Q about stepped starters

[Smellyglove]

Lets say I need to step a starter. I make a starter half the final volume as the first step. Now I have lots of yeast cells. Will the growth-factor be as big in the second step as in the first one?

I dont get this. Since I have a big amount of cells after my first step, why will they not just ferment the second step without creating an equal amount of daughter cells as in the first step? They are probably enough to just ferment it with the cell count they allready are at.

 

[WoodlandBrew]

For the most part biomass yield is directly proportional to the available extract. You'll see this in Kai's equations but not the other ones. From experimentation and research I think Kai has it right. White's experiments were done with no agitation. Even if you don't have a stir plate you'll at least introduce some oxygen by giving it a good shake directly following inoculation. While White's experimental results were turned into the Mr. Malty calculator that has been widely accepted, I think they poorly model the way most home brewers create a starter. The settings for various agitation methods were added after the fact as a sort of magic scale factor.

So if you add the same amount of DME to each step, then expect the same number of cells to be grown.

This calculator gives a visual representation of the growth:
http://www.woodlandbrew.com/2015/02/starter-calculator.html

 

[brewguyver]

dont get this. Since I have a big amount of cells after my first step, why will they not just ferment the second step without creating an equal amount of daughter cells as in the first step? They are probably enough to just ferment it with the cell count they allready are at.

That's pretty much exactly what will happen. The recommended step is 10x, so a 35 ml vial of wlp yeast into 350-500 ml of wort into a 3500 ml starter.

If you're not making a crazy big beer or a lager you can probably do a 1200 ml starter or less.

 

[Smellyglove]

I rarely do stepped starters but some bells started ringing after about 8 hrs of my second step today.

But I quote from the book Brewing Engineering, this is taken a step further from what Balling discovered way long ago:

Or put another way, for every gram of sugar consumed there are 1 billion cells produced.

It doesnt add up with what I "know". Also somewhere else in that same book he mentions that 10x thing..

Since my second and current step is 2.5l I should make a 25 liter starter to get the same growth as I did in the firat step?

Then these stepped starter calculators are partly bogus?

 

[WoodlandBrew]

Yes, generally one gram of extract will produce one billion yeast cells. (As you mentioned, this is the balling observation)

An extension of this can be applied to the standard pitch rate for ales. Dr. Fix proposed the widely used 0.75 Billion cells per Liter Degree Plato. If you apply the one gram of extract producing one billion cells you will find that the pitch rate that Fix proposed produces a 10 fold growth of yeast. If you aren't pitching 0.75 Billion cells per liter degree Plato then the growth will not be ten fold, but the number of cells produced will be the same.

 

[catdaddy66]

For the most part biomass yield is directly proportional to the available extract. You'll see this in Kai's equations but not the other ones. From experimentation and research I think Kai has it right. White's experiments were done with no agitation. Even if you don't have a stir plate you'll at least introduce some oxygen by giving it a good shake directly following inoculation. While White's experimental results were turned into the Mr. Malty calculator that has been widely accepted, I think they poorly model the way most home brewers create a starter. The settings for various agitation methods were added after the fact as a sort of magic scale factor.

So if you add the same amount of DME to each step, then expect the same number of cells to be grown.

This calculator gives a visual representation of the growth:
http://www.woodlandbrew.com/2015/02/starter-calculator.html

Thanks for the link! I needed that.

 

[Smellyglove]

For the most part biomass yield is directly proportional to the available extract. You'll see this in Kai's equations but not the other ones. From experimentation and research I think Kai has it right. White's experiments were done with no agitation. Even if you don't have a stir plate you'll at least introduce some oxygen by giving it a good shake directly following inoculation. While White's experimental results were turned into the Mr. Malty calculator that has been widely accepted, I think they poorly model the way most home brewers create a starter. The settings for various agitation methods were added after the fact as a sort of magic scale factor.

So if you add the same amount of DME to each step, then expect the same number of cells to be grown.

This calculator gives a visual representation of the growth:
http://www.woodlandbrew.com/2015/02/starter-calculator.html

Is it me who's doing something weird (I've enabled macros) or doesn't it work in openoffice?

And, I found this "Agitation Effects on Growth Rate and Yield of Brewer’s Yeast ". Where it concludes that you'll end up with more or less the same result with a stir plate as without one. Why are all calculators saying you'll end up with way more yeast with a stir plate?

 

[WoodlandBrew]

Is it me who's doing something weird (I've enabled macros) or doesn't it work in openoffice?

It may not work in Open Office. I haven't tested it. That's too bad. I would like to make it entirely web based, but that would be a considerable effort.

And, I found this "Agitation Effects on Growth Rate and Yield of Brewer’s Yeast ". Where it concludes that you'll end up with more or less the same result with a stir plate as without one. Why are all calculators saying you'll end up with way more yeast with a stir plate?

This is something that is debated. The commonly accepted equations that Jamil Zainasheff created show that aeration effects biomass yield, although as you saw, my research and experimentation don't show this. It is common in both the labrotory and when culturing cells for brewing to allow propagation for 48 hours and then considering the stage "done." After 48 hours on a stir plate the yeast will have typically consumed more than 90% of the extract that they can metabolize. However, without agitation this can take much longer. I suspect that this is the cause for the deviation that you see in Jamil's equations.

