Cold crashing, bottle conditioning, and thermal shock to yeast

[GrumpyOldGit]

Sorry - bit of a mouthful that title.

I finally cobbled together a ferm chamber from a fridge (currently holding my latest Saison at a pretty solid 70F) and was wondering about cold crashing my beer before bottling. I've read that thermal shocking for yeast occurs going from warm to cold, but cold to warm is fine and as I'm bottle conditioning I want to keep the yeast viable.

So given this, to cold crash a brew and keep the yeasts happy should I take a lager-like approach and cool it from 70 to 35 over a few days - say cooling by 5F per day - and then leave it at 35F for 24 hours? I'd then bottle as normal and put away in my usual conditioning space around 65F (and not back in the fridge at 35F, just to be clear) and let it warm up without concern.

Also, are there some beers that it's not desirable to cold crash? For example Witbiers, Weizenbock and Weissbier spring to mind where a cloudy aspect seems to be key to their style? (For example, the BJCP has for Witbier the appearance "will be very cloudy from starch haze and/or yeast, which gives it a milky, whitish-yellow appearance") Are there other styles that don't really benefit from a crash?

 

[McKnuckle]

The point of a cold crash is to clear the beer of suspended yeast, and to cause chill haze proteins to come out of solution and fall to the bottom. Both contribute to goals of visual clarity, and the yeast aspect also contributes to fresh taste. The yeast part would happen at room temp with enough time. The chill haze, not so much.

For wheat beers that are cloudy by nature, it's a waste of time (I don't crash those). I crash just about everything else, and never worry about yeast health - and haven't had any trouble with bottle carbonation. I don't drop the temp slowly; I just lower it all the way down and let it cool naturally.

Think of it this way: Do you harvest yeast? If you do, you store them cold. Eventually you take them out of the fridge and expect them to ferment a new batch of beer. And... they do. It just seems to work.

 

[GrumpyOldGit]

...For wheat beers that are cloudy by nature, it's a waste of time (I don't crash those). I crash just about everything else, and never worry about yeast health - and haven't had any trouble with bottle carbonation. I don't drop the temp slowly; I just lower it all the way down and let it cool naturally.

Thanks for the reply. it's good to know you've not had any issues with crashing the yeast. Thanks for confirming my thoughts on the wheat beers - I'll leave them be.

 

[microbusbrewery]

Usually when you're talking about thermal shock with yeast, it's large temp swings in a short period of time. For example, pulling a dry yeast packet out of a 37F fridge and dumping it in 80F water...that would be more likely to shock the yeast than cold crashing over a five day period.

On a somewhat related note, Jamil was recently talking about cold crashing lagers. I'm paraphrasing, but he indicated for the cleanest lager character, it's important to bring the temps down gradually. If you drop the temps too quickly, it can cause the yeast to express byproducts associated with off-flavors.

 

[GrumpyOldGit]

I took the plunge and set the ferm/fridge to 32F to see. From 70 it dropped to 45 in a day but took another day to get down to 34F - so more a grinding halt than a crash...

However, the beer was the clearest I've ever racked - another week and it'll be about ready to taste (though another week or 2 before fully ready).

I'm definitely going to try this again with the ESB I have fermenting away in a couple of weeks.