Temperature and Carbonation

[Ian Davis]

I've been trying to figure this out for some time and seen a lot of conflicting information on other forums.

If I am using a carbonation calculator like the following:

http://hbd.org/cgi-bin/recipator/recipator/carbonation.html

Where it says beer temperature at bottling is this really the temperature of the beer at bottling, the fermentation temperature or the highest temperature reached during the fermentation process?

I am currently fermenting a beer a 16c and will bring it up to around 20c until it's finished then cold crash for at least a few dais if not a week.

There is a big difference between the amount of sugar required if cold crash temp is used vs fermentation temp.

Thanks and apologies if this has been covered before :)

[JR]

For bottling I put in the highest temp that the beer has been post fermentation.  in your case 20.  This is when the beer is least co2 soluble and will determine how much co2 remains in your beer from fermentation.

This is different from keg carbonation calculators that tell you what pressure to set the regulator at.  in those cases you want to use the temp that the beer is when it is being carbonated.

[Dougal]

Hi Ian,

In practice, it's usually pretty straightforward. Use the highest fermentation temperature you reached most recently as the temperature of the beer, even if you've cold crashed. the exception to this would be a lager which has been sitting at 2C for a month or so. In this case you use the current temperature of the beer as there is more CO2 dissolved in solution because it's had a chance to reach equilibrium at the cooler temperature.

If you left your beer a couple of weeks at cold-crash temperatures you can still use the fermentation temp. I'd just let it warm up a bit before bottling, and stir the priming sugar in to free any excess CO2 from solution.

[Ian Davis]

Thanks guys really appreciate this!