Cold crashing - what it is, and why do you care?

[RickBeer 6,086]

If you think this is cold crashing, please immediately sell your kit on Craigslist and exit the hobby. To find out what cold crashing is, read the next post.

 

No beer was harmed in the posting of this picture.

[RickBeer 6,086]

Cold crashing is a simple method that accomplishes 2 purposes.  First, it allows the trub (layer of dead yeast and byproducts on the bottom of the LBK) to compact.  Why is that good?  Because more beer comes out of the spigot before the trub SLOWLY makes its way to the spigot.  Second, cold crashing allows the beer to clarify, as particles fall out of suspension and settle to the bottom.  I personally don't care about clear beer, but I do want to get every drop out of the LBK.  If you're making a wheat beer, the second goal probably isn't something you want to have happen.  

 

How do you cold crash?  Well, it's very difficult so I'll lay out the steps below.  Please study them carefully before undertaking this difficult task.

 

1) When your beer is ready to bottle (determined by waiting 3 weeks and or testing with a hydrometer and getting matching readings 48 hours apart), pick up the LBK.

 

2) Walk over to your refrigerator.

 

3) Open the refrigerator door (or have someone else do it so you don't drop the LBK).

 

4) Put the LBK inside the refrigerator.

 

5) Close the refrigerator door.

 

6) Leave it in the refrigerator for 24 - 72 hours (it will thicken in 24 hours, takes 72 to settle the particles).

 

On bottling day, prep everything and remove the LBK only when you're ready to bottle - you don't want to warm it up and undo all the difficult work that you accomplished.

 

Questions:

 

1) Does cold crashing kill the yeast?     - No, it just puts them to sleep.

 

2) Does cold crashing impact how my beer will carbonate?    - No.  Yeast wake up and it carbonates fine.

 

Remember to angle your LBK during fermentation, and cold crashing (and bottling) to keep the trub away from the spigot.  See this post: http://community.mrbeer.com/topic/32908-propping-up-your-lbk-no-trubal/

 

First picture below shows the inside of my LBK after bottling my latest brew.  I have about an ounce, if that, of liquid left in there with the trub, which you can see in the 2nd picture (a little milky at that point because I sloshed it taking the pic).  I had 5 gallons of liquid split between two LBKs, and that gave me 600 ounces of beer or 93.8% of what I started with.  The most I've ever gotten is 614 ounces.

 

 

[sabres032 1,170]

So if I'm to fully understand, the dead yeast will fall out of suspension once their job is complete and they've expended all their energy, correct? Then how is it the live yeast, that goes dormant when cold, stay in suspension ready to eat once they wake?

[RickBeer 6,086]

Because enough yeast cells are in suspension.  

[sabres032 1,170]

Because enough yeast cells are in suspension.

I'm more interested in the science of why. Call it the paramedic in me. I'll have to search and read up on this because now I'm really interested in why.

[Vakko 697]

It does seem like if they go dormant, they would fall out of suspension.

[gophers6 1,114]

I was very skeptical too before I tried it thinking the yeast would fall to the bottom. All I know is I've never had a problem. Evidently, enough yeast stays in suspension.

[mcasselman 16]

Think I am going to try it this weekend. Going to cheat a little and put the lbk's in the fridge Friday (only day 20) so I can bottle Saturday. Thinking 1 day should not hurt anything.

[C-ya 357]

Mac, I'd go Thursday. I tried an overnighter and it warmed up pretty quickly when I started bottling.

[baup5f 12]

What would be your recommendation for days for cold crashing on a raspberry wheat?

[RickBeer 6,086]

3 days is normal but the wheat will clear up some.

[USMCMatt 2]

I've always done this exact same method and have never had an issue, good info.

[gophers6 1,114]

I've gone 1 day several times when that's what would fit my schedule. I think it works better than expected.

[HoppySmile! 2,296]

recommend angling or tilting lbk during fermentation? I didn't do that, didn't know, but did see a youtube video of a guy tilting it when bottling to help prevent trub release. do u tilt it while its in the fridge?

[RickBeer 6,086]

3rd link in my signature... And in this post in the explanation... Reread it...

[HoppySmile! 2,296]

got it!

[jmead9758 4]

So you bottle it cold and how much longer to condition?

[RickBeer 6,086]

Not a minute. See #2 in the post.

2) Does cold crashing impact how my beer will carbonate? - No. Yeast wake up and it carbonates fine.

[brybry 132]

I'm ready to cold crash, but very limited on space in the fridge and not sure the wife would be OK with me getting rid of the milk and other things in the top self. Is it OK to use the big ice box that mother nature created? I'm thinking of taking the cooler outside and letting it sit on my desk for three days. Is it possible to cold crash at too low of a temp?

[Jim Johnson 1,262]

well yeah, you don't want it to freeze.

[brybry 132]

well yeah, you don't want it to freeze.

 

So as long as it doesn't freeze this would be OK? I'd guess my fridge is at about 40 but outside would/could be colder, I was thinking about the yeast is the possibility of the colder temp OK for them?

[Vakko 697]

Because it's alcohol, you can actually get around 32 degrees without it freezing.  However, the point of cold crashing is really to solidify the trub and to clear up your beer.

[RickBeer 6,086]

Most refrigerators chill at 35 - 37 degrees.  40 is too warm for some foods over time.

 

You want to refrigerate it, NOT freeze it.  And, the temp needs to stay consistent, like a refrigerator would.  So putting it outside in winter temps, or when it's below freezing at night, would NOT be a good idea.  Putting it outside where the temp varies up and down by more than a few degrees would not be a good idea - you don't want it seesawing from 35 at night to 48 in the daytime.  

 

Lastly - remember critters - whether bugs or animals. 

 

You should talk to your wife about what's important more in life - milk or cold crashing beer.  

 

And since this is your first batch, perhaps cold crashing isn't top of your list...

[Vakko 697]

Pour the milk into tupperware

[brybry 132]

Disaster averted.

 

The milk has been force fed to the cat, the 5 gallon jar of pickles have been consumed. And room has been made. T minus 38 hours and counting until the first bottling.