Cold Crashing -Do I really get anything better for the fuss?

[hotbeer]

I just bottled a Berliner Weisse sour beer. I decided to cold crash it. However I don't really know why as it was pretty clean when I put it in the fridge at not quite 3 weeks of fermenting. But I'm still experimenting with various things and thought I'd see if this helps in any way.

Currently I don't think it did. It sort of complicates the priming sugar calculation since chilling the beer causes it to absorb back into solution more CO2 from the headspace and that has to be accounted for in figuring the priming sugar amount. But from what I've read it's anyones guess how much actually got back in solution as the variable of how much headspace was there and was it still primarily CO2 as the beer chilled and other things that just seem to be " it should have been this but there is a good chance it wasn't. "

Visually it actually seemed a little hazy. I don't think it was a chill haze as I doubt it got below 40°F (4.4°C) that the fridge is set to. But... I didn't check to be sure. It was in the fridge for 3 full days. The FG was 1.010 if that matters.

I think I was half expecting that the trub and yeast cake would be a little more compact and firm, but I didn't find that to be so compared to my experiences with beers I didn't cold crash.

The common reason I see for cold crashing is getting a clean beer. But I don't think I've had any issues getting a clean beer when I don't cold crash.

So what did I gain for doing it? Is there anything I should look for in the finished product that will tell me I need to do it again?

 

[Bassman2003]

I think it is relative. We all do a form of cold crashing when we serve the beer from a refrigerator. Slow ramp down or a quick crash both drop the particles out of suspension. The slower ramp is more about saving the yeast activity. For me, cold crashing in the fermenter was always best so one could leave more stuff behind and out of the keg. That was before I spunded, so now I only lower the temp in the keg, after activity is complete.

In your case, I would guess you cold crashed before putting the beer into bottles? You might want to make sure you did not put your yeast to sleep that are supposed to be awake and carbonating the beer. Correct me if I misunderstood.

 

[hotbeer]

Well unless I've been mis-reading, I thought cold crashing was something done after the ferment and before bottling or kegging. Though I do realize some actually cold crash in the keg. Some I think move it to another keg for carbonation, some do not.

Essentially I put the entire fermenter in the fridge. It's only 5 litre capacity. So not large at all. Then I siphoned the beer into a pot to be primed with sugar and bottled it cold.

I'm assuming enough of the sleepy yeast got in there and will wake up to carbonate it since it's now at 72 - 74°F. At least that happened for the one other time I cold crashed. The beers had plenty of CO2. I hope these will too.

 

[Jaybird]

Just depends on the beer and the process. Some I cold crash, some not so much. Not all beers are going to have the same process. If you have been in primary for 3 weeks and it's clear... Package. If it's been in primary for 7 days and you want to package... Maybe a crash for 72 hours might help clean it up a little.

Cheers
Jay

 

[Bassman2003]

You are correct that usually cold crashing takes place before the end product package to drop particles out of the beer. But, you can cold crash (sudden, sharp temperature decline) or ramp the temp down 5 degrees a day to gently change the temperature. The second way allows any active yeast to stay active and not freak out. If you drop the temps quickly the yeast go dormant and then you risk them not waking up to the extent of if they were not put to sleep in the first place. So cold crashing before bottling with an ale strain is risky because you are asking the yeast to operate in the temp zone lower than they like and you stunned them on top of it!

Notorious bottle conditioners like the Belgian brewers will cold crash the beer then add new yeast and raise the temps to generate carbonation. Traditional German technique is to slowly ramp the beer down so the lager yeast stays active then either trap the final bits of activity for carbonation or add some active fermenting wort to kick up activity to get some CO2 production.

Or, you could bottle first then crash the bottles after they have carbonation. This would clear the beer in the bottles as long as they are not moved very much. The particles could be left in the bottle upon pouring and there would be some benefit from that and your carbonation would not be at risk. If you know you are bottling a batch, try to brew extra clean and not bring much trub into the fermenter in the first place as well.

 

[hotbeer]

Thanks for the info.

The priming sugar calculation for the current temp of the beer results in quite a bit less sugar needed for a cold beer. I think that is the assumption that the beer absorbs more CO2 back into solution from the headspace. However can that be accurate? Am I just leaving myself more open the possibility of under or over carbonating by cold crashing?

