Yeast Starter for a 12 Gallon Batch

Ingredients
1

I’m sure this has been discussed before and I missed the answer. I’m plan on making a ½ gallon starter and want to split into 2 (6 gallon ea.) carboys. Is one Wyeast pack enough ( OG will be below 1.060)? I normally start out with 12 gallons batches so I net out with 10 gallons by the time I keg.

2

Check www.mrmalty.com or www.yeastcalc.com.

Depending upon the mfg date, you look good at one pack in a 4L starter if it’s an ale.

Dave

3

Mr. Malty and Yeast Calc are good tools.  I would skip entering the manufacture date.  They estimate viability very low compared to cell counts I have done.  Also, for yeast propagation, a single step of 4L might be a little large.  (It will take longer to generate the cells and use more DME per cell produced)  If you want to get the most yeast for your DME then the inoculation rate should be about 65 million cells per ml.

If it were me, I would step it up dailiy based on cell counts, but if I didn’t have a microscope I would do the following:

  1. 1.5 liters with 150g of DME in a 5 liter container or larger.  Culture for one day on a stir plate.
  2. add 1.5 liters of water and 300g of DME.  Culture for one day on a stir plate.
  3. add 1 liter of water and 400g of DME.  Culture for two days on a stir plate.  Crash, measure slurry in ml.  Estimate 1 billion cells per ml.
4

Shouldn’t it be the other way around? Lower pitching rate, so more reproduction per unit of fermentable extract.

5

Every setup is a little different but the experiments done by Dr. Chris White at White labs indicate a “sweet spot” at 65 million per ml.  If you plot the data he collected as inoculation rate vs growth factor you will see it.

See the 9 Plato line on this chart:

6

Interesting… Where are those numbers from? MrMalty/Yeastcalc? Kai’s recent results look more like the curve I would expect: Estimating yeast growth | Braukaiser

BTW, your Plato-SG conversions are a little off.

7

The Plato numbers are rounded.  The numbers are simply a guess.  The 9 degree Plato Line is from Yeast Calc or Mr. Malty.  They use nearly identical equations.  I’m looking forward to seeing Kai’s results as well.