Starter math help

[joshesmusica]

I'm really trying to understand all of the functionality of a starter. Especially because I'm working on propagating a certain yeast into a very large amount to store away and to send off.

I'm wondering what is the difference for the yeast between 1.5L at approximately 1.075 and 2L at approximately 1.056? This is still 300g of DME into each one, meaning the same amount of total sugars in each wort. I read on the Mr. Malty 14 questions article that 1L of 1.040 wort (approximately 100g of DME) will result in 150% growth. While a 2L starter would result in 200% growth. This is taking into account pitching one vial of approximately 100 billion cells into each wort.

But how can I determine how much growth I will have according to innoculation rate and size of the wort?

I'm working on stepping this up, but I'm wondering if I've got the logic wrong. I did 1L and 100g of sugar 1st. Then 1.5L with 200g of sugar second. I was thinking of doing 2L with 300g sugar for the third and final step. But should I have just been aiming to have 1.040 with each step, and only increasing the volume size (and therefore the total sugars)?

 

[eber1988]

From what I have read is you want around 1.040 because too high of a gravity may shock the yeast.

 

[kh54s10]

You want all the steps to have a gravity of about 1.040. High gravity will shock the yeast and you will have a less health batch of yeast.

There is more sugar in a 2L starter than a 1L starter. You are using 100 grams in the 1L starter and 200 grams in the 2L starter so there is twice the amount of sugar.

Try this step starter calculator: http://www.yeastcalculator.com/

 

[seven9st_surfer]

I'm a fan of this calculator:

http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

 

[joshesmusica]

You want all the steps to have a gravity of about 1.040. High gravity will shock the yeast and you will have a less health batch of yeast.

There is more sugar in a 2L starter than a 1L starter. You are using 100 grams in the 1L starter and 200 grams in the 2L starter so there is twice the amount of sugar.

Try this step starter calculator: http://www.yeastcalculator.com/

Ok, but do you (or anybody else who might stumble upon this question) know why 200g of sugar in 2L of water is more shocking to the yeast than 200g in 1.5L water? In the end it's still 19.4 total gravity points. The only difference is that one is in .396 gal of water, and one is in .528 gal of water. For a difference of 1.049 in one and 1.038 in the other.

 

[flars]

A high gravity starter will stress the yeast. This will reduce the potential viability of the yeast. A high gravity starter will produce fewer healthy viable cells to ferment the wort.

I like this calculator, especially if I plan to over build the number of yeast cells. An over build allows you to save part of your starter, fresh yeast, to build another starter later on with healthy yeast.
http://www.brewunited.com/yeast_calculator.php

 

[joshesmusica]

A high gravity starter will stress the yeast. This will reduce the potential viability of the yeast. A high gravity starter will produce fewer healthy viable cells to ferment the wort.

I like this calculator, especially if I plan to over build the number of yeast cells. An over build allows you to save part of your starter, fresh yeast, to build another starter later on with healthy yeast.
http://www.brewunited.com/yeast_calculator.php

Yeah, but why does it stress the yeast? And what is the limit for it to start being considered high gravity?

 

[brewkinger]

1.040 is the limit, hence it is the recommended gravity for a yeast starter.
You asked above about why 200g DME in 1.5L (1.049) is more shocking to the yeast than 200g DME in 2L (1.038).
Your answer is that 1.038 is less than 1.040 and 1.049 is more than 1.040.

Yes it is 200g of sugar in both cases but they are dissolved in different amounts of water.
The density (sugar molecules PER mL) is higher in the smaller starter, so the yeast have a harder time acclimating to the environment. The osmotic pressure on the cell walls does not allow for adequate permeability.

Does that help you with the understanding?

 

[joshesmusica]

1.040 is the limit, hence it is the recommended gravity for a yeast starter.
You asked above about why 200g DME in 1.5L (1.049) is more shocking to the yeast than 200g DME in 2L (1.038).
Your answer is that 1.038 is less than 1.040 and 1.049 is more than 1.040.

Yes it is 200g of sugar in both cases but they are dissolved in different amounts of water.
The density (sugar molecules PER mL) is higher in the smaller starter, so the yeast have a harder time acclimating to the environment. The osmotic pressure on the cell walls does not allow for adequate permeability.

Does that help you with the understanding?

Haha, the second paragraph helps. The first few sentences came off snarky. But this is the internet, so I won't assume that you were attempting to be that. I know the title is help with starter math, but I guess the real question is why is the starter math the way it is. Can you point me to anything that explains why 1.040 is the limit?

