[brulosopher]

Curious about rumors regarding the impact higher pressure fermentation has on yeast character, Greg chose Saison for the second xBmt on this topic. Check out this comparison of the same beer fermented at drastically different pressures!

http://brulosophy.com/2015/09/07/under-pressure-pt-2-the-impact-of-pressurized-fermentation-on-saison-xbmt-results/

[ynotbrusum]

Another interesting study that seems to debunk a widely held belief - so much for open fermenting being better - although yeast strains may vary with respect to this factor, I imagine.

[brewinhard]

Cool!  Well done.  I love reading these.  Thanks for the hard work!

[chumley]

You should do this with the Dupont strain, to see if the pressurized fermentor stalls.

[MDixon]

I did an experiment long ago and found with a particular yeast you could reach a high enough pressure to stall the ferment. When the pressure was lowered/released the fermentation restarted. I was only doing sugar water and Doric yeast in a keg which had not been cleaned after a previous batch. The pressure where the fermentation stopped was 45 psi with that mixture.

[brulosopher]

Another interesting study that seems to debunk a widely held belief - so much for open fermenting being better - although yeast strains may vary with respect to this factor, I imagine.

At this point, I believe pressure sensitivity is a strain by strain thing.

Cool!  Well done.  I love reading these.  Thanks for the hard work!

Cheers!

You should do this with the Dupont strain, to see if the pressurized fermentor stalls.

Absolutely plan to play around with that yeast, may test Drew's theory by doing foil vs. airlock first.

I did an experiment long ago and found with a particular yeast you could reach a high enough pressure to stall the ferment. When the pressure was lowered/released the fermentation restarted. I was only doing sugar water and Doric yeast in a keg which had not been cleaned after a previous batch. The pressure where the fermentation stopped was 45 psi with that mixture.

Whoa, and we thought 18 psi was high!

[denny]

AFAIK, it's the Dupont stsain that's sensitive to back pressure.  The other ones, not so much.

[brulosopher]

AFAIK, it's the Dupont stsain that's sensitive to back pressure.  The other ones, not so much.

I think Greg chose Wallonian partially because it's a relatively new strain. We definitely plan to play around with Dupont!

[denny]

AFAIK, it's the Dupont stsain that's sensitive to back pressure.  The other ones, not so much.

I think Greg chose Wallonian partially because it's a relatively new strain. We definitely plan to play around with Dupont!

But what did he really prove?  Is that strain pressure sensitive?  I mean, obviously not, but who said that it was?  I guess to me he simply "proved" a foregone conclusion.  Is it "conventional wisdom" that all saison yeasts are pressure sensitive?  If so, I guess I missed that since I don't generally make saison!

[narcout]

Cool.

I should really try to make it to one of those Pacific Gravity meetings.

[brulosopher]

Cool.

I should really try to make it to one of those Pacific Gravity meetings.

I hung out for a bit at the Pacific Gravity booth on club night at NHC, cool bunch of folks, to be sure!

[erockrph]

A couple of thoughts:

A) Maybe this wan't enough pressure to see a noticeable difference? I believe some commercial lager breweries go as high as 30 PSI.

B) It wouldn't surprise me at all if this was a highly strain dependant factor - I'd definitely give it a try with either A) the DuPont strain, which allegedly stalls under pressure or B) a strain that is typically open fermented like WLP037

C) To maximize the pressure differential, the non-pressurized batch could be done as an open fermentation. When using WLP037 and some other strains, I just sanitize a paint strainer bag and put it over the top of the fermenting bucket until the krausen falls. That leaves you with no back pressure at all. A typical bucket/airlock configuration is going to feel at least a little extra pressure.

Another good experiment and food for thought!

[dbeechum]

I should really try to make it to one of those Pacific Gravity meetings.

You would also be welcome to come up into the deep dark heart of the Valley this Sunday and hang with the Falcons!