Author Topic: Yeast/Starter size calculator  (Read 553 times)

Offline x3la

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Yeast/Starter size calculator
« on: March 06, 2020, 10:05:24 AM »
I am creating a starter from a Slope/Slant.

Cell Colony -> ~ 5ml test tube of DME wort = ~ 50 million cells (10M/ml)

I want to create a liquid "Yeast" in BeerSmith so that I can associate it with my Recipe and have it create my starter sizes accordingly, so I enter "Cells Per Pack", as 0.05 billion (50 million).

When I hit save the value is displayed as "0.1" yet when used in a recipe as a starter appears with "0.05 Billion viable cells" as expected (seems there's a bug in the yeast tab display on values less than 0.1?).

The "Starter" section of the recipe seems unable to calculate starter sized for such a small number of viable cells, however the "Yeast Starter" tool is able to calculate starter size needed and DME required.

This might be a bug in BeerSmith's handling of 2 decimal places in the Yeast Ingredient and Recipe/Starter section?
« Last Edit: March 06, 2020, 10:39:56 AM by x3la »

Offline Oginme

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Re: Yeast/Starter size calculator
« Reply #1 on: March 06, 2020, 11:30:11 AM »
Not a bug, just rounding for display.  The underlying calculations all will use the original .05 M/5 ml as added by your yeast profile.  I do this all the time when doing cell counts.  I may have a cell count of 0.625 B/ml of yeast and enter it that way in the starter page.  The starter will display 0.6 B cells only, but the calculation for quantity always works out such that the program is using the 0.625 B number.

Using such a small number will cause the starter section a problem.  There is a limit to the number of times cells will replicate (somewhere around 5x) so the cell growth is capped.  When I take colonies off a culture plate, I will scale them up in 5 ml of 1.020 wort to start and then increase the volume to 10 ml.  From there, I transfer the contents into 25 ml of 1.036 wort before pouring that into 100 ml of the same wort.  At this point, I have enough cells to give me 30 B to 50 B cells which will scale up on the starter tab using a standard starter size a lot more easily.
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Offline x3la

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Re: Yeast/Starter size calculator
« Reply #2 on: March 06, 2020, 11:43:59 AM »
Not a bug, just rounding for display.  The underlying calculations all will use the original .05 M/5 ml as added by your yeast profile.  I do this all the time when doing cell counts.  I may have a cell count of 0.625 B/ml of yeast and enter it that way in the starter page.  The starter will display 0.6 B cells only, but the calculation for quantity always works out such that the program is using the 0.625 B number.

Using such a small number will cause the starter section a problem.  There is a limit to the number of times cells will replicate (somewhere around 5x) so the cell growth is capped.  When I take colonies off a culture plate, I will scale them up in 5 ml of 1.020 wort to start and then increase the volume to 10 ml.  From there, I transfer the contents into 25 ml of 1.036 wort before pouring that into 100 ml of the same wort.  At this point, I have enough cells to give me 30 B to 50 B cells which will scale up on the starter tab using a standard starter size a lot more easily.

Thanks for your reply. I'll do the same then and scale up to 100 - 200ml before considering it my Starter in BeerSmith.

Do you have any insights on the purpose of the 'Slant' form in BeerSmith? what does it change?
« Last Edit: March 06, 2020, 11:46:34 AM by x3la »

Offline Oginme

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Re: Yeast/Starter size calculator
« Reply #3 on: March 06, 2020, 11:58:23 AM »
To my knowledge, setting the yeast type to 'slant' changes the viability of the yeast to default to 50% and the number of cells per pack to 0.1 Billion.  Beyond that, I don't know what other implications it has in the software as I have never played around with that setting.  I always worked the picked colonies up using the method I described before hitting them with a bigger starter.  It seems to work just fine when I do a cell count on the finished starter to measure out the volume of yeast slurry needed for the batch I am brewing. 
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