Residual Co2

[Julez]

Good morning fellow brewers,

I've been reading conflicting information on this topic, hoping someone out there can provide some clarification.

From my understanding, the lower the fermentation temp, the more CO2 is likely to remain in solution at the end of fermentation. This has to be allowed for when bottle priming. Some texts suggest that it is the temp of the beer when bottling that is important, while others state that it is the actual fermentation temp that matters. I found a good BYO article, which states;

"Keep in mind that, if your beer warms up after fermentation, it will lose CO2. This will not happen instantaneously, though. However, lowering your beers temperature will not increase the level of CO2, unless a source of CO2 is present. (Continuing fermentation or CO2 from an outside source like CO2 cylinder are the two most likely possibilities.)"

Is this correct? If so, residual CO2 should be worked out, based on the actual fermentation temp, not the temp after crash-chilling/immediately before bottling. This would assume of course, that fermentation was complete, prior to crash-chilling. Would you agree?

Cheers,

Julez :icon_cheers:

 

[Zwickel]

"Keep in mind that, if your beer warms up after fermentation, it will lose CO2. This will not happen instantaneously, though. However, lowering your beers temperature will not increase the level of CO2, unless a source of CO2 is present. (Continuing fermentation or CO2 from an outside source like CO2 cylinder are the two most likely possibilities.)"

Is this correct? If so, residual CO2 should be worked out, based on the actual fermentation temp, not the temp after crash-chilling/immediately before bottling. This would assume of course, that fermentation was complete, prior to crash-chilling. Would you agree?

Julez, thats absolutely correct!

:icon_cheers:

 

[Julez]

Julez, thats absolutely correct!

:icon_cheers:

Great! Thanks for the confirmation, Zwickel!

 

[buttersd70]

I always give it as "the maximum temperature that the beer has been at any point in the process between the start of active fermentation, and up untill it is bottled".

This covers raising temperatures as well, such as diacetyl rests where the higher temperature is held long enough for co2 to be lost out of solution, whilst ignoring higher temperatures between pitching and active fermentation starting (if thats part of your process).

 

[matti]

I never did a calculation of Co2 remaining in beer whenI used to bottle, but I found that if were to prime with 7g/L at room temperature. I tend to use a gram less per liter if bottling the beer cold.

In this case 6g/L or 138g Dextrose for 23L batch as opposed to 161g in room temperature.

Since I bulkprimed in most cases some Co2 dis appeared in transferal.

My advice to newbies is to prime beer at 18 degrees and never more the 8-9g/L to avoid bombs.