How long do yeast cultures last?

I have two yeast cultures that have hops in them that are maybe a month old. They don't have anything floating on top of the beer and the yeast cake looks healthy and is half hops... is it ok to pitch? It's been warm =/ I know you normally refrigerate them after 12 hours of making them....

I'd not want to pitch them directly into a full batch of beer, however there is no reason you can't make a starter to check and proof the yeast, viability and characteristics.

It doesn't sound like you've washed your too well if there is hops floating on the surface. But if your storing washed yeast or wondering about old smack packs and tubes.

If you're stepping up a starter, then the age of a yeast isn't really an issue.

Bobby M did a test on year old stored yeast here; https://www.homebrewtalk.com/f13/testing-limits-yeast-viability-126707/

And my LHBS cells outdated tubes and packs of yeast dirt cheap 2-3 dollars each and I usually grab a couple tubes of belgian or other interesting yeast when I am there and shove it in my fridge. and I have never had a problem with one of those tubes.

I usually make a starter but I once pitched a year old tube of Belgian High Gravity yeast directly into a 2.5 gallon batch of a Belgian Dark Strong, and after about 4 days it took off beautifully.

With any stored, old yeast you just need first to apply the "sniff test" if it smell bad, especially if it smells like week old gorilla poop in a diaper left on the side of the road in the heat of summer.

Then make a starter, and if it takes off you are fine. The purpose of a starter is to reproduce any viable cells in a batch of yeast....that;s how we can grow a starter form the dregs in a bottle of beer incrementally...and that beer may be months old.

Even if you have a few still living cells, you can grow them....That's how we can harvest a huge starter (incrementally) from the dregs in a bottle of some commercial beers. You take those few living cells and grow them into more.

If yeast can be grown from a tiny amount that has been encased in amber for 45 million years, 45 million year old yeast ferments amber ale we really don't need to sweat too much about how old a yeast is, if it's properly stored.

we just need to think in terms of making starters. Viability isn't really an issue if you are reproducing a lot of healthy cells. Which is what you are doing when you make a starter.....

Really even with "old yeast" if there is a few cells, they will reproduce.

Revvy said:

With any stored, old yeast you just need first to apply the "sniff test" if it smell bad, especially if it smells like week old gorilla poop in a diaper left on the side of the road in the heat of summer.

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Very informative post Revvy.
However, I've had some yeast (Kölsch yeast for example) turned into starters that smell pretty bad for the first couple of steps, that went on to perform as expected and produce very nice beer. While I don't know what roadside diapered gorilla poop smells like, these did smell like old rotten moldy burnt rubber tires, which I imagine is just as bad.

Wolfy said:

Very informative post Revvy.
However, I've had some yeast (Kölsch yeast for example) turned into starters that smell pretty bad for the first couple of steps, that went on to perform as expected and produce very nice beer. While I don't know what roadside diapered gorilla poop smells like, these did smell like old rotten moldy burnt rubber tires, which I imagine is just as bad.

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I don't know if you know the story of Charlie Papazian's yeast (White Labs "Cry Havoc") or not. He talked about it on basic brewing. The recipes in both Papazian's books, The Complete Joy of Homebrewing and The Homebrewers Companion, were originally developed and brewed with this yeast. Papazian had "Cry Havoc" in his yeast stable since 1983.

He has used it nearly continuously since 83, sometimes pitching multiple batches on top of a cake, sometimes washing or not washing, etc. In a basic brewing podcast iirc last year he talked about how a batch of the yeast after a lot of uses picked up a wild mutation, and he noticed an off flavor in a couple batches.

Now most of us would prolly dump that yeast. Instead he washed it, slanted or jarred it (I can't recall which,)marked it, and cold stored it, and pretty much forgot about it for 10-15 years. He had plenty other slants of the yeast strain, so he left it alone.

Well evidently he came across that container of yeast, and for sh!ts and giggles made a beer with it. Evidently after all those years in storage, the wild or mutated yeast died out leaving behind a few viable cells of the "pure" culture, which he grew back into a pretty hardy strain...which iirc is the culture that White Labs actually used for their cry havoc...because of it's tenacity and survivability.

It really to me, just goes to show once again how really hard it is to f up this beermaking, and that to give the yeast the props they deserve.

I have found that it is usually NOT the yeast that fails, but the brewer's faith.

From the OP's post it sounds like his yeast has been sitting out instead of the fridge. Hard to tell from his wording, but I'd think twice about using it if that were the case.

samc said:

From the OP's post it sounds like his yeast has been sitting out instead of the fridge. Hard to tell from his wording, but I'd think twice about using it if that were the case.

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Yeah that's what I said in the initil post; it didn't sound like it was washed and stored yeast...I was giving my info based on proper yeast handling, or commercial yeast.

Revvy said:

Yeah that's what I said in the initil post; it didn't sound like it was washed and stored yeast...I was giving my info based on proper yeast handling, or commercial yeast.

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I pulled some yeast from the bottom of a primary bucket after I had racked the batch into a carboy 7 days in, and put it into some wort I had boiled with pellet hops in a couple of growlers to make starters. It's been sitting warm for a month. The bottom looks like a healthy yeast cake mixed with pellet hops, and there is NOT hops or some sort of infection floating on the top.

I usually put them in the fridge after 12 hours to settle the fermentation and I warm and rouse it up before pitching.... unfortunately we had too much beer and there was no room in the fridge for the starters so they've been sitting warm in the fermentation closet for a month.

My question is what impact has the warmth had on these? I don't think they're ok to pitch anymore, but can I step them into another round of starters? Or am I going to get flavor problems....

Revvy said:

I don't know if you know the story of Charlie Papazian's yeast (White Labs "Cry Havoc") or not. He talked about it on basic brewing. The recipes in both Papazian's books, The Complete Joy of Homebrewing and The Homebrewers Companion, were originally developed and brewed with this yeast. Papazian had "Cry Havoc" in his yeast stable since 1983.

He has used it nearly continuously since 83, sometimes pitching multiple batches on top of a cake, sometimes washing or not washing, etc. In a basic brewing podcast iirc last year he talked about how a batch of the yeast after a lot of uses picked up a wild mutation, and he noticed an off flavor in a couple batches.

Now most of us would prolly dump that yeast. Instead he washed it, slanted or jarred it (I can't recall which,)marked it, and cold stored it, and pretty much forgot about it for 10-15 years. He had plenty other slants of the yeast strain, so he left it alone.

Well evidently he came across that container of yeast, and for sh!ts and giggles made a beer with it. Evidently after all those years in storage, the wild or mutated yeast died out leaving behind a few viable cells of the "pure" culture, which he grew back into a pretty hardy strain...which iirc is the culture that White Labs actually used for their cry havoc...because of it's tenacity and survivability.

It really to me, just goes to show once again how really hard it is to f up this beermaking, and that to give the yeast the props they deserve.

I have found that it is usually NOT the yeast that fails, but the brewer's faith.

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Cool post Revvy,
I would be interested to know if the "Cry Havoc" yeast today is really has the same characteristics it had in 1983.

RavenChief said:

Cool post Revvy,
I would be interested to know if the "Cry Havoc" yeast today is really has the same characteristics it had in 1983.

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That I dunno, and I don't think Charlie was able to conduct any experiments beyond brewing with the old batch. I haven't come across any info on that anywhere.

soGGy said:

My question is what impact has the warmth had on these? I don't think they're ok to pitch anymore, but can I step them into another round of starters? Or am I going to get flavor problems....

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If it was me, and I wanted to reuse that yeast, I'd work on the assumption that most of it is dead. I'd add a small sample to a small starter (say 5ml) and work up in steps from there.