chains made of pigments, tannins and other phenolic compounds. These polymers form as a wine ages, so many red wines accumulate sediment as they get older (though some young reds, especially those that haven’t been fined or filtered, can “throw” sediment too). Certain wines—particularly Bordeaux, Vintage Port and other highly concentrated reds—are famous for forming significant amounts of sediment as they age.
Just like in white wines, red wine sediment isn’t harmful. It’s primarily made of organic grape and yeast material that was already suspended in the wine anyway. Often, sediment contains a high concentration of spent yeast cells, so people with a yeast allergy may want to steer clear. That said, since all wine contains some amount of yeast material, anyone worried about a yeast allergy may be best avoiding wine entirely.
Even though consuming wine sediment is harmless, anyone who’s gotten a mouthful of the stuff knows it can detract from an otherwise pleasurable vinous experience. Especially in red wines, sediment is gritty and may taste bitter to some people. It also makes the wine look murky and dull in the glass. Luckily, it’s easy to separate a wine from its sediment by decanting—and don’t forget that you can decant white wines, too.
As always, talk to your healthcare provider about incorporating wine into a healthy lifestyle.—Kenny Martin
