How many cells do I have?

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NYShooterGuy

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So I've been making yeast starters now for about a year-and-a-half, and whenever I get finished I always pour the yeast into a mason jar that has graduation marks on the side. On one side is ounces, on the other is milliliters. Now, the Yeast Starter doesn't have much brake material or hop sediment, so it's safe to say that it's almost entirely pure yeast. I never know, however, how much yeast I have. Highly focculant strains look like cottage cheese but then compact after time just the way that other low fucculating cells would. My question is, is there a hard and fast rule as to how many yeast cells there are in my mason jars based on the graduation mark at which the cells finally compact, or I really would need a microscope to measure the size of a yeast cells and then estimate how many billions are are based on their density and size?
 
To answer your questions, no and no.

Base your estimate on your yeast calculator's estimate. Homebrewing is not an exact science, you have a lot of leeway. If not sure, rather err to overpitching rather than gross underpitching.

When I store yeast from an overbuilt starter, aside from the strain#, I write the ranching date, estimated cell count, and her generation on a piece of blue tape affixed to the mason jar. When making a new starter from it, I plug those numbers into my yeast calculator.
 
to answer your questions, no and no.

Base your estimate on your yeast calculator's estimate. Homebrewing is not an exact science, you have a lot of leeway. If not sure, rather err to overpitching rather than gross underpitching.

When i store yeast from an overbuilt starter, aside from the strain#, i write the ranching date, estimated cell count, and her generation on a piece of blue tape affixed to the mason jar. When making a new starter from it, i plug those numbers into my yeast calculator.

+1
 
When I store yeast from an overbuilt starter, aside from the strain#, I write the ranching date, estimated cell count, and her generation on a piece of blue tape affixed to the mason jar. When making a new starter from it, I plug those numbers into my yeast calculator.

I do the same except I use white tape.

So I've been doing it right the whole time. Guessing is the only science here.
 
I find 1.2 - 1.5 billion cells per milliliter of slurry to be common in my cell counts on starters.
 
I find 1.2 - 1.5 billion cells per milliliter of slurry to be common in my cell counts on starters.

I use the cells from the previous starter, (that was cells created from a pure strain). Is this still considered slurry even if it has no hop or grain material?
 
Yes. The beauty of starter slurry it is clean and probably mostly viable cells. Determine the volume and multiply by 1.2-1.5 should give you a pretty good idea how many cells you have.
Harvested slurry from a batch of beer can be more tricky since some of what is in your slurry is likely to be trub and the sample is probably not as viable as it was in your starter thus the density of viable cells will vary.
Thoroughly rinsing the harvested slurry would help to remove trub and dead cells getting you back closer to starter quality then you could start using the above formula again.
 
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