Have you ever opened a bottle of wine and discovered tiny pieces of sparkly grit on the top of the cork or in the bottle? Either way, I hope you did not toss the wine thinking it was bad. It was anything but…maybe even better quality because of it.
That grit is Tartrate. Many in the wine industry affectionately refer to this as “wine crystals” or “wine diamonds.” Tartrate is natural and completely harmless. It occurs when potassium and tartaric acid bind together and solidify when wine reaches near freezing temperatures. A little bonus trivia, the scientific name for tartrate is potassium bitartrate known in culinary circles as cream of tartar.
Many wines are cold stabilized to prevent wine crystals from forming. Cold stabilization is the process of chilling wine for several days to let the tartrates form then filter out before bottling. By performing this process in the winery, you, the consumer, will not have to worry about the crystals forming when you chill that bottle of white wine in the refrigerator a day or two before your dinner party. The downside of cold stabilization is, if performed at too low a temperature, the aromas and flavors of the wine will be less outstanding. Thankfully, many producers are careful to maintain the aromatics of the grapes.
The next time you open a bottle and see sparkly grit on the cork, be pleased knowing the wine maker chose a delicate approach to the production process and appreciate the beauty of the “wine diamonds” then simply wipe them away before serving your guests. If the crystals are in the bottle, decant the wine stopping at the point of the sediment to avoid any particles falling into the decanter then enjoy your wine as usual.