"Research varies, but a starter of 1 quart (or liter) will yield approximately 150 billion cells, and a two quart (or liter) starter will yield from 200-240 billion cells."
Originally Posted by Jayhem
I'm curious, where are you getting that a 2L starter will only double the initial cell count? From Mr. Malty
it says it would at least triple or quadruple the cell count.
-- "Home Brewing with BeerSmith," Bradley J. Smith
So I figured if I start with a smack pack (100 billion cells) and brew a 2L starter, I'll end up with 200-240 billion cells (a doubling). If I then decant off the spent wort and do it again, they'll double again. If I'm doing it wrong, I welcome a correction!
EDIT: This article in BYO
is even more pessimistic:
Yeast in a starter will grow to roughly 50 million cells per milliliter of wort or 1.5 billion per ounce of wort no matter what the starting number of cells. [...] A 500 ml starter will grow to: 500 x 50 million = 25 billion.
So a 2L starter would only produce 100 billion cells - which is what I started with in the smack pack in the first place.
As another general principle, a 2-liter starter will approximately double your yeast count
They cite Jamil Zainasheff's article in the March/April 2007 issue of Zymurgy, "The Secret to Healthy Yeast: Making a Starter."
The answers seem to be all over the map! If yeast pitching rates are so vital, how do you guys reconcile all the wildly conflicting "math?"