Should I move my beer off the trub/yeast cake and let it warm up first?

I am sort of thinking I'll not cold crash beers that have cleaned themselves up decently. And maybe just cold crash for beers that are otherwise ready but maybe not so clean.

I've only cold crashed 2 out of the last 9 beers and none had any issues that I think will have been better for cold crashing.

Interesting to know about some adding fresh yeast at bottling time.

 

[balrog]

since chilling the beer causes it to absorb back into solution more CO2 from the headspace and that has to be accounted for in figuring the priming sugar amount. But from what I've read it's anyones guess how much actually got back in solution as the variable of how much headspace was there and was it still primarily CO2 as the beer chilled and other things that just seem to be " it should have been this but there is a good chance it wasn't. "

I really think you just use the temp at fermentation, prior to cold crashing, to calc priming sugar.
Unless more CO2 is being produced, and you're doing fermentation with an airlock not spunding fermenting under pressure. Then you have to do something @doug293cz -ish massive calculation.

 

[TheMadKing]

Well I'll agree with what Jay said above it depends on the beer.

I'll add that cold crashing causes a few things:

Edited per Doug's correction below

• The density of the liquid increases but particles coagulate into larger particles and drop out more easily, yeast, fruit, dry hops, etc. So it's a useful tool for preventing a clogged transfer tube in beers with lots of solids in them
  • In addition to removing solids, it can also precipitate out proteins and get a jump start on clearing your beer, while leaving less trub in the bottom of your keg
• Yeast activity ceases, so you can use cold crashing to modify your ester profile in certain beers. I like to use it in english ales to keep the yeast from cleaning up too efficiently and losing all those great esters at the very end of fermentation
• If your fermenter can hold pressure, it's easier to carbonate cold beer as you've already mentioned

The big downside is that cold crashing contracts the gas in the head space, so it will pull in oxygen unless you can backfill the negative pressure with CO2. I refused to cold crash for years because I didn't have a good way to prevent this.

Now I have a pressure-capable fermenter and 5PSI before the cold crash prevents any issues entirely.

 

[MaxStout]

I really think you just use the temp at fermentation, prior to cold crashing, to calc priming sugar.
Unless more CO2 is being produced, and you're doing fermentation with an airlock not spunding fermenting under pressure. Then you have to do something @doug293cz -ish massive calculation.

That's the conventional wisdom I always heard: carb based on highest pre-crash temp of fermentation. The idea was that little CO2 will re-enter solution during cold-crashing.

 

[TheMadKing]

That's the conventional wisdom I always heard: carb based on highest pre-crash temp of fermentation. The idea was that little CO2 will re-enter solution during cold-crashing.

Yep, the amount of CO2 in solution in your fermenter is dependent on the temperature of the liquid and the partial pressure of the CO2 in the headspace. In a non-pressurized fermenter the partial pressure always stays at atmospheric (or close to), so the temperature of the beer becomes a "one way valve". Once CO2 leaves due to the beer warming, it can't dissolve back into solution unless the partial pressure increases

 

[doug293cz]

...

• The density of the liquid drops so things sink more easily, yeast, fruit, dry hops, etc. So it's a useful tool for preventing a clogged transfer tube in beers with lots of solids in them
  • In addition to removing solids, it can also precipitate out proteins and get a jump start on clearing your beer, while leaving less trub in the bottom of your keg

...

Actually, chilling increases the density of the beer. Faster drop out is probably due to increased floculation at cooler temperatures, as I doubt the reduction in Brownian motion is enough to account for the effect.

Brew on

 

[Bassman2003]

Thanks for the info.

Should I move my beer off the trub/yeast cake and let it warm up first?

I am sort of thinking I'll not cold crash beers that have cleaned themselves up decently. And maybe just cold crash for beers that are otherwise ready but maybe not so clean.

For something like an ale, you could cold crash the fermenter down to the 30's and when you transfer to bottle, add some CBC yeast in with the sugar solution and warm the bottles up to the high 60s. Then chill the bottle down for serving/aging. At least you would know that mainly only yeast will be in the bottles, your carbonation will not be in jeopardy and the CBC yeast is a good floccer, so the beer will be clear.

