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Yeastcalc.com (Now two stir plate options?)

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bradfordmonk

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Now this just got confusing...why are there all of a sudden two different stir plate options?

  1. Stir Plate (K. Troester)
  2. Stir Plate (J. Zainesheff)


And I get completely different sets of numbers for each. See below...Anyone know what the difference is...aside from numbers; and which should I go with? :drunk:

Screen Shot 2013-03-11 at 11.48.55 PM.jpg


Screen Shot 2013-03-11 at 11.49.06 PM.jpg
 

diS

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Growth rates are not fully researched jet, that is the main reason why different authors states different results.
Yeastcalc is using results from 3 common resources:

Chris White researched growth rate at non-stirred starter, results are published in "Yeast".
Jamin Zainasheff then multiplied those results to get growth in stirred starter, I think he uses 2.5 as multiplier.
Kai Troester researched growth rate in stirred starter as function of growth per gram of extract.

That said, when using stirred starter you will make slightest mistake if you use Troester's growth rate. I think it is the best resource that we have at the moment, but I hope that further experiments will be made on this topic.
 

raouliii

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Kai Troester has published information on this subject here.


Woodland Brewing published information related to yeast growth vs sugar concentration here.

On a related note, Woodland Brewing has also published viability test results, here, which call into question the viability calculations being used as well.
 
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bradfordmonk

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So you think I should go with the Troester option of Stir Plate? I would like to believe that, as I'd only have to make a 1 step starter @2L.

but the numbers are so widely different. So its tough to say...i do now when I've made yeast starters with step starters (I assume using the Zainesheff stir plate model being what was defaulted by yeastcalc before) that my fermentations were very vigurous and fast...maybe a dig that I had alot more cells than the calculator was estimating? Possibly?
 

CloverBrew

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Kai's stirplate data la used in conjunction with sugar concentration data on brewersfriend also
 

WoodlandBrew

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Thanks for the mention Rauliii.

Use Kai's equation. Especially if you let it ferment to completion. His equations were produced from stirred starters instead of scaling still starters. It also more closely follows Ballings observation.

If you really want to dial in the measurement of cell growth without a microscope there are some calculations that can be done based on starting gravity, and final gravity as measured with both a refractometer and hydrometer. But for all practical purposes, Kai's equation will get you plenty close.

On my blog is a comparison of various calculators and actual growth of over 50 starters. These were all still starters, but it may be of interest.

http://woodlandbrew.blogspot.com/2013/03/starter-calculators-revisited.html
 

Hermit

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Pitching rates are well studied. Try and get close to the number. There are taste tests done on this if you care to google it up.
 

Kaiser

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Dustin mentioned to me that he would add my model for growth on a stir plate. I guess it will get quite some scrutiny now.

I almost always propagate yeast from slants or work with fresh yeast cultures. That's how all my experiments were run. I don't see all that much variation between strains but the more systematic experiments were done with WY2042, a non flocculating lager yeast.

One thing I'll have to do soon is buy WL vial or two and run experiments with yeast straight from a vial. I don't expect much different results but that's the only difference I can see between my yeast propagation and most other home brewer's yeast propagation.

It would also be useful if other brewers with microscopes could chime in with their yeast counts for yeast grown on a stir plate. I know Woodland has done some work and maybe he has some data for stirred starters as well.

I respect Jamil and his work on yeast and I wouldn't mind some back-up for the model I have given that our models differ quite a bit for the lower inoculation rates (less than 1.5 L wort for 100 B cells)

Kai
 

WoodlandBrew

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It would also be useful if other brewers with microscopes could chime in with their yeast counts for yeast grown on a stir plate. I know Woodland has done some work and maybe he has some data for stirred starters as well.
Most of what I have done is with still starters. I've been working out the kinks with my stir plate, but do have one data point. It does seem to follow pretty close to your model.

1.040 wort (Note that entering the initial gravity to the left hand side of YeastCalc is crucial when using Kai's equations)
Initial cell count: 34 million per ml.
Final cell count: 199 million per ml => 165 million per ml grown.

Kai's model estimated:
Final cell count of 186 million per ml => 152 million per ml grown

Pretty darn close! This was yeast harvested from a bottle of Aventinus.
 

Sulli

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Given that starter sizes for the average homebrewer range from 0.5 to 4 liters, and that all these calculations can vary by as much as +/-30% in the real world anyway. The numbers between the two formulas are not that far off from each other.

