Harvesting yeast to freeze from overbuilt starters

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

MajorJC

Too many hobbies... not enough time.
HBT Supporter
Joined
Aug 20, 2014
Messages
249
Reaction score
394
Location
Central Mississippi
Lot's of details here, if you don't want to read all this then at least skip to the bottom for my question. :)

The Yeast is:
IMG_9553.JPEG


I wanted to brew on the 9th but my ADHD got in the way, but I had built up a starter as follows:

Yeast House A01 2022-08-09 062837.jpg


I did these three starter steps before I punched any numbers into this calculator. When I realized I wasn't going to brew, I punched the numbers in to see how many cells I made.

Looking at the numbers, I realized that those second and third starter steps were a waste of time due to the low growth factor, so I ordered a 2L flask.

So, when my brew day didn't happen and It was time for my 7days on of 12° night shifts I put my starter flask in the fridge and left it for a week.

Yesterday morning I put the yeast into my new 2L flask and started it up again on the stir plate, and then into the fridge last night.
This morning I decanted and did another 2L starter step, which is still fermenting strongly as I type this right now.

Screenshot 2022-08-20 191236.jpg


So, I'm thinking I will have plenty of cells to pitch, along with a lot of yeast to drop into my 30% glycerin vials to put in the deep freeze.

Ok, here is my question.

Above it says to pitch 0.646L and harvest 1.354L, I'm planning on cold crashing tonight so I can decant before pitching. So I'm guessing tonight I simply pour off about 0.7L into another flask for pitching tomorrow and then split what is left between a couple of quart mason jars to make the yeast collection easier for my glycerin vials?

Anybody see any problems with my plan or process?
 

Protos

The Gulper
Joined
Jan 7, 2019
Messages
773
Reaction score
801
Location
Valle Lacrimarum
I've read some big boys suggesting exactly 15% Glycerine solution for deep freezing yeast. They said it's the chemically optimal concentration, don't ask me for details. In my experience, 15% Glycerine solution retains some fluidity even when deep frozen (and it worked perfectly for my yeasts frozen for more than a year).
I'd suggest to research the subject of the optimal Glycerine concentration.
 
OP
OP
MajorJC

MajorJC

Too many hobbies... not enough time.
HBT Supporter
Joined
Aug 20, 2014
Messages
249
Reaction score
394
Location
Central Mississippi
I've read some big boys suggesting exactly 15% Glycerine solution for deep freezing yeast.
Yep, that's correct. My 30% glycerin solution will dilute to 15% glycerin when I double the volume in the vials by adding the yeast slurry.

I'm following the direction in this article by Pete Geisen.
Double the volume of each vial using the cooled 25% glycerin solution (for example, after decanting you are left with 50ml of yeast slurry. Add 5 ml slurry to each vial and add 5ml 25% glycerin to each vial. This will give you a final concentration of 12.5% glycerin).

Looks like he used a new account to write the article, but then replied using his original account.
Truth be told, anywhere from 10%-20% final glycerin concentration would give pretty similar results.
 
Top