Yeast for pressure fermentation

[JayF]

Hi

I just bought a fermentausaurus to try do a lager a room temperature. I have 2 questions.

Can you use any yeast to ferment under pressure ?
Would there be any adverse effect if i ferment an ale yeast under pressure?

I already have my grains for my next few recipe and they're all ales. I would like to try this asap.

JF

 

[Robert65]

Hi

I just bought a fermentausaurus to try do a lager a room temperature. I have 2 questions.

Can you use any yeast to ferment under pressure ?
Would there be any adverse effect if i ferment an ale yeast under pressure?

I already have my grains for my next few recipe and they're all ales. I would like to try this asap.

JF

I do pressurized lager fermentation (in a 10 gallon corny in my case) with my current house yeast, WLP833. Even though White Labs sells a "high pressure lager yeast," note that Chris White himself used 833 for all his own pressure fermentation experiments. Not that there's anything special about that one either. Kind of a coincidence I settled on it. I'm not aware that commercial German brewers using the method use any special yeast. So AFAIK there's no reason not to use any yeast you like.

I have tried a couple of ales under pressure, in my case with S-04. I wouldn't do it again. I found it does what you want it to do with a lager: suppress esters and other fermentation products. Makes for an un-ale-like ale, IMO.

Note that because you are fermenting at ale temperatures, lagers will finish as fast as ales, and because they are so clean after pressure fermentation, they're ready to crash, clear and package as fast as an ale. Since ales are already going quickly, I don't see any practical advantage to using pressure fermentation on them.

But hey, try what you want and see how you like it. And maybe different ale yeasts will perform differently, or you want clean fermentation characteristics in a particular style. Play around with it and report the results!

(BTW my pressure fermented lagers are equal if not superior in every way, IMO, to the traditionally made ones I was doing for a couple decades. Wish I'd tried it sooner. You'll love it.)

 

[schematix]

See what you like but pressure fermenting is not some holy grail.

In my experience it didn't do much to change the beer aside from making the yeast take forever to finish, and typically quit early.

I get MUCH better results from atmospheric fermentation.

 

[Robert65]

See what you like but pressure fermenting is not some holy grail.

In my experience it didn't do much to change the beer aside from making the yeast take forever to finish, and typically quit early.

I get MUCH better results from atmospheric fermentation.

Quite the opposite of my experience and several published reports, at least WRT lagers. Good reason for the OP to try and see what actual experience under specific conditions proves.

 

[JayF]

Thank you,

Do you pressurized your keg with co2 right when you pitch your yeast or you just let the pressure build up? Alson what would be a good pressure setting on the spunding valve?

Thank you

JF

 

[Robert65]

I don't pressurize right away. In fact I put an "airlock" (tube into a jar of Star San) on and wait till I see good bubbling activity (~5 hours) on the theory that I don't want pressure to suppress initial growth, but I have no real data to show that this procedure makes any difference. Anyway, at that point I put the valve on. (I have in fact just put the valve on right at pitching and seen no ill effects.) It builds quickly from there. I go for about 15 psig at peak fermentation. Tip: to adjust your spunding valve. I realized early on that the valve can only release gas so fast, so setting it to hold 15 psig static would cause pressure in the fermenter to exceed that considerably. The trick is to put just a little more than target pressure (for me 16 psi) on the liquid side of a spare keg. Then put the valve on the gas side and adjust until it holds target pressure (e.g 15) steady while hissing away nicely. You'll notice it drops considerably after fermentation activity abates, so if you intend to carbonate in the process, you'll need to make further adjustments. Happy brewing! [emoji482]

 

[SanPancho]

Isnt 833 one of the yeasts used for high temp lagers? If so id imagine starting warm at atmospheric is no big deal. But ive started others warm while waiting for the pressure build up and the results were no bueno.

I havent bothered with pressue since ive moved to doing room temp with 34/70, so this is based on limited experience, but id venture to say your results will be strain dependent. Especially if you wait on the top pressure.

 

[Robert65]

Isnt 833 one of the yeasts used for high temp lagers? If so id imagine starting warm at atmospheric is no big deal. But ive started others warm while waiting for the pressure build up and the results were no bueno.

I havent bothered with pressue since ive moved to doing room temp with 34/70, so this is based on limited experience, but id venture to say your results will be strain dependent. Especially if you wait on the top pressure.

I have heard of good results with 34/70 warm and at atmospheric pressure. I also know that according to Kunze and other professional literature, it is not uncommon to wait until 50% AA to apply top pressure; but these things go off so fast, I'd miss that while sleeping off my brew day, hence capping earlier in active fermentation. I think that, WRT how all this plays out on the homebrew scale and relative to our goals, more empirical data is needed. Hopefully the OP will be another correspondent.

