starter cell count factors

[Duane]

Beginner question about yeast starters.

Does final cell count have more to do with volume of wort or amount of sugar (gravity) in the starter?

I get the feeling from reading around about how yeast works that it has more to do with volume of wort. If that's the case, why not use a minimal amount of DME in a larger volume of water (1 gallon) from the very beginning rather than going through the trouble of "stepping up?"

Thanks!

 

[Beernik]

It's both.

Ideally, you want a starter with an OG between 1.030 and 1.040 that will give you the final cell count you want. You can go with a bigger or smaller volume of water with the same amount (weight) of malt which would give you a bigger or smaller OG and result in the same cell count. But your yeast won't be as healthy for pitching.

An OG greater than 1.040 stresses the yeast. I'm not really sure what the downside is of having a starter lower than 1.030 is other than it could still shock the yeast going into a high sugar environment.

If I had a 4L flask, I could do starters without stepping. But I have a 2L, so I have to do one step if I want to make 10 gallons of ~1.060 beer.

I have a 1 gallon jug, but it doesn't have a flat bottom, so I can't get my stir bar to spin in it. The bar gets thrown into the corner.

 

[Duane]

So if I understand you correctly the amount of water really doesn't affect final cell count - just potentially the yeast health.

I thought during the reproduction phase, prior to fermentation, the yeast cells multiplied to fill the volume of sugar solution, however much that might be - not to match the gravity of the solution, however much that might be.

Anyone else want to weigh in?

 

[flars]

Two points to always consider:

The viability of your yeast will determine how many cells will be propagated in a starter of a certain OG and volume. Production date of the yeast must be taken into consideration when building a starter.

When a starter wort exceeds 3.5% ABV the propagation rate of healthy cells changes. This is the reason for keeping the starter wort below 1.040.