The harvester unloading the chenin blanc grapes
Simon's wine blog today is on a matter that every winemaker wrestles with and one which the real natural winemaker will have to use all his guile in order to avoid the outcome. Tartrate crystal deposits are a difficult problem and one which has to be tackled if the tartrate is not to form in a bottle of wine. Although it is quite harmless, potassium bitatrate and calcium tartrate will form crystals that are not acceptable to the average consumer.
Large producers, cooperatives, negotiants, as well as smaller producers who are not concerned about natural wines and who want to release their wines as soon as posible will have to use one of a number of processes in order to remove the tartrates. These include the contact process of adding micro crystals of potassium bitatrate in a cold environment and then filtering the wine. These micro crystals help the crystalisation of the tartrates. Other methods include Ion exchange, electrodialysis, addition of Metartataric acid, cellulose gums, and mannoproteins.
The best way is through minimal intervention and if the winemaker uses time and cold conditions he should be able to acheive the deposit of the crystals. Firstly the colloids in the wine prevent the formation of the tartare crystals but the colloids change properties after some time and this allows a natural crystalisation to occur. So probably the most important ingredient in wine ie 'TIME' will allow a natural process to occur, and this will happen as the wine is allowed to age in the vat or in a barrel. In the winter some winemakers put their wine outside so it cools and the reduced solubility of the tartrates allows a naural crystalisation. There are still many small winemakers, in France at any rate, who do not have the luxury of climate control in their winerooms and so the natural ageing process over the winter is a good natural solution. Cheers.