Tartrate Crystals [Tar-trate]
I’ve worked in restaurants my whole life and have encountered tartrates quite a bit.
Before a wine is bottled to be sold, wineries usually employ a procedure called cold stabilization (which brings the wine down to a near freezing temperature) in order to remove these “wine diamonds” as they’re sometimes more fondly called. It’s worth noting that Potassium Bitartrate (to give tartrates their full name) is a natural byproduct of the fermentation process.
After the tartrates are removed, the winery can then go on to sell them to the baking industry as Cream of Tartar. Winemaking is the only known source of Cream of Tartar.
The main problem is that consumers in the U.S. are used to seeing clear, pure, filtered white wines with no particles, and so the presence of crystals can sometimes create panic in the streets! Maybe a slight exaggeration, but I know there must be a good amount of wine needlessly wasted each year due to “wine diamonds”. I’ve even heard of wine distributors refusing to carry certain wines due to the presence of tartrates.
In Europe, tartrates in a bottle of wine tend to be more common-place and even encouraged, due to their presence being an indicator of a more naturally made wine.
How to tell if your wine is affected
Tartrate crystals unfortunately can resemble tiny shards of glass, but more often just resemble salt granules, and are usually quite noticeable in white wines. You’ll also sometimes see them on the underside of a cork.
Your course of action
Let the wine warm up for a few minutes, normally they will just disappear into the wine. Don’t go to the trouble of sending the wine back. Normally tartrates sink to the bottom of the bottle, so just pour it slowly, the same as you would if your bottle has sediment.
Click here for the rest of my —-> A Guide to Wine Faults posts.