For lager, just do a slower ramp to the low 40's then bottle and raise up to the mid 50's. Your yeast should remain active. Or you can add some dry lager yeast as well.

 

[doug293cz]

I did a full analysis of cold crashing (without CO2 backfill or pressurization) here. The net is that you want to use the highest temp the beer has seen post-fermentation to calculate the required priming sugar, as that is the temp that has the most effect on the amount of residual CO2 in the beer (before carbonation starts.)

The beer will absorb some CO2 from the headspace during cold crash, but the total amount depends on time. What I show in the linked analysis is that even if the cold crash is long enough for the max CO2 to reabsorb, the error in carbonation level is small, and the carb level error will be higher if you use the crash temp to figure priming, than if you just use the highest temp.

Brew on

 

[TheMadKing]

Actually, chilling increases the density of the beer. Faster drop out is probably due to increased floculation at cooler temperatures, as I doubt the reduction in Brownian motion is enough to account for the effect.

Brew on

Well now that you say that I'm sitting here saying "duh... of course it's more dense... hydrometers show that regularly around here" thanks for straightening me out as always

Yes, flocculation (not just of yeast, but of anything colloidal that can coagulate together to form larger particles) is why it all drops out

 

[balrog]

I did a full analysis of cold crashing (without CO2 backfill or pressurization) here. The net is that you want to use the highest temp the beer has seen post-fermentation to calculate the required priming sugar, as that is the temp that has the most effect on the amount of residual CO2 in the beer (before carbonation starts.)

Will immortalize that, right next to the "does 5gal fermentation purge a keg sufficiently" post.

 

[hotbeer]

Most all of you have some interesting considerations that I hadn't quite thought about. When ever I think cold crashing might be useful in the future, I'll have more to think about.

As for the dissolved CO2 in a cold crashed beer or straight from the fermenter at what ever that temp is, then this is the statement that got me thinking about it...

However, if the beer was cold crashed, or put through a diacetyl rest, or the temperature changed for some other reason... you will need to use your judgment to decide which temperature is most representative. During cold crashing, some of the CO2 in the head space will go back into the beer. If you cold crashed for a very long time this may represent a significant increase in dissolved CO2. There is a lot of online debate about this and the internet is thin on concrete answers backed by research. We are open to improving the calculator so please let us know of any sources that clarify this point.

The equation this calculator uses to compute the amount of dissolved CO2:
CO2 In Beer = 3.0378 - (0.050062 * temp) + (0.00026555 * temp^2)

https://www.brewersfriend.com/beer-priming-calculator/
And similar note in the priming sugar calculator of another site.

I'm actually wondering if I'm confused in my notes about which beer I cold crashed the first time. I put it down as my second batch I made, but the third batch was only a couple days behind bottling and I might have mixed up my notes since I'm bad about updating them till several days after the fact.

My third batch of beer is the one that every bottle was a volcano. I mostly put that up as me figuring the sugar for 108 fl oz but only winding up with enough for about 90 fl oz. I think probably planned for 2.3 vols.

However it's possible I might have confused the two batches in my notes and the wheat beer was the one I cold crashed. If so, at that time, I probably used the ferment temp and not the cold crash temp it was bottled at. So possibly almost double the priming sugar I should have used.

But that leaves a lot for just conjecture. Also, how much CO2 will be reabsorbed from the headspace if the beer is not agitated, stirred or otherwise moving? And not under pressure.

 

[micraftbeer]

I always cold crash to precipitate out "stuff" in my beer. And I always get a layer of sediment at the end of a 3-day cold crash in my super-cold (32-35F) beer fridge. I initially did this because I was going after clearer beer and used the cold crash before adding gelatin finings. Although I no longer use gelatin finings, I still cold crash because the sludge on the bottom of the cold crashed keg/fermentor has a nasty odor and taste to it.

I have never done a side-by-side comparison of a beer cold crashed and not cold crashed for aroma or flavor difference. But in my tiny little world of chasing beer "perfection", I can't help but think that a layer of bad tasting/smelling stuff sitting in my serving keg is not a good thing. So I continue the cold crash.

 

[doug293cz]

...

