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Old 10-14-2011, 05:38 AM   #31
diS
 
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This experiment sounds great, I am highly interested about the results.
Great job Brewitt!

 
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Old 10-15-2011, 03:11 AM   #32
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Wow, I can't wait for the results Brewitt! This is the kind of experiment that homebrewers will quote to each other for years.

Science: it works.

 
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Old 10-21-2011, 06:46 PM   #33
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I haven't done anything toward plating out the cells and counting yet. Probably be next month now given the way time is going. However, I did freeze up about 1/3 liter worth of cells in 30 ml 15% glycerol by chilling to refrigerator, then freezer, then ultracold freezer (-80C) temperature. I thawed that out last night and used it to start a 1.5 liter starter. This morning it is full density and cold crashing. I will keep that cold, dump the slurry of settled cells into 1.5 liter of fresh wort Sunday morning and use it to start my fermentation.

I think this is probably an equally good plan for the general user. Grow up a gallon of starter, split it into 8 half liter portions, cold crash, freeze the cells in 15% glycerol and use one of those to start an overnight starter of up to a gallon as needed. I will do the same without the ultracold step next time and see whether I get equally satisfying results for the home brewer. As long as there is not a significant lag, it should be great. Always good to wake up your cells for a bit before pitching anyway so the overnight is a good idea.

 
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Old 10-26-2011, 06:29 PM   #34
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Wow... one of the coolest threads I've seen on here... as an engineer, this is very fascinating! Great work guys, I can't wait to see the final results! AWESOME!!!

 
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Old 10-26-2011, 09:29 PM   #35
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I don't have the -80 degree freezer to work with but I did tests with some of the extra washed yeast (washed twice, separated out, pouring off the excess, and resuspending for division into glasses which was done by weight) I knew I wasn't going to use. With ~30% by volume glycerine I did three batches (WLP001). One went into the Freezer immediately after mixing and shaking, the other two were placed into the fridge and one was shaken vigorously every day for three days.

They were left in the freezer for 2 weeks (+ 3 days for the straight to freezer one) and all three brought out and added to Malta based starters (I had extra bottles, sue me). The one put straight into the freezer was actively started within just under 60 hours. The other two were active within ~30 hours. The shaken daily while refrigerated before freezing one was active *MAYBE* 4-6 hours faster, but just over 30 hours later they seemed equal so I don't know if that was coincidental or not.

All three were done in 1 cup freezer safe jars (Ball) and pitched to 1L flasks for starting (@~750ml of wort) and ran on stirplates with a 1.5" stirbar until my curiousity was satisfied. All three seem to have washable yeast that looked quite healthy and the starters tasted pretty much identical to my tastebuds. I know the above is far from scientific but I didn't have fancy things like microscopes and cyclotrons (centrifuge but cyclotron sounds so much cooler!) to work with.

 
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Old 10-26-2011, 09:37 PM   #36
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Quote:
Originally Posted by Accidic View Post
All three seem to have washable yeast that looked quite healthy and the starters tasted pretty much identical to my tastebuds. I know the above is far from scientific but I didn't have fancy things like microscopes and cyclotrons (centrifuge but cyclotron sounds so much cooler!) to work with.
That's awesome, thanks for the results! So refrigerate for a few days before going to the freezer? Sounds like they need some time to get their parkas on.

And hey, if they taste and look good (well as good as a starter can), who needs fancy microscopes?

 
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Old 10-27-2011, 03:45 AM   #37
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The chilling at refrigerator temperatures for several hours seems to make a significant difference. Not sure if giving them several days should make a difference. My culture grew very well and was at full density after overnight with shaking. Remember, if you start with a good dense slurry of yeast you are not asking for very much growth to reach a maximum density starter. The cells only need to go through a few rounds of division and they are there. I do think there is a very substantial advantage to getting your starter going overnight rather than just pitching it. My fermentation that is just finishing up was actively bubbling away in 4 hours after pitching with couple liter overnight starter made with my tube of glycerol frozen yeast, thawed in 100 F water with shaking until just thawed. Based upon this experience I think this is a very good approach and the one I will be using. I am going to make up half a dozen tubes of frozen cells of a couple different yeasts over the next couple weeks and keep them for exactly this purpose.

 
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Old 10-27-2011, 11:09 AM   #38
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I agree but my question is does the refrigeration thing only chill it to reduce the size of the resulting ice crystals or do the yeast cells have more time to imbibe more glycerine into their cells preventing even further cell damage? At least that was my impression of how the glycerine aids it if it isn't in high enough volume to completely prevent freezing...

 
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Old 10-27-2011, 11:11 AM   #39
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Btw, per mr malty I was around only 40-45b cells. I wasn't holding them for a batch after all but just for testing.

 
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Old 10-27-2011, 11:40 AM   #40
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Oh, and I should probably mention mine was from a self defrosting freezer. If I go library this route I will use icepacks but did not this time.

 
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