Yeast Starter - Decanting and Stepping up?

[Oktober]

Hey All,

I'm preparing a lager starter in order to get up to 4 vials worth of yeast (from a single vial). My plan is to do a 2L starter and then step it up to a gallon - which should be ~4 vials worth.

I am planning to cold crash the 2L starter after it has finished its growth. Once it all falls out, I was going to decant off most of the spend wort and then pour the remaining yeast slurry into a gallon of new wort. However, I have read/heard that instead of decanting, people just pouring the full 2L starter into an additional 2L (totaling 1 gallon) to step it up. I'm curious to know which is the better way to step up the yeast volume?

Thanks!

-Okt

[6thstreetbrewer]

I usually decant and then throw the new starter onto the cake in the flask

[Thuglas]

I would decant and pitch into new wort. I can't remember where I read this (either JZ or Palmer), but it was confirmed from WL that pitching 1 vile into a 1L starter then into a 4L starter will produce 400b yeast cells. Does anyone else remember reading/hearing that?

[Nate Diggler]

I would decant if just to get rid of all the things in the starter that you wouldn't want in your full batch if you hadn't pitched enough yeast (fusels, etc.) since the process of propagating a starter is to purposely stress the yeast into overdrive cell multiplication... granted, the amounts of these things is much smaller in a starter sized batch, but why keep them when you can decant them off.

[bsegroves]

Why should a starter be stepped up gradually?
Why not just pitch straight into a gallon? It seems like yeast would grow more in a gallon of wort than 1000 ml of wort?
Does it not have a different growth rate?
I'm just trying to understand the science behind it.


thanks,
Brannon