Author Topic: Yeast Starter Calculator Accuracy  (Read 19495 times)

Offline philm63

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Re: Yeast Starter Calculator Accuracy
« Reply #15 on: August 15, 2012, 04:29:11 AM »
Could this be the reason there are no step calculations in BS2? Is there an assumption that if you need a larger cell count; you'll need more vials/packets?
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Re: Yeast Starter Calculator Accuracy
« Reply #16 on: August 22, 2012, 01:44:04 PM »
Im trying to get to the bottom of this. I emailed white labs and asked them what they think. I also emailed Jamil to see what he has to say on this. I havent heard back from him but will post what he says about it.

Here is the email I typed and the response I got from white labs...

I read the thread you provided the link for and tried to figure out which method is best.  From Chris White's book, pitching into a 0.8L starter will give you about a 38% growth rate with no agitation or supplemental oxygen added; essentially a "worst case" scenario.  He also mentions that you can get two to three times as much growth when using a stir plate, so let's use the 2.66 number that both programs use and see how it comes out.

75 billion cells x 1.38 (for 38% growth) x 2.66 gives a final number of about 275 billion cells.  That's pretty close to the 308 billion that the BS2 calculator came up with, so I'd lean towards that one as being more accurate.  However, I'd highly recommend picking up Chris's book and reading the yeast propagation section for homebrewers, starting on page 132.


---------- Forwarded message ----------
Date: Wed, Aug 22, 2012 at 7:11 AM
Subject: growth factors
To: "" <>

Im trying to figure out why 2 yeast calcs come up with different numbers. Specifically Mr. Malty and Beersmith 2. Both calculators use a stir-plate multiplier of 2.66, but in different places in the equation.  BS2 divides the growth factor by the multiplier to reach the growth needed for the starter.  Mr. Malty seems to calculates the volume of the starter using one package of yeast and divides that volume by 2.66 when you change the settings to stir plate. Which one is correct, or are they both correct? Or am I missing something here. There is a big dispute over this on some of the forums. Thanks for taking the time to answer your customers questions!,5895.msg29390.html#msg29390

John Carroll
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