The great bottle carbing debate

[beerlover77]

So when you prime in bottles which temp do you put in the calculator? I always used the fermentation temperature (not the cold crashed temp) and had perfectly carbed beers... my friend was bringing me under carbed beers and he claims you should use the cold crashed temp in the calculator. THERE IS A HUGE DIFFERENCE as my additions had me add around 4-4.5 oz of corn sugar for 2.5 vol and his additions are around 2.5-3oz

Check out the following priming calc:
http://www.tastybrew.com/calculators/priming.html?mobify=0

It states to input the FERMENTATION temp

This one simply states temp of beer:
https://www.brewersfriend.com/beer-priming-calculator/

...however there is a note:
The beer you are about to package already contains some CO2 since it is a naturally occurring byproduct of fermentation. The amount is temperature dependent. The temperature to enter is usually the fermentation temperature of the beer, but might also be the current temperature of the beer. If the fermentation temperature and the current beer temperature are the same life is simple.

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.

 

[day_trippr]

Debate? The carbonation calculators need to know residual CO2 content, hence the warmest temperature is used.

Dead simple physics: the beer at its warmest post-fermentation temperature sets the carbonation content.
Dropping the temperature doesn't add any CO2 - but it does maintain what was there at the higher temperature (at least to a large extent).
The head space argument is interesting but as post-fermentation head space CO2 content will not be 100% it may at best be a second-order effect...

Cheers!

 

[doug293cz]

@day_trippr is mostly correct. But the beer will eventually absorb some additional CO2 after an extended cold crash. However, the error that might cause in carbonation levels is much smaller than the error caused by using the cold crash temp in the priming calculator. I published a detailed analysis of all of this a while back, and you can find it here: https://www.homebrewtalk.com/forum/...-question-seeking-advice.564962/#post-7275311. So, as day_trippr said, there is no debate.

Brew on

 

[thehaze]

I have used the fermentation temp. as input and all my beers carbed fine. I am a beginner and only started last year, but out of my 19 batches, neither had any issues being carbonated in the bottle. In fact, most beers are already OK carbonated in 5-10 days, but some require additional time to fully develop the flavours, etc.

 

[Miraculix]

Debate? The carbonation calculators need to know residual CO2 content, hence the warmest temperature is used.

Dead simple physics: the beer at its warmest post-fermentation temperature sets the carbonation content.
Dropping the temperature doesn't add any CO2 - but it does maintain what was there at the higher temperature (at least to a large extent).
The head space argument is interesting but as post-fermentation head space CO2 content will not be 100% it may at best be a second-order effect...

Cheers!

Exactly my thoughts as well. Always went well for me using those assumptions.

 

[beerlover77]

Debate? The carbonation calculators need to know residual CO2 content, hence the warmest temperature is used.

Dead simple physics: the beer at its warmest post-fermentation temperature sets the carbonation content.
Dropping the temperature doesn't add any CO2 - but it does maintain what was there at the higher temperature (at least to a large extent).
The head space argument is interesting but as post-fermentation head space CO2 content will not be 100% it may at best be a second-order effect...

Cheers!

Good responses.

I agree with your statements (as I originally stated that I use the ferment temp) but started this post for a reason. I think there are calcs out there that wrongly imply that you use the temp of the beer at bottling time, not at the end of fermentation. My friend and at least one member on HBT have stated you use the cold crash temp so there is some confusion out there. I personally can't see how chilling a beer will cause MORE carbonation. All the chilling should do is absorb the Co2 that is already present in the fermenter into the beer, not add to it.

Also to play the Devil's advocate I think there there may be other variables in there. Here is an example:
If you make a beer and then bottle it in 7 days there will in theory be more Co2 present compared to a say a beer bottled at day 30, no?

 

[doug293cz]

...

Also to play the Devil's advocate I think there there may be other variables in there. Here is an example:
If you make a beer and then bottle it in 7 days there will in theory be more Co2 present compared to a say a beer bottled at day 30, no?

Not usually, if cold crashing. If the fermenter remains sealed, such that none of the CO2 that was in it at the end of fermentation leaves the fermenter, then the older beer will have slightly higher CO2 levels than the younger beer. This is because some of the CO2 in the headspace will dissolve into the beer at the lower temps. The longer the wait before bottling, the more CO2 will dissolve, at least until equilibrium is reached.

It's really all about the CO2 partial pressure in the headspace, and whether it is higher, or lower, than the equilibrium CO2 partial for the carbonation level of the beer at the beer temperature.

The analysis linked in post #3 above takes all of this into account.

Brew on