I understand the density is much higher in a smaller wort. I just didn't understand the chemistry/biology as to why that was a bad thing. The yeast acclimating makes a little bit of sense on say the first step, as they presumably haven't been in that sort of environment in a long time. But on the third step, they're being introduced into that environment for a third time now in about 1 1/2 weeks. I feel like they should be used to it by now, haha. But do they need to get acclimated every single time? The pressure of the higher gravity wort is what makes the most sense out of all of the explanation. But again, do you have anything that shows that a 1.049 vs. a 1.040 wort is introducing an extreme amount of pressure so that the permeability much, much less?

I'm not trying to sound like a doubter, I just know that the same phrases are often easily tossed around on here without any technical explanation. You gave some very basic technical explanation, but I guess I'm hoping for a little bit more.

The reason I ask is simply for propagation of a certain strain, not necessarily a yeast starter from a fresh vial in order to pitch into a batch of beer. So if I can get more healthy yeast growth out of each step, then by the end, that exponential growth should amount to a pretty significant amount. But I obviously want them to still be healthy at the end of it.

 

[brewkinger]

Haha, the second paragraph helps. The first few sentences came off snarky. But this is the internet, so I won't assume that you were attempting to be that. I know the title is help with starter math, but I guess the real question is why is the starter math the way it is. Can you point me to anything that explains why 1.040 is the limit?

I understand the density is much higher in a smaller wort. I just didn't understand the chemistry/biology as to why that was a bad thing. The yeast acclimating makes a little bit of sense on say the first step, as they presumably haven't been in that sort of environment in a long time. But on the third step, they're being introduced into that environment for a third time now in about 1 1/2 weeks. I feel like they should be used to it by now, haha. But do they need to get acclimated every single time? The pressure of the higher gravity wort is what makes the most sense out of all of the explanation. But again, do you have anything that shows that a 1.049 vs. a 1.040 wort is introducing an extreme amount of pressure so that the permeability much, much less?

I'm not trying to sound like a doubter, I just know that the same phrases are often easily tossed around on here without any technical explanation. You gave some very basic technical explanation, but I guess I'm hoping for a little bit more.

The reason I ask is simply for propagation of a certain strain, not necessarily a yeast starter from a fresh vial in order to pitch into a batch of beer. So if I can get more healthy yeast growth out of each step, then by the end, that exponential growth should amount to a pretty significant amount. But I obviously want them to still be healthy at the end of it.

Unfortunately I don't know the specifics of the starter math. The 1.040 does seem to be an arbitrary number.
When I was just a noob, the number I used was 1.036. Cannot even remember where that came from.

I understand better now where your thoughts and questions are coming from.
I wish I could be more helpful, but alas I am merely regurgitating information that I have absorbed in my experiences in biology, chemistry, Zymurgy and life.

My suggestions would be
1) get a copy of "Yeast" (mine is on the way as we speak)
2) Look up Chris White and Jamil (can't think of his last name)
They are yeast gods.
3) look up WoodlandBrew on HBT. He has a wealth of information about yeast and research about the whole yeast process. He has a blog that is very helpful and he probably could shed some light on the solution.

Bk

 

[joshesmusica]

Unfortunately I don't know the specifics of the starter math. The 1.040 does seem to be an arbitrary number.
When I was just a noob, the number I used was 1.036. Cannot even remember where that came from.

I understand better now where your thoughts and questions are coming from.
I wish I could be more helpful, but alas I am merely regurgitating information that I have absorbed in my experiences in biology, chemistry, Zymurgy and life.

My suggestions would be
1) get a copy of "Yeast" (mine is on the way as we speak)
2) Look up Chris White and Jamil (can't think of his last name)
They are yeast gods.
3) look up WoodlandBrew on HBT. He has a wealth of information about yeast and research about the whole yeast process. He has a blog that is very helpful and he probably could shed some light on the solution.

Bk

I have read the book, but it was when I first started, so a lot of the deeper scientific stuff didn't stick.

I'll have to look up woodlandbrew for sure.

