Stepping Up a Yeast Starter

[Duncan83865]

I've made starters plenty of times, but am currently working on "stepping up" my first starter. After looking at the calculations a couple different ways, I decided on starting with a 1L starter, decanting, and then stepping it up with another 1L starter. However, now that I've got it going, I read where Mr Malty recommends against the same starter size with both steps because it can be overpitching the yeast.

Anyone have any experience with this they can share? What are the downsides to what I did (if any), and am I going to notice anything in the final beer? Thanks!

 

[prandlesc]

I think you're on the right track. For most homebrewers, over pitching is not an issue, and with a stepped 1 liter starter I think you'll be fine. I've done this in the past, but bought a larger flask just so that I don't have to step them up any more.

 

[chickypad]

I think the main issue is trying to optimize growth rates. In Yeast they talk about innoculation rates and the yield for growth. Starter innoculation rates of 50-100 million/ml gave the largest yield, but anything from 25-125 is quite good. When you get up toward 200 there is essentially almost no additional growth from another step.

I like to use yeastcalc for stepped starters. You can play around with the numbers and easily see the innoculation rate for each step. I don't know that overpitching the second step is bad for yeast health necessarily, it just may not be worth the risks of an additional step for minimal extra yield of yeast cells.