Author Topic: yeast bummer  (Read 6488 times)

Offline thirsty

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Re: yeast bummer
« Reply #15 on: May 18, 2012, 11:14:03 AM »
How long do they last in the fridge?

Offline Joe Sr.

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Re: yeast bummer
« Reply #16 on: May 18, 2012, 11:17:12 AM »
Not sure.  I've read where others here have said they keep them for up to six months or so.

I've used them after a couple weeks and they go without a starter, no problems.

Longer than that, I've built up a starter.

But I haven't yet tried long term storage, or more accurately I haven't yet tried the yeast I've had in the fridge for several months.
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Offline euge

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Re: yeast bummer
« Reply #17 on: May 18, 2012, 11:32:34 AM »
Not sure.  I've read where others here have said they keep them for up to six months or so.

I've used them after a couple weeks and they go without a starter, no problems.

Longer than that, I've built up a starter.

But I haven't yet tried long term storage, or more accurately I haven't yet tried the yeast I've had in the fridge for several months.

I built up a smack pack that was nearly two years old last month. Took a week. Not much of the yeasties left. Old and dry is no problem but liquid yeast need more TLC especially after a few months.
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Offline nateo

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Re: yeast bummer
« Reply #18 on: May 18, 2012, 07:23:08 PM »
I built up a smack pack that was nearly two years old last month. Took a week. Not much of the yeasties left. Old and dry is no problem but liquid yeast need more TLC especially after a few months.

I had a year-old smack pack I tried to bring back to life. 1.020 starter, 1L. No movement at all. Gravity didn't budge a tick after three days. Dumped it and bought a new pack.
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Offline kylekohlmorgen

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Re: yeast bummer
« Reply #19 on: May 21, 2012, 07:01:09 AM »
I'm always shocked when I calculate viability by mfg date with Mr. Malty, but it holds true.

Use it or lose it.
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Offline tschmidlin

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Re: yeast bummer
« Reply #20 on: May 21, 2012, 02:47:50 PM »
If you want to store it longer, rinse it with distilled and water and store it with distilled water.  It will significantly extend the life of the yeast, but of course you'll still have to make a starter.  I don't have numbers for you, but the yeast will be healthier than if they are stored in even a 1% beer.
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Offline kylekohlmorgen

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Re: yeast bummer
« Reply #21 on: May 22, 2012, 08:15:47 AM »
Could I freeze yeast slurry and refresh it with a little wort on/before brewday?
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Offline morticaixavier

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Re: yeast bummer
« Reply #22 on: May 22, 2012, 11:36:04 AM »
unless you preserve the yeast before freezing you will get ~99% die off from freezing. Tom can clarify. you can just keep it in the coldest part of your fridge for a while, particularly if you are going to wake them up with some wort a day or so before pitching.
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Re: yeast bummer
« Reply #23 on: May 22, 2012, 11:39:34 AM »
Could I freeze yeast slurry and refresh it with a little wort on/before brewday?

It needs to be mixed with glycerine and kept in a freezer that does not self defrost.  As Morty mentioned, Dr. Tom is the guy with the details.
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Offline tschmidlin

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Re: yeast bummer
« Reply #24 on: May 22, 2012, 12:05:48 PM »
Yes, you can mix it with 10-20% glycerol (final concentration) and freeze it solid, but in my experiments it still degrades over time (years) and freezing will kill some no matter what you do.  A better solution is to add enough glycerol to depress the freezing point below the level of your freezer (about 0F) so that the mixture doesn't freeze solid, preventing die off.  But unless you have a cheap supply of glycerol on hand, adding enough to make it 50% glycerol get expensive fast, especially if you are doing slurries as opposed to the 1.5 ml tubes I use.

Really the best solution for most people is to keep it under distilled water, as cold as possible but not frozen, and then make a starter when you're ready.

This assumes you don't want to play with agar, and you really insist on ranching vs. buying yeast.
Tom Schmidlin

Offline tubercle

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Re: yeast bummer
« Reply #25 on: May 23, 2012, 02:48:02 PM »
 Mix the yeast in with pine sap and let it fossilize into amber in a million years - give or take a hundred thousand or so - and it will keep a couple of million more.

