Question from Sarah: When I opened a bottle of white wine there was shiny stuff on the cork. Is that sugar or what? Does it mean there’s something wrong with the wine? Thanks for your help.
Reply: Hi, Sarah. Thanks for writing! Those crystals aren’t anything to worry about. White wine tends to be high in acid, especially tartaric acid. The crystals, which are usually called “tartrates”, sometimes form during production and also when the wine is cold for a period of time – for instance when you store it in your fridge. The tartaric acid binds with potassium to become potassium bitatrate or cream of tartar! Wineries can remove tartrates through a process call cold stabilization, but it doesn’t much matter one way or the other. When you visit a winery, sometimes you can see the tartrates shining inside an empty barrel. Next time it happens, you can look very knowledgeable by telling your friends “Oh, don’t worry about that – it’s just tartrates.”
Trivia: Lots of people like to call the tartrates “wine diamonds”!
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