Cold stabilisation is an important step in the process of winemaking. It is the means by which the excess tartaric acid in wine is precipitated out as potassium-bitartrate salt. Tartaric acid is very soluble in wine, it's less soluble mono-salt, potassium-bitartrate preciptates out in an effect known as 'salting-out'. This lowers the total acidity, and alters the final pH, of the wine.
Now some people may like wine diamonds in their glass, but most consumers prefer a little less crunch in their wine beverage of choice. The purpose of potassium-bitartrate stabilisation is to prevent the crystallisation of the tartrate in the bottle.
This is a 3 week long operation at the winery with the tanks being frozen down to 27F, resulting in a good half inch of ice on the outside of the stainless steel. Additions, in ppm, of isinglass and bentonite aid in the fining process which produce a beautifully clear wine that is however still rich in ML bacteria...on to the filter.
On a 90F day, like it was yesterday, I try to find any excuse to be in the tank room so that I can give a frozen tank a hug...even if it does contain Chardonnay!