First time cold crashing .. Need some advice

[p_p]

Hi everybody,
This is the first time I cold crash a beer and I wonder if you could offer some advice.

A 6% IPA which will be bottled. fermented with wlp007 which I understand is quite flocculent, on top of that I decided to use gelatine and the beer has been sitting at 43f for a couple of days... Have I gone a bit overboard? May I encounter issues getting this beer carbonated in the bottles?

Secondly, I don't really know how to judge how much CO2 is in solution. Should I reduce the amount of priming sugar compared with non-cold crashed beers assuming some of the CO2 in the head space may have gone back in solution?

And finally, should I bottle while the beer is cold or bring back to ambient?

Thanks for the help.
PPP

 

[billl]

a) the beer should carb fine
b) use the highest temp the beer got to, not the cold crashed temp
c) cold or warm - either works - you do have to store the bottles at room temp to carb though.

 

[CJ-3]

^^^
I couldn't agree more. Bill is right on all 3 points.

 

[jonny24]

Yup. Done a crash/ gelatin for like 10 brews now, works great.

I still wonder every damn time what number to put for temp in the calculator though...

 

[gromitdj]

Always use the highest temperature the beer has reached. If you cold crash, the beer is not going to re-absorb an appreciable amount of CO2. I think it would need to be under pressure for that, and in all likelihood it is probably under a slight vacuum. Which is why you will likely suck up the starsan in the airlock/blowoff eventually (like me).

 

[CA_Mouse]

As https://www.homebrewtalk.com/member.php?u=17309 said, it is under a slight vacuum, it will only absorb the CO2 while under pressure. I've never used gelatin on any of my beers, but cold crash them all and they all carbonate correctly. If I'm not mistaken (please correct me anyone if I) gelatin will only remove the proteins and some of the yeast in suspension, extended aging will cause the rest of the yeast to drop out of solution.

 

[Northbank]

..... gah ..... I used the current temp when I bottled my lager last week, 40f and 3.7oz of corn sugar ...... I did the diacetyl rest, then stepped it down and lagered it at 32 ....

Gonna be under carbed isn't it?

 

[gromitdj]

Gonna be under carbed isn't it?

That would be my experience.

 

[doug293cz]

..... gah ..... I used the current temp when I bottled my lager last week, 40f and 3.7oz of corn sugar ...... I did the diacetyl rest, then stepped it down and lagered it at 32 ....

Gonna be under carbed isn't it?

Yes.

Brew on

 

[doug293cz]

As https://www.homebrewtalk.com/member.php?u=17309 said, it is under a slight vacuum, it will only absorb the CO2 while under pressure.

Sort of, but not quite. Lowering the temp will lower the pressure in the fermenter, and air will get sucked back into the vessel (along with some air lock/blow off liquid.) However, there is still a significant CO2 partial pressure in the headspace, and the beer will absorb CO2 as long as the headspace partial pressure is higher than the equilibrium pressure for the beer's current temp and carbonation level. The CO2 partial pressure will be less than atmospheric pressure, so that mitigates the amount of CO2 that can get absorbed.

Brew on

 

[doug293cz]

I answered the "what temp do I use in the priming calculator?" definitively in this post. You should use the highest temp the beer has experienced post fermentation. The linked post contains a detailed analysis of residual CO2 in the beer post fermentation, with and without cold crashing, and how much under carb you can be if you use the cold crash temp in the priming calculator (warning: the analysis is not suitable for those with a math aversion. )

Brew on

 

[gromitdj]

I'll maintain that it is under a slight vacuum. Any partial pressure (regardless of composition) would prevent suck back of starsan, air, or otherwise. At any rate, it's not enough to make a difference.

 

[p_p]

I answered the "what temp do I use in the priming calculator?" definitively in this post. You should use the highest temp the beer has experienced post fermentation. The linked post contains a detailed analysis of residual CO2 in the beer post fermentation, with and without cold crashing, and how much under carb you can be if you use the cold crash temp in the priming calculator (warning: the analysis is not suitable for those with a math aversion. )

Brew on

Awesome, one more set of numbers I can add to my spread-sheet

 

[p_p]

Thank you everybody for your replies.

Would you alter your cold-crashing / fining regime based on the yeast strain?
I mentioned that I used WLP007 which seems to flocculate quite well.
I am planning to try WLP002 in the future, which I understand just drop like a stone so I wonder if I should adapt the technique or stick to a fixed process regardless.

 

[doug293cz]

I'll maintain that it is under a slight vacuum. Any partial pressure (regardless of composition) would prevent suck back of starsan, air, or otherwise. At any rate, it's not enough to make a difference.

You're using "vacuum" in the sense of negative gauge pressure (i.e. the headspace pressure is slightly less than atmospheric pressure.) "Partial pressure" is totally independent of gauge pressure and is always positive (there is no such thing as a negative partial pressure or a "partial pressure vacuum".) If there is any gas in the headspace, that gas has a partial pressure. So no, a partial pressure will not prevent suck back. If you cold crash, you will get suck back, unless you have a totally gas tight system.

Brew on

 

[doug293cz]

Thank you everybody for your replies.

Would you alter your cold-crashing / fining regime based on the yeast strain?
I mentioned that I used WLP007 which seems to flocculate quite well.
I am planning to try WLP002 in the future, which I understand just drop like a stone so I wonder if I should adapt the technique or stick to a fixed process regardless.

I recommend keeping the cold crash process to two days or less. Because of the suck back of air, you will get O2 in the headspace, and that will start oxidizing your beer. Cold crash and then package as soon as possible to minimize oxidation.

Brew on

 

[billl]

Re temps.

Detailed physics arguments aside, the CO2 levels in your fermenter are due to the yeast burping it out. You end up with essentially 100% CO2 in the head space and in the beer. Once fermentation stops, that's all the CO2 you are going to get. Dropping the temps won't create a new source of pure CO2.

The only way you would want to use the cold crash temp in your priming calculations is if you were adding pure CO2 to the fermenter and then giving it enough time to reach equilibrium - ie about a week.

 

[doug293cz]

Re temps.

Detailed physics arguments aside, the CO2 levels in your fermenter are due to the yeast burping it out. You end up with essentially 100% CO2 in the head space and in the beer. Once fermentation stops, that's all the CO2 you are going to get. Dropping the temps won't create a new source of pure CO2.

The only way you would want to use the cold crash temp in your priming calculations is if you were adding pure CO2 to the fermenter and then giving it enough time to reach equilibrium - ie about a week.

Correct.

Brew on