Staging up a Starter

[Xoxon]

Is it really necessary to make multiple starter cultures to grow a large amount of yeast? Is there any reason to let one stage finish out completely, or is it better to just keep feeding wort to a starter? Palmer or Zainesheff suggest a ten to one ratio i.e. pitch a 125ml Wyeast to 1.25L or wort. What happens if I pitch a smack pack into 5L or wort and run it on a stir plate?

 

[pabloj13]

Is it really necessary to make multiple starter cultures to grow a large amount of yeast? Is there any reason to let one stage finish out completely, or is it better to just keep feeding wort to a starter? Palmer or Zainesheff suggest a ten to one ratio i.e. pitch a 125ml Wyeast to 1.25L or wort. What happens if I pitch a smack pack into 5L or wort and run it on a stir plate?

It's all about inoculation rate. It is very well explained here. You can use their tool to set up different scenarios and test them yourself here.

Edit: It looks like a 5L starter will give you ~470 billion cells. You could achieve the same thing in 2 steps with a 1L and 2L starter, requiring less DME and a smaller vessel.

 

[duboman]

The purpose of making a tarter is two-fold. The first is to grow the yeast up to appropriate pitching rate, the second is to ensure that the yeast you grow are the healthiest yeast you can grow. When deciding upon the size of the starter you want to be sure that you do not stress out the yeast as you grow them.

IMHO, I like the idea of stepping up each starter as I think this produces the least stress on the yeast rather than trying to get the yeast to multiply in one huge batch, I obviously cannot prove this is better, just what I feel.

Also, keep in mind that when using a stir plate, heat is generated by the stir plate action so you want to be sure you do not go crazy with the speed and generate enough heat to create additional stress on the yeast.