[morticaixavier]

ken/mark - how many vials/packs of lager yeast are you starting with?

Yes, I too am curious about this one as well.  1 pack in 1 qt starter (1.040) shaken method pitched at high krausen sounds really low to me especially when pitched at 50F...

At least compared to past practices (and every pitching rate calculator out there). And if the starter is supposed to ferment at room temps (i.e. 70F or so) and then pitched at high krausen isn't there risk of shocking the yeast when pitching the warmer starter into significantly cooler wort?

the key, as Mark has pointed out, is that the difference between 200 billion cells and 400 billion cells is ~ 90 minutes of lag time. as long as the cells are really healthy and have a good reserve of sterols and o2 they are fully capable of reproducing the rest of the way in your wort without throwing stress flavors. It's a different paradigm than the yeast calculators use.

[evil_morty]

the key, as Mark has pointed out, is that the difference between 200 billion cells and 400 billion cells is ~ 90 minutes of lag time. as long as the cells are really healthy and have a good reserve of sterols and o2 they are fully capable of reproducing the rest of the way in your wort without throwing stress flavors. It's a different paradigm than the yeast calculators use.

has anyone tested this out with a lager yet? 

[morticaixavier]

the key, as Mark has pointed out, is that the difference between 200 billion cells and 400 billion cells is ~ 90 minutes of lag time. as long as the cells are really healthy and have a good reserve of sterols and o2 they are fully capable of reproducing the rest of the way in your wort without throwing stress flavors. It's a different paradigm than the yeast calculators use.

has anyone tested this out with a lager yet?

I have not.

[evil_morty]

the key, as Mark has pointed out, is that the difference between 200 billion cells and 400 billion cells is ~ 90 minutes of lag time. as long as the cells are really healthy and have a good reserve of sterols and o2 they are fully capable of reproducing the rest of the way in your wort without throwing stress flavors. It's a different paradigm than the yeast calculators use.

has anyone tested this out with a lager yet?

I have not.

I'm planning to brew next week and while I will likely use a stir plate for the first small step of my starter I was planning on pulling about 1.5 gallons (out of 10 gallons) and using this as my second "starter" before pitching the whole 1.5 gallons into the remaining 8.5 gallons at high krausen.  on the 1.5 gallon ferment I don't plan on constantly aerating it or anything.

[blatz]

i've been doing, including two recent lagers, the process you mention evil_morty

on my pilsner i grew up 3 vials in 2.75L in a 5L flask, put on my stir plate, fermented, crashed.  on brewday, I decanted and ran 4L of the chilled main wort into the flask, aerated and put into my fermentation fridge, then ran the remaining 11gal into my conical.  once the 4L was at high krausen i pitched the whole flask into the conical.

I did the same, albeit collected yeast from dump valve for the pils and ran 4L of vienna into the flask and followed the same procedure in my other conical.

so far, i've been very happy with my results.  my pils finished quickly and cleanly - i just kegged and it seems great.  vienna is still awaiting to be kegged, but it also seemed to ferment strongly and samples have been great.

I should caveat this is NOT the process that Mark is recommending. 

for an APA, i pitched 2 vials of 001 into 2L of chilled wort from the kettle, and once at high krausen, pitched in the main wort - similar to my lager process, but without and prior growth on stir plate.

[evil_morty]

i've been doing, including two recent lagers, the process you mention evil_morty

on my pilsner i grew up 3 vials in 2.75L in a 5L flask, put on my stir plate, fermented, crashed.  on brewday, I decanted and ran 4L of the chilled main wort into the flask, aerated and put into my fermentation fridge, then ran the remaining 11gal into my conical.  once the 4L was at high krausen i pitched the whole flask into the conical.

I did the same, albeit collected yeast from dump valve for the pils and ran 4L of vienna into the flask and followed the same procedure in my other conical.

so far, i've been very happy with my results.  my pils finished quickly and cleanly - i just kegged and it seems great.  vienna is still awaiting to be kegged, but it also seemed to ferment strongly and samples have been great.

I should caveat this is NOT the process that Mark is recommending. 

for an APA, i pitched 2 vials of 001 into 2L of chilled wort from the kettle, and once at high krausen, pitched in the main wort - similar to my lager process, but without and prior growth on stir plate.

I think it has at least the similarity that the goal is healthy, active yeast vs just having a lot of yeast (which may not be as healthy or active, jury maybe still out on that??)

[S. cerevisiae]

I'm planning to brew next week and while I will likely use a stir plate for the first small step of my starter I was planning on pulling about 1.5 gallons (out of 10 gallons) and using this as my second "starter" before pitching the whole 1.5 gallons into the remaining 8.5 gallons at high krausen.  on the 1.5 gallon ferment I don't plan on constantly aerating it or anything.

I would recommend against using a stir plate and my method.   You will not get the same effect because the stir plate will have stressed the cells.  Plus, can you shake a six-gallon carboy like it owes you money? 

[evil_morty]

I'm planning to brew next week and while I will likely use a stir plate for the first small step of my starter I was planning on pulling about 1.5 gallons (out of 10 gallons) and using this as my second "starter" before pitching the whole 1.5 gallons into the remaining 8.5 gallons at high krausen.  on the 1.5 gallon ferment I don't plan on constantly aerating it or anything.

I would recommend against using a stir plate and my method.   You will not get the same effect because the stir plate will have stressed the cells.  Plus, can you shake a six-gallon carboy like it owes you money?

firstly, I'd like to do 2 steps as a little insurance to make sure that the yeast is good before I commit to the brew day.  I could skip the stir bar on that and just ferment 1-2L in my 5L flask with some extreme shaking.

I would be fermenting the second step (1-2 gallons) in a bucket so yes, I could shake the living hell out of that.

[mabrungard]

has anyone tested this out with a lager yet?

