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Phunhog · 01-12-2013, 02:49 AM

So I routinely make starters and step them up for the sole purpose of harvesting yeast. My process goes something like this...1L starter with fresh vial of yeast on a stir plate for 36 hours. Crash for 24-48 hours. Decant and add yeast to a 2L starter for 36 hours. Crash again for 24-48 hours. Decant off as much liquid as possible. Pour yeast slurry into sanitized White Lab vials..it usually takes 6-7 vials. Once done the vials look "identical" to a fresh White Labs vial. Using various yeast calculators I should be generating roughly 500 billion cells or approx. 70-80 billion cells per vial. Here is where I wonder where my yeast went....
I had two different yeast samples counted and analyzed. They were different strains but used the same exact process. My counts averaged 1 billion cells/ml...which means my vials only contained on average 30B/ml..... or less than half of what was predicted by the yeast calculators. So rather than ending up with almost 500 billion cells I ended up with 180-210 billion cells total cells. Obviously that is a HUGE difference!!! So where did my yeast go??!!
When I make starters I use 3/4 cup DME for a 1L starter and 1.5 cups DME for a 2L starter.

theveganbrewer · 01-12-2013, 05:21 AM

Even if you used the yeast the day it was produced, you wouldn't get 500 billion cells with your process. How old are the vials when you harvest them? Plus, your starter wort is about 1.060 OG if you're putting 3/4 cup of DME in the liter starter. You should be putting something like 3.5 ounces in there and you're putting in 6. Your 2 liter should be more closer to 7 and you're putting in 12.

**BBL_Brewer** · 01-12-2013, 05:41 AM

There are a lot of variables. Just the difference in yeast strains alone makes it difficult to accuartely predict cell counts with an all-in-one calculator. They are only for ball park figures. If you want to know exactly what's going on you'll have to start counting cells. Something I've been wanting to do. I think this is why Mr. Malty is more on the conservative side and recommends larger starters than other calculators.

Phunhog · 01-12-2013, 12:51 PM

Quote:

Originally Posted by theveganbrewer

Even if you used the yeast the day it was produced, you wouldn't get 500 billion cells with your process. How old are the vials when you harvest them? Plus, your starter wort is about 1.060 OG if you're putting 3/4 cup of DME in the liter starter. You should be putting something like 3.5 ounces in there and you're putting in 6. Your 2 liter should be more closer to 7 and you're putting in 12.

I am sorry I didn't explain myself..I am putting in 3/4 cup of DME by volume which equals roughly 3.5 ounces by weight. But even if I was putting in more DME I should be getting MORE yeast not less.

Phunhog · 01-12-2013, 01:05 PM

Quote:

Originally Posted by BBL_Brewer

There are a lot of variables. Just the difference in yeast strains alone makes it difficult to accuartely predict cell counts with an all-in-one calculator. They are only for ball park figures. If you want to know exactly what's going on you'll have to start counting cells. Something I've been wanting to do. I think this is why Mr. Malty is more on the conservative side and recommends larger starters than other calculators.

That is why I wanted to get my yeast samples counted. I wanted to see how my process is and have a more accurate measurement when I am making starters. Using Mr. Malty a relatively fresh vial pitched into a 2L starter should yield about 300 billion cells. I took a fresh vial of yeast made a 1L starter and then stepped up to a 2L and only ended up with roughly 210 billion cells? According to YeastCalc I should have almost 500 billion cells after stepping up. I trust the cell counts and I trust the yeast calculators as being accurate. Somewhere...somehow I must either be not creating nearly as much yeast as I think OR I am losing a LOT of yeast in the transfer process.

highgravitybacon · 01-12-2013, 01:11 PM

Quote:

Originally Posted by Phunhog

Obviously that is a HUGE difference!!! So where did my yeast go??!!

Yeast rapture.

It's just a calculator, not gospel. A lot of people have been talking about the wild inaccuracies in the calculators lately. Some getting far more than they need, some far less yeast.

Does the beer taste okay?

Phunhog · 01-12-2013, 01:58 PM

Quote:

Originally Posted by highgravitybacon

Yeast rapture.

It's just a calculator, not gospel. A lot of people have been talking about the wild inaccuracies in the calculators lately. Some getting far more than they need, some far less yeast.

Does the beer taste okay?

Yes. The beer tastes fine....which really should be the ultimate test!! My fermentations seem to be going fine. They start within 12 hours everytime, no attenuation problems, finish within 3-4 days generally. Maybe I am too stuck on a "number" and should instead just do what I have been doing....making starters with heathy yeast.

Phunhog · 01-12-2013, 06:30 PM

Well I found one of my mistakes....I thought a WL vial held 30 ml. It doesn't. It holds 47 ml. So each of my vials holds roughly 50 billion cells. At least I can use that for my calcs.