Okay, as I lay here about to go to bed I just realized something. The way I oxygenated my wort might have killed all of my yeast.
So, I have this Jaybird stainless steel stir paddle that I love since I can use it for so many things. It has many very sharp edges. But tonight I did something I’d never tried before. Usually I oxygenate the wort by running this paddle attached to my drill motor VERY vigorously for a couple minutes. But this time I pitched the yeast first. Before you think I’m nuts I just read that one way to rupture yeast cells is by using a blender.
So, what do you guys think?
UPDATE:
I had rehydrated this yeast exactly as Fermentis says to. US-05 btw.
Oh man, after posting this I saw the talk about shear stress from stir bars! This paddle is more like a blender compared to a little round edged stir bar.
You will be fine. Yeast are pretty tough, adaptable microorganisms. Keep us posted as to how your fermentation progresses. I will be curious to hear if you had an “abnormally” long lag time, even if.
So, has no one read about one of the methods to rupture yeast cells uses a blender? This paddle has some seriously sharp edges.
Nonetheless, I simply couldn’t risk losing this batch (way too excited about it) so after starting this thread at about 2 am I decided not to take any chances and pitched another packet of US-05. This was about 6 hours after pitching the first time. It eventually took off and had plenty of activity.
As much as I’d loved to have let it sit to at least learn something from the batch I couldn’t risk it.
A blender has much sharper edges and there’s also the whole RPM thing. I’m pretty sure you’re not spinning the paddle @ 20,000+ rpm. No harm in being cautious but you’re just not going to kill your yeast with a stir paddle.
Yeah, a drill will not have enough RPMs to create the shear forces needed to disrupt yeast cell walls. Yeast cells are small enough they could butt slide on the edge of your paddle and think they were having fun on an amusement park ride.http://www.homebrewersassociation.org/forum/Smileys/default/shocked.gif
I use one of those to aerate my wort in a five gallon carboy on brew day. Run it on my drill for 10 minutes. Never had a problem. Lot’s of healthy yeast.