Cold Stabilization of Unfermented Juice?

[sgx2]

A local winemaking shop has a cold stabilization room where they store unfermented juice. They claim that it works the same way pre-fermentation as post-fermentation, but I've never seen it work that way!

So, I'm reaching out to the experts here -- is he right, or does tartaric acid crystal precipitation really only happen post-fermentation?

 

[stickman]

Some of the tartaric acid will precipitate in unfermented juice, but the addition of potassium containing materials like sulfite change the chemical balance, and the production of alcohol will lower the solubility of potassium bitartrate. This simply means more precipitation will occur after the usual fermentation and treatments.

 

[vacuumpumpman]

A local winemaking shop has a cold stabilization room where they store unfermented juice. They claim that it works the same way pre-fermentation as post-fermentation, but I've never seen it work that way!

So, I'm reaching out to the experts here -- is he right, or does tartaric acid crystal precipitation really only happen post-fermentation?

I believe cold stabilization will slow down or stop the fermentation process all depending on the temperature.

It will not to my knowledge create any crystal precipitation, It will only happen after fermentation has been completed then cold stabilized at the correct temperatures.

 

[JohnT]

There is a TON of professional wineries that cold stabilize juice, especially whites. This results in a much clearer, less tannic juice.

I do not know if a lot of tartaric crystals fall out of the must or at least I have not really noticed any. It could be that the crystals are buried within the discarded lees.

I do know that a cold soak will reduce exposure time to pulp, bits of skin, etc that contribute to tannins developing in the resulting wine. The cold also reduces solubility, which also further reduces tannic absorption.

The trouble I have always had with whites is that they always came out to be too tannic (sharp and bitter). Since cold soaking before fermentation, then filtering the juice before fermentation, my whites have drastically improved.

 

[sgx2]

Really great information, folks -- thanks!

It sounds to me like there's some benefit...This will make for an interesting conversation!