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Old 11-20-2009, 08:34 PM   #1
petep1980
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I've used washed yeast with starters before perfectly fine, but I'm just curious how large a starter you make with your washed yeast? I'm not sure how you can possibly know the cell count.

 
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Old 11-20-2009, 08:42 PM   #2
GilaMinumBeer
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Hemocytometer cell, a good microscope, and blue dye.

 
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Old 11-20-2009, 08:46 PM   #3
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without doing as Gila suggested, you don't. It's an educated guess based on how good you think your technique is, and the results on the pitching calculator on MrMalty.com......until you get really expert at it yourself.

 
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Old 11-20-2009, 09:32 PM   #4
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You can start with 1 cell or 10,000,000,000, the cell count in a starter is determined by the amount of nutrients. If you are off by a factor of ten in the washed yeast, that's only an 8 hour difference in incubation time.
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Old 11-20-2009, 10:31 PM   #5
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Anyone know the minimum magnification to reasonably be able to count yeast cells in a haemocytometer? I have a 30x scope that I would love to do this with but I realize that that magnification will likely not be enough.

I think I can replace lenses and get to 50x or 60x, so that is the answer I am hoping for!
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Old 11-21-2009, 03:02 PM   #6
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The Brewing Network did a show on yeast washing that gives a good way to do it. They make assumptions about the cell count in a volume of settled yeast and then measure by volume. In summary (and from memory), it went something like this...

Collect the yeast from your carboy into a Nalgene bottle (with the ml marked on the side). Let it settle and decant off the remaining beer. The density of the yeast is about what the MrMalty.com pitching rate calculator assumes when you use the "Repitch from Slurry" tab. Jamil poses that most 5 gallon batches will give you 400-500ml.

From there they describe how to wash the yeast and the key thing is to remember to scale the amount of slurry you have as you add water to rinse it. i.e., if you add another 500ml of water to 500ml of starting yeast slurry, remember that to get a given cell count you now need to add double the volume of slurry.

What I'm describing above will be more clear if you listen and relisten to the show.

 
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Old 11-21-2009, 08:44 PM   #7
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Thanks for that. I listen to these podcasts in my car. I'll look for this one. Brew Strong, I'd assume.
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Old 11-22-2009, 02:46 PM   #8
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Quote:
Originally Posted by passedpawn View Post
Thanks for that. I listen to these podcasts in my car. I'll look for this one. Brew Strong, I'd assume.
Yes. It is Brew Strong. August 10, 2009.

 
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Old 11-22-2009, 03:28 PM   #9
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Thanks for the advice guys.

 
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