A question about cold crashing

[BernardSmith]

Over the last couple of weeks different people have been asking about cold crashing. But it seems to me that different people are talking about CC in different ways. Some posts refer to the effects of CC as a means of dropping tartaric acid crystals out of the wine but others seem to be talking about CC as a method of stabilizing the wine. That is to say stabilizing without any need to add K-M or Ksorbate.

If I stay with the second version, beer makers cold stabilize (I think) to "kill" the yeast, but I don't know that cold kills the yeast as much as puts the yeast into a dormant state. That means that if you raise the temperature again the yeasts will reawaken. Beer will be drunk within weeks so that may not have any impact but if you age the wine then the yeasts will be doing what yeasts do. yes?

I presume the trick is then to remove the yeasts from the wine and I presume that CC results in the yeast dropping to the bottom of the carboy. If I then rack the wine I will have racked a yeast free wine, so it is stabilized without chemicals. Is that correct?

Do ALL wine yeasts drop out of suspension when the wine is chilled?
What is the minimum temperature at which this happens and how long will it take for the population of yeast to drop inside a five gallon carboy?

Last question. If I rack from such a carboy will I really have no yeast in the target carboy? In other words, after "cold stabilization" can I backsweeten without fear of refermentation?
Thanks

 

[salcoco]

Cold Stabilizing is the proper term. It is used to reduce acid in a high acid wine post fermentation rather than use chemical means. It has nothing to do with yeast. It does not negate the use of sorbate or K-meta, these must be used to stabilize the wine from refermentation. racking the wine at three days from press, then three weeks and at three months should remove most of the yeast. Proper use of K-Meta at each stage will also kill the yeast and end up as fine lees. Yeast will always be present unless you perform a sterile filer before bottling. If back sweetening and K-Meta and sorbate post sweetening wait one week or more to insure fermentation does not restart.

Cold Crashing is sometimes a term used to stop a fermentation at a certain specific gravity to maintain some of the fruity flavor and sweetness of the juice in the final product. It normally is a crap shoot. Kemta and sorbate have to be added as well to kill all the yeast. warming the wine back up still has the hazards of refermentation.

In summary cold stabilization is to remove acid, cold crashing is to stop fermentation and kill yeast.