German wine - wine basics
Weinstein (crystal tartrates) - quality
Many of Germany's white wines are treated to cold stabilization before being bottled. This is the process of storing wine in below freezing temperatures in order to eliminate the tartaric crystals (Weinsteine) that tend to form in finer wines, especially in good harvests.
These tiny crystals (crystal tartrates) which you may find on the cork or at the bottom of a bottle are not flaws, they are harmless, tasteless and in no way detract from the flavour of the wine. On the contrary, they are considered a sign of quality.
Weinstein = "winestone", Einstein = "onestone"
Tartrate Crystals – A Feature of Fine Wine
To set the record straight: tartrate crystals in wine, known as "Weinstein" in German, are neither harmful nor a sign of poor quality. On the contrary, they are characteristic of wines that are rich in minerals. While tartrates can crystallize in young wines, they are most likely to precipitate in older, top-quality wines, such as Auslese, Beerenauslese or Trockenbeerenauslese. The tiny crystals that form on the bottom of the cork or on the sides of the bottles are the mark of a wine that has had the benefit of long bottle aging.
Layers of tartrate deposits slowly develop on the walls of wine barrels, too. When illuminated, the interior of an old cask resembles an icy cave full of glistening crystals.
How do Crystals Develop in Wine?
Riper grapes have higher levels of tartaric acid. The longer grapes ripen on the vine, the longer they have to absorb minerals from the soil. Little by little crystals can develop when these minerals come into contact with tararic acid. Rather than dissolving in the wine, they precipitate and form a deposit on the sides or bottom of the bottle, on the cork, or on the inside of the barrel.
Crystals in the Bottle – More Aroma in the Wine
Although tartrate crystals do not influence the quality of a wine, there is an interesting correlation between the two. Slow fermentation at low temperatures helps conserve a wine¹s aroma compounds. It also results in tartrate deposits developing later, in the bottle, rather than while the wine is still in cask. As such, crystals can be regarded as the mark of a good winemaker and a wine of quality.