# Freezing Yeast



## sean_0 (5/12/14)

Had an interesting afternoon. I mentioned to a colleague that I had a package of very special yeast that was going to expire soon and that this was not a good thing. The interesting thing is that I work in a biochem lab as a computer nerd, so my colleague wanted to help out. (He's as interested in my beer as I am). Thought I might throw this up here so that people get an idea of actual lab yeast glycol stock making procedures.

1. Washed gloved hands in ethanol - according to Dave, the key to sterile lab work is lots of alcohol.

2. We made a 30% glycol stock from glycol and milli-Q water. In a fume hood we pushed this through a filter (0.22um I think), which Dave assures me will eliminate all bacteria.

3. In a fume hood: Using a pippette (sterile) transferred 0.5ml of the 30%glycerol solution to each of 24 steile 1 ml screw cap vials

4. Under a fume hood: Opened my precious last package of W1026 cask ale, transferred by pippette 0.5 ml of the contents to each of the 24 screw cap vials

5. Shook all vials by hand and put in a bath of liquid nitrogen to snap freeze.

6. Placed vials in -80 freezer.

At many points we cleaned our hands and any spillages with ethanol. Otherwise I've described the whole procedure above.

To get this yeast back into action, the usual procedure is to dip an inoculation loop into the glycerol solution and streak it on a dish with suitable media. I think I will probably just dump a single 1ml vial into a 10ml wort solution and step up from there. 

The whole procedure was done under the supervision of somebody well versed in making glycerol yeast stocks, so it's close to best practise. I know a lot of it might be difficult to replicate at home but hopefully it will be useful to record it here.

Here's me enjoying myself:


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## Yob (5/12/14)

not sure if you've seen it, over the last 12 months or so Ive been right into this sort of stuff, even doing some re culturing and faffing tonight in fact..

HERE is the thread we've been adding into.

Ive got about 20 or so different yeasts frozen off (about 100 vials) as it stands with more on the way from a few folks who have been kind enough to share their library.

I plan to use a tub and crate a 'block' of ice to store them in, like zis..




Needs to be done in layers so they can be effectively positions as I found out tonight 

Not as good as -80 but will be good enough for a home setup


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## sean_0 (8/12/14)

Yob said:


> not sure if you've seen it, over the last 12 months or so Ive been right into this sort of stuff, even doing some re culturing and faffing tonight in fact..
> 
> HERE is the thread we've been adding into.
> 
> ...


Read through that thread over the weekend, lots of good info there. Hopefully my experience adds to that a little. Would have put my post there had I seen it.

Another thing I forgot to mention about sterile lab work I was taught on Friday is to assume that everything is covered in bacteria. This means that you don't touch the pipette tip on any of the containers you are taking liquid from or putting liquid in. 

Pretty impressive to have 20 yeasts in your collection! I'd be happy to have three - WY1026PC cask ale (got it!), WY1764 Pacman, and WLP037 Yorkshire Square. All are limited release and being the very odd man I am I really like all three. Hopefully I'll be able to get the Yorkshire square yeast pretty soon and repeat the above procedure to bank it, but I have no idea when I'll be able to get Pacman again.


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