Enartis

The presence of tartrate crystals in a bottle is commonly perceived as a fault by consumers. Crystals are mostly composed of potassium bitartrate but precipitation of calcium tartrate is becoming more and more frequent. While the formation of potassium salts can be prevented with the use of protective colloids, calcium stabilization requires specific interventions.

There are various methods that can be used during the winemaking process to reduce potassium bitartrate (KHT) precipitation in bottled wines.

Some techniques are considered “subtractive” and involve reducing the concentration of tartaric acid and/or potassium in wine (tank cooling, electrodialysis, cation exchange resins). Other “additive” techniques make use of protective colloids or crystallization inhibitors which can be added to wine.

Additive techniques are more respectful to sensory qualities, environmentally friendly and economically sustainable. Instead, with regard to calcium stabilization, the only colloid that has a significant effect is metatartaric acid. Unfortunately, since it hydrolyzes quickly, its effectiveness is short and can only be used for wine with a very rapid rotation. Alternatively, techniques based on calcium or CaT removal provide a more reliable and long-lasting stability. This can be achieved by using physical treatments or chemicals like electrodialysis, very effective but not broadly available to everyone and, by removing tartaric acid and potassium making an impact on wine sensory qualities and ageing potential. Cation exchange resins help reduce calcium content, but their effectiveness on CaT stability is mainly due to their action of lowering wine pH.