Pitching Rates for a 1.048 lager, fast turn.

[mchrispen]

Hey guys,

Planning to reboot my failed A/B Bav Helles-like experiment. Since I lost a week (overdosed the SMB and the beer is not good), I plan to proceed with a slightly revised recipe (there were some really nice honey like notes despite the compounding sulfur problems and lack of attenuation). That said - 11 gallon recipes @ 1.048. Going to skip the sparge and top up the boil with DO liquor to get to my preboil volume/gravity.

So, to the question. I plan to purchase fresh yeast, and get them into a 5L starter (using a very slow spin on stir plate for 12 hours + a hit of pure O2). Most calcs put me at 743 billion cells for 11 gallons @ 48 points. I understand that a few of you pitch nearly double.

In this case, I am planning primary pitch at 48F, free rise to 52F to hold (the rise is slow in a freezer, about 24 hours). 4-5 days till it hits about 1.025, then free rise till 60F for a 3 day D-rest. Then a 24 hour crash to 34F and lager as long as possible (14 days or until FG). Might take longer, but I have turned mediocre (by old measures) lagers this way. I would like to gather some A/B data at a home-brew club meeting early June.

So - comments on pitching rates, O2 saturations after pitching and recommendations on ferment schedule for a quick turn.

CAVEAT - this is for an experiment and not for an optimally cold fermented, long lager helles. This should NOT be construed as good advice for any authentic German lager. I don't want folks thinking this is the PROPER way.

[Owenbräu]

Higher pitching rates help ensure complete attenuation at colder temps (less risk of stalling) and the reduced yeast growth will increase sulfite levels in the finished beer. This may be how some German breweries produce higher sulfite levels in their beer while complying with the RHG.

Not sure about the stir plate protocol. Typically, you'll see more growth with faster speeds. A vortex dipping down 1/2"-3/4" is adequately fast. The continuous movement will quickly off-gas any supersaturation from the pure O2 charge, so I doubt there is much benefit to it.

With your higher temps and above average pitching rate, you should be able to turn this over pretty quickly.

[mchrispen]

Allegedly, the problem with stir plates are the sheer forces on the yeast, with the potential of off-flavors. The spin (as I understand it from White Labs) should be incredibly gentle - just enough to suspend the yeast and prevent CO2 buildup in solution (especially for high floc ale yeasts), and not to increase the surface area exposure. I need to gather some direct data, but I have had adequate cell mass production with fewer petite mutant cells slowing things WAY down. The starter supernatant is actually drinkable with the slower spin. White Labs uses a gentle orbital shaker table to propagate.

Are you using a vitality styled starter? (pitching at high krausen and oxygenated) or crashing/decanting with yeast in dormancy? I realize this takes longer with lager yeasts (dormancy).

[caedus]

I actually was curious about the "best" way to grow yeast when you need ~550 B cells for a 5 gallon batch. I would imagine a 3L starter, then decant after a day or two in the fridge, *then* a vitality starter on brewday would be the best thing.

Do you use a microscope? If so, what model? That is my next purchase after all my brewing gear is complete.

[Owenbräu]

I've been tracking the weight of yeast slurry at the end of my starters for various strains. It may be time to take it a little more seriously and put some data together.

http://braukaiser.com/blog/blog/2013/03 ... st-growth/

BTW, which method did you use to confirm that you had fewer petite mutant cells?

[mchrispen]

Important to remember that weight and cell count vary a lot, so mass works only when pitching for consistency after confirming viability and cell concentration.

I also stop the stirring after 6 hours to let krausen form. Mark Van Ditta proposed using a media flask and shaking until the entire starter is foamed, maximizing yeast to O2 available surface area, and pitching at high krausen - roughly within 8-10 hours. I adapted my process to mimic his "Shaken, not Stirred" methodology.

I cannot claim lab quality results. Using a hemocytometer, do basic counts, noting all budding cells at 90 minute intervals over 4-6 hours. Then using higher optical power, look at both mother and daughter cells to determine scars and new buds. This is done in a normal starter, with 100x dilution and m/b staining (added during dilution). With what I have seen, yeast subjected to sheer forces yield a substantial larger number of very small daughter cells, many that cannot metabolize the meth blue dye. I have not done GC or MS analysis to determine off-flavors empirically. I tend to favor viability over cell mass - as a replication cycle is only 90 minutes. Viability (in my method) is to count and compare mothers with 2+ buds at least 50% of the mother size. With some zinc and magnesium in the starter, along with a shot of pure O2, you should exit the lag phase within an hour (assuming tempering the yeast to room temps). Then it is a simple matter of setting timers, using a hemocytometer, meth blue staining, and a decent scope, and a lot of free time. (all done in a 1.040 starter wort with extra pale DME + yeast nutrient). I need to look this up in the Boulton/Quain Yeast and Fermentation book to confirm.

