Yeast Propagation

[porter]

Looking for advice on yeast propagation.

My goals are to: save money on yeast pitches, prop non-house strains for higher gravity brews, manage 3 strains at once in our brewery (sometimes).

We have a 15bbl brewhouse with mostly 30 and 60bbl fermentors. We don't consistently produce a lower O.G./ ideal prop beer and so I'm looking for advice on how to do propagation. We have a 1/2 bbl pilot system we could easily produce wort from- or pull wort from runoff and process on pilot system.

I'm thinking: 4 bbl conical w/ O2 stone and possible recirc with pump to emulate more expensive "propagation systems"?

What are others doing? Advice?

[porter]

Really? No one?

I posted this question again on the BA Forum and got a lot of responses from people who have the same question, but not from anyone who could answer.

Does everyone just buy a lab pitch for every specialty brew?

[brewmaster 2011]

Call dave he sets them up.

[ColdFusion]

We grew up some yeast recently to a 7BBL pitch for a one-off. Kept stepping it up to a 50L final volume. Nothing fancy, just oxygenating the wort at the beginning of the starter. It ended up being plenty of yeast. I'd imagine with some constant aeration, monitoring growth, and batch feeding, you'd easily be able to get enough for a 30BBL pitch out of a 4BBL conical. I think 60BBL would be pushing it without optimal conditions.

If you want really healthy yeast, ideal is to keep them growing in log phase (early to mid; 1x10^6 cells/ml to 5x10^7 cells/ml). If it were me (and I had time to do it), I'd start with testing by seeding at 1x10^6 and at 27C with constant aeration (pumping filtered air) through a stone. Some type of impeller to mix would be nice, but I don't think it's absolutely necessary. After an initial lag phase, you could keep the yeast in log growth by batch feeding (adding wort). You'll have to play with it to figure out the timing. I could probably go on but I'm speculating since I've never done this with yeast before.