Fermenting Under pressure to finish off faster?

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m3B.eer

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Hi all,

My beer has been fermenting for 1 week. No more blow-off tube activity "bubbles". OG was 1.050 and Just took gravity readings : 1.020 with the hydrometer.
Next, it's a Saison yeast, so active at higher temp but it stays in a 22-23C environment, so it should be enough for it I believe.
What else could I do to stimulate fermentation? Shaking / Agitating the fermenter?
I also recently put together a spunding valve. Would fermenting under pressure at this point stimulate the process ? The fermenter is still with blow-off tube for now. I realize my Saison needs the esthers for flavours though....
 

odie

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I don't believe pressure would actually slow anything down. But it will allow you to raise the fermentation temps without getting any off flavors. So you could speed up the fermentation by raising the temps higher than normal.

With a saison though, I really see little benefit.
 

odie

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It does though.
to what extent? 10% slower? 50%? 90%? how much psi does it take to actually start slowing it down? Does the pressure affect the speed of the yeast's sugar eating or the speed of it's reproduction? There is a point at which the reproduction will cease but that PSI is many times greater than the vessel can ever handle.

Has anyone ever cataloged the effects of different psi on the same beer/batch? Say 5psi, 10psi, 25psi, 50psi for example.

A bunch of us are pressure fermenting...But I think most are not running controlled experiments...
 

VikeMan

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^ All good questions. I don't know that there's a chart anywhere, but the phenomenon is real. I mentioned it because @m3B.eer was contemplating pressure as a way of speeding up fermentation, which is the opposite of what it would do.

A lot of (most?) people who ferment under pressure also increase temperature to offset the effect of the pressure. Or alternatively, they ferment under pressure in an attempt to reduce the increase in fusels and esters that would otherwise result from higher temperature fermentation. Having tasted high temperature pressurized "lagers," my opinion is that this doesn't work as well as some think/hope.

Here's as interesting summary of a study which seems to say that pressure (to offset higher temps) does not prevent an increase in fusels, but does suppress esters (though I'm not sure by how much).

 
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m3B.eer

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I don't believe pressure would actually slow anything down. But it will allow you to raise the fermentation temps without getting any off flavors. So you could speed up the fermentation by raising the temps higher than normal.

With a saison though, I really see little benefit.

By raising the temp you'd mean to put it in some sort of hot chamber I assume?

But indeed, saison needs its esthers...
 

VikeMan

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By raising the temp you'd mean to put it in some sort of hot chamber I assume?

A common way to raise temperatures is to use a heat wrap, controlled by a thermostatic temp controller:
33625.png

38705.jpg




But indeed, saison needs its esthers...

I'm not the grammar/spelling police and I make quite a few typos myself, but every time I read "esther," it makes me smile.

Ester:
ethyl-acetate-3d.png


Esther:
C7zjKvyXgAA2Xi5.jpg
 
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m3B.eer

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Hahaha. Esther, for sure! ;-) ( tbh I don't know this reference, but you made me laugh^^)
 

eric19312

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Drew Beechum advocates fermenting Saison under no pressure at all...even pressure from standard three piece airlock or a blowoff tube in a bucket of sanitizer being too much pressure and likely to cause the yeast to stall.
Would seem to advocate against using pressure fermentation to try to move this beer along...
 

VikeMan

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Drew Beechum advocates fermenting Saison under no pressure at all...even pressure from standard three piece airlock or a blowoff tube in a bucket of sanitizer being too much pressure and likely to cause the yeast to stall.
Would seem to advocate against using pressure fermentation to try to move this beer along...

A physicist on another forum computed the pressure added by the liquid in a standard 3-piece airlock at about 1/400th (not a typo) of an atmosphere, which is much smaller than natural fluctuations in atmospheric pressure. Personally, I think Drew drew a false conclusion from his observations. My own observations of the yeast strain in question (Dupont) is that I've never had it stall. Not even once. I've even naturally carbonated with it, to 4 volumes, which was over 50 PSI at my room temp. There were no problems as the pressure increased smoothly all the way up to the end. My consistent experience with the strain is that it does just fine with proper pitch rate, oxygenation, and nutrients.
 
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m3B.eer

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There seems to be a consensus that fermenting under pressure does not make fermentation faster unless we bring the vessel to a higher temperature environment. Got it then, thank you
 
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m3B.eer

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A physicist on another forum computed the pressure added by the liquid in a standard 3-piece airlock at about 1/400th (not a typo) of an atmosphere, which is much smaller than natural fluctuations in atmospheric pressure. Personally, I think Drew drew a false conclusion from his observations. My own observations of the yeast strain in question (Dupont) is that I've never had it stall. Not even once. I've even naturally carbonated with it, to 4 volumes, which was over 50 PSI at my room temp. There were no problems as the pressure increased smoothly all the way up to the end. My consistent experience with the strain is that it does just fine with proper pitch rate, oxygenation, and nutrients.
Pressure fermenting the Dupont saison yeast then, with presence of the "wanted" esters?
 

VikeMan

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Pressure fermenting the Dupont saison yeast then, with presence of the "wanted" esters?

No, not pressure fermenting. Unless you mean the carbonation step, which if course does happen under pressure. But if you're asking if the presence of an airlock affected ester production, I really doubt it. Again, it adds about 1/400th of one atmosphere of pressure.
 
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m3B.eer

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No, not pressure fermenting. Unless you mean the carbonation step, which if course does happen under pressure. But if you're asking if the presence of an airlock affected ester production, I really doubt it. Again, it adds about 1/400th of one atmosphere of pressure.
In regards to your natural carbonation, I meant. In this case do you use a spunding valve, and ferment in what kind of vessel?
 

VikeMan

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In regards to your natural carbonation, I meant. In this case do you use a spunding valve, and ferment in what kind of vessel?

For natural carbonation with the Dupont strain, I didn't spund. I kegged the finished beer along with the appropriate amount of sugar...just like bottle conditioning, but with one big "bottle." The main fermentation hadn't been under any significant amount of pressure.
 

DuncB

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As mentioned by others above Pressure might slow the ferment down not significantly in my experience, but time is saved with the carbonation, I didn't have any stalling problems with an open ferment of WLP 590 french saison that I then spunded when 15 gravity points above projected final letting it rise to 30 psi whilst bumping the temp up to 28 celsius. I did use yeast nutrients, pure oxygen to aerate and built my starter.
When finished crashed, added finings and a few days later transferred to the keg closed for maturation and consumption.
 
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