Yeast starter still going 36hrs later

[Pharaoh Bob]

I just got a stir plate and this is my first yeast starter using it. I made a 1.5 L starter on Wednesday evening and pitched just after 8pm. It is now about 36hrs later and I was going to put the starter in the fridge to cold crash before I brew tomorrow but the starter still looks like it is going. There is a ring of bubbles on top and ones floating up. I have never used a stir plate before so I'm not sure if it is still fermenting or if the bubbles are just from the stir plate. Also I am running out of time for my cold crash.

Should I let it go on the stir plate another 12hrs and then cold crash or cold crash now or let it go another 12 hrs and just forgo the cold crash?

WLP001 is the yeast

 

[Keith81]

I'm a stir plate noob but in the few that I have done I've figured out that if I turn the stir plate off for as little as 30 min the yeast will settle out enough to convince me that it's done.

 

[kh54s10]

18-24 hours is the cell count growth phase when using a stirplate. After that you might still be getting some cell count growth but not much. The yeast are then expending their energy fermenting the wort. It's ready, cold crash it. Some of the foam around the edge of the surface is just from the agitation.

 

[Pharaoh Bob]

Ok, ill go home during my lunch break and throw it in the fridge, thanks for the advice

 

[logos]

It probably depends on the number of cells your pitch to begin with. If you put in a vile from white labs then it should be done, more than done. If you start with a very small number of cells then perhaps it’s not done yet. I like taking refractometer readingsSo I start with 10 Brix And can follow it down.In any case, if you start with a full commercial vial You should have plenty of cells by now even if the fermentation is not complete.