I did end up finding an article last night about osmotic pressure and specifically osmoadaptation and osmolarity. Unfortunately it was late, and very long and very detailed. But it didn't really answer my question as to the maximum that yeast can handle before they become stressed. It merely discussed what happens when yeast enter hyper- and hypo-osmostic shock and how they adapt. To call it shock in either instance seems much more dramatic than it is, as was described in the article a bit, when yeast go from a vial to any liquid with more sugar than that vial, it will experience hyperosmotic shock, and have to adapt. It seems like (as we all really do know) that yeast are experts at adaptation, yet, I could still see how extreme osmolarity could cause lasting damage to the yeast.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC120784/

 

[joshesmusica]

This sentence really stuck out to me from that article:

"The underlying molecular mechanisms for survival of a hyperosmotic shock and adaptation to high osmolarity are probably distinct but overlapping: cells adapted to moderately high osmolarity survive a severe osmotic shock better than nonadapted cells."

So I'm thinking that maybe on the second and third steps, the yeast can handle a bit more than we expect. But again, that's just one snippet, and never really explains the extremity that they can handle.

 

[brewkinger]

This sentence really stuck out to me from that article:

"The underlying molecular mechanisms for survival of a hyperosmotic shock and adaptation to high osmolarity are probably distinct but overlapping: cells adapted to moderately high osmolarity survive a severe osmotic shock better than nonadapted cells."

So I'm thinking that maybe on the second and third steps, the yeast can handle a bit more than we expect. But again, that's just one snippet, and never really explains the extremity that they can handle.

Interesting....
Send me a link to that article if you would please.

Now my brain is kicking in with regards to

The underlying molecular mechanisms for survival of a hyperosmotic shock and adaptation to high osmolarity are probably distinct but overlapping: cells adapted to moderately high osmolarity survive a severe osmotic shock better than nonadapted cells.

The cells that we start the process with... in a 1.040 wort will acclimate and reproduce with no "shock"
BUT.... the new cells that are produced... are they what are sensitive?

 

[joshesmusica]

Interesting....
Send me a link to that article if you would please.

Now my brain is kicking in with regards to


The cells that we start the process with... in a 1.040 wort will acclimate and reproduce with no "shock"
BUT.... the new cells that are produced... are they what are sensitive?

The article was at the end of the first post about that particular article.

No, the cells that are in the vial, and then being introduced into any size wort are going through osmotic shock. So within every starter, and any beer that is pretty much not pitched at high krausen, it seems the yeast will be going through osmotic shock because they aren't adapted to the situation. But I'm wondering if, since the 2nd and 3rd steps are very near each other (the 2nd is only about 24 hours removed from finishing up on the 1st step, and the 3rd only about 24 hours removed from finishing up the 2nd step), that they are already pretty well adapted. Or if they need to adapt after any kind of incubation period, no matter how small it might be.

Anecdotal for sure here: but on the second step-up, I was able to go and observe fermentation just a couple of hours after the fresh wort was pitched. The same with the third step, which I pitched that fresh wort last night. I had it in a 2L jar and had 1.5L wort pitched onto prolly about 250ml slurry and malt drink. Then I had that in my ferm chamber set at 38C (this yeast likes to be fermented at about 40C). When I checked back before bed there were clear signs that it got crazy active and had been overflowing into the pot that the jar was sitting in. All that to say, it seemed like it didn't need much adaptation time at all.

 

[brewkinger]

Perhaps my question was not clear.

Lets say cell "A" is in the very first step.
We pitch it into a 1.040 wort (because that is what we have been instructed to do) so that we do not shock the cell.

So yeast cell A begins the process and produces cell B, C and D
Are these new cells more sensitive to shock??
OR....
since they have been produced under 1.040 conditions, they are all set right from the get go?

ughh.. my brain hurts.

 

[joshesmusica]

Perhaps my question was not clear.

Lets say cell "A" is in the very first step.
We pitch it into a 1.040 wort (because that is what we have been instructed to do) so that we do not shock the cell.

So yeast cell A begins the process and produces cell B, C and D
Are these new cells more sensitive to shock??
OR....
since they have been produced under 1.040 conditions, they are all set right from the get go?

ughh.. my brain hurts.

I think the thing to understand, at least from that article, is that osmotic shock happens anytime the yeast are introduced to a new substance. When we often see the term "shocked yeast" on here, they are more talking about severe osmotic shock. So I would think that those subsequent cells wouldn't experience the shock, because their genetic makeup would be the same as the adapted "parent" cell. It's not like cell A just popped out babies, it's a cell, so it divided.

But I could be wrong. haha That's why I came on here hoping some people smarter than me could help me understand it a little more in depth.

 

[brewkinger]

First of all I apologize for not seeing that link to the article originally in your message. It was late and I was not wearing my glasses (that's my story and i am sticking to it.)