I sort of have. I just made a Munich Dunkel with WY 2308 and first created a 2L starter that was fuller fermented out and then chilled and decanted.

I use an in-line oxygenation system. I ran off about 4L of oxygenated Dunkel wort into the 6L starter vessel and spun up the stir plate for about 15 minutes. That wort was probably around 70F. I can attest that I had one angry and ready to go army of yeast in about an hour or two.  The subsequent fermentation was very active at 50F.

[S. cerevisiae]

I would be fermenting the second step (1-2 gallons) in a bucket so yes, I could shake the living hell out of that.

Hopefully, your bucket seals better than an Ale Pail.

[evil_morty]

I would be fermenting the second step (1-2 gallons) in a bucket so yes, I could shake the living hell out of that.

Hopefully, your bucket seals better than an Ale Pail.

I've never noticed them to leak just from shaking in my pre-O2 stone days.

[S. cerevisiae]

Yeast biomass grows exponentially, not linearly; therefore, the difference between 200 billion and 400 billion cells is not as great as people think when pitched into 19L of non-high osmotic pressure inducing wort.   The yeast biomass grows at a rate of 2ⁿ, where n is the number of minutes that have elapsed since the end of the lag phase divided by the replication period in minutes, which is approximately 90 minutes for ales on average, slightly longer for lagers due the effect that reduced temperatures have on metabolism. 

Maximum cell density is approximately 200 million cells per milliliter.  The maximum cell density for 1L of wort is approximately 1,000 * 200 million = 200 billion cells. The maximum cell density for a 5-gallon batch is 19 * 200 billion = 3.8 trillion cells.  All of these densities are bounded by having sufficient carbon (sugar is carbon bound to water) and O₂ to support maximum cell density growth.

If we know the initial cell count and how long the culture has been in the exponential phase, we can obtain a rough approximation of the cell count using the following formula:

cell_count_at_time_t_in_minutes = initial_cell_count * 2^{(t / replication_period_in_minutes)}

Re-writing the equation to solve for (t / replication_period_in_minutes) (a.k.a. number of replication periods)

number_of_replication_periods = log(target_cell_count / initial_cell_count) / log(2)


initial_cell_count = 200 billion (1L starter)
number_of_replication_periods = log(3.8 trillion/ 200 billion) / log(2) = 4.25

initial_cell_count = 400 billion (2L starter)
number_of_replication_periods = log(3.8 trillion/ 400 billion) / log(2) = 3.25

In essence, the difference between pitching a 200 billion cell culture and a 400 billion cell culture is roughly 90 minutes of replication time with ales, slightly longer with lagers due to reduced metabolic rate.

initial_cell_count = 100 billion (500ml starter)
number_of_replication_periods = log(3.8 trillion/ 100 billion) / log(2) = 5.25

The difference between pitching a 100 billion cell culture and a 400 billion cell culture is roughly 180 minutes of replication time with ales, slightly longer with lager due to reduced metabolic rate.


As long as there is enough carbon to support growth, enough O₂ to support cellular health, and our brewery hygiene is sound, it does not make a difference if we pitch 100 billion or 400 billion cells.  The only time that pitching a huge starter over a smaller starter pitched at the peak of health makes sense is when we are pitching high gravity wort because it is more difficult to dissolve O₂ into high gravity wort, and high gravity wort places osmotic pressure on the cells.  Dissolved O₂ is critical to yeast cell health, and high osmotic pressure takes its toll on yeast cells.

[evil_morty]

So what would you suggest here.  I'm looking at making 10 gallons of 1.051 lager.  Since I mash overnight the night before the actual brew day I'll be able to pull some amount of 1.046ish wort off to make a "shaken not stirred starter" that would hopefully be ready the next day to pitch into the rest of the wort.

I'm starting from a vial so I would like to do one step ahead of time.  I don't really have a small vessel I can shake.  I guess I could try a growler?  not sure how much I trust myself to get one of those super clean.  I have a 5L flask b/c I've typically used a stir plate.  So for step one what volume and gravity (1.040 like usual?) of wort should I make?  Should I decant off the beer from this starter like I have in the past?  If no should I ferment this at lager temps?

And then the night before I actually complete the brew how many gallons should I be pitching my first step into?  I was planning to ferment this at lager temps.  Is it likely this will be going strong by mid day the next day?

in case it's relevant I'll be using WL833.

[RPIScotty]

I think you'll find all your answers back a few posts in this thread.


Sent from my iPhone using Tapatalk

[S. cerevisiae]

So what would you suggest here.  I'm looking at making 10 gallons of 1.051 lager.  Since I mash overnight the night before the actual brew day I'll be able to pull some amount of 1.046ish wort off to make a "shaken not stirred starter" that would hopefully be ready the next day to pitch into the rest of the wort.

There is no need to step the starter.  The difference between a 1L starter and a 2L starter is one replication period. You will be incubating your lager starter at room temperature, so a 2L starter will require roughly 90 minutes of an additional incubation time (and a vessel of at least 8L in volume).  A 2L starter will be ready pitch if you make it the evening before you brew.  I would make the 2L starter with 200 grams of DME. If you do not have a scale that can weigh in grams, 200 grams is 7 dry ounces.   You should be able to get at least 300 billion cells in addition to the viable cells in the vial.   If you pitch that starter at high krausen, it will get the job done. 

If you want to eliminate the possibility of shock, you may want to start to cool your starter an hour or so before you pitch by placing it in your fermentation chamber.  When making lager,  I usually pitch a starter at 20C/68F into approximately 18C/65F wort and then place the fermentation vessel in my lager fermentation chamber set to hold the wort at 13C/55F.  I rarely if ever ferment a lager below that temperature.  Most production lager strains were selected for their ability to produce a quality product at 13C/55F.