Best way to store yeast slurry for re-use

[dave-o]

-Can it be frozen?

-Some people recommend sticking a jugful in a big sealy bag, removing excess air/water and leaving in the fridge. Can sealy bags (new, of course) be trusted to be sterile?

-How long can it reasonably be stored by either method?

-Is either method considered to be generally safe from infection?

[mysterio]

- It can be frozen in a glycerol solution. It will store for a long time with this method.

- I wouldn't trust these personally but if people are getting away with it, why not. I use a kilner jar that has been boiled for 15 minutes, cooled, and stored with the lid loosely on.

- Viability drops off at a rate depending on the yeast strain, if you're just harvesting from your primary FV and storing under beer, the guideline is two weeks. Try Jim's method of storing yeast he describes in the above links, I've kept yeast for a few months with this method. Quicker the better. Make a starter if growing up from a small sample.

- That depends on how careful you are, I can't answer that.

[Bloozrocker]

My method is to make the last bottle very yeasty it stores for long enough
then fire it up again for next brew day

[dave-o]

My method is to make the last bottle very yeasty it stores for long enough
then fire it up again for next brew day

That's a damn good idea.

Do you cap it? Is that risky?

[Bloozrocker]

very lightly primed and after a day keep it in the back of the fridge
Been doin it for years and brew on average once every 6 weeks.
I do not brew at all during juy / august .
Far too many variables floating about in the atmosphere.

[Dr. Dextrin]

I used to keep slurry in the fridge, maybe for up to a month depending on the strain. But it can start to smell a bit off after a few weeks. If that happens I used to sling it out. Although I've never had an infected brew doing this, I felt that relying on sense of smell alone was a bit risky, so I've stopped doing it now.

These days, when I buy a new yeast, I do one brew with it and then bottle say 8 fairly yeasty pints, which I save (the rest goes in a keg). Then I re-start the yeast from those 8 bottles to get yeast for my next 8 brews. That way the yeast is only ever 1 generation old and doesn't have much chance to mutate or pick up an infection. Once bottled in a clean brew, yeast seems to keep for a long time.

Of course, you can still run out of yeast if you forget to re-stock.

[dave-o]

Thanks guys.

This seems like the simplest solution.

[Blackaddler]

very lightly primed and after a day keep it in the back of the fridge

Good idea.

What ratio slurry/beer do you use, and how much do you need per 25 litre brew?

[coatesg]

http://www.mrmalty.com/calc/calc.html - there's an option for repitching from slurry. Usually better to slightly overpitch than underpitch.

I sometimes do it by harvesting slurry from the bottom of the FV and keeping it in a sanitised plastic takeaway container in the fridge - in fact, I have some in there right now that I'm going to try to use on Friday night.

[Minimasher]

My method is to make the last bottle very yeasty it stores for long enough
then fire it up again for next brew day

That's a damn good idea.

Indeed it is. I've been faffing about doing all sorts but that's simplicity itself! Cheers