I can't take it anymore! What is the answer on cell count with a stir plate?

[BaldyOnFire]

Jeez, if I haven't been reading over a combined 20 hours in the last few months I'd be shocked. I just want to pitch the right amount of yeast, but I also don't want to over-pitch too much either

So, I now have both a 1 and 2 liter flask and a stir plate. Let's say I'm brewing a pale ale with an OG of 1.056. I'll need about 227 billions cells (going off memory). Let's say I'm starting with 70bn cells (a not exactly new smack pack).

The main issue is that I can't find anywhere that can tell me how much growth a stir plate adds vs. no stir plate in a starter. One place I see about 10x more cells. I see all these calculators (and have used them as well as Beersmith) then the difference in growth rates from Kai and Jamil.

Once and for all, if I were to take these 70 bn cells, put them in a OG 1.040 starter, throw on the stir plate, how many cells should I have after 18 hours in both the 1 liter flask and the 2 liter flask? I also see varying amount of wort to be used in the starters.

Obviously, if we know the growth rates it will be smarter to work backwards, as in, how big should my starter be if I need to get from 70bn cells to 230 bn cells using a stir plate?

Lastly, I'd like to generally just build big starters in a 2 L flask, figure out how much I need and save the rest for a future batch too.

TIA

 

[specharka]

Over pitching is really only a concern for yeast starters with poor viability. If you slightly over pitch from making too large a starter there will not be any adverse consequences. The variance in propagation is inconsequential -- just use the Brewers Friend tool for specific values.

 

[cantrell00]

Most tools are only estimations. Give it take a few billion cells. Heh

 

[Big Monk]

You are bounded by the maximum cell density of the starter medium.

Maximum cell density for 1L of starter wort is ~200x10^9 cells. So:

230/200=1.15L

Your ~70x10^9 initial cell count has the potential to produce ~230x10^9 cells in a 1.15L starter.

Approximate is the keyword here.

I don't own a stir plate and am only familiar with the "Shaken, Not Stirred" starter method but the concept of maximum cell density is universal across methods.

 

[RM-MN]

Most tools are only estimations. Give it take a few billion cells. Heh

Most cell counts are only estimators too. Look at the methods used to count cells. Take a small amount of yeast, dilute it a great amount, take a small amount of that and dilute it even further so the numbers to count in the sample are within a reasonable range so the count doesn't take years. Attempt to get a known quantity of the sample, count the cells that you see, then extrapolate the number by a huge factor to get the number of cells in the package. Hrmph.. A wild guess might be just as close. Chris White and Jamil Jainasheff would disagree with me but I think I am as close to right as they are. Do some reading about yeast cell counting. Look at lots of sample pictures and then tell me how exacting this yeast count might be.

 

[cantrell00]

Most cell counts are only estimators too. Look at the methods used to count cells. Take a small amount of yeast, dilute it a great amount, take a small amount of that and dilute it even further so the numbers to count in the sample are within a reasonable range so the count doesn't take years. Attempt to get a known quantity of the sample, count the cells that you see, then extrapolate the number by a huge factor to get the number of cells in the package. Hrmph.. A wild guess might be just as close. Chris White and Jamil Jainasheff would disagree with me but I think I am as close to right as they are. Do some reading about yeast cell counting. Look at lots of sample pictures and then tell me how exacting this yeast count might be.

Sierra Nevada doesn't leave it to chance. They literally count each viable cell going into each batch. I'm sure other breweries do this also.

 

[zacster]

My guess, and this is only a guess, is that the breweries have a way to measure cell density, and hence can be more accurate. But overall, it is still just an estimate.

 

[Big Monk]

At the homebrew level it just isn't necessary. Estimates are all that are required to make fantastic beer.

 

[Rhumbline]

Sierra Nevada doesn't leave it to chance. They literally count each viable cell going into each batch. I'm sure other breweries do this also.

I'm having a hard time believing this. If a five gallon batch requires 300 billion cells, how many does a thousand gallon batch require?

Count each cell individually? Color me doubtful.

 

[ScrewyBrewer]

I now have both a 1 and 2 liter flask and a stir plate. Let's say I'm brewing a pale ale with an OG of 1.056. I'll need about 227 billions cells (going off memory). Let's say I'm starting with 70bn cells (a not exactly new smack pack).

Once and for all, if I were to take these 70 bn cells, put them in a OG 1.040 starter, throw on the stir plate, how many cells should I have after 18 hours in both the 1 liter flask and the 2 liter flask? I also see varying amount of wort to be used in the starters.

Obviously, if we know the growth rates it will be smarter to work backwards, as in, how big should my starter be if I need to get from 70bn cells to 230 bn cells using a stir plate?