The real difference, with regards to smackpacks and vials, is in the way the viability of the initial cells pitched affects the final cell count.

According to Kai's model it doesn't really matter if you pitch 100 million cells or 100 cells you still end up with a crap load of cells at the end of fermentation.

Here is where I feel we need to be careful though, because the purpose of making a starter isn't to just propagate a crap load of cells. The purpose of making a starter is to propagate a crap load of healthy cells; and in order for the cells to have an environment conducive to healthy reproduction there needs to be a balanced ratio of cells to food.

This is where the importance of inoculation rates come into play. Too much wort (low inoculation rate) and the yeast become stressed from excessive budding, (this is talked about in Boulton & Quains "Brewing Yeast and Fermentation") There is a limit to how many times a yeast cell can bud before it becomes senescent, something like 24 to 40 generations.

Yes, theoretically you could toss 100 yeast cells into 2 liters of wort and end up with 281 billion cells, but how many of those 281 billion cells are still up to the task of fermenting 20 liters of wort?

Keeping the inoculation rate of your starter in the range of say 25 to 100 million cells per ml will help ensure that the cells you have propagated are strong, healthy and vital to the task of fermenting that recipe you spent so much time deliberating over.

If your going to use Kai's formula (or Jamil's for that matter) I'd suggest trying to keep the inoculation rate for your starter close to 25 to 100 million cells per ml.
 

WoodlandBrew

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At 24 generations the cell population multiplies almost 17 million times (2^24). The home brewer does not need to worry about it. Viability of yeast is also much better than most of the estimators show. It will take longer to reach completion with a lower inoculation rate, but unless you are starting with just a pinch of yeast in 4 liters there is no issue with health or senesents. Even in extreme situations 5 generations or budding scars will be the top made in a starter. That would be a growth factor of 32.
 

Kaiser

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Given that starter sizes for the average homebrewer range from 0.5 to 4 liters, and that all these calculations can vary by as much as +/-30% in the real world anyway. The numbers between the two formulas are not that far off from each other.
I expect the accuracy of a yeast growth calculator to be +/-25%. Even in my own yeast propagations I see rather large variations that I don’t fully understand yet.


According to Kai's model it doesn't really matter if you pitch 100 million cells or 100 cells you still end up with a crap load of cells at the end of fermentation.
This is because my model is not as sensitive to the initial cell density. And when you grow 300 B cells a difference of +/- 30B cells caused by the initial viability is in the noise. My assumption is that the nutrients that are not consumed by the dead cells are consumed by the living cells and them get to divide a little more which makes up for the dead cell’s inability to grow more cells.

This is where the importance of inoculation rates come into play. Too much wort (low inoculation rate) and the yeast become stressed from excessive budding, (this is talked about in Boulton & Quains "Brewing Yeast and Fermentation") There is a limit to how many times a yeast cell can bud before it becomes senescent, something like 24 to 40 generations.
I don’t follow this argument. In a homogenous culture you’ll always have about 50% cells with no scars, 25% with one scar, 12.5% with 3 scars and so forth. This is the result of the way yeast grows by budding. While low inoculation rates means that there has to be more budding it also means that the initial population, which ends up with the most scars, will be small.

I do think extremely low inoculation rates are bad for yeast starters but for a different reason. Yeast needs to drop the pH of the wort for efficient nutrient uptake. This is easier for larger populations than for small populations. But even in this case the amount of cells that will have experienced that stress in the beginning is small and the bulk of the cells will have been grown in favorable conditions.

Another argument is protection from infection. The smaller the initial population the easier it is for an infection to take hold. That’s why I have to start with sterile wort when I propagate from a slant. But if you are starting with a vial (or even ½ a vial) you should have a large enough yeast population to suppress the growth of other microbes.

Kai
 

Sulli

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I do think extremely low inoculation rates are bad for yeast starters but for a different reason. Yeast needs to drop the pH of the wort for efficient nutrient uptake. This is easier for larger populations than for small populations. But even in this case the amount of cells that will have experienced that stress in the beginning is small and the bulk of the cells will have been grown in favorable conditions.

Kai
If this is the case why bother with a starter at all?

Pitching 10 million cells into 2 liters of wort, is the same as pitching 100 million into 20 liters. It's going to ferment regardless.
 

Kaiser

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If this is the case why bother with a starter at all?

