I bottle condition underwater with frozen water bottles to keep the temperature down. I probably bottle conditioned my last batch of beer beneath 60 °F, and it didn't carbonate all that well, or at all.

I have brewed a new batch of beer at 58-63 °F while the WYeast website indicates its optimal temperature range from 64-72 °F.

I intend on letting it bottle condition in the range of 64-68 °F.

If I cold crashed the yeast (and lowered attenuation) while the batch was brewing, would bottle conditioning at a higher temperature range incline the bottles to explode? I figure this would be the case because the yeast would reactivate and consume the non-attenuated wort in combination with the priming sugar.

  • 3
    "I bottle condition underwater with frozen water bottles ... in the range of 64-68*F" - Sounds like you are giving yourself more work for no reason. Just put the bottled beer into a 70F closet for a week or two and you'll be better off.
    – GHP
    Commented Sep 9, 2013 at 12:02

1 Answer 1


Yes, there is a potential risk of bottle bombs, as with any incomplete ferment. The residual fermentables can be fermented by the remaining yeast in the bottle along with the priming sugar and produce more CO2 than intended. Ideally you should cold crash only after you are sure primary is complete. Many brewers simply leave the beer in primary for at least 2 weeks, which pretty much guarantees completion, (assuming a fairly stable or slightly increasing temperature.)

If you're unsure about primary being complete, you can try a forced ferment, to determine what the FG should be.

I'm not surprised conditioning at 60°F didn't produce much carbonation - the yeast need a fair activity level for the beer to carbonate. There is relatively little yeast in the beer during bottling - less than 100,000 cells/ml, which is typically less than 2% of that which was available during primary. With the low cell count and low temperature the yeast will not be very active at all. Better to condition for a week at 68-70*F before cold crashing to serving temps. During that time the yeast will ferment the priming sugar, produce the CO2 which then will dissolve into the beer over an additional week - faster if the beer is then kept cold.

Keeping the temperature low during bottle conditioning during the first week, is nowhere near as important as temperature management during the primary ferment, and sounds like for you it's causing more problems than it's solving.

  • 1
    An excellent answer! Keep in mind that if your wort attenuated fully, the only fermentation in the bottle will be due to the priming sugar you add. As mdma said, there is so little fermentation going on during carbonation that off flavors due to higher temps are not an issue. And you can never fully stop fermentation by cold crashing the yeast. There will be enough yeast left to continue slowly fermenting the wort.
    – Denny Conn
    Commented Sep 8, 2013 at 20:01

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