Glycerol freeze experience?

[nigelsch]

I'm killing my yeast!

Ive tried twice now, and both have shown no activity when creating a starter. Id like to
master the technique as its a useful way to keep my yeast for a few months. This is what
ive done:

1) my mix is: 50% compacted yeast, 25% water & 25% glycerol
2) mix well & freeze.
3) My freezer is only set at -7oc & isn't a defrost one.
4) Bring to room temp, good swirl & throw the whole lot into a 1L starter (1036).
5) stirplate for 3 days
6) no luck still 1036.

The only thing I can think, is that my freezer temp isn't cold enough; the yeast mixture isn't actually
freezing. I'm only keeping the sample for a month, but would have thought -7oc after a month is better
than fridge temp.

Any pointers?

[Pinto]

Was reading an interesting article on long term, room temperature storage of yeast in distilled water - surely much easier..

http://hbd.org/brewery/library/SterileDW1096.html

[BrannigansLove]

I overbuild starters, pour the excess in a sanitised jam jar, and keep them in the fridge. Never had any issues reviving them, sometimes needs a couple of steps, but not had any fail.

[vacant]

@nigelsch "a few months" Agar agar slants in the fridge are fine for that timescale. I only bother reslanting mine every four months. As for freezing, I don't think I ever found a good explanation as to why beer yeast is so fussy compared to bread yeast. I have frozen 500g of fresh bread yeast divided into clingfilm "baggies" simply mixed with flour and produced good bread each time. I followed these instructions (pdf).

@pinto I tried distilled water storage once and it was a total disaster, infected yeast. I don't now what I did wrong. I was only playing, if I had a really extensive yeast bank and only got around to using some yeasts every few years I'd put more effort into mastering the technique.

[nigelsch]

Cheers guys, all useful information. The reason I'm trying to do this is to store enough yeast cells
so that I don't have to grow cells for a ferment. This really being my pilsner yeast, as growing 700b cells
is a real faff & I only do a pilsner once every 4 months; I don't want to grow 700b cells & then have to do the
same next time. So this is the one I'm shooting for; my ale yeasts simply get recycled 3-4 times & then thrown;
no freezing required.

The distilled water approach, seems to be aimed at storing only a small number of cells and not for
mass storage. It appears freezing/glycerol is the right approach for what I'm trying to achieve & many
people do it with success.

[barneey]

I'm killing my yeast!

Ive tried twice now, and both have shown no activity when creating a starter. Id like to
master the technique as its a useful way to keep my yeast for a few months. This is what
ive done:

1) my mix is: 50% compacted yeast, 25% water & 25% glycerol
2) mix well & freeze.
3) My freezer is only set at -7oc & isn't a defrost one.
4) Bring to room temp, good swirl & throw the whole lot into a 1L starter (1036).
5) stirplate for 3 days
6) no luck still 1036.

The only thing I can think, is that my freezer temp isn't cold enough; the yeast mixture isn't actually
freezing. I'm only keeping the sample for a month, but would have thought -7oc after a month is better
than fridge temp.

Any pointers?

Apart from the -7c & using a large 1 litre starter I cannot see anything wrong , I use normal temps -18c and maybe a starter of 100 to 250ml to start with. Experiments upto 11months have proved OK but the last two frozen for 16months were both duds.

[nigelsch]

ok cheers, will try once more with a cooler temp.