how long can I keep harvested yeast for?

[Pdaigle]

I have a bunch of harvested yeast in my fridge and Im wondering for how long this is good for?

Cheers All

 

[flars]

I just tossed some yeast from this last April and June because it looked a little greyish. Used some yeast from June of 2015 for a new starter. How long yeast can be stored is variable. A lot depends upon temperature, sanitation, and fermentation stress. Plan for at least 6 months if your harvest technique is good.

 

[Pdaigle]

I just tossed some yeast from this last April and June because it looked a little greyish. Used some yeast from June of 2015 for a new starter. How long yeast can be stored is variable. A lot depends upon temperature, sanitation, and fermentation stress. Plan for at least 6 months if your harvest technique is good.

have some from last April 2015... maybe I will try to do a starter with it. Yeah they start to grey out as they age.

 

[sky4meplease]

I don't mind making fresh yeast so I may be a little conservative but in the summer when I don't have as much time to propagate I harvest more often.
I will direct pitch two weeks after harvest anything longer than that up to a month gets a starter and after a month I toss it in the trash and start from fresh.
Life is too short to brew with old yeast.

 

[catdaddy66]

I have used yeast that was 18 months old from my fridge. I had to step up a starter 3 times but it worked and they fermented my batch as they should have.

Yesterday I made two starters and one was abbey ale yeast (wlp530) that was at least that old. I anticipate a lag in growth but should see some activity by tomorrow.

 

[Pdaigle]

I have used yeast that was 18 months old from my fridge. I had to step up a starter 3 times but it worked and they fermented my batch as they should have.

Yesterday I made two starters and one was abbey ale yeast (wlp530) that was at least that old. I anticipate a lag in growth but should see some activity by tomorrow.

Wow. I may try this. So you are saying I should do my starter gradually. I dont have to do a big one just one liter starter

Thx

 

[oujens]

Wow. I may try this. So you are saying I should do my starter gradually. I dont have to do a big one just one liter starter

Thx

I believe this is recommended when you anticipate a low cell count in your harvested yeast. The idea would be to not stress the yeast by pitching them into a big starter until they have been refreshed and closer to a cell count for a normal starter. I haven't used yeast that old before, but maybe you could put a little bit of the slurry in 100ml of wort for a couple of days. If all goes well, kick it up to a liter (or whatever your calculator tells you) and you should be set. Using a small amount of slurry and stepping it would also produce a cleaner starter to pitch.

 

[brewstergalVT]

Not to be the negative one here but ideally, harvested yeast which has been refrigerated should be used in a week, maybe 2 weeks (depends on the strain). Yes, you can ferment with very old yeast and yes, your beer may be fine but it will be better with fresher yeast. Much depends on the strain of yeast, some can handle stress better than others. Some depends on what the yeast last fermented, was it stressed by temperature, high alcohol, lots of adjuncts, etc.? If you could stain the yeast and look at them under a microscope you'd see how many (or should I say how few) yeast are looking healthy. I used to save yeast (for too long), make up a starter and let it grow up and pitch it, sure that all was fine. Once I got a microscope and saw the condition of my yeast, I changed my practice. So yes, you can brew with old yeast, just like you can brew with moldy LME or stale grain, it just won't give you the best end result. Think of yeast like fresh vegetables: don't forget about them at the back of the fridge.

 

[sky4meplease]

Not to be the negative one here but ideally, harvested yeast which has been refrigerated should be used in a week, maybe 2 weeks (depends on the strain). Yes, you can ferment with very old yeast and yes, your beer may be fine but it will be better with fresher yeast. Much depends on the strain of yeast, some can handle stress better than others. Some depends on what the yeast last fermented, was it stressed by temperature, high alcohol, lots of adjuncts, etc.? If you could stain the yeast and look at them under a microscope you'd see how many (or should I say how few) yeast are looking healthy. I used to save yeast (for too long), make up a starter and let it grow up and pitch it, sure that all was fine. Once I got a microscope and saw the condition of my yeast, I changed my practice. So yes, you can brew with old yeast, just like you can brew with moldy LME or stale grain, it just won't give you the best end result. Think of yeast like fresh vegetables: don't forget about them at the back of the fridge.

Amen!

I think if what you are brewing relies on the yeast for more than just an acceptable attenuation level then starting with a pure culture, harvesting in as sterile an environment as possible, using the harvested yeast within a few weeks or a month at most and not harvesting yeast beyond a handful of generations unless you have a way to verify its purity would be beneficial.
Additionally, I think using proper pitch rates, yeast nutrient, sufficiently oxygenated wort and an appropriate PH helps to minimize drift in harvested samples.

 

[flars]

Amen!

I think if what you are brewing relies on the yeast for more than just an acceptable attenuation level then starting with a pure culture, harvesting in as sterile an environment as possible, using the harvested yeast within a few weeks or a month at most and not harvesting yeast beyond a handful of generations unless you have a way to verify its purity would be beneficial.
Additionally, I think using proper pitch rates, yeast nutrient, sufficiently oxygenated wort and an appropriate PH helps to minimize drift in harvested samples.

At how many generations do you quit harvesting yeast or do you overbuild your starters to use yeast which has never fermented a batch of beer?

 

[JohnSand]

I've used 6 month old yeast successfully. I did make a starter, it took right off, same in the batch.
Many people don't have an LHBS, weekly yeast purchases are not an option.

