Recently we were asked about crystals that have formed in some of the KFV wines. Don't panic! Those small crystals are called tartrates and they are harmless to you and your wine. Tartrates – or more lovingly, “wine diamonds” – are formed from tartaric acid which is naturally occurring in all wines and provides structure, balance and flavor.
Some geeky info about acidity Tartaric acid is one of three main acids found in wine grapes alongside malic, and citric acids. Each type of acid plays a key role in the wine production process and contribute different flavor profiles and textures to the end wine. While malic acid does contribute to the aromas of a wine, it is more known for its role during the winemaking process through malolactic fermentation. In this process, the stronger malic acid is converted into the softer, smoother lactic acid. On the other hand, tartaric acid is arguably the most important in wine due to the prominent role it plays in maintaining the chemical stability of the wine, the wine’s color and influencing the taste of the finished product.
What are tartrates and why do they form? Tartaric acid’s solubility in wine is temperature-dependent. When a wine is chilled to temperatures below 40 degrees, the remaining tartaric acid will bind with the naturally occurring potassium in the wine to form crystalline deposits (potassium bitartrates), or tartrates.
Tartrate crystals in wine have been described as having a similar appearance to shards of glass or have been mistaken for unwanted or unnatural sediment – this is simply not the case. Though their appearance may be a bit off-putting, tartrates are completely harmless.
More geeky info-Cold Stabilization: negative effects on wine Some winemakers choose to cold stabilize their wines to eliminate the future formation of tartrate crystals. Cold stabilization is the process of cooling the wine to around freezing temperatures in large stainless steel tanks for several days or weeks after the wine has aged and just before bottling. By cooling the wine prior to bottling, the potassium bitartrates will crystalize and drop to the bottom of the tank where they can then be filtered out of the wine. By doing this, the winemaker is ensuring that further tartrate crystals do not form in the bottle mainly for aesthetic reasons. However, at the same time, cold stabilization strips the wine of acidity, takes away from its natural flavor profile and impacts the wine’s long-term ageability.
At Kahal Family Vineyards, we choose not to cold stabilize in order to maintain the natural acidity, flavors and texture of our wines and protect the wine’s quality and aromatics. Many in the industry - Winemakers, Sommeliers and Academics -view “wine diamonds” as a sign of quality, indicating that the wine was not over processed or manipulated.
What to do if wine diamonds appear
If wine diamonds do appear, don’t panic! You can simply push the crystals down the neck and wait for them to settle or pour the wine through a filter or cheese cloth and decant prior to serving.