Stir Plate Process?

[biertourist]

I just moved from my sanitary filter + air stone setup to a yeast stir plate and I'm now curious what the recommended process is for using a yeast stir plate.

My biologist buddy responded to my FB post that running a stir plate too fast for too long can result in cell lysis but I don't have any guidance around what the recommended procedure is.

How big of a vortex should I have and how long should I leave the starters on the stir plate? I have a simple home brewer-focused stir plate and not one of the fancy heated professional models.

I would typically make an ale starter 24 hours prior to propogation or with lagers I normally make a starter at 60F for 3 days; if my base beer is dramatically different and I need a large (1 gallon) lager starter I will let it ferment until low krausen and then crash cool the starter and decant the wort off of the yeast. -I'm not sure what the equivalent process is when using a stir plate.



Thanks,
Adam

 

[biertourist]

Did my own research. And got a reply from White Labs.

Cell lysis CAN result from over stirring. You only need a TINY dimple in the surface; you want to drive off CO2 as it's produced and allow O2 exchange. 18 hours for a 1.030 - 1.040 gravity starter should result in full attenuation and then 6 hours for yeast to start flocculating.

I also need to increase the temp of my lager starters to room temp to get max cell reproduction.


Adam

 

[biertourist]

I'm changing the subject of the original question a bit, but has anyone come across a home brewer trying to use a really low gravity stirred starter and small continual glucose feedings to keep the crabtree effect at bay and maximize cell growth via aerobic respiration? -Like in a commercial yeast propagator?



Adam

 

[Steve271828]

I'm changing the subject of the original question a bit, but has anyone come across a home brewer trying to use a really low gravity stirred starter and small continual glucose feedings to keep the crabtree effect at bay and maximize cell growth via aerobic respiration? -Like in a commercial yeast propagator?



Adam

White and Zainasheff discuss this in "Yeast" but I think they recommend against it because it's not practical. I'm at work, otherwise I would find the citation for you.