First all-grain, pressure fermentation goof

[geeball]

This is my first all-grain batch. I did a pressure fermentation but found after about 24 hours that my spunding valve wasn’t on properly and my keg pressured up to over 40 psi! I vented back down to 12 psi and fermentation went fine for a day but then stopped. I sampled and gravity was 1.032 instead of 1.010. Fermentation was done at 25 C. Using US-05 in an IPA. Should I pitch more yeast?

 

[Mack]

How many days has it been doing "nothing"? I'm guessing you opened the keg to pull gravity from it - Did you put the spunding valve back on afterward? I've seen mine lift back to 10-12 psi over a few days, letting me know that there is some slow fermenting going on...

 

[bestcoast]

When you say fermentation stopped, what are you basing that on? Appearance of the wort? Live gravity readings from a tilt or something? How long has it been since you put the batch in the fermenter?

 

[geeball]

Yes, I put the spunding valve back on, added my dry hops and pressured it back up to 10 psi with CO2. The fermentation continued, albeit slowly, for another 24 hours or so and then quit completely. I've let it sit two more days and dropped the spunding valve pressure back to about 5 psi and it bubbled for a bit but then stopped (I have the downstream tubing from my spunding valve in a jar of water so I can see the CO2 being released so that's how I'm tracking the fermentation). I'm just wondering if it "killed" the yeast by mistakenly allowing the pressure to get up over 40 psi. At this point I assume all I can do is pull another gravity sample and see if it's at the target gravity of 1.010. I just need some advice on what to do if the gravity is still high. Thanks in advance for any insight.

 

[fluketamer]

welcome to homebrewtalk
fwiw i have not had great success pressure fermenting ales.. i have spunded them with a few points left to carb up after most of fermentation is done without issue. but i have found ale yeasts dont like pressure like say 34/70 does ( this yeast likes everything . hi pressure. hot , high pressure cold , atm pressure cold or hot its fool proof. )

how are you measurig gravity?

i just googled 25 celcius is 77 deg !

thats the upper range for 05, you may be finished.


does it taste sweet. 1.035 is definately sweet tasting. 1.010 tastes like flat beer. whatever you do wait a week. to package .

 

[geeball]

welcome to homebrewtalk
fwiw i have not had great success pressure fermenting ales.. i have spunded them with a few points left to carb up after most of fermentation is done without issue. but i have found ale yeasts dont like pressure like say 34/70 does ( this yeast likes everything . hi pressure. hot , high pressure cold , atm pressure cold or hot its fool proof. )

how are you measurig gravity?

i just googled 25 celcius is 77 deg !

thats the upper range for 05, you may be finished.


does it taste sweet. 1.035 is definately sweet tasting. 1.010 tastes like flat beer. whatever you do wait a week. to package .

Yes - when I pulled the sample and tested gravity using my hydrometer and got 1.032. I did taste it and it definitely tasted sweet which reinforced my thinking that fermentation was incomplete.

What I've been reading and hearing on podcasts about pressure fermentation is that it's fast and it's ok to ferment at higher temperatures (5 to 10 C (or 9 to 18 F)) above the yeast temperature range. The US-05 packet suggests 18-26 C (64.4-78.8F) so I just picked a temp near but not past the upper range.

Now, it is possible that the internal temp of my fermenter (corny keg) is higher than 25 C because I have the corny keg sitting in a large bucket of water with an immersion heater in the water maintaining the water temp at 25 C (77 F). It's pretty cold in my basement so the immersion heater kicks on and off to keep the temp at 25 C.

(It's sounding like I need to invest in an ispinle or a tilt to be sure I know gravity and temperature.)

 

[fluketamer]

no if it tastes sweet its likely 1.035 and not done.
you prolly shocked or killed your yeast.

i asked professor google and he seems to think so.


Yes, a pressure of 40 psi is likely to kill most ale yeast, as typical fermentation pressures for ales are much lower, usually ranging between 8-12 psi; exposing yeast to significantly higher pressure like 40 psi can be detrimental and potentially lethal to the yeast cells.


i doubt you killed ALL of your yeast so perhaps reducing pressure to 0 and leaving it for a few days perhaps a swirl or two and they may rouse. other options is to pitch a new pack.

i am curious are there a lot of pressure fermenting ale recipes out there. after a little experimenting i found that only lager yeasts make good pressure fermented beers. specifically 34/70.

us05 at 64 degrees if you have that ability is really clean and drops very clear. in my experience

 

[odie]

You can't kill the yeast with pressure...well not without blowing up your system, yourself and home... I've read lab studies where is takes well over a thousand psi to actually stop or kill yeast.

yeast "propagation" or colony growth will be affected by relatively low PSI. 40psi is certainly in that range. You may have stopped the growth phase prematurely with 40 PSI. So you have a small yeast colony trying to eat a lot of sugar. But dropping is back to around 10psi it should have resumed propagation/growth...unless there was not much fermentable sugars left...

but even at 40psi...that yeast is gonna eat...

Give it time...