Here is a blurb from that article that sticks out to me though:

Water activity is defined as the chemical potential of free water in solution. Low water activity limits yeast growth, a fact that has been used for centuries for the preservation of fruits in dry form or with very high sugar levels, such as in marmalades (486). In the yeast's natural environment, the water activity can range widely and rapidly, due to both external influences and the activity of the yeast itself. In order to maintain an appropriate cell volume and a ratio of free to bound water favorable for biochemical reactions, the water activity of the cytosol and its organelles has to be lower than that of the surrounding medium. In this way, a constant force is maintained, driving water into the cell along its concentration gradient.

So that would explain why the 1.040 (or roughly in that gravity range) is a go to number.

Every water molecule that is bound to sugar is not "free", therefore in a 1.040 wort the ratio of free water is acceptable to the yeast.
The yeast get nice and plump and happy doing their thing...

Then we step it up and the

water activity of the cytosol and its organelles has to be lower than that of the surrounding medium. In this way, a constant force is maintained, driving water into the cell along its concentration gradient.

So we have to maintain that 1.040 in successive steps to be sure that we do not shock them

(although I would argue that we could go up to 1.060ish and still be OK.) Is that not what most of us do when we make a starter and pitch into a beer????

When we pitch into a higher gravity wort, I am sure that there is some loss of cells due to shock (which is probably why the number of needed cells is so much higher when we start talking 1.070 and higher worts, and it is probably built into most yeast calculators)

I think I may have a slight grasp on this now....

 

[Warthaug]

1040 is not an arbitrary number - in "Yeast" as well as a number of other sources, yeast yield per point gravity has been assessed. Most strains of yeast give the optimal number of yeast, per mass of sugar, at gravities between 1.035 and 1.040. Below that and you are not providing sufficient food to get maximum growth; above that you are providing excessive sugars which leads to cell stress and lower yields.

Bryan

 

[joshesmusica]

First of all I apologize for not seeing that link to the article originally in your message. It was late and I was not wearing my glasses (that's my story and i am sticking to it.)

Here is a blurb from that article that sticks out to me though:



So that would explain why the 1.040 (or roughly in that gravity range) is a go to number.

Every water molecule that is bound to sugar is not "free", therefore in a 1.040 wort the ratio of free water is acceptable to the yeast.
The yeast get nice and plump and happy doing there thing...

Then we step it up and the
So we have to maintain that 1.040 in successive steps to be sure that we do not shock them

(although I would argue that we could go up to 1.060ish and still be OK.) Is that not what most of us do when we make a starter and pitch into a beer????

When we pitch into a higher gravity wort, I am sure that there is some loss of cells due to shock (which is probably why the number of needed cells is so much higher when we start talking 1.070 and higher worts, and it is probably built into most yeast calculators)

I think I may have a slight grasp on this now....

Yeah that makes sense. I was reading that at nearly 2:00 a.m. here so that part about the free water didn't stick out to me. But that would certainly make more sense as to why the solution would work better being diluted, and therefore having more "free" water. Good catch.

I guess that's what I was really thinking about the up to around 1.050-55 still being safe enough to produce healthy yeasts. As you stated, we're often going from a 1.040 environment (so the yeast have adapted to that environment) to a much higher gravity and a much higher volume in the beer.

 

[Gavin C]

I think you are getting hung up on a non-arbitrary number which arises form a simple effective way to make starters.

100g of DME and add water to reach a 1L volume and you've got a ~1.040 wort.

Take 1L of water and add 100g of DME and you've got yourself ~1.037 wort

It's easy maths for anyone to do and the sugar concentartion of these worts seems well suited to propagating yeast from a cost standpoint. Decent growth rates can be achieved without subjecting them to undue stresses of an osmotic nature.

Add more sugar and you'll get greater yeast growth. Best to add more volume too if stresses are to be kept to a minimum.

What is important to understand is that as with many biological systems, factors can have cumulative albeit stochastic effects. There is not a demarcating line between good and bad.

If taken to the extreme, no one would advocate using a 1.200 wort to propagate yeast as the resulting colony will be full of stressed out yeast cells with lots of mutants and the like. (Again nothing to back up this supposition) Lots and lots of sugar. If you aggree that this is a nonsense wort than the corrollary is that there is a more ideal concentration.

Another example of this type of thing would be exposure to ionizing radiation. We all accept having an x-ray exposes us to some. Keep being exposed thousands of times and you WILL die. Where is the cutoff between safe and deadly? Where is it, is a harder point to define.

I guess your question is what is the ideal concentration?

A wort with a plato of 10 (1.040) seems to be the sweet spot.

