Author Topic: Cold crashing a lager  (Read 1382 times)

Offline Pi

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Cold crashing a lager
« on: October 14, 2015, 03:08:16 PM »
Actually 2 questions:
How long should a diacetyl rest go and
Does it matter to go from 65° to 38° versus -2°/day?
Seems alot of brewers jump from 48° up to 65° in a 24 hour period, but go down slowly so they dont stress the yeast. 
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Offline BrodyR

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Re: Cold crashing a lager
« Reply #1 on: October 14, 2015, 03:24:42 PM »
I only have 2 lagers under my belt so far. The first I did a 3 day diacytel rest and it cleaned it up well. Then I crashed it straight to 30f. Came out solid. From what I understand, once it's finished and cleaned up you can crash it.

The second I did with the brulosphers quick lager method so the temp ramp up cleaned it up and I used the step down in temperature. But, again, from what I gather theres no harm crashing it all out if gravity is stable and the beer cleaned up.

Offline Wort-H.O.G.

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Re: Cold crashing a lager
« Reply #2 on: October 14, 2015, 03:25:43 PM »
ive done it both ways- controlled rise and descent in temps, and free rise to 62-65F and then crashed thereafter.

as far a I can tell- no difference.


once i hit about 65% ADT, i let it free rise in temp to 62-65F, and hold until its all done (usually at day 12-14). i just give it plenty of time at warmer temp to finish up and clean up.  as i said , from there i now tend to just drop it 5F per day, but have cold crashed as well.
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Offline denny

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Re: Cold crashing a lager
« Reply #3 on: October 14, 2015, 04:19:38 PM »
Actually 2 questions:
How long should a diacetyl rest go and
Does it matter to go from 65° to 38° versus -2°/day?
Seems alot of brewers jump from 48° up to 65° in a 24 hour period, but go down slowly so they dont stress the yeast.

A 2-3 d rest should be plenty.  That said, I seldom do one. 

It matters not at all if you change the temp radically like that.  I also don't bother going down slowly.  By the time I want to crash it, the yeast is done working so lowering slowly doesn't matter.
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Offline HoosierBrew

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Re: Cold crashing a lager
« Reply #4 on: October 14, 2015, 04:24:08 PM »
With the modified lager fermentation schedule that's so popular (rightfully so), I crash right down rather than going X degrees/day. I feel like the yeast has cleaned up and done its job by that point. No negatives from doing this.
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Re: Cold crashing a lager
« Reply #5 on: October 14, 2015, 04:34:59 PM »
I heard a famous podcaster state that he had "read a study" that yeast express 30% more esters when rapidly chilled. Like many, I took what he said as fact even though he didn't actually reference the study. Its kind of an EF Hutton thing. I switched from one-step rapid cold crashing to slowly lowering the temp. Now days I have gone back to the one-step rapid cold crash.

I have a theory which ive picked up along the way and its been reinforced by sour beer brewing. The hydrometer tells us one thing about our beer. But we also should taste and look. If your beer has reached terminal gravity, AND it tastes done, AND it is at least starting to look done (no foam on the surface and not full of yeast in suspension) then rapidly cold crashing makes little to no difference. If the yeast are still busy, it might make a difference. So why not give them (for example) 9 more days to finish up at a temp they thrive in then crash in 1 day, rather than slowly crashing by 3 degrees per day for 10 days?

I only have one fermentation freezer so I can't do a side by side, but ive got enough experience to know which one to bet on...
If you brewed two identical beers side by side, at day 14 you ramp to a D Rest, and at day 16 you started slowly dropping the temp of one beer a few degrees per day till it hit 30F on day 28, but let the other beer sit at that D Rest until day 27 then rapidly crashed it to 30F overnight... my money is on either no difference or the rapidly chilled beer being better. (This is an analogy, I don't brew by a calendar)

Offline hopfenundmalz

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Re: Cold crashing a lager
« Reply #6 on: October 14, 2015, 04:40:35 PM »
Taste the beer. If it is clean, crash it.
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