 

[SanPancho]

if the idea is to balance high temp with high pressure then id think youd need to add pressure from the get go. But pressure does inhibit growth, so thre must be some way to balance then at the start. Maybe pitch normal temp and let both factors rise together as the ferment takes off? Or start with low pressure like 5psi and then a big and kinda warm pitch?

Ive never seen specifics on the protocol at pitching, and I never had the time to experiment. But id be interested to hear the results.

 

[Robert65]

if the idea is to balance high temp with high pressure then id think youd need to add pressure from the get go. But pressure does inhibit growth, so thre must be some way to balance then at the start. Maybe pitch normal temp and let both factors rise together as the ferment takes off? Or start with low pressure like 5psi and then a big and kinda warm pitch?

Ive never seen specifics on the protocol at pitching, and I never had the time to experiment. But id be interested to hear the results.

Yeah, I think you're making sense. You want growth early, and then suppressed metabolism later. There are probably lots of different viable permutations. My own system, which works a treat, is to pitch warm, but with the same pitch rate I would use with a cold lager pitch/fermentation (like double what I'd do for an ale at atmospheric pressure,) and, as mentioned above, apply top pressure fairly quickly. One compromise.

Something else that really intrigues me is implied in my second sentence in the above paragraph: the fact that we've been conditioned to believe that it's the early stage conditions that determine ester character, yet experience with warmer pitching and later capping (as well as other novel fermentation methods) puts the lie to this. Much more study is needed. But, practically (and I am fundamentally a pragmatist,) this works.

 

[Vale71]

Yeah, I think you're making sense. You want growth early, and then suppressed metabolism later.

Actually when doing a warm fermented lager you want to suppress growth as this is the phase where most of the off flavors (such as, for example, diacetyl precursors) and unlager-like compounds are generated. That's why a standard warm fermentation profile combines a higher pitch rate, lower oxygenation levels (current research aims at no oxygenation at all), lower pitch temperature with free-rise until target temperature is reached and immediate pressure build-up with gradual increase all the way to full carbonation pressure.

 

[Vale71]

Can you use any yeast to ferment under pressure ?

Of course you can, the results might just be better with some strains and worse with some others.

Would there be any adverse effect if i ferment an ale yeast under pressure?

Besides suppressing ale character as reported by another poster this really wouldn't make any sense from a practical standpoint. The point of fermenting a lager at higher temperature under pressure is, in a commercial setting, to shorten fermentation time by 2-2.5 days (through higher fermentation temps) while suppressing unwanted side effects (through the use of pressure and the other factors I mentioned in my other post). For homebrewers of course the main reason (other than the novelty factor) is to eliminate the need for temperature control. With an ale you're already fermenting warm, applying pressure would just make fermentation proceed at a slower than normal pace, which is simply counterproductive and would make no sense at all.

 

[JayF]

Lots of great info. Thank you all.

Ill do a standard fermentation for my next ale recipe than try the lagers.


Thanks

Jf

 

[Gnomebrewer]

With an ale you're already fermenting warm, applying pressure would just make fermentation proceed at a slower than normal pace, which is simply counterproductive and would make no sense at all.

This is absolutely my experience - ales fermented under pressure have taken more than two weeks to reach FG - one crawled along for about four weeks. For ales, I find it much better to perform most of the ferment at normal pressure, then close/spund the ferment with a few to 10 points remaining if I want to carbonate in the fermenting keg (which I really like doing).

FWIW though, I haven't found lager ferments to be any faster warm/under pressure than they are cool/no pressure. I prefer the results as per ales - ferment cool/normal pressure most of the way, then close/spund towards the end.

 

[Robert65]

FWIW though, I haven't found lager ferments to be any faster warm/under pressure than they are cool/no pressure.

Just checked my current one. 82% AA in 3 days. Absolutely typical of my pressure-fermented lagers. So about half the time. But I will leave it several more days before crashing and lagering a few weeks to clarify, so not much time gained overall. But the results are superior, and the time gained would be greater if I were filtering my beer, and that time would be significant I were a commercial brewer. (For me, the main attraction is being able to get yeast pitched within 40 minutes of knockout, as opposed to waiting several hours to get all the way to cold pitching temperature, during which time wort is subject to oxidation.)

 

[Jtvann]

Any disadvantage to pressure fermenting lagers at 15 psi while maintaining traditional temps in the low 50s?

 

[Robert65]

Any disadvantage to pressure fermenting lagers at 15 psi while maintaining traditional temps in the low 50s?