But that leaves a lot for just conjecture. Also, how much CO2 will be reabsorbed from the headspace if the beer is not agitated, stirred or otherwise moving? And not under pressure.

Apparently, you haven't read and understood this post yet. It removed the conjecture almost six years ago. It was also linked just a few posts before yours.

Brew on

 

[AZ Maverick]

I use a temperature controlled fermentation chamber.
After fermentation (whether lager or ale) I drop the temp to 38°F and let it sit for two weeks, then I fine with gelatin and drop the temp to 30°F and let it sit for four days.
Then I keg.
I do this with all my beers no matter the style light or dark.
They always come out extremely clear and clean and taste crisp and wonderful.
As an example, here's one of my Helles:

 

[Beermeister32]

For those who old crash, you have to make sure you don’t have suck-back of air into the fermenter as it chills. Some brewers capture CO2 in a keg or Mylar balloon for this purpose.

 

[CascadesBrewer]

The common reason I see for cold crashing is getting a clean beer. But I don't think I've had any issues getting a clean beer when I don't cold crash.

Personally, I only cold crash my dry hopped beers. It does wonders for dropping out hops and give me much more control over my dry hopping schedule vs just waiting an hoping they drop out before I am ready to package. Once you get above 2 or 3 oz of dry hops in a 5-gallon batch, they really don't like to settle out at room temp. Even just dropping the temp about 10F seems to do wonders. That said, I mostly keg my beers, so they get kegged and sit cold in the fridge to clear.

For those who old crash, you have to make sure you don’t have suck-back of air into the fermenter as it chills. Some brewers capture CO2 in a keg or Mylar balloon for this purpose.

When I cold crash a beer I use a mylar balloon setup. An added benefit is that I can take a gravity reading out of the spigot without sucking back air or solution into the fermenter.

 

[hotbeer]

Apparently, you haven't read and understood this post yet. It removed the conjecture almost six years ago. It was also linked just a few posts before yours.

Brew on

No, I think I'm fairly understanding the posts in the link as well as I can. And I tend to agree with this statement in it...

Conclusion: Use the max temp the beer has seen in the priming calculator.

however the notes for the calculators I've been finding still seem to think the current bottling temp matters.

So is this similar to many recipes and kits still mentioning to move beer to a secondary? I should just ignore them I suppose is your answer.

 

[hotbeer]

If cold crashing makes the beer cleaner, then doesn't that happen when I put my bottles in the fridge after they've had time to naturally carbonate?

I usually put them in 3 or 4 days before I drink them and most all my brews have been very clean with out being cold crashed prior to bottling.

I might side somewhat with some that talk about flavor being slightly different. That seems more likely an issue since the less you put in to be turned to trub in the bottom of the bottle the less chance of it getting turned into an off flavor over the time it takes for the bottle to be opened and consumed.

My taster probably isn't that refined though.

 

[MaxStout]

If cold crashing makes the beer cleaner, then doesn't that happen when I put my bottles in the fridge after they've had time to naturally carbonate?

I usually put them in 3 or 4 days before I drink them and most all my brews have been very clean with out being cold crashed prior to bottling.

I might side somewhat with some that talk about flavor being slightly different. That seems more likely an issue since the less you put in to be turned to trub in the bottom of the bottle the less chance of it getting turned into an off flavor over the time it takes for the bottle to be opened and consumed.

My taster probably isn't that refined though.

The advantage of cold-crashing in the fermenter is that it settles before you package. But yes, chilling bottles has the same effect, just a little more dregs at the bottom. Careful pouring avoids much of that.

 

[doug293cz]

No, I think I'm fairly understanding the posts in the link as well as I can. And I tend to agree with this statement in it...



however the notes for the calculators I've been finding still seem to think the current bottling temp matters.

So is this similar to many recipes and kits still mentioning to move beer to a secondary? I should just ignore them I suppose is your answer.

Yes, you should ignore information that you know is obsolete. The calculators that don't really know what temp should be used haven't kept up with the latest available information (they don't read the right posts on HBT )

Brew on

 

[Oleson M.D.]

We cold-crash every beer. At 32 degrees, for at least 5 days, sometimes 10 days. The benefit is the settling out of the yeast, providing a more clear beer.