Maximal growth at 3billion yeast/gram of DME is seen.

Comparable yeast growth at lower concentrations using the same weight of DME (3billion cells/gram) but of course with lower concentrations and larger volumes means bigger vessels in which to propagate the yeast. back to the practicality issue.

I'm sure there is lots more solid data out there but this graph should answer your question better than I can verbalise above. This is taken from the Braukaiser's body of work.

 

[brewkinger]

I think the thing to understand, at least from that article, is that osmotic shock happens anytime the yeast are introduced to a new substance. When we often see the term "shocked yeast" on here, they are more talking about severe osmotic shock. So I would think that those subsequent cells wouldn't experience the shock, because their genetic makeup would be the same as the adapted "parent" cell. It's not like cell A just popped out babies, it's a cell, so it divided.

I guess I am not seeing that bold part.
If we follow the guidelines, are we not preventing the shock if we stick to the osmolarity guidelines that they suggest?

 

[joshesmusica]

I guess I am not seeing that bold part.
If we follow the guidelines, are we not preventing the shock if we stick to the osmolarity guidelines that they suggest?

"For instance, yeast cells in a water droplet on a grape berry may suddenly be exposed to high sugar levels when the berry breaks open due to animal or fungal activity. Then yeast cells experience a hyperosmotic shock (or osmotic upshift), accompanied by rapid water outflow and cell shrinking. On the other hand, cells adapted to high sugar levels on drying fruits or flowers may be washed away in a rain shower into essentially distilled water. Such a hypo-osmotic shock (or osmotic downshift) increases the water concentration gradient and leads to rapid influx of water, cell swelling, and hence increased turgor pressure. Within wide limits, the yeast cell wall prevents cell bursting."

So according to that author, an osmotic upshift will cause the cells to experience hyperosmotic shock. and the reverse, hypo-osmotic shock.

 

[joshesmusica]

I think you are getting hung up on a non-arbitrary number which arises form a simple effective way to make starters.

100g of DME and add water to reach a 1L volume and you've got a ~1.040 wort.

Take 1L of water and add 100g of DME and you've got yourself ~1.037 wort

It's easy maths for anyone to do and the sugar concentartion of these worts seems well suited to propagating yeast from a cost standpoint. Decent growth rates can be achieved without subjecting them to undue stresses of an osmotic nature.

Add more sugar and you'll get greater yeast growth. Best to add more volume too if stresses are to be kept to a minimum.

What is important to understand is that as with many biological systems, factors can have cumulative albeit stochastic effects. There is not a demarcating line between good and bad.

If taken to the extreme, no one would advocate using a 1.200 wort to propagate yeast as the resulting colony will be full of stressed out yeast cells with lots of mutants and the like. (Again nothing to back up this supposition) Lots and lots of sugar. If you aggree that this is a nonsense wort than the corrollary is that there is a more ideal concentration.

Another example of this type of thing would be exposure to ionizing radiation. We all accept having an x-ray exposes us to some. Keep being exposed thousands of times and you WILL die. Where is the cutoff between safe and deadly? Where is it, is a harder point to define.

I guess your question is what is the ideal concentration?

A wort with a plato of 10 (1.040) seems to be the sweet spot.

Maximal growth at 3billion yeast/gram of DME is seen.

Comparable yeast growth at lower concentrations using the same weight of DME (3billion cells/gram) but of course with lower concentrations and larger volumes means bigger vessels in which to propagate the yeast. back to the practicality issue.

I'm sure there is lots more solid data out there but this graph should answer your question better than I can verbalise above. This is taken from the Braukaiser's body of work.

ok, that graph is really interesting. so is it actually saying that there will be more growth in a less concentrated wort? and that would be assuming the exact same inoculation rate in all three right?

i'm not trying to overcomplicate it. i'm just really trying to understand the science behind it. besides just someone online telling me that 1.040 is the sweet spot, i just have this innate desire to know why it's the sweet spot. and what exactly will happen to the yeast if i deviate from that sweet spot maybe due to equipment, or maybe due to time, or maybe due to any number of factors. that's why i gotta know haha. i don't wanna be that guy that has to come on here for every single question that i have. i want to be able to start understanding the deeper sciences behind some of the major aspects so that i can troubleshoot this stuff myself. i'm an independent american damnit!

i did happen across a cheap 3.5L jar today, so at least i can go higher. but again, i want to know the limits of this new jar!

 

[Gavin C]

ok, that graph is really interesting. so is it actually saying that there will be more growth in a less concentrated wort? and that would be assuming the exact same inoculation rate in all three right?

