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Old 11-29-2012, 12:18 PM   #11
WoodlandBrew
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From counts on washed yeast from slurries, I have seen less than that. About 250 million / ml to 1.4 billion / ml. The ball park number I have seen is 1 billion / ml if you can't count the cells. (see the "why not pitch on a yeast cake" thread)
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Old 11-30-2012, 04:27 AM   #12
panfishrfun
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just to keep going with this...
assume 1billion cells/mL
the mason jar is 16 oz or ~473mL
so I have 473 billion cells?? and I don't have to make a starter

I'm sorry if this is way easier than I'm making it
for some reason I can't get my head around this

 
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Old 11-30-2012, 06:24 AM   #13
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Quote:
Originally Posted by panfishrfun View Post
just to keep going with this...
assume 1billion cells/mL
the mason jar is 16 oz or ~473mL
so I have 473 billion cells?? and I don't have to make a starter

I'm sorry if this is way easier than I'm making it
for some reason I can't get my head around this
It's ML of settled yeast slurry... not the entire starter size.
Start with a known amount of yeast and grow them in a starter.
Cold crash and decant the spent wort.
Measure the yeast slurry left over, and depending on how dense the slurry is, assume about 1B/ML.
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Old 11-30-2012, 08:30 AM   #14
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Quote:
Originally Posted by WoodlandBrew View Post
From counts on washed yeast from slurries, I have seen less than that. About 250 million / ml to 1.4 billion / ml. The ball park number I have seen is 1 billion / ml if you can't count the cells. (see the "why not pitch on a yeast cake" thread)
This (2-2.5 B/ml) is density of thick portion of slurry so you are correct, when it comes to total density (slurry + liquid above) it is closer to 1 B/ ml.
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Old 11-30-2012, 10:08 AM   #15
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I'm just saying my experience is different that yours. I count thick slurry as much closer to 1 billion per ml than 2 billion. That also seems to be the consensus that others have come to. (see acid rains's post and the tread I linked) Where is your 2 billion number from?

My procedure is based on white labs method and is here:
http://woodlandbrew.blogspot.com/201...viability.html
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Old 11-30-2012, 03:29 PM   #16
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As I said I didn't count it, it is estimation based on wyeast suggestion. I contacted them about it and Jess from lab says that it should put me in ball park.

I am open to new cognition's.
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Old 11-30-2012, 03:40 PM   #17
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I sanitize my dining room table, lay out all the cells and have my 3 kids manually count them, they are all math wiz's
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Old 11-30-2012, 04:09 PM   #18
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Quote:
Originally Posted by diS View Post
As I said I didn't count it, it is estimation based on wyeast suggestion. I contacted them about it and Jess from lab says that it should put me in ball park.

I am open to new cognition's.
We are probably just splitting hairs here. In all practicality a factor of two on the cell count is not a big deal. I see a variance by a factor of 6 in density of "thick slurry" and between 60%-97% viability from freshly harvested cakes. This seems to be a common finding by people doing cell counts. The combined error when pitching from a slurry is over 10 times just between these two variables.

I just am trying to understand where the difference comes from. Perhaps the yeast from their lab has much less additional material such as protein. Under the scope I can see that there is about 10-25% as much protein mass as yeast cells. (That's just a complete WAG at it based on relative size. You can see it to the top and right of this image:trub)

Perhaps 1 billion cells per ml is more accurate for slurries, and 2 billion cells per ml is more accurate for the material that comes out of a WYeast package.
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