Yeast count - small batch to brew big batch

[Judochop]

I’m going to brew 11 gal of 1.053 lager. Mr. Malty offers the following advice:

11 packets of yeast pitched direct, or
5 packets of yeast in a 2.5L starter, or
~460ml slurry (~815 billion cells)

I’m not super excited about the idea of #1 or #2. So… in order to save money and to be able to show a little something for my time and effort, I am strongly considering brewing up a 2.5 gallon batch of 1.045 lager using the ol’ extract/stovetop method. According to Mr. Malty 2 packets of lager yeast pitched direct is all I need.

Q: If I brew this 2.5 gallon batch, will that get me to the ~460ml (815 billion cells) of slurry that I need for my 11 gal of lager?

I tried to answer this myself making use of Mr. Malty again. I plugged in the numbers for my 11 gal of lager, and set the starter settings to replicate a regular 2.5 gallon batch. I set it to “simple starter w/O2 at start”, and slid the bar to where it accounted for a 10L (~2.5 gal) starter. Doing this tells me I need 3 packs of yeast pitched direct, whereas to brew the small beer I only needed 2. Still, that seems pretty close, and if I tweaked viability %s enough, maybe even the same. So I'm thinking I got it right, and that my 2.5 gallon batch/starter plan is a solid one. Yeah?

 

[WoodlandBrew]

Mr. Malty seems to under estimate cell growth, especially when you don't select the stir plate option, and starting with a low pitch rate. Mr. Malty also assumes a 9°P or 10°P wort, but yield is directly proportional to the amount of extract. I've found (by reading papers and doing experiments for years) that pitch rate and aeration don't effect the yield as much as the speed of propagation. So when the beer reaches completion you should have plenty of yeast.

Try this calculator:
http://www.woodlandbrew.com/2015/02/starter-calculator.html

 

[Bamsdealer]

That seems like a crazy amount of yeast. I usually do one gal w liquid lager yeast and use the slurry for a 5 gal batch

 

[BigFloyd]

I think you'll be fine using the whole yeast cake from the smaller batch for the 11 gallon lager.

Use a blowoff tube. It's common for a batch using fresh yeast slurry to really take off on the second day after pitching.

 

[RM-MN]

While I think Mr. Malty serves a purpose, I question the necessity of the large pitches required by his calculations. There are a lot of ways to achieve good beer and pitch rate is only one of them. You might want to read through this experiment on pitch rates noting the three pitches used.

http://sciencebrewer.com/2012/03/02/pitching-rate-experiment-part-deux-results/