Lastly, I'd like to generally just build big starters in a 2 L flask, figure out how much I need and save the rest for a future batch too.

TIA

I think a lot of your frustration has to do with what to make of yeast cell growth as it relates to inoculation rate. Remember the primary goal when creating a 'brewery' propagation is to ensure you will have enough clean, healthy cells to ferment your beer. It is far better to rely on fewer young and healthy cells than it is to rely on a larger number of weaker cells to ferment your beer.

The inoculation rate, or pitching rate, has the biggest impact on cell growth. It is best described as the ratio of yeast cells to wort volume. With a higher ratio of cells to wort volume, less cell growth will occur and cell health will improve. With a lower ratio of cells to wort volume, the yeast is in effect making beer and developing unwelcome flavor precursors in the process.

With your inoculation rate of ~70bn cells, and using a 7.7 yield factor, then a 1.5 liter starter wort will produce ~200bn cells once terminal gravity has been reached. Expect to add an additional 10% of cell growth to this number if a stir plate is used. With this inoculation rate, maximum cell density will be reached within 12-18 hours.

As a general rule pitching ~100bn cells into 2 liters of 1.030-1.040 gravity wort should produce ~200bn cells when the wort reaches terminal gravity. When using a stir plate add on another 10% cell growth.

 

[Electrake]

Mett-c dependent

 

[lbond2]

I think a lot of your frustration has to do with what to make of yeast cell growth as it relates to inoculation rate. Remember the primary goal when creating a 'brewery' propagation is to ensure you will have enough clean, healthy cells to ferment your beer. It is far better to rely on fewer young and healthy cells than it is to rely on a larger number of weaker cells to ferment your beer.

The inoculation rate, or pitching rate, has the biggest impact on cell growth. It is best described as the ratio of yeast cells to wort volume. With a higher ratio of cells to wort volume, less cell growth will occur and cell health will improve. With a lower ratio of cells to wort volume, the yeast is in effect making beer and developing unwelcome flavor precursors in the process.

With your inoculation rate of ~70bn cells, and using a 7.7 yield factor, then a 1.5 liter starter wort will produce ~200bn cells once terminal gravity has been reached. Expect to add an additional 10% of cell growth to this number if a stir plate is used. With this inoculation rate, maximum cell density will be reached within 12-18 hours.

As a general rule pitching ~100bn cells into 1.030-1.040 gravity wort should produce ~200bn cells when the wort reaches terminal gravity. When using a stir plate add on another 10% cell growth.

What this guy said....Another good note is that the initial inoculation rate doubles the first time as mentioned above; however, this is reduced by half at the same volume of 1.040 wart for each time you do this. For example--->

Start with 1L of 1.040 wort and 100billion cells. On a stir plate over 2 days will yield 200billion cells. If you make another starter with this slurry(assuming decanting the spent wort) at 1L again with 1.040 wort you will only yield half of the cell count...So after 2 days this time you will only yield 300billion cells. I believe the only way you can double the amount is to double the volume of wort each time. However, the information above is all you need to know as a home brewer. Remember vitality and viability are key to great fermentation's!!! Stay thirsty my friends...

 

[blizz81]

Better gets to countin'.

 

[Auger]

Per JZ and JP in one of their Brew Strong podcast episodes on yeast and pitching....its all crap. The whole thing is just a crapshoot to one degree or another. As you've learned, you can drive yourself absolutely bonkers by overthinking it...analysis paralysis. Pick a yeast calculator and go with it. I use this one:

http://www.mrmalty.com/calc/calc.html

Am I getting accurate yeast cell counts in what I'm pitching vs. what the calculator tells me I'll end up with? Hell if I know. I'm not buying a microscope to try and confirm either. But, using fresh yeast and that calculator for starters, I get airlock activity within hours of pitching and I've never had a stuck ferment or off flavors associated with unerpitching, so I'm going with it.

 

[yeastylad]

I'm having a hard time believing this. If a five gallon batch requires 300 billion cells, how many does a thousand gallon batch require?

Count each cell individually? Color me doubtful.

And doubtful you should be. Sierra Nevada literally does not count every yeast cell going into a batch, and neither does any other brewery. I work in Biotechnology where some of the most accurate cell counting equipment and techniques are used, and we only extrapolate from cell counts in samples. I'm willing to bet breweries do the same. It would take a very long time to count every cell in one of our 20,000L fermenters...

 

[broadbill]

I think all of these pitch rate calculators have fooled us into thinking there is more to this than there really is. Even if you do have an accurate yeast count (within a few billion on either side, heh) you would still want to know the viability of those cells. Even if you do those viability tests (stain exclusion assays, etc), it is still unclear how that translates into an appreciable change in beer quality.