If I let the yeast go dormant (like a missed brew-day, so crashing the starter), then decanting and adding a 1.030 starter wort on it - and timing to pitch at high krausen yields impressively short lags, especially at 1 M/P or higher cell counts.

I have not done the plating over sequential starters (96 samples over the log/exponential phase from iterative starters is the golden standard proposed by Luria & Delbrück). So take it as anecdotal at best. (qualification, I clearly muffed my first LODO experiment). YMMV.

A simple experiment to confirm is to run a "shaken" or mildly stirred starter side by side with a "stirred" starter, and simply smelling and tasting the supernatant - it is striking. Let it run till expected FG, cold crash - taste the resulting clear beer. A partial hop pellet included in the starter wort seems to eliminate or suppress any unwanted LAB growth.

[Bryan R]

You know, I made about 500 lager batches with accelerated fermentations. I thought it was the shit. Then I was pressured to try the traditional cold. I did it once and I thought, hmm maybe its a fluke this is so good, so I did it again. I am now about 24 batches in with Cold fermentations and spunds. I look back and shake my head at all those batches I wasted
So I am going to stay out of this one.

[Owenbräu]

A microscope is my own personal red line in the sand. I spent such a large part of my day staring through one, analyzing counts, measuring growth, etc. etc. that I refused to incorporate it into my hobby. It's easy to get lost in the weeds, and sometimes going down the rabbit hole is rewarding and fun, but I tried to focus the majority of my time on brewing beer and not the microbiology. That said, I did seize the opportunity and took samples from home to work on a fairly regular basis

I've found that wet weight works fine. Unless you are having contamination issues, a monoculture will have a relative consistency of cell sizes. That is, the percent mother, daughter and in between sizes are relatively constant between batches, especially if your technique is consistent. Undoubtedly, higher viability, healthier and younger cells, will perform best, but I have yet to worry about counting scars and assessing the age of the culture in order to anticipate performance. If a culture starts to decline, then I can replace it for $6-7. It's a hobby. Wet weight begins to get tricky once you introduce trub and a higher percentage of dead cells after pitching cone to cone for a few generations, which may be partly why Kunze recommends higher pitching rates. The best way to manage your yeast is top cropping, of course, but really requires the structured schedule of a brewery to pull of optimally.

I've not heard of the shaken, not stirred method, but honestly, I haven't looked very hard either. Sounds like what I do is very similar though. One thing I have always done is focused on maintaining optimal "beer performance" with my cultures. That concept guides most of my thinking when it comes to process. One of the things I do is turn my stir plate off before the culture hits terminal gravity and let the yeast consume the remaining oxygen and begin to ferment and then flocculate under normal fermentation conditions. After that, I rarely ever cold crash my starters. Once they flocculate, I simply pour off the liquid. This removes (presumably) any respiratory and flocculation mutants, while preventing the yeast from going into a deeper dormancy. Additionally, this is why I always use wort as my growth medium. While a standardize nutrient broth with glucose and peptones will yield optimal cultures, they tend to lag the first generation after you introduce them into wort. What I actually do now is commit one brew day to making starter wort. With this batch, I will mash for an extended period at both a FAN and albumin rests, followed by a maltose rest. This ensures optimal nutrient levels for wort based culture medium. Afterwards, I will pressure cook the wort at 15 psi for 15 min so that I have sterile nutrient medium of the same quality over many yeast starters. Overall, my fermentations take off quickly and I'm usually within 1-2 points of FFT, so I don't worry too much. Honestly, I've found focusing on aseptic technique is most important, which is why I use a pressure cooker on everything and have a flame next to any vessel when I plan to remove its cover or cap.

Yeast are as complex or as simply as you want to make them. TBH, they may be the last frontier of brewing. Theoretically, you'll get flavor differences from different strains, pitching rates, viability, oxygenation rates, temperature profiles, hydraulic pressures, pH, wort composition, hopping rates, mineral additions, vitamin levels - I mean, the permutations to test will make you go cross-eyed.

Priest and Cambell is also good resource. I recently added Annemüller et al., and I am very pleased with it. If you buy Kunze, go ahead and add it, as the VLB will charge you the same for shipping one book as they will two books

[Owenbräu]

[Techbrau]

I'll also vouch for the traditional ferment done properly. I know it sounds crazy at first but so did low oxygen brewing, no?

Give it a try and after the second ferment convinces you it's not just a fluke, you will start turning white as a ghost when somebody mentions pitching any warmer than 46 F (I won't personally pitch above 43-44 F). Lager fermented at 50 F tastes like ale to me now.

If you read the chapter on fermentation in Kunze, you will see that the accelerated schedules are specifically meant for large cylindroconical fermenters whose height is typically on the order of 20 meters. The size and shape of these vessels creates enormous hydrostatic pressure on the yeast which completely changes their metabolism.

For traditonal shallow fermenters (which our tiny fermenters most resemble), the traditional warm and traditional cold fermentations (both outlined in detail on the Quest for Edelstoff blog) are the only schedules Kunze (and Narziss as well) recommends.