[Robert]

That’s the podcast I mentioned in another thread concerning yeast behavior after recycling yeast. Pretty interesting how quickly they morph.


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Pretty interesting how quickly they morph.


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 But does it matter, or is it maybe a good thing?   I repitch just because I assume, and experience confirms, that there will be some adaptive changes, and that these will normally be desirable or neutral, after which the yeast may be still be changing but there is no longer any observable change on the practical level, out to a very large number of pitches.  Probably part and parcel of how their evolution has been directed by brewers.  A propensity to suddenly start doing things brewers don't like wouldn't be conducive to a genetic legacy.  It's also interesting how remote culture yeasts are from anything "natural."

[BrewBama]

No telling if the changes are good or bad until a negative impact to the beer is detected. Until then, it’s just change.

... and you can trust fermentation is pretty much complete in 2-3 days.

^^^^This is the golden ticket right here^^^^     I enjoy brewing lagers and it isn’t the largering phase that kills my pipeline, it’s the fermentation phase.  Ales are wham bam done in 4-5 days, but Lager yeast seem to take their sweet time getting to full attenuation. If you can get Lager yeast to the same timeline as Ale yeast I think you have something. Even the hybrid (Cali Common) fermented at Ale temps seem to quickly chew thru a large percentage of the sugars then slow to a crawl to get those last few FG points in. I plan 2 weeks but Lager yeast seem to laugh at my plan and take 2.5 or slightly more. ...or at least that seems to be how Lager yeast react in my brewery.

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[ynotbrusum]

Initial pitches seem to be the slowest, so I think Robert’s adaptation thoughts are likely true and on repitching we are probably repitching a lot more yeast cells than the initial pitching.  Plus the lag time (Low Krausen or whatever you want to call the initial time frame prior to significant yeast activity that is noticeable) always seems a bit (though not hugely) greater on the initial pitch, even with a vitality starter or multiple yeast pack pitching.

2.5 weeks in I can be drinking the lagers, but I often let them age at cold temps a little bit (another week or so) anyway, especially if I have plenty on tap.

[Robert]

2.5 weeks in I can be drinking the lagers, but I often let them age at cold temps a little bit (another week or so) anyway, especially if I have plenty on tap.

All of my beers (ale or lager) get that extra cold time too, it's just the way my "pipeline" has evolved.   They get about 3 to 4 weeks lagering just above freezing, then go into the keezer for about 2 weeks carbonating at serving temperature before tapping.  Brew every 2 weeks, a new keg tapped every 2 weeks (I only have one on at a time,) and it usually seems like just the right amount of aging.  Could I turn them around faster?  Probably.  Would they benefit from any more storage time?  Doubt it.  As long as the pipeline remains full and there's no disruption I may never know.

[BrewBama]

I must be doing something wrong then ‘cause Lager yeast seem to take their sweet @$$ time around here. Good thing I plan a three week cycle.

For example I brewed May 10, used Cali Common yeast, and just hit expected attenuation yesterday on the 28th. I kegged today. These are typical results from all Lager yeast which fit the schedule pretty well.


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[Robert]

Big @$$ pitch (1.5M * mL * °P, but lacking a lab to count cells, I just stick with "big @$$" as a guideline,) O2nate well, and make sure they get enough zinc ($ervomyces or WY Nutrient.)  If that doesn't get you done in 7 days, then I guess things just move at a relaxed pace at your place.   Fair enough.

[BrewBama]

Well, I do all those things so...

LOL


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[Robert]

That Southern pace of life is rubbing off on the yeast.    (Gives you time to smoke another brisket...)

[tommymorris]

Well, I do all those things so...

LOL


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Have you tried warming it up?

[Robert]

Well, I do all those things so...

LOL


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Have you tried warming it up?

Good point, what is your temperature program?   No need to keep it at 50°F.  After about 4 days you'll probably be around 50% AA, at which point you can let it free rise and finish fermenting out warm (essentially the Narziß program.)  Even without checking gravity, as soon as the yeast is not generating as much heat (you don't need to apply as much cooling to maintain temperature) and/or bubbling slows a bit, that's a sign that the yeast is moving from primary to secondary fermentation, and it's time to let it warm up.  Otherwise you're just putting it to sleep.

If you already do that... 

[BrewBama]

Well, my last three: I ran the Cali Common at 65*F the entire fermentation.

My Augustiner yeast (Imperial Harvest) I ran at 53*F and gradually increase to 62*F after the first 5 daze.

The Czech Pils yeast (Imperial Urkel) I ran at 55*F and gradually increased to 63*F after the first 5 daze.

Each of these has taken 15-18 daze to reach full attenuation.  They were beautiful beers and once the kegs kicked i mourned. ...until I tapped the next beer. LOL


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[Robert]

Well if the result is good, and you have consistency and predictability, I guess  that's what matters.

[Robert]

Well the 7th generation finished at 76.1% AA and pH 3.88.  The lower pH is exactly as expected with 24% of extract from corn flakes.   But I'm more convinced I'm seeing a real downward trend in attenuation, though still within (actually well above) the manufacturer's stated attenuation.  And no other changes in yeast performance; in fact with each batch lag has shortened and it has reached final attenuation quicker, with pH drop following the drop in density at an identical  rate. What I can't say is whether this drop in attenuation is directly attributable to fermentation under pressure, or something else emerging in my process as I adapt to pressure fermentation.  I'm comfortable calling it anyway, and saying I have an answer to the question I started with in this experiment:   pressure fermentation doesn't seem to do any SIGNIFICANT long term harm to yeast.  It's going to remain my SOP.   I'll repitch this yeast for an 8th generation this weekend, as I've no time to prop up a new pitch.  But I'll do so after this batch, and take that out as far as I feel comfortable doing.  At some point in the future I'll report if there are any new insights,  and hope others might do so here as well.  BTW, these beers are excellent lagers, with fine, clean, crisp flavor and EXCELLENT foam qualities.  So there are a couple of proposed possible drawbacks of pressure fermentation debunked.

[Robert]

I think the logical next experiment will be to ferment under higher pressure, ~30 psig, to achieve a fully carbonated beer, crash cool and CP transfer to keg for lagering,  and then -- the salient point -- see if I can manage decompressing and harvesting viable yeast, and see how that yeast performs over multiple pitches.   And of course how the beer tastes.   It may be a while, but I'll eventually report results here.


EDIT I'm working beyond my charts here, but I'm guesstimating I'd get a good initial level of carbonation (it will of course be adjusted with bottled gas before serving) at around 1.5 bar/ 21-22 psig @ ~70°F?  Anybody who knows better, little help?

[ynotbrusum]

I am enjoying a Helles that I brewed on May 25, fermented at 50F and 12 PSI, racked on June 10.  As you reported on your results, it has a very clean, yet malty profile.  I see this as a very viable approach with lager beers.  S-189 yeast (Hurliman Strain) was used and re-pitched into 2 batches brewed on June 15 (yesterday).  I will report back on this first repitch with S-189 as it completes.  With the quick turns of these beers, I am facing storage shortage issues!