 

[Smellyglove]

But what about Troester? He has been doing the same research, havent he?

 

[WoodlandBrew]

Yes, he has quite a bit of research and experimentation. He asked me to duplicate his experiments for correlation when he was developing his equations. His equations do not show a link between pitch rate and growth. He also only modeled stir plates.

 

[brewguyver]

Since my second and current step is 2.5l I should make a 25 liter starter to get the same growth as I did in the firat step?

Yes, but ... Do you rely need that much yeast? That's a lot of frikkin yeast

 

[Smellyglove]

Haha. No. I misunderstood my own term of growth.

 

[Twotaureanbrewing]

I downloaded the excel calculator.

My next brew at 1.095 OG requires 322 billion cells.

If I change the DME to 180 grams the output shows desired cells.

Im using wyeast. Is it possible to multiply 1 billion to over 3 billion cells in a single starter? If so should I increase water as well? What size flask should I use?

Any recommendations would be greatly appreciated! Thanks!

 

[WoodlandBrew]

Is it possible to multiply 1 billion to over 3 billion cells in a single starter? If so should I increase water as well? What size flask should I use?

Good questions. Yes, tripling the cell count is very reasonable in one step of a starter. Breweries often use fermentation of beer to produce the volume of yeast that they need and have great success. Even in the adverse propagation conditions during fermentation including lack of agitation and no additional oxygen, the biomass generally grows ten times larger.

The amount of water should generally be ten times the weight of the extract. It's the amount of extract that drives the yield so water volume is not as critical as extract weight. The lower left box on the calculator will display warnings if your water volume is unreasonable.

 

[Smellyglove]

Good questions. Yes, tripling the cell count is very reasonable in one step of a starter. Breweries often use fermentation of beer to produce the volume of yeast that they need and have great success. Even in the adverse propagation conditions during fermentation including lack of agitation and no additional oxygen, the biomass generally grows ten times larger.

The amount of water should generally be ten times the weight of the extract. It's the amount of extract that drives the yield so water volume is not as critical as extract weight. The lower left box on the calculator will display warnings if your water volume is unreasonable.

Tanks for your knowledge so far.

I have another Q, it might be stupid..

Referring back to Ballings observation, where 1g of fermentable extract yields 1 billion new yeast cells. How come when using stir plate calculators they say that new cells created is more than I even have extract in the starter?

It seems like Ballings "law" should yield a finite amount of new cells given the amount of fermentable extract, but these yeastcals doesn't seem to agree.

 

[WoodlandBrew]

Here is a blog post I am working on that goes into some details. I need to link the references, but I hope it still explains it well enough:

I'm sure Jamil Zainasheff had the best intentions when creating his Mr. Malty Starter Calculator, however it seems that brewers have taken the results out of context and drawn conclusions from the calculator that I doubt Jamil intend. The data behind the vastly popular Mr. Malty equation are from growth that had no aeration and no agitation. (Details of this experiment can be found in the widely acclaimed book: Yeast by Dr. Chris White and Jamil Zainasheff. [1] If you haven't read this book I highly recommend you get a copy.) There is an anecdotal reference to increased yield from agitation in Yeast, however without more detail on how the yield was compared we can only guess as to what the author observed. It is also common in scientific papers to use "specific growth rate" (a measure of the speed of propagation) interchangeable with yield. [2] Without further explanation I can only assume this is what Dr. Chris White may be refereeing to.

The lack of oxygen make Chris White's experiments questionable when used to predict growth on a stir plate. Oxygen is critical for sterol production in yeast. Without aeration an the onset of fermentation the yeast membranes will lack the pliability they need to bud new cells. Given proper aeration at inoculation yeast can double four times, growing to sixteen times the initial population. [3] Without aeration, as was done by Chris White for the experiments that Jamil used for his calculator, the data show that cell budding was extremely limited.

By shaking the starter at inoculation cell growth is only limited to growing to about 16 times the initial population. Much more that would be grown in a typical starter.

Stir plates produce yeast faster, but do not produce more yeast.

In scientific papers on yeast propagation you will generally see that the time frame used is 48 hours. [4][5] Propagation occurs much more rapidly with a stir plate so at the 48 hour mark there is often substantially more yeast produced with some form of agitation. However, given enough time, without agitation a similar amount of yeast is produced. [6]

Yeast can metabolize sugar much more efficiently in the presence of oxygen aerobically than without anaerobically. [7] Using a stir plate oxygen is constantly introduced. The common conclusion from these two facts is that with a stir plate considerably more sugar will be metabolized aerobically than without. This is, however, not the case due to the Crab Tree Effect.[8] When the sugar concentration is typically above 0.5% w/w (0.5°P or 1.002 SG)[9] yeast will metabolize sugar using anaerobic fermentation. The balance between aerobic respiration and anaerobic fermentation is similar independent of agitation.

 

[SilverZero]

And, I found this "Agitation Effects on Growth Rate and Yield of Brewer’s Yeast ". Where it concludes that you'll end up with more or less the same result with a stir plate as without one. Why are all calculators saying you'll end up with way more yeast with a stir plate?

I know this is an old thread. Does anybody have a copy of this report? The links are dead and I feel like this point needs to be kept in mind.