No what it is showing is that yeast growth rate will get to 3billion cells per gram of DME but only so long as the wort doesn't get to concentrated.

A plato of 10 (1.040 SG) will provide this as will a lower plato but not a higher plato.

The rationale behind using 1.040 is therefore as follows.

Maximal yeast growth per gram of DME while keeping the volume to a minimum

A lower concentration will still get you 3Bil/gram but the starter will need to be bigger as a result of the lower concentration.

A plato greater than ~10 i.e. SG greater than 1.040 will show less growth. The example given in the table as 20 Plato with 2Billion yeast cells/gram of DME

Your getting a poorer return on your investment of DME if your starter concentrations rise above 1.040 or 10 plato.

 

[ScrewyBrewer]

A lower gravity starter wort [1.020] is said to be easier on the yeast cells and is recommended for stepping up healthy yeast cell count from the dregs of a bottle conditioned beer.

For growing healthy cells from a fresh vial of yeast a higher gravity starter wort [1.030 - 1.040] is said to produce more growth of healthy cells.

Using a higher gravity starter wort [1.050 - up] is said grow more cells although those cells will be under more stress and less than healthy. Some old brewer myths said to make a starter in wort matching that of a high gravity beer, but its just that a myth.

For my starters made from full vials of yeast I always target a 1.040 starter wort. Depending on the age of the yeast and how it was stored I may sometimes pitch the decanted yeast from the first starter into another 1.040 starter and repeat the process. I don't really know how else to explain it but if I sense a lackluster cell growth in a starter I won't pitch it into my beer.

 

[joshesmusica]

So if I'm stepping up simply for the purpose of propagating the yeast to end up with a few vials' worth of fresh yeast, I should just step up the volume every time and leave it at 1.040. Got it. No pushing the boundaries for me then.

I'm just really wanting to know the boundaries, because for example if I start with about 100b cells, it's said I'll end up with ~220b after the 1.040 1L starter right? So then I've got 220 in a 1.040 2L starter. Then is it correct to assume I would end up with ~480b after that?
So then I step that up, 1.040 3L wort. Does it just keep multiplying by the same amount? So then I would have ~ 1 trillion cells?
But then at that point I've reached the maximum volume my jar can handle. So should I just be splitting the slurry up and just starting again if I'm wanting to get the most reproduction out of the dme being used?
How much is the inoculation rate affecting the growth percentage?

 

[Gavin C]

If you've got a 3.5 l flask why not just make a 3 L starter with 1 vial of yeast

Your calculations do not seem to match that of the folks in the know.

Images from the calculator I use which makes use of Braukaisers data

You will not get the exponential growth you are planning as you supplying the same amount of DME at each step for an increasing population of yeast.

The pickings are getting slimmer and slimmer at each step. Not really sure why you would want to do this. I know what method I would use.

1 3L starter with 1 fresh vial (that's what I'd do)


Your Needlessly Complicated Stepped method


NB: I assumed a fresh vial of yeast about 1 month old with 80% projected viability.

 

[joshesmusica]

If you've got a 3.5 l flask why not just make a 3 L starter with 1 vial of yeast

Your calculations do not seem to match that of the folks in the know.

Images from the calculator I use which makes use of Braukaisers data

You will not get the exponential growth you are planning as you supplying the same amount of DME at each step for an increasing population of yeast.

The pickings are getting slimmer and slimmer at each step. Not really sure why you would want to do this. I know what method I would use.

1 3L starter with 1 fresh vial (that's what I'd do)
View attachment 305261

Your Needlessly Complicated Stepped method
View attachment 305262

NB: I assumed a fresh vial of yeast about 1 month old with 80% projected viability.

It's not the same amount of dme at each step. It's the same size wort at each step. The 2L would need ~215 grams to be 1.040; the 3L ~ 325 grams.

I'm not saying that my calculations match what people in the know are saying. I'm attempting to understand what the people in the know are saying!

I've got down the part about I should use a fresh vial of yeast in a 1.040 wort. Trying to understand the steps after that. Firstly because the only calculators I had found up until this point only had steps in order to reach a final goal to pitch in a specific sized wort. Secondly because I just wanna understand the math better so that I can get a better idea on the fly if I have to.

I wanna be able to understand what exactly is happening to the yeast at each stage and how different sized starters affect all that.

Can you send me a link to that calculator?

 

[Gavin C]

http://www.brewunited.com/yeast_calculator.php