Pitching 10 million cells into 2 liters of wort, is the same as pitching 100 million into 20 liters. It's going to ferment regardless.
The idea of having a proper population of yeast cells in the beer fermentation is to ensure the desired flavor profile. The conditions during fermentation are also not comparable to a homogeneous stater.

Kai
 

Sulli

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So what I'm getting from this conversation is that viability is a non-issue when it comes to making starters.
 

Hermit

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So what I'm getting from this conversation is that viability is a non-issue when it comes to making starters.
I would think it would take longer to grow up the starter with a smaller number of yeast to start so you would have to take that into consideration. I think the yeast book says a division happens about once per 18 hours which is why it is recommended to wait that long to give a second shot of oxygen for big beers.
 

lockwom

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Jamil's formula has warnings of being proprietary. His warning on "Mr. Malty" about reverse engineering is anti-scientific. With all due respect, the results reek of a strange curve fit, especially the kludge for a stir plate scaling a curve-fit.

Kai's makes the most sense to me. I use that now when starting from my slants. That said, one wouldn't want to step from a slant to 2 L as his formula suggests you could, but hopefully nobody ranching yeast would do something so absurd.
 

lockwom

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So what I'm getting from this conversation is that viability is a non-issue when it comes to making starters.
I wouldn't go that far, but if I understand correctly, live yeast will definitely cannibalize on dead yeast pitched in your starter. I think all steps on a starter are contingent on reasonable initial pitching rates.
 

Kaiser

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Jamil's formula has warnings of being proprietary. His warning on "Mr. Malty" about reverse engineering is anti-scientific. With all due respect, the results reek of a strange curve fit, especially the kludge for a stir plate scaling a curve-fit.
Geez. I wonder if I'm now in trouble and a potential target. I did not notice this warning before. Does anyone know regarding the legal situation regarding "reverse engineering"?

I just don't want to become a target given that I have reverse engineered curves on my blog. I can easy drop them and state that I'm not allowed to publish them.

I'm also interested if this clause appeared just recently. In that case I'm fine, according to Wikipedia and in Wikipiedia we trust :)

Kai
 

lockwom

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Geez. I wonder if I'm now in trouble and a potential target. I did not notice this warning before. Does anyone know regarding the legal situation regarding "reverse engineering"?

I just don't want to become a target given that I have reverse engineered curves on my blog. I can easy drop them and state that I'm not allowed to publish them.

Kai
If Jamil pursued legal action against you for curve fitting on a sample of points, or looking at simple scripted source code, then he would definitely suffer from the "Streisand effect" among the homebrew community.

I respect his opinion on many aspects of homebrewing, but I'm thinking a lawyer advised him to give an absurd warning banner on otherwise simple math that most scientists would transparently publish. Otherwise, it comes across as defensive against weak data. Then again, Microsoft received a patent on the double click in 2004.

I didn't post that as a warning to anyone, more to contrast with your transparent matching of hypothesis, source data and conclusions like a proper scientist.

Jamil's yeast book is not on my brewshelf; I previewed it and the text seemed to refer to this opaque "tool" rather than substantial information. If anything reeks of consultation, I run for the hills.
 
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bradfordmonk

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so when using kai option in yeast calc...is there any difference to length of time spent on the stir plate...i usually leave for about 24hrs. This one I just did I left on for maybe 36 hrs then put it in fridge this morning. So an extra 8hrs or so than i'm used to.

Also, I used a smack pack from wyeast, forbidden fruit, from Dec. 2nd 2012. I pitched it into my starter that I made a 2L of 1.040 wort. Any issues with this? My OG of my beer is 1.054.
 

WoodlandBrew

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In the first 24 hours you will generally get about half of the cell growth, but the speed of growth is very dependent on a number of factors. Even with a stir plate 48 hours has been pretty much the minimum competition time I have seen. I've also see yeast grow for much longer on a stir plate.
 
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bradfordmonk

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In the first 24 hours you will generally get about half of the cell growth, but the speed of growth is very dependent on a number of factors. Even with a stir plate 48 hours has been pretty much the minimum competition time I have seen. I've also see yeast grow for much longer on a stir plate.
so you think i should have left on longer? any idea if brinign out of fridge and putting back on plate?
 

WoodlandBrew

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It's hard to say. What was the inoculation rate, OG and temperature? What is the gravity now? My guess would be that another day on the plate will grow more cells.
 
