how do I double the propagation

[karbinator]

Sorry if this has been posted somewhere else.
Can I decant the starter liquid, and put newly chilled
starter back onto the yeast cake? Seems logical , but
am I missing something? how do you guys double your
original starter?

Thanks

 

[ajf]

If I'm going to step up a starter, I usually start with a small starter (say 1/2 pint) and just add the extra wort when the small starter begins to ferment. If your first step was large, I would probably let it ferment out, chill, and decant the clear liquid before adding the new wort.

-a.

 

[Got Trub?]

You will get diminishing returns as yeast can "sense" how dense their numbers are and stop reproducing. To truly double your yeast numbers you need to step it up. If you start with 250cc then add 250cc and grow for 24-36 hours then add 500cc, grow for 24-36 hours, then add 1000cc...

GT

 

[krops13]

Yeast grow until they are no long able to. I.E. dissolved o2 or nutrients. As long as there is o2 and nutrients they will keep on growing. Do a search on pasteur effect. pasteur outlines that fermentation doesn't start until the o2 is used up.

 

[mattldm]

So if I make a 1qt (32oz) starter with one vial of whitelabs yeast, the yeast should have doubled from what was in the vial originally?

If I want to make a larger starter in steps, can I keep adding wort 1qt at a time or do I need to increase the amount of wort each time?

 

[ajf]

Check out http://maltosefalcons.com/tech/yeast-propagation-and-maintenance-principles-and-practices
It's not the easiest article to read, but it really does answer a lot of questions on yeast starters

-a.