Yeast Pitch Rate and Starter Calculator

Discussion in 'General Brewing Discussions' started by brentconn, Feb 25, 2015.

  1. brentconn

    brentconn New Member

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    Is there someone who can explain how to use this calculator? I specifically need help with:

    Target Pitch Rate: Choosing from the drop down box. How do I choose the correct one?

    Cell Density: Do I use the default?

    Yeast Pitch Rate: Always use •Middle of the road Pro Brewer 0.75 (ale) for O.G. less than 1.060?

    Growth Model and Aeration: Can someone explain this drop down box?

    I should have looked at this before making my yeast starter. My first brew is Thursday. For the yeast starter I used 1 quart of water and 3.5 ounces of LME. The recipe calls for 1.043 O.G. and I got a 1.038 from a refractometer reading. Is this ok? The yeast starter is fermenting at 72 degrees right now.

    Thanks for any help in advance. I really want my first brew to be a success.

    Brent
     
  2. MrBIP

    MrBIP Active Member

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    For you first brew, at a 1043 OG, you would be fine without the starter. Just trying to guess that you might be using US05, you'll be fine (if I understanding everything). Without a starter, with a starter not on a stir plate, on a stir plate; it will work regardless.

    Good luck. Have fun.
     
  3. Nosybear

    Nosybear Well-Known Member

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    Slight addition: Rehydrate US-05 and you will be fine. Just sprinkling it on the top of the wort will kill half the cells, resulting in an underpitch.
     
  4. Ozarks Mountain Brew

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    as for the actual question, on the yeast calculator you just pick the type, I usually pick pro Brewer 1 and thats high for most beers, then add the number of packets , a dry packet is 11 grams usually so if using 2 packets you put 22 in the Dry Yeast Amount: blank then click update and below that "grab from above", this will say in red if you need a starter, then below that pick your starter method I pick Braukaiser stir plate, click the size of your starter, most people get this part wrong, half of a 1L flask is not a 1L stater , click update to the right, below it will say if any cells are needed or if green your all good

    if you do need more cells you can increase the size of the starter or add more yeast
     
  5. MrBIP

    MrBIP Active Member

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    ^ Good point... yes, always rehydrate your dry yeast.
     
  6. surfmase

    surfmase Member

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    To revisit the pitch rate calculator...

    I've just noticed that part 2. the yeast starter asks for the size, gravity and growth model in addition to the starting count. Now if I choose Braukaiser, my (starter) gravity input will have an effect on the ending cell count. If I choose any of the other C. White models, the gravity has no effect on the ending cell count. Can someone explain this? Is there an assumption under C.White that I'm missing? How is the Braukaiser model different from the C.White model?

    Thanks guys,
     
  7. Ozarks Mountain Brew

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    its really just asking do you have a very good stir plate or not, a good stir plate will not let the yeast ferment but just grow in the flask and its strong enough to give a good consistent vortex to add plenty of oxygen, a cheap stir pate might not let the yeast grow enough because its weak and lets the yeast ferment instead of just grow
     
  8. surfmase

    surfmase Member

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    Well, I didn't see the explanations listed below the calculator before, but after reading it and the Braukaiser information there is a fundamental difference in the equations. Unfortunately I don't have the yeast book from Chris and Jamil.

    The Bruakaiser equation is a function of inoculation rate and available extract. This why a higher gravity starter outputs a higher end cell count.

    The original empirical data from White's equation was for a simple starter. Brewers Friend has taken the data and created an equation which is only a function of inoculation rate. It assumes 9 plato available extract. They also created additional factors for increased levels of agitation.

    I have to disagree with the proposition that the two selections are differentiating between good and bad stir plates. Although the consensus agrees that keeping a homogeneous solution produces a higher growth rate, the fundamental difference is that the Brewers Friend White growth models make the assumption of 9 plato starter extract, and do not take deviations into the equation.
     

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