Explain this to me please

[Beer-lord]

Tomorrow I'm brewing an 11 gallon batch and splitting it in to 2 fermenters (5.5 each duh!).
So, why, if I were putting this in 1 fermenter with 11 gallons would 3 liters of yeast not be enough but splitting into 2 fermenters and using 1.5 liters in each, is more than enough?

See these charts? 11 gallons require 401 billion cells yet 3 liters only yields 366 billion (not enough). However, 5.5 gallons need only 200 billion and 1.5 liters is 266 billion. (more than enough.)
Does the larger volume make a difference? Size really does matter?

11 gallons.JPG (79.24 KiB) Viewed 1036 times

5.5 gallons.JPG (78.63 KiB) Viewed 1036 times

[Gymrat]

Osmosis

[BlackDuck]

Thanks for reassuring me on why I continue to use dry yeast!!!

[Kealia]

#Stumped

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[bpgreen]

Take a look at the inoculation rate. It's twice as high for the smaller starter.

[Beer-lord]

Take a look at the inoculation rate. It's twice as high for the smaller starter.

Yes, but why is that?

[John Sand]

It's magic. Don't try to make sense of it.

[bpgreen]

Take a look at the inoculation rate. It's twice as high for the smaller starter.

Yes, but why is that?

Because you're starting with the same number of cells for a 1.5 liter as for a 3 liter starter. If you're splitting the yeast between two batches, you should adjust the starting cell count.

[Beer-lord]

Ahhhh, nice! So easy it went right by me.
Thanks for this. I was racking my feeble mind.

[ScrewyBrewer]

We're did you locate the link to YeastCalc, I tried it and the domain was parked and no longer available?

[Beer-lord]

It's spelled out now.....not calc, yeastcalculator.com





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[mashani]

That led me down this path to this link, which explains the other stir plate option that is available in that calculator.

http://braukaiser.com/blog/blog/2012/11 ... st-growth/

If it is correct, then J's formula (which Mr. Malty uses and is the one selected in the pics posted above) is under estimating cell growth for stir starters by a good bit.

[Beer-lord]

I've had that link bookmarked for some time now. I've also listened to way too many podcasts on the subject and done more reading than I care to and am better prepared but still feel inferior when dealing with yeast and water (I feel I have the malt side down pretty well).
Jamil has said that his version is based on his research as well as personal brewing and that he'd feel better having users follows his chart and overpitch rather than the possibility of underpitching. The dangers are under pitching are much worse for most homebrewers than over pitching and that's the way I've approached my starters.

Yesterday's brew I had planned to split a 3 L starter over 2 beers but in the end, I also split a pack of 05 in each one as insurance. I didn't have time to do a step up starter nor did I have enough yeast to make a starter big enough in time so I took the safest way out. It was already blowing up this morning so I have no worries at all.

[mashani]

The dangers are under pitching are much worse for most homebrewers than over pitching and that's the way I've approached my starters.

In general I would agree for many home brewers but:

Your mostly brewing IPAs and APAs I think, and yeah it's really hard to overpitch those because you aren't going for yeast driven flavors. But overpitching can be a real problem for some styles depending on the character you want, where the yeast character is most of what you taste.

It's mostly if you pitch to the point that the yeast won't grow about 3 generations of wort adapted daughter cells that it can become an issue, especially for yeast that you actually want significant estery yeast character from. I know from my own experience that Mr. Malty's pitch rate calculator makes starters that are too big for some types of wheat beers strains, certain Belgian strains, and some English strains in some types of beer if you want the full character of the yeast to shine through, vs. just a limited subset of that character. But this is a matter of yeast strain, temperature control (or lack of), and wort composition too. So it's "complicated" and can't be simplified just down to just pitch rates based on OG, it's getting into more of an experience and feel for a yeast strain and what it does, and pitch rate is simply a part of that puzzle. I've not been able to quantify why they are too big because I can't physically count the cells produced. I just know they are, because the end results taste wimpy.

I guess a simple "test" as such would be perhaps try the other formula for a wheat beer (not American "I hate yeast character" wheat, but a real Hefe or Dunkle or the like) where you want banana (or apple/pear with some strains). Ideally split between 2 fermenters, using J's starter rate # for one of them and the other # for the other, and see what you think of the end products. If you like what's behind door #2 better, then J's numbers are possibly creating more cells then he thinks.

Of course that experiment only works if you like yeast character driven beers, which most Americans seem to not. Their loss...