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Yeast Starter

cowboy up

Brewer
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Dec 21, 2008
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I brew 10 gal. batches of beer at a time. Previously I would make two separate yeast starters for the two 5 gal. fermenters. I am interested in purchasing a stir plate and flask. My question is would it be better to make say one liter batch for each fermenter or would I be better off making a two liter batch and the splitting it between the fermenters? Would splitting it at the one liter graduation on the flask be close enough (approximately) for the same amount of yeast cells in each fermenter? I'm sure it would be more difficult getting "half" in each one if I were to decant  the excess wort. Any advise would be appreciated. Any recommendations on a good stir plate?  Thanks Cowboy up.
 
Cowboy, I got my Stir Plate from Northern Brewer.  It has served me well.
It is my experience that under the proper conditions; mainly plenty of oxygen, the yeast will multiply to consume the sugars available.  [oxygenate the starter wort by shaking vigorously and use the stir plate]  Based on [Chris White, Yeast] the maximum yeast cell density is about 200 billion per liter.  Based on a 100 million cells per milliliter per point pitch rate, a 60 point 10 gallon batch would need about 225 Billion yeast cells.  I would use a 2 liter erlenmeyer flash with 1.25-1.50 wort at 40 points in one starter batch with one commerical yeast pack (Wyeast or Whites).  I would ferment the starter to completion, chill and decant most of the liquid.  Allow the starter to come back to room temperature and pitch.  If you want to go one more step you can add a bit more sweet wort to the starter and pitch when that starts showing signs of fermentation.

Just my own humble opinion 
 
I try to avoid getting too much starter wort into my beer. Even though it's a relatively low percentage of the overall volume, I feel that it can alter the flavor if excessive.  Using two flasks would probably be the most accurate in terms of pitch rate calculation, but that might be a hassle If you follow the method cowboy up described, which is basically what I do as well, I bet you can reasonably approximate half of the yeast slurry into each carboy. So I would chill the starter, or at least allow the yeast to settle to the bottom, bring the starter back up to room/pitching temp, decant the spent beer (leaving just enough liquid to get the yeast in suspension again), then pitch half the starter volume into each carboy.
 
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