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Fermentation Under Pressure

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Mutant

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Anybody have any experience (positive or negative) or thoughts with fermenting under pressure? I'm testing three lagers (WLP815, WLP885 and Imperial L28) simply using 5 gallon kegs with modified 35psi (Red) pressure relief valves. I've modified these valves to get ~13psi.

I have no results, as these will not be ready until roughly Christmas or New Years. Just wanting to hear what others have experienced or know.
 

FunkedOut

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I remember a tale of testing fermenting under pressure at the Homebrew scale.
I believe it was an effort by John Blichman and Chris White?
The take away was lower esters and phenols (lab tested) were produced as the pressure increased.
No negative effects south of 2 bars (30psi).
I read a .pdf with graphs but don’t remember where.
Don’t remember the yeast.

I always ferment in a keg.
In the beginning of my ferments, I find I get a lot of wicked smells that are not present near the end.
I always let those initial few days vent off and capture the cleaner smelling gas.
 
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Mutant

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I have three lagers on the secondary that will be ready at Christmas/New Years: Intl Pale Lager, Intl Amber Lager and Helles.

Each were initially using a blow-off tube, then all were fermented under 13psi in Corneys. I had my son build some pressure relief valves (red) to work at that pressure.

When I transferred the Intl Pale Lager, it was the best beer I'd ever sampled out of the primary. Being under 13psi, there was some natural carbonation when I tasted it - super fine/small bubbles.

After ~two weeks in the secondary the three have not cleared yet, but there is an obvious benefit. Very smooth. The Intl Pale Lager was a variation of a beer that won 1st Place at CA State Homebrew Competition and is much better than what won. This could be a mid-40 score beer which is difficult in that category.

The Helles is also turning out very nice. The Intl Amber seems fine at this point, but will keep monitoring.

Not likely going back an airlock.

The next three lagers will come off the primary next week: Pre-prohibition, Intl Dark Lager and American Lager. All of these are new recipes using the same yeast - WLP840 American Lager yeast. The Intl Dark Lager is my attempt to recreate the Dixie Voodoo Lager - I figure it will take me several batches to fine tune as I likely will need a different yeast and other subtle tweaks.
 

Tegra

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There is a huge thread on it somewhere here.

It is the only way I ferment now!
 

Mer-man

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What? Final fermentation under pressure results in a better textural experience? Heavens no, that would mean that spunding for carbonation is different than fermenting to FG and then force carbing!
;)
 

VirginiaHops1

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What? Final fermentation under pressure results in a better textural experience? Heavens no, that would mean that spunding for carbonation is different than fermenting to FG and then force carbing!
;)
I've heard natural carbonation supposedly helps with mouthfeel but what's the science behind it? I don't think CO2 gas knows whether it's coming from yeast or a CO2 tank. I know carbing slowly over time(whether natural or from a tank) will allow the CO2 to be absorbed into finer bubbles or whatever rather than shaking the sh!t out of your keg, but that's different from saying natural carbing does something gas from a tank doesn't.
 

Vale71

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That nonsense gets repeated ad nauseam, especially in Germany where it's used to further "prove" German beer's superiority (because of the Reinheitsgebot swindle which, ironically, doesn't really prohibit force carbonation).

Funnily enough this has never been tested scientifically and nobody can venture a scientific explanation for this "phenomenon". Ask any physicist and they well confirm this is total nonsense.
 

VirginiaHops1

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There's a lot more I don't know about brewing than do know so I'd love for someone to enlighten me, but I can't think of why the quality of CO2 would be different. I know the CO2 from yeast is more "pure" than the tank which is not 100% CO2, whether that matters or not I don't know. But the actual CO2 molecules are identical right?

I would venture a guess that any difference people taste is just the CO2 gas being absorbed over a much longer period of time when they natural carb vs finishing up fermentation and trying to get it carbed from a tank much quicker. But in theory you could just not be impatient when you're force carbing and let it condition/carb for as long as you want.
 

Vale71

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All CO2 is pure since it's made of... CO2. Any impurity exists at a macroscopical level (i.e. gas mixture) and is irrelevant as molecules in a gas are not bound to other molecules of the same gas or different gases. That's the very definition of a gas BTW.
I've heard all sorts of silly theories to "explain" this "phenomenon", some unfortunately from otherwise very reputable sources. For example one theory is that CO2 molecules from fermentation enter the beer "one molecule at a time" and therefore "bind differently". Yeah right, after all when force carbing we all add "big CO2 chunks", right? This is obvious nonsense because of the very nature of gases which I mentioned above.
 

tbaldwin000

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That nonsense gets repeated ad nauseam, especially in Germany where it's used to further "prove" German beer's superiority (because of the Reinheitsgebot swindle which, ironically, doesn't really prohibit force carbonation).

