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Proper bottling temp to calculate sugar amount?

http://www.thebrewingnetwork.com/forum/viewtopic.php?f=5&t=31632

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Proper bottling temp to calculate sugar amount?

Posted: Wed Jan 22, 2014 7:46 pm
by Hopmonkey
I know, I am still in the dark ages by still bottling.
I have not been able to find a definitive answer/reasoning on the temp to use when bottling. Carbonation tools need a temperature to calculate the amount of sugar to bulk prime. I have been using the temp of the fermentor at time of bottling. Years ago, I used to use the fridge temp, since that is what I was going to serve the bottles at.

I worry that using a higher temp (room temp, fermentor temp), the bottles will be over-primed. I have had a bunch of violent gushers and have (I think) ruled out the usual suspects (infection, sanitation). I use Beersmith to calculate the amount of sugar and usually target around 2.2-2.4vols.

Any advice would be greatly appreciated
Hopmonkey

Re: Proper bottling temp to calculate sugar amount?

Posted: Thu Jan 23, 2014 9:06 am
by hoodie
Those calculations are based on the temperature of your beer at the time of bottling not the temperature you will condition them at. These calculators take into account the amount of CO2 left over from fermentation, which there will always be some. https://byo.com/brown-ale/item/1271-priming-with-sugar , http://www.northernbrewer.com/documenta ... ioning.pdf , http://www.northernbrewer.com/shop/prim ... DOSE_Slide

Re: Proper bottling temp to calculate sugar amount?

Posted: Thu Jan 23, 2014 1:54 pm
by Hopmonkey
Thanks for the quick reply. From reading the links, It seems that the temp in the calculation is only to accommodate for residual CO2 in solution. And when lowering the temp to serve, the volumes CO2 won't change, in the bottle. The difference is how the CO2 leaves the solution once opened.

This makes sense, if I have read it correctly.


Thanks
Hopmonkey

Re: Proper bottling temp to calculate sugar amount?

Posted: Tue Feb 24, 2015 6:52 am
by simchuck
The thing that is never discussed (at least as far as I have been able to find) is how cold crashing after fermentation affects the residual carbonation.

Clearly, if your active fermentation finishes at 64°F, then as long as you don't agitate the carboy to drive off CO2, you should have about 0.9 vol CO2 in solution. Bottling at that temperature, it is relatively straightforward to determine how much priming sugar to add to get to the right carbonation level.

But if at the end of a 64°F fermentation you cold crash to 40°F, again without agitating the carboy, I DON'T think you can expect 1.4 vol CO2 in solution, since the fermentation was already done and the only additional CO2 available would be from the headspace in the carboy. The effect of concentration of the CO2 due to volume shrinkage of the beer at this lower temperature is probably relatively insignificant.

So for my bottling, I have been assuming that I need to use the temperature at the end of active fermentation to calculate the residual CO2. I tried for a few batches to use the peak temperature during the fermentation, but those bottles seemed to be somewhat overcarbonated.

Has anyone seen a reference that specifically addresses residual CO2 after cold crashing?

Re: Proper bottling temp to calculate sugar amount?

Posted: Tue Feb 24, 2015 3:28 pm
by brewinhard
When you allow the beer to warm up to room temps before bottling, which is a solid practice, wouldn't the CO2 dissolved into the beer from cold crashing return to the typical concentration as before cold crashing (more or less)?

Re: Proper bottling temp to calculate sugar amount?

Posted: Tue Feb 24, 2015 5:39 pm
by simchuck
That would make sense to me... but only if the CO2 was generated by fermenting at the cold temperature. If you chill the beer after active fermentation, the only additional CO2 to absorb is that in the headspace, so CO2 concentration would be less than the saturation level when chilled. When you warm it back up, the CO2 should stay in solution until it reaches saturation.

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