Author Topic: Stir plate starter analysis  (Read 841 times)

Offline narvin

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Stir plate starter analysis
« on: June 26, 2015, 11:55:27 PM »
I'm making a starter for an IPA, and by popular request I'm doing a methylene blue stain and cell count on it.

Vital stats:

2 vials of WLP 001, expiration date Oct . 5 (produced on June 5)
2.5 L of canned starter wort:
  - Best Pilz malt,  enough calcium sulfate to hit 50 ppm ca, phosphoric acid to mash pH 5.4 room temp, yeast nutrient.
- No sparge, canned wort at 15 psi for 15 minutes.
  - OG 1.045 or so.  Higher than usual but part of an experiment with accommodating yeast to fermentation wort gravities.

I shook the starter for a whole minute, which is an eternity for one this big. 



Put on the stir plate this morning and left it alone.  After 10 hours:





I plan to stain and put on the microscope later, although if the krausen hasn't gone down yet before bed the cell count won't be accurate.
« Last Edit: June 26, 2015, 11:59:00 PM by narvin »
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Offline narvin

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Re: Stir plate starter analysis
« Reply #1 on: June 27, 2015, 03:16:39 PM »
Update: krausen is still holding strong at the 24 hour mark, which is a bit unusual but could be due to the higher starter gravity.  Going to wait a few hours before taking a sample.

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Re: Stir plate starter analysis
« Reply #2 on: June 27, 2015, 03:52:38 PM »
Or it could be because of the shake?  :D

Offline narvin

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Re: Stir plate starter analysis
« Reply #3 on: June 27, 2015, 04:31:28 PM »
I usually shake before pitching, though maybe not for as long.  The aim is saturation at 8ppm O2, but I don't have a DO meter so it's a guess how long I need to shake.  I'd be afraid to use pure O2, but maybe over saturation and oxygen toxicity is not a concern when pitching so many cells in a small volume?
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Offline a10t2

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Re: Stir plate starter analysis
« Reply #4 on: June 27, 2015, 05:07:31 PM »
I think he meant that if your goal is to isolate the stir plate as a variable, you shouldn't do both.
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Offline narvin

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Re: Stir plate starter analysis
« Reply #5 on: June 27, 2015, 05:33:48 PM »
I don't think starting with aerated wort discounts the effects of a stir plate, given how fast O2 dissipates/ is absorbed by yeast.  This isn't a side by side experiment, anyway, but rather to show yeast viability being affected by stirring (or not).

Actually, it's not really an experiment at all.  Just some data during the brewing process.  :)
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Offline narvin

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Re: Stir plate starter analysis
« Reply #6 on: June 28, 2015, 02:11:15 AM »
Finally got around to this:



There were only a few stained cells, less than 0.5%.  Unfortunately there was already a lot of flocculation by the time I pulled a sample, so I doubt the cell count was accurate.  It calculated to around 375 billion, extrapolating just from the liquid taken from the top.

Also, the lab technician seemed to be inexperienced.

« Last Edit: June 28, 2015, 02:34:02 AM by narvin »
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Offline narvin

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Re: Stir plate starter analysis
« Reply #7 on: June 28, 2015, 02:26:37 AM »
After two hours in the fridge, some indeterminate amount of yeast slurry:
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Offline klickitat jim

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Re: Stir plate starter analysis
« Reply #8 on: June 28, 2015, 01:26:28 PM »
Looks like a lot to me

Offline narvin

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Re: Stir plate starter analysis
« Reply #9 on: June 28, 2015, 02:13:36 PM »
That's what the cat said too :)
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Online brewinhard

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Re: Stir plate starter analysis
« Reply #10 on: June 28, 2015, 03:29:24 PM »
After two hours in the fridge, some indeterminate amount of yeast slurry:


Man, that is a ton of yeast!