At the end of the day the best you can do is establish a few good best practices (use the freshest yeast you can, make a starter, etc.) and be consistent. I'm guess even the large breweries lean more on a consistent process figured out via trial and error than scientific principles and tests from a lab.

 

[ScrewyBrewer]

What this guy said....Another good note is that the initial inoculation rate doubles the first time as mentioned above; however, this is reduced by half at the same volume of 1.040 wart for each time you do this. For example--->

Start with 1L of 1.040 wort and 100billion cells. On a stir plate over 2 days will yield 200billion cells. If you make another starter with this slurry(assuming decanting the spent wort) at 1L again with 1.040 wort you will only yield half of the cell count...So after 2 days this time you will only yield 300billion cells. I believe the only way you can double the amount is to double the volume of wort each time. However, the information above is all you need to know as a home brewer. Remember vitality and viability are key to great fermentation's!!! Stay thirsty my friends...

Correction:
As a general rule pitching ~100bn cells into 2 liters of 1.030-1.040 gravity wort should produce ~200bn cells when the wort reaches terminal gravity. When using a stir plate add on another 10% cell growth.

 

[Talgrath]

I've underpitched a bit and I've overpitched a bit, and never noticed an appreciable flavor change compared to a supposedly perfectly calculated batch. As long as you're within about 20 billion cells, I think you're fine. Pick a yeast cell calculator, plug in the numbers and run with it. Ultimately this is not as exact a science as some would have you believe, we're trying to predict how billions/trillions of microscopic fungi that have been stored in vials and packets that have been shipped all over the country will react with a unique solution of water, grain sugars and hops (and maybe some other stuff) that have been boiled on a stove or burner for an hour or so, we're making beer not finding a cure for cancer here. Calm down, relax, do the best you can and RDWHAHB.

 

[pricelessbrewing]

You've gotten some good replies already but I'll add my two cents.

There's two limiting factors on how much growth you get, one is starting with an appropriate innockulation rate. Too high and very few new cells are created aside from maintaining the cell density. The other limiting factor is the maximum cell density which varies slightly from strain to strain and probably from culture to culture. Just like flocculation varies from generation to generation I'm sure this properly does as well.

I prefer Kai troesers growth rate formulas to mr malty, as the supporting data has been published and has been confirmed by other homebrewers. Mr malty has not been. For now, my preferred starter calculator is the one at brewunited, at least until omega yeast labs releases there's based on each specific strain, which will be interesting to see.

 

[bigken462]

19hrs and 45min of that time could have been spent making good homebrew. Trust the technology and proven methods of making a simple starter based on your recipe from one of many apps.

Don't over stress it.

 

[Queequeg]

If you that worried buy a microscope and do a cell count.

 

[sky4meplease]

So the moral of the story is...Keep Reading!!!
You are probably realizing that 20 hours is not enough and it's not.
We are not Brewers but yeast farmers/scientists and the beer we brew is a way for us to quantify our work.
It's a good thing it tastes good!

 

[BaldyOnFire]

I just wanted to let you guys know that your time hasn't gone to waste; I think I've read through this at least 5 times. I've read the article either by Kai or about his findings but it doesn't help me in a practical sense. Is there a formula I can use as a brewer?

Lastly, I guess I'll just use the Mr. Malty calculator going forward. I have both a 1 liter and 2 liter flask and with my stir plate I'm sure I'll be fine

 

[DurtyChemist]

Brew 10 gallons. Pick one calculator. Pitch the correct amount in 5 and over pitch by a double in the other. Taste the beer when it's finished and see if it really makes a difference...


























Or ask the brulosopher website.

 

[biestie]

I just wanted to let you guys know that your time hasn't gone to waste; I think I've read through this at least 5 times. I've read the article either by Kai or about his findings but it doesn't help me in a practical sense. Is there a formula I can use as a brewer?



Lastly, I guess I'll just use the Mr. Malty calculator going forward. I have both a 1 liter and 2 liter flask and with my stir plate I'm sure I'll be fine

You will. Your original question mentioned a concern about over pitching. With a 2L stir flask, and a standard gravity starter, I don't think you could over pitch to the point where it would be a flaw in the beer for a 5 gallon batch.

 

[Brewsncrabs]

I use http://www.yeastcalculator.com/ . It has several options depending on who you believe is correct in their thinking. I start using Kai's theory and my FG started coming out closer to what they should be.
This is the old Yeast Calc that used to be available and disappeared a few years ago. I dont know where I found it, but it works for me. Kai's numbers with a stir plate seem to match up to Beersmith pretty closely as well. I am no expert, so YRMV.