Funnily enough this has never been tested scientifically and nobody can venture a scientific explanation for this "phenomenon". Ask any physicist and they well confirm this is total nonsense.
I wouldn't be so quick to make that assumption. Hydration of carbon dioxide is a very slow process at low temperatures, but massively faster at higher temperatures, which is one scientific theory as to the difference between the two, at least before the cold-carbonated beverage has time to fully hydrate.
 

Vale71

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The assumption here is that you'd spot the difference if you were to taste two identical beers one spunded and one force carbonated. Of course both beers will have to be fully carbonated and conditioned under the same conditions for the test to be meaningful. I don't see how the temeperature at which each beer was carbonated with either method (which could very well be the same temperature BTW) could make a difference unless one wants to invoke some ridiculous notion such as a "memory effect" of either CO2 or beer?
 

ba-brewer

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The assumption here is that you'd spot the difference if you were to taste two identical beers one spunded and one force carbonated. Of course both beers will have to be fully carbonated and conditioned under the same conditions for the test to be meaningful. I don't see how the temeperature at which each beer was carbonated with either method (which could very well be the same temperature BTW) could make a difference unless one wants to invoke some ridiculous notion such as a "memory effect" of either CO2 or beer?
As fermenting under pressure can result in less attenuation, that might give a different mouth feel to the beer if one had a little more residual sugar. Would also explain more head retention.
 

Bilsch

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All CO2 is pure since it's made of... CO2. Any impurity exists at a macroscopical level (i.e. gas mixture)
You can see impurities in gasses with your eyes? Cool.. I wish I had that superpower.
 

Vale71

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You can see impurities in gasses with your eyes? Cool.. I wish I had that superpower.
Very droll. Can I have fries with that?

I was ridiculing the idea that individual CO2 molecules would somehow behave differently depending on how they got into the beer, which is is clearly nonsense. Every CO2 molecule is identical to every other CO2 molecule. It cannot have "impurities" or anything like that, and that's the "microscopical" level.

The concept of "impurities" exist in a gas mixture, which is made up of a ridiculously large amount of molecules, and that's what I referred to as "macroscopical" level. I certainly can't detect that with my eyes but we got instruments and lab tests for that.

Single molecule = microscopical
Mixture of a huge number of molecules = macroscopical

You got it now or should I try and simplify even more for you?
 

Bilsch

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Very droll. Can I have fries with that?

I was ridiculing the idea that individual CO2 molecules would somehow behave differently depending on how they got into the beer, which is is clearly nonsense. Every CO2 molecule is identical to every other CO2 molecule. It cannot have "impurities" or anything like that, and that's the "microscopical" level.

The concept of "impurities" exist in a gas mixture, which is made up of a ridiculously large amount of molecules, and that's what I referred to as "macroscopical" level. I certainly can't detect that with my eyes but we got instruments and lab tests for that.

Single molecule = microscopical
Mixture of a huge number of molecules = macroscopical

You got it now or should I try and simplify even more for you?
No, I understand how you might get that from Wikipedia even though it isn’t the correct usage of the word in this case. Regardless of the fact that CO2 molecules by themselves are by definition pure, CO2 as a gas does not come from any compressed gas source alone but with some friends: O2, CO, NH4, hydrocarbons, SO2, H2S to name but a few while natural carbonation does not. I would consider this a difference between the two sources and quite possibly another reason there is a taste difference.
 

Bigarcherynut

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I've been looking for threads on fermenting under pressure. I received a FermZilla fermenter for Christmas and was interested with pressure fermentation. I searched for awhile in different forums in regards to pressure levels and beer styles but haven't found much.

I liked what I heard in the video. My question is about a beer I just brewed. It's a Founder's Backwoods Bastard clone. Most of my readings said to ferment between 12 & 15 PSI. When I posted on another forum, I was told that fermenting under pressure, a beer with a high OG will not ferment fully because I will kill my yeast. Hearing that I backed my regulator from 12 PSI to 5. After hearing what they said in the video, I wouldn't have to worry. I stayed with 5 PSI to be safe because I just cannot find much info of pressures and beer styles.

Any info would be appreciated.
 

mkopec1

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This dude has some videos on pressure fermenting, hes been doing it for a while. He also did an experiment doing brews for a whole year on one yeast cake at the bottom of the pressure fermentor until it got bad. He usually ferments under 2-2.5 bars 30-36 psi. Check him out, hes also pretty funny...

https://www.youtube.com/channel/UCTS_GWRi84txMj0zWanv_Cw/featured

Lager in 3 days..

 
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