Author Topic: Yeast starter calculation stops at some starter size  (Read 7204 times)

Offline FlyingZayin

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Yeast starter calculation stops at some starter size
« on: April 12, 2016, 11:55:51 PM »
Did some search but didn't find exactly what I was looking for, so have to start a new thread.

I'm trying out the BS (nice abbreviation, btw) and probably I will buy and register it anyway but there are a few snags.

Like, I'm trying to enter starter values... Screenshots 1 to 5 show gradual increase of number of cells following the increase of starter size. Then, at 1.7L it just stops adjusting and re-calculating the cell number. It freezes at 238.2 bln and stays constant no matter how big a starter I make.

Has anyone bumped into this? Am I doing anything wrong?

Thank you!













Offline brewfun

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Re: Yeast starter calculation stops at some starter size
« Reply #1 on: April 13, 2016, 08:20:31 AM »
Am I doing anything wrong?

Yes. You're not understanding the science.

In general, a starter of any size, will give you 3x growth. The addition of a stir bar or constant aeration/oxygenation can double that. Your upper limit had the stir bar on and reached 6x growth.

Beyond that 6x growth, the starter size doesn't matter much. In fact, most yeast vials and dry packets are good for direct pitching a 5 gallon batch up to 13.5 Plato, and expect about a 3.5x growth.

The point of a starter isn't to grow infinite amounts of yeast, but to grow a viable, healthy population which will at least double in the intended wort. Overpitching can be fine or have some unintended consequences, but at the very least, it's a waste of beer because the extra cells have to hydrate with it.
Beer Appreciation is the space between pints.

Offline FlyingZayin

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Re: Yeast starter calculation stops at some starter size
« Reply #2 on: April 13, 2016, 06:01:49 PM »
a starter of any size, will give you 3x growth
Wow, how then I managed to propagate buckets of yeast from a single cell?
I might indeed miss the logic of this limit in BeerSmith but the BeerSmith then clearly misses the logic (and the very fact) of some people propagating yeast by steps or by dilution.
From a starter calculator I would not expect a set limit, anyway. If this "3x" is really a reason for the calculator coming to stupor, then at least there should be a note, like "you've reached a limit on a single step starter".
Or, better even, it should just continue calculation. People who make starters generally know a thing or two about how to do it...

Offline Oginme

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Re: Yeast starter calculation stops at some starter size
« Reply #3 on: April 13, 2016, 06:41:26 PM »
The limit is not on BeerSmith, it on the growth rate of the yeast.  This has been studied and demonstrated several times by a number of well respected people.  White/Zainasheff, Kai Troister, and others have this well documented.

I propagate up from single colonies of cells by stepping up from a couple of ml of wort to a couple hundred ml of wort to a 1.5 liter starter.

If you would rather have the software lie to you about how much yeast you will produce, then you are looking in the wrong place. 
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Offline brewfun

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Re: Yeast starter calculation stops at some starter size
« Reply #4 on: April 13, 2016, 07:07:28 PM »
Wow, how then I managed to propagate buckets of yeast from a single cell?

No. Why don't you explain it to me? I'd love to learn.

What is your propagation process and method?
What is your pitchable cell count?
How are you measuring viability?
What is your final glycogen level?
What's your trehalose level at pitch?
What's your lipid level curve during propagation?
What's your post fermentation lipid and glycogen levels?
What is your real attenuation rate?
What is your measured contaminant level pre/post ferment?

Quote
People who make starters generally know a thing or two about how to do it...

Yup. So, from your declaration, the above questions should be easy.
Beer Appreciation is the space between pints.

Offline FlyingZayin

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Re: Yeast starter calculation stops at some starter size
« Reply #5 on: April 13, 2016, 07:35:09 PM »
Yup
The point you stated in HBT thread ("Previous starter steps are omitted, as you set the viable cell count in this last addition step") does make sense. Hope you forgive me for ignoring the rest of your message, I don't usually reply to spam.

Offline VincentGR

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Re: Yeast starter calculation stops at some starter size
« Reply #6 on: February 28, 2018, 11:48:44 AM »
I also have the same issue and do not understand what limits the growth of yeast in a starter other then the absence of needed nutrient or the presence of to much by-products. Can you explain?

Offline GigaFemto

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Re: Yeast starter calculation stops at some starter size
« Reply #7 on: February 28, 2018, 01:48:13 PM »
I am not a yeast expert, but I think you have it there. There are only so many times that the yeast can replicate based on the initial supply of oxygen, sugar, etc and the buildup of byproducts. You can make a second starter from the first one by refrigerating to settle the yeast, decanting the liquid and pitching the slurry into fresh  wort. You can then get the same multiplication factor again. That is called a "step-up" starter or a "two-stage" starter, and it allows you to grow arbitrarily large yeast populations in stages. I wish the BS starter calculator could handle this, but it can't. There are other online calculators you can use for this:

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

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

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Offline brewfun

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Re: Yeast starter calculation stops at some starter size
« Reply #8 on: February 28, 2018, 02:36:46 PM »
I also have the same issue and do not understand what limits the growth of yeast in a starter other then the absence of needed nutrient or the presence of to much by-products. Can you explain?

In a way, this is what stops further growth in starters or in full batches. In an underpitched batch, yeast will update O2 and bud as far as it can, then once it senses proper pH, convert to fermentation; but may not produce a result desired by the brewer. The same is true in starters. So, in both cases, optimal wort volumes for the desired result is important. This is easily observed in simply doing side by side fermentations.

The why is more complex. Yes, nutrients, pH and sugar availability contribute a great deal to growth and a healthy fermentation. However, it begins with the sterols stored by the mother yeast cell, before she buds daughter cells. Sterol storage happens during the late phases of fermentation in preparation for dormancy.

Yeast under constant growth has a sterol issue because eventually enough is spent in budding that the mother cell can no longer metabolize correctly. In the meantime, the early daughter cells have started strong, but later daughter cells have weaker cell walls.

Again, why? Yeast cant do much more than one process at a time, internally. They store byproducts outside the cell and reuptake what's needed, when needed. The sterols have to go through an esterification process (not to be confused with later esters in beer aromatics), and then yeast make an enzyme to convert these to ergosterol. It's the ergosterol that's vital to forming healthy cell walls that will process maltose, not just glucose; plus keep the important trace nutrients inside the cell. Imperfect cell walls limit the transfer of molecules and allow important molecules to leak out. The result is dead yeast and/or early dormancy.

In underpitched situations, additional O2 will help sterol synthesis, but only up to the point that cells can produce the enzymes. Then the cells convert to fermentation and dormancy in order to rebuild their sterol levels. At that point, the brewer needs to decant the yeast and place it in a fresh starter to continue cell growth.

A healthy starter goes through most of fermentation (you should detect low acetaldehyde). At that point, sterol synthesis is complete and uptake of sterols has begun. Constant aeration speeds and aids this process. The resulting slurry can be used for another starter if more volume is needed, or used to make a batch.



Beer Appreciation is the space between pints.