2025 Quarter 4 Community Recipe

[Craigerrr]

I brewed this Monday, and was surprised that the 34/70 was very busy 18 hours after pitching. I was expecting a longer lag time. Fermenting at 15C, and about 15PSI, as of last evening it seems like actual fermentation is completed.
No more off gassing happening, seems to have dropped pretty clear as well.
It has been a few years since the last time I used 34/70, should I bump the temperature up a few degrees for the next few days?

 

[Josh Hughes]

Yes. Odds of diacetyl with that yeast at 59 are pretty low but it wouldn’t hurt.

 

[Craigerrr]

Yes. Odds of diacetyl with that yeast at 59 are pretty low but it wouldn’t hurt.

Cool thanks

 

[J A]

I brewed this Monday, and was surprised that the 34/70 was very busy 18 hours after pitching. I was expecting a longer lag time. Fermenting at 15C, and about 15PSI, as of last evening it seems like actual fermentation is completed.
No more off gassing happening, seems to have dropped pretty clear as well.
It has been a few years since the last time I used 34/70, should I bump the temperature up a few degrees for the next few days?

If fermentation is done and yeast is dropping, there won't be any benefit to raising temp. If yeast is not active, it can't metabolize the diacetyl. The good thing is that ferment at near 60 degrees, a D-rest isn't mandatory. Some brewers will ferment closer to 50 degrees and raise to around 60 for D-rest. And 34-70 isn't a big producer of diacetyl to begin with. I'd wager you're good to go.

 

[Craigerrr]

I will take a gravity sample tomorrow, if it is at FG I will set it to cold crash for a few days

 

[Donoroto]

If fermentation is done and yeast is dropping, there won't be any benefit to raising temp. If yeast is not active, it can't metabolize the diacetyl. The good thing is that ferment at near 60 degrees, a D-rest isn't mandatory. Some brewers will ferment closer to 50 degrees and raise to around 60 for D-rest. And 34-70 isn't a big producer of diacetyl to begin with. I'd wager you're good to go.

I respectfully disagree with the assumption that if there are no bubbles, yeast is not active.

Persuade me differently?

 

[J A]

I respectfully disagree with the assumption that if there are no bubbles, yeast is not active.

Persuade me differently?

I said, "If fermentation is done and the yeast is dropping..." Yeast cells that are falling to the bottom are going dormant - they're done.

I didn't mention bubbles but since you bring it up, there can absolutely be off-gassing and bubbles and even pretty substantial airlock activity after a beer is at gravity and the yeast is completely finished metabolizing. Because there's CO2 in suspension and that is temperature-dependent, a slight rise in temp can release a fair amount of CO2. Also, even in a dead-finished fermentation, if you swirl the bucket or carboy and agitate the liquid, a lot of bubbling and foaming is going to occur.

As you allude to, the same can be extrapolated in terms of continued yeast activity (and CO2 production) with no active bubbling...if a carboy cools even a few degrees, the pressure of the CO2 is offset by the contraction of the liquid and increased gas suspension and airlock activity stops before yeast metabolism is at a stand-still.

 

[Donoroto]

Fair enough!