[ynotbrusum]

Here here!

[coolman26]

What a great read, thanks everyone   
I’m going to get a few half bbls to ferment in. May take me a little while to get them adapted. I looked at the 10g cornies, dang they are pricey. I’ve tried to make my current fermenters work, not happening. It is time to make this move to pressurizable fermenters for many reasons stated here.


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[Robert]

Warm Pressure Fermentation of a Lager

Notes

• I hope this post summarizes any details relevant to this thread.
• Pitching and oxygenation rates were what I use for a first generation pitch in a normal, cool-fermented lager.
• Fermentation temperatures refer to the temperature of the ferment, not ambient.
• The PRV was pre-adjusted to maintain a maximum head pressure of 15 psig during active fermentation.
• At no time during fermentation did I detect the prominent sulfur expected in a lager fermentation. The beer at racking seems exceptionally clean, crisp and properly lager-like, even without lagering.
• Tasting notes will eventually follow.

Wort Production

100% 2-Row Pale malt

146°F 30 min 160°F 30 min 170°F 10 min

Mash pH 5.55, wort pH 5.55, adjusted in kettle at 10 minutes with lactic acid to 5.02

13.1°P

Fermentation

WLP833 pitched and oxygenated at 62°F, atmospheric pressure

8 h 63°F active (1-2 bubbles per second in jar;) airlock replaced with PRV

18 h 65°F 14.5 psig

24 h 67°F 15 psig 8.5°P pH 4.43

48 h 70°F 15 psig 3.4°P pH 4.22

72 h 70°F 14 psig 2.9°P pH 4.17

5 d 68°F 12.5 psig 2.6°P pH 4.30

7 d 68°F 12.5 psig 2.6°P pH 4.30; cooling and incrementally venting pressure

10 d 37°F 1 psig 2.6°P pH 4.33; racked and transferred to storage at 34°F

[SOP will be for the keg to remain in the "lagering" freezer for at least a couple of weeks until there is room in the keezer, then to carbonate at serving temperature and pressure for at least a couple of weeks.]

[MattyAHA]

Im gonna get a kegmenter, this is really cool stuff

[Robert]

BTW, just repitched the yeast for pressure lager #2.  Will report later on how this generation performs.  Plan to follow the previous procedure as closely as possible.

[MattyAHA]

so if you ferment under pressure you should not reuse the yeast?

[Robert]

so if you ferment under pressure you should not reuse the yeast?

I'm reusing it, as I said just above.   Harvesting and repitching is important to me.

There's been some suggestion out there that pressure fermentation may cause long term harm to the yeast.  But I think that may be specific to conditions like really high pressure (like 28 psig,) certain strains, or other things (like rapid decompression.) 

If yeast couldn't be harvested and repitched,  this would never have become a thing in German commercial practice.   I think it just has to be handled correctly.

My 2nd generation is performing exactly like the first so far.  I'm going to keep repitching it until it doesn't seem normal, or I get tired of making lagers, to see if it really does shorten the number of generations you can go.  Stay tuned. 

Some things I've taken into consideration in designing my process are, first, that pressure suppresses yeast growth, which could lead to less yeast in the current batch and fewer new cells in successive generations.   To address that,  my procedure is to pitch warm and leave it at atmospheric pressure until active, then let pressure build to 15 psig over a number of hours.  This (based on the German process as described in Kunze, 4.4.3.5) should maximize growth.  I've also targeted a pitch rate as for pitching at normal (cold) lager temperatures; this won't directly affect future generations, but will ensure sufficient yeast in the current  batch.  And to avoid sudden decompression that could rupture cells, I'm incrementally decreasing the pressure over a couple of days during cooling at the end of fermentation.  If you don't want to reduce the pressure on the beer before transferring to a keg (say if you're spunding,) you could just slowly depressurize the fermenter after racking and before harvesting.  Or not and let us know if it makes a difference.

All in all, I won't expect to take this yeast out the 18-25 generations some of us have previously done with lager yeasts.  But I do expect to be able to get enough generations to make this a viable, practical method of lager fermentation.   I'd be happy with 5. 

Again, stay tuned.  Can't wait for some others to get those Kegmenters and cornys and  whatnot going and hear how your experiences compare.