 

[Pdaigle]

At how many generations do you quit harvesting yeast or do you overbuild your starters to use yeast which has never fermented a batch of beer?

Ive heard 10 is max

 

[burdbrew]

I don't mind making fresh yeast so I may be a little conservative but in the summer when I don't have as much time to propagate I harvest more often.
I will direct pitch two weeks after harvest anything longer than that up to a month gets a starter and after a month I toss it in the trash and start from fresh.
Life is too short to brew with old yeast.

I went to BYO boot camp a couple of months back, and what you describe is exactly what Chris White recommends. To the tee.

As for myself, I have pitched 6 week old harvested yeast with no issue. I always measure FG, and performance was on par.

I once used the same pitch 15 times just to see what would happen, and the yeast performance never degraded a bit (I tapped out at 15, but I surely could have kept going).

I made a starter with year old yeast once, just to see what would happen. The yeast performed admirably after being woken up. Beer was great.

It really all depends. I'm not looking to pitch crappy, tired yeast, I just don't find yeast to be particularly fragile when I experiment.

 

[masonsjax]

Yeast is tough. Not that I'd recommend it, but I have made beer using a yeast cake that had completely dried to the inside of a carboy for 7 or 8 months and it took off quickly, fermented clean and tasted great. I just wanted to see if it would do anything and it worked far better than I would have hoped.

I usually store yeast in the fridge in mason jars under a little beer from the batch they came from. Every 3-6 months if I haven't used it, I'll decant most of the beer off the top and add some fresh wort. This keeps the yeast happy and healthy.

I usually make 5-10 batches on the same yeast cake, dumping a little out each time so I'm not way overpitching. I can't remember ever having any issues with the yeast, off flavors or attenuation changes.

To each his own. I try to keep my yeast as healthy as possible, but they seem to be all but invincible and are very good at what they do, despite my outright negligence.

 

[sky4meplease]

At how many generations do you quit harvesting yeast or do you overbuild your starters to use yeast which has never fermented a batch of beer?

I don't normally harvest from starters but that is fine for storing a culture assuming it is done antiseptically.
Regardless it is still harvested and should be used while it is fresh.
Once yeast gets strung out generationally it has been exposed to bacteria and wild yeast during transfers. If you have a microscope you can view for this to visually verify purity and perform tests to assess viability. Things can get out of hand quickly.
That being said I have read that a pure culture can get better after a couple generations and hit a stride so it can be beneficial to harvest yeast and assuming all is well 5-10 generations is not out of the question.
If you don't have a lab set up then play it safe and harvest to five generations and start over.
When I harvest I normally get enough yeast for 2-3 batches depending on what I will brew with it. If I do that five times I get 10 batches for $8.00. $.80 a batch?! I'm good with that.

 

[DurtyChemist]

I save mine about three or four months before deciding if I will use it again or if I'm keeping it because I'm trying to be cheap. If it's a special strain it might be worth brewing a batch of whatever it is to keep it fresh. I have some yeast that's 3 months old and next weekend I'll be doing a brew with it for a competition and to freshen up the yeast since the description says it is a good house strain.

 

[wingnutbrew]

The most I've ever let yeast stay in the fridge is 4 months and results were fine. That's not to say I wouldn't push it even more just that's all I have done so far. I moved a while back and did not brew for 8 months so I just scrapped everything and now rebuilding my yeast inventory. There were a couple jars that I cracked open and did the smell test and was thinking they'd be just fine but didn't want to take any chances so they went to the compost pile.

Bacteria infestation is the main thing you want to prevent. Try not to have much or any head space in your jars and have read where adding some hops on top before sealing can also help in this regard though I've not tried that technique but as of yet have not had an issue with bacteria.

There is a lot of advice and opinions out there but I am always very skeptical taking advice on reusing yeast from a company that sells yeast. I mean they're not gonna tell you all you have to do is buy one vial from us and if your harvesting technique is adequate you'll never have to buy that strain from us again. The other side of the coin is that they do need us buying yeast from them so they have the financial resources to continue to work on new strains for us to use. I do like some of the newer suppliers of liquid yeast upping the cell count to 200 billion. Giga Yeast & Imperial Organic come to mind.

I agree with masonsjax in that yeast is a pretty tough organism.

 

[RM-MN]

I went to BYO boot camp a couple of months back, and what you describe is exactly what Chris White recommends. To the tee.

As for myself, I have pitched 6 week old harvested yeast with no issue. I always measure FG, and performance was on par.

I once used the same pitch 15 times just to see what would happen, and the yeast performance never degraded a bit (I tapped out at 15, but I surely could have kept going).

I made a starter with year old yeast once, just to see what would happen. The yeast performed admirably after being woken up. Beer was great.

It really all depends. I'm not looking to pitch crappy, tired yeast, I just don't find yeast to be particularly fragile when I experiment.

This is really good advice. Especially so if you happen to own a yeast lab that sells fresh yeast. Color me just a little skeptical.

 

[drunkinThailand]

Breweries reuse yeast indefinitely, so you can keep reusing it as long as it tastes good. It will mutate over time and taste differently, but as long as it still tastes good...

as for how long to save, as said here can be over a year. just make a starter to proof it and make sure its still alive, and wake it back up.

the proof is in the pudding as they say... or you can just buy new yeast for a couple bucks. but where i live yeast can cost half the price of a whole batch, so i avoid buying more at all costs (or at the cost of half a batch)