You'd have two mechanisms, temperature and pressure, working to suppress yeast metabolism. I'm unaware of the practice ever having been pursued. You can, of course, apply pressure near the end of fermentation (spund the fermenter) to carbonate the beer. That is standard practice. But applying top pressure early in a cold fermentation would likely result in laggy and incomplete fermentation. What other effects it might have on the character of the beer, if it did go to completion, no idea off the top of my head.

 

[Jtvann]

Whelp, guess I'll be the first. I'm on day 3 of an Oktoberfest with Wlp838. Fermenting at 50 degrees and 15 psi.

 

[Robert65]

Whelp, guess I'll be the first. I'm on day 3 of an Oktoberfest with Wlp838. Fermenting at 50 degrees and 15 psi.

Do report back!

 

[Gnomebrewer]

I've done it a couple of times, the ferments were slow but still complete and tasted really good. Much the same as with the ales.

 

[Jtvann]

Yeah, I dont mind slow. I figure why rush if you're making a lager in the first place. I'm sure I could crank up the temp and get closer to that balance of ester production vs not, but why not just go pressure and low temp to be off the scales of no weird flavors.

We'll see. I've got a tilt hydrometer in the unitank. Spunding valve is singing.

 

[BruceH]

Any disadvantage to pressure fermenting lagers at 15 psi while maintaining traditional temps in the low 50s?

I just started spunding awhile ago. What I've done is fermented in a bucket for 3 days then transferred to a keg with a spunding valve set to 18 psi (it didn't get above 15psi on the gauge). Gravity at transfer was 1.013 for something that usually finishes at 1.007. All of this for a lager fermented at 52 degrees.

This brew is a German Pils. Due to my lack of patience I put a picnic tap on it today and pulled a glass after 3 weeks total fermentation which included a room temp rest with a 30 psi spunding valve.

It is carbonated and tastes good but is not clear yet. Lack of patience on my part.

 

[Jtvann]

4.5 days in and 50% attenuated. Fermentation rate is about .0070 per day and holding steady. Down from 1.060 to 1.030 so far.

I overshot my OG by 5 pts. This is the first time making this recipe.

 

[Robert65]

4.5 days in and 50% attenuated. Fermentation rate is about .0070 per day and holding steady. Down from 1.060 to 1.030 so far.

I overshot my OG by 5 pts. This is the first time making this recipe.

Well, that looks like fairly normal progress for a fermentation ar 50°F, so apparently no sign of detrimental effects so far! Will be curious to hear if it slows at some point, or if there's any detectable difference in the finished beer.

 

[Jtvann]

I figure once I see the fermentation slowing I'll start increasing by 4 degrees per day for a d-rest. Really only have about 20 more points to go before I expect to see that. So many 3 days at most.

 

[Jtvann]

Holy crap that stuff is good. Just tried a sample of it even though it's no where near finished. The smell, texture and taste of this one could easily turn me off IPAs

 

[couchsending]

One interesting note I have on pressure fermentation for Ale Yeaat..

I got to talking with a brewer about their beer and they use a specific English Ale yeast that’s not available on the homebrew scale. I started harvesting some from cans just to play around with it and reached out to him again about any tips/tricks he had for me regarding ferm schedule, pitch rate, and oxygenation.

His reply was that they ferment it at 7-10 PSI for the first 3 days of fermentation and then release the pressure and ferment under no pressure for the last three days. He said they see better ester formation, an overall higher cell density in the slurry and in suspension, as well as a quicker fused alcohol pickup. They ferment it at 68.

Haven’t had a chance to try it out as my spunding valve sucks and don’t feel like spending the money on the SS Brewtech ones for my unitank.

 

[Smellyglove]

I've done some 1-1.5BAR pressure lagers. What I can say is that pressure fermentations requires more yeast comparing to what you'd pitch normally at the same temperature. I've tried to just take is as far as I can and have tried several 7C pressure fermentations, totally failed them all. I've concluded that there's no need to do low temp pressure fermentations, since ester production is already very low at that temperature. It was just to play around.

The main reason you'd want to do a pressure fermentation is that you ferment at at higher temperature, but don't want the yeast to go haywire, and still be able to control the esters somewhat, and finish early.

So unless you NEED to to a pressure fermentation, there's no need to do it. But this doesn't exclude that you WANT to do it.

I see a lot of people doing it because they can, (fermentasaursus, unitanks etc), but without knowing why they do it, and don't pitch accordingly.

If you'd want to do a pressure fermentation lager try 14C and a lot of yeast. The pressure really inhibits the yeast. Co2 is poison to the yeast just like it is to us humans.