Limit on Yeast Starter Cell Count Calculation

[umrmepe]

Is there a limit on the number of cells calculated based on the starter size? For example: The yeast starter tab recommends a 2.28 liter starter, but when I input a 2.5 liter starter the cells calculated value (107.2 Billion) is less than the cells required (221.8 Billion), if I change the volume to 3 liter, the cells calculated value does not change even when I check/uncheck the stir plate box (to refresh calculation). The yeast package date is approximately 6 months older than the brew date and I have checked to make sure these values are being used.

 

[McMullan]

What you start with, in terms of yeast, limits the end cell count. It's not really a case of just increasing the volume of starter wort. You probably need to do a step-up starter or add more than one pack of yeast.

 

[BeerSmith]

There is a limit to growth that applies here - generally around 5x the starting cell count. So even if there is a lot of wort, you won't get much more than 5-6x growth in a single generation of yeast. Yes you can do an extended starter which will eventually ferment out (over several yeast generations) but that's not the goal for a starter where you want a large volume of health active yeast.

So you then either need a two stage starter (two generations of yeast done sequentially) or you need to pitch more yeast up front.

 

[umrmepe]

Thanks for the answer. That is what I had assumed. I am still getting used to yeast manufacturers using a "Best By" date versus a "Packaged By" date. I have been using a date of 6 months prior to the "Best By" date to set up the yeast starter tab.

 

[BeerSmith]

That is probably a good estimate for liquid yeast - most have a 6 month shelf life.