biertourist wrote:Sorry,
I'm not following you. I don't see how I can get from where I am (knowing the number of viable cells to where I need to be). -How many cells will result from adding my initial cell count to a 1L starter.
I can go to the Mr. Malty calculator and select the "liquid starter" option, then select the date of the yeast (let's say September 2009 because that gives us a very low viability (10%)).
I know that the Wyeast Propagator packs initially have 25 billion cells when fresh, and I know that (from the Mr Malty Calculator) that it's likely that I only have 10% of that 25 billion as viable cells (2.5 billion).
What I need to know is if I pitch this 2.5 billion cells into a 1 L starter how many resulting yeast cells will I have? (Because I will use this as my new starting yeast population for propagation to a 2nd larger starter.)
As far as I can tell the Mr. Malty calculator doesn't help with this at all.
If I select the drop-down option "Continuous Aeration", and drag the slider bar to "use larger starters" it still says that I will need 3 vials or packs and a 3.46 L starter to get to the 177 billion cells that I need for a 1.048 gravity ale in a single step.
-If the slider bar would let me say "single vial" that would be helpful.
The real problem is that I can't find the math behind the calculator anywhere. The Mr. Malty calculator makes the "total yeast cells needed" a constant and the number of packets and the size of the starter as variables; I need the starting yeast population and the yeast starter size as a constant and the final total number of yeast cells as a variable.
-This is effectively what the Palmer chart does but it doesn't go under an initial yeast cell count of 35billion and doesn't get even close to the 2.5 billion cells that someone with a less than 12 month old Wyeast Propagator pack could be dealing with.
Does anyone have a formula or a solution for this scenario?
(Is the math behind the Mr. Malty calculator published anywhere? Or a version of the Palmer chart that goes well below a starting population of 35 billion cells?)
I just found out that Wyeast used to have a "Cell Growth Calculator"; this is pretty much exactly what I'm looking for...
Anyone have a cell growth calculator?
Adam
Go to the calculator and do what I say and get the numbers I'm describing. You'll figure it out. You have to understand 100% is 100 billion cells. You need to set the viability manually to match the numbers you have. 25 billion = 25% of 100billion, so it's the same of as 25% viability.
You use the pogram to tell you that you have 10% viability. However, it's 10% viability on top of the fact that a propigator is 25% of an activator pack. 10% of 25% is .1 x .25 = .025 or 2.5%. So set your starter to a viability of 2.5% and work from there.
You then need to then change the volume of the beer you want to make. what you change it to doesn't matter, but you should do it until the starter recommends 1 pack at 1L (what you wanted to know). for me it was 0.45 gallons of beer. This say it'll give you 15 billion cells. from your 2.5 billion using continuous airation.
Assuming you then chill the beer, decant and repitch, and that 1L is still your limit, you now set viability to 15% (That's the same as 15 billion cells). Again, move the volume of beer you want to ferment up as high as it'll go and still stay at 1L, 1 vial needed. For me that's 2.15 gallons, and it says you'll get 70 billion cells. Again, chill it down, decant and repitch into a starter
Now you have 70 billion cells. That's right 70% viability. Set the calculator to 5.25 gallons, that's 170 billion with continuous aeration, close enough to your 177 needed (only about 5% off)
So that's the process. That said, that's a lot of work. For 3 dollars you could buy a fresh pack of yeast that requires significantly less work to build up. Plus you'll use at least a couple bucks of DME in the process, so really you're not saving anything unless you are using a limited release that's not available. And even then I'd say be sure that you specifically want to use that yeast.
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