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-   -   Stir plate efficiency (http://www.homebrewtalk.com/f163/stir-plate-efficiency-232417/)

stunsm 03-15-2011 12:39 PM

Stir plate efficiency
 
So how much does a stirplate really increase cell count? I've read some posts and literature that claim up to a 10 fold increase, but the Wyeast calculator seems to show only about a 30% increase. I've used a stirplate on all of my starters and have always had very vigorous fermentation, but I'm curious what the real effects are, and if the 30% figure is accurate, I've been grossly underpitching but still getting very good results.

kanzimonson 03-15-2011 01:10 PM

That depends on what you're comparing it to. It's about 30% more than "shaking the starter every hour." It's probably twice as many as a straight starter that isn't touched after pitching.

Pezman1 03-15-2011 01:44 PM

I was wondering this thing myself. I use the "shake when you walk by" method with great results. However, a stir plate IS a cool piece of gear...

Pez.

stunsm 03-15-2011 03:01 PM

I've used the calculators at mrmalty and wyeast, but they seem to give slightly different results. Anyone with a hemocytometer ever do any side by side analysis?

Pivovar_Koucky 03-15-2011 05:29 PM

I too am interested in hard data regarding the effectiveness of stir plates. Specifically, how does O2 get into the starter after fermentation begins and CO2 starts billowing out?

BoundForBeer 03-15-2011 05:37 PM

Quote:

Originally Posted by Pivovar_Koucky (Post 2739552)
I too am interested in hard data regarding the effectiveness of stir plates. Specifically, how does O2 get into the starter after fermentation begins and CO2 starts billowing out?

Never thought of that very interesting point.

BoundForBeer 03-15-2011 06:42 PM

Quote:

Originally Posted by 724b (Post 2739695)
Isn't O2 constantly getting absorbed because of the movement? That's one of the reasons that growth rates are so much higher with a stir plate.

But when it is fermenting it produces co2 which would push the o2 out of the container...the co2 blankets the wort


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