[MattyAHA]

Thank you Robert for the information, i look forward to learning more about pressure fermentation and how things turn out for you, like i mentioned i plan on getting a few kegmenters so when i ferment in one i plan to jump the beer to another to get it off the yeast and stuff, in my head i was thinking maybe i can pour sterile water onto the cake and re pressurize just enough so i can harvest the yeast by jumping it into a small 1 gallon corny, like you im trying to come up with ways to keep all, if not most transfers closed if i can even yeast harvesting, i dont want to ramble on but what do you think? add sterile water, seal it up give it a shake to separate the trub from the yeast, maybe use a cut pick up tube so i only draw the "cleaned" yeast up when i jump to a 1 gallon corny, idk i just got my wheels turning now

[Robert]

Don't add water.  It may be a topic for another thread, but "rinsing" is very bad for yeast.  Yeast should be stored in the beer it made, so just leave a little behind.  Using the 10 gallon corny  I do all closed transfers of the beer, but to harvest yeast, I just open the lid and swirl up the slurry and pour into a sanitized jar (sanitize the lip of the fermenter opening first.)  Seems most practical,  especially since your fermenter will be designed specifically not to pick up yeast  -- whether it's the floating dip tube in the Kegmenter or the trimmed tube in my corny.  Only ones who can dump yeast without opening the fermenter are those with conicals.  (Unless maybe you can pick up enough yeast from the Kegmenter once you get to the bottom. Never seen one up close.  Anyway pouring into a jar seems easy enough.)

[Robert]

My 2nd generation is performing exactly like the first so far.  I'm going to keep repitching it until it doesn't seem normal, or I get tired of making lagers, to see if it really does shorten the number of generations you can go.  Stay tuned. 

Actually it seems to have finished at the same FG (identical wort) in just 3 days this time.  (I'm still waiting till day 7 before starting cooling.)  I'd expect some improvement in performance in the second generation, of course.   Since yeast generally doesn't really start to perform "normally" having fully adapted from laboratory conditions to brewery conditions until somewhere between the 3rd and 5th generations,  it will be interesting to see if this is the case with pressure fermentation, or if it actually adapts more quickly for some reason.  At any rate there is certainly no sign of detrimental effects at this point.

[MattyAHA]

Hey Robert, just wanna make sure i fully understand even though you made it crystal clear, pitch yeast into aerated wort with airlock for the first 8 hours until the fermentation is actively off gassing, then attach the PRV and the pressure starts building naturally from fermentation correct? in other words you are not pressurizing the vessel with a c02 tank? excuse me if this seems like a stupid question

[Robert]

Exactly.  My first pressure fermentation (with S-04) way back in this thread, I pressurized from the start, and it underattenuated.  I don't know if something else strain specific was going on, but I realized that it could have been suppressed growth,  and that the lager procedure outlined in Kunze didn't apply pressure until partway through fermentation.   So I tried waiting for bubbling (however long that might take, YMMV) with these two lager fermentations,  and it seems to be working like a charm.  My first attempt I preadjusted the PRV brilliantly if I may say so.  The second time I did some fiddling as it went.  Either way I reached full pressure  by the 24 hour mark, and around 30% AA.  Seems to be a good plan based on the results.

[MattyAHA]

awesome cool, another possibly stupid question, are you letting the temp rise from 62F to 70F just from the heat of fermentation naturally?

[Robert]

awesome cool, another possibly stupid question, are you letting the temp rise from 62F to 70F just from the heat of fermentation naturally?

Kinda sorta.  My ferm chamber is a fridge in my basement (which varies a lot in temperature through the year.)  I control the ambient temperature in the chamber with an Inkbird, both cooling and also heating the chamber as needed, probe in the air, not probing the temperature of the beer.  So I adjust ambient temperature to allow the beer to rise on its own or limit that as needed, I just know from experience how fermentation temperature and ambient in the chamber relate.  IOW, my PID controller is between my ears!

[MattyAHA]

i dont want to get off topic on your thread again, but i gotta try your method of temp control, i use a thermowell but not too happy and quite shocked with the swings i get, maybe if you can make a thread describing in detail how you control temps, im not the brightest bulb in the tanning bed so excuse me