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bradfordmonk

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It's hard to say. What was the inoculation rate, OG and temperature? What is the gravity now? My guess would be that another day on the plate will grow more cells.
if i got max usage out of what yeastcalc was calculating, then i still would have ended with about 100 billion cells too many. So I think i'm going to be good now looking at it.


but for numbers you asked 13.5 inoculation rate, og was 1.040 and temp was room temp around 70, maybe slightly warmer.
 

WoodlandBrew

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Sounds like you are good. I'll have to compare that to some metrics, but my hunch is that with that inoculation rate it probably didn't complete in 12 hours
 

StMarcos

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I thought growth has ceased by the time you are fully in the anaerobic regime. My starters are almost always fermented dry by 24hrs, so I was guessing that the growth was completed in much less time than this.
 
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bradfordmonk

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Sounds like you are good. I'll have to compare that to some metrics, but my hunch is that with that inoculation rate it probably didn't complete in 12 hours
yea i had older yeast from dec 2nd. so it ran nonstop for about 36hrs. hopefully it'll be enough. maybe it'll balance out and i'll rdwhahb...since i was shooting for a number way over what i needed.
 

mtnagel

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one wouldn't want to step from a slant to 2 L as his formula suggests you could, but hopefully nobody ranching yeast would do something so absurd.
Pardon my ignorance, but why wouldn't you want to do that? I'm assuming a yeast slant is different than storing rinsed yeast right? And you could start with a 2 L starter for rinsed yeast, right?
 

WoodlandBrew

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I thought growth has ceased by the time you are fully in the anaerobic regime. My starters are almost always fermented dry by 24hrs, so I was guessing that the growth was completed in much less time than this.
Anaerobic fermentation occurs when there is no oxygen which is not the case with a stir plate. Cell production happens both during aerobic respiration and anaerobic fermentation. However it is much slower an less efficient during anaerobic fermentation.

http://woodlandbrew.blogspot.com/2013/03/yeast-propogation-with-aerobic.html

By "ferment dry" do you mean that a hydrometer measures 1.000 or less?
 
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bradfordmonk

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Pardon my ignorance, but why wouldn't you want to do that? I'm assuming a yeast slant is different than storing rinsed yeast right? And you could start with a 2 L starter for rinsed yeast, right?
lol...i think i did the absurd, and dropped my 27% viability yeast into 2L. I didn't notice any issues so far. after 24hrs...the solution was creamy/milky and looked just like any other one i've ever done. i don't have a microscope...so maybe it's bad...don't know.
 

WoodlandBrew

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lol...i think i did the absurd, and dropped my 27% viability yeast into 2L. I didn't notice any issues so far. after 24hrs...the solution was creamy/milky and looked just like any other one i've ever done. i don't have a microscope...so maybe it's bad...don't know.
How did you determine 27% viability without a microscope?
 
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bradfordmonk

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How did you determine 27% viability without a microscope?
i have really good vision haha...no...

just by going by date using yeastcalc...which i've been reading that those calculations are probably off too. i don't know if that means the calculations are estimating a lower viability or a higher viability than what the calc is coming up with.
 

WoodlandBrew

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i have really good vision haha...no...

just by going by date using yeastcalc...which i've been reading that those calculations are probably off too. i don't know if that means the calculations are estimating a lower viability or a higher viability than what the calc is coming up with.
Typically Mr. Malty (and the derivative: Yeast Calc) both estimate low from counts I have done:
http://woodlandbrew.blogspot.com/2012/12/refrigeration-effects-on-yeast-viability.html

Chances the viability of you your yeast was in the 80's or 90's. The glycogen was probably depleted which means it might start a little slow, but once it is going it will do fine, which matches what you observed.
 
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bradfordmonk

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Typically Mr. Malty (and the derivative: Yeast Calc) both estimate low from counts I have done:
http://woodlandbrew.blogspot.com/2012/12/refrigeration-effects-on-yeast-viability.html

Chances the viability of you your yeast was in the 80's or 90's. The glycogen was probably depleted which means it might start a little slow, but once it is going it will do fine, which matches what you observed.
The data you have is more than i've seen. Looks like a lot of information, but I'll see how this one goes. If it goes well, I'll hardly have to do step starters anymore and may have just been doing it out of one way to read the data.
 

mtnagel

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So using the 0.7% loss per day I've seen quoted online, my yeast is down to 44% viability (yes, I know this might not be accurate). I have ~150 ml of rinsed yeast and I'm estimating I'm starting with 252 billion yeast cells.

So should I not make a 1.75L starter with this?
 
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