I believe a starter would still be necessary.

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Offline ynotbrusum

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Re: yeast bummer
« Reply #26 on: May 30, 2012, 07:42:37 PM »
I just store in ziplock bags.  Use it within a month and you will have no problems pitching directly.  Longer than that and a starter is necessary.  After 3-4 months consider tossing it (you really should brew frequently enough to use it up in that time or just get new yeast).
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Offline Alewyfe

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Re: yeast bummer
« Reply #27 on: May 30, 2012, 09:38:23 PM »
Yes, you can mix it with 10-20% glycerol (final concentration) and freeze it solid, but in my experiments it still degrades over time (years) and freezing will kill some no matter what you do.  A better solution is to add enough glycerol to depress the freezing point below the level of your freezer (about 0F) so that the mixture doesn't freeze solid, preventing die off.  But unless you have a cheap supply of glycerol on hand, adding enough to make it 50% glycerol get expensive fast, especially if you are doing slurries as opposed to the 1.5 ml tubes I use.

Really the best solution for most people is to keep it under distilled water, as cold as possible but not frozen, and then make a starter when you're ready.

This assumes you don't want to play with agar, and you really insist on ranching vs. buying yeast.

Tom, I have a neighbor who is a retired biologist who has offered my a very large container of glycerin. He apparently used it for preserving bugs and stuff. Tell me, please, exactly how to use it for freezing yeast samples.
I trust with an amply and free supply, I can freeze fairly large samples which would help speed up the stepping up process.
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Offline tschmidlin

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Re: yeast bummer
« Reply #28 on: June 03, 2012, 11:08:56 PM »

Tom, I have a neighbor who is a retired biologist who has offered my a very large container of glycerin. He apparently used it for preserving bugs and stuff. Tell me, please, exactly how to use it for freezing yeast samples.
I trust with an amply and free supply, I can freeze fairly large samples which would help speed up the stepping up process.
Oops, sorry i missed this.  It's really easy.  All you need to do is first, determine the concentration of glycerol you have.  It will say it on the bottle, and it's probably 100%. 

If you plan to freeze it solid (10-20% glycerol), the next thing you want to do is chill your yeast sample for 3 days or so.  This will maximize trehalose in the cells, which serves as further cryoprotection.  It is not strictly necessary, but it should help more cells survive freezing.  You also want to chill your glycerol, because within a few minutes of warming up the yeast will lose the trehalose.  Mix the glycerol with the yeast sample (keeping it all chilled) and stick it in the freezer.  The slower it freezes the better.  To figure out how much glycerol to add, use 25% of the volume of the yeast sample - so for 20 mls, you'd use 5 mls of 100% glycerol, this will give you 25 mls at 20% glycerol.  It's that easy.  I don't recommend mixing them and then leaving it in the fridge for a few days, because healthy yeast can use the glycerol as a carbon source and will break it down.  Slower at cold temps obviously, but it might still be a problem (I haven't tested it).

If you are mixing it to get 50% glycerol final, then don't worry about chilling anything, the sample won't freeze anyway so the trehalose isn't important.  Just mix the sample 50/50 with 100% glycerol you'll end up with a sample at 50% glycerol concentration.

I wouldn't go with large volumes, you'd be better off making starters from small samples because glycerol can affect the mouthfeel of the final beer.  Doing 30 ml samples or so should be fine though.

I think the other thing to worry about is the sanitization of the glycerol.  I don't know what it had previously been used for, but you could just end up contaminating your yeast.  If you have a way to sterile filter it that would be good.  We've never autoclaved it so I don't know what that would do, but I imagine it would darken and chemically change it somewhat, so sterile filtering is preferred.
Tom Schmidlin

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Re: yeast bummer
« Reply #29 on: June 04, 2012, 05:49:50 AM »
If you want to store it longer, rinse it with distilled and water and store it with distilled water.

I thought it was recommended to use (sterile) tap water to reduce the osmotic pressure differential. Thoughts?
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