Harvesting yeast, expiration?

[azazel1024]

I've seen many people claim that harvested yeast, vials, etc. lose roughly 25% viability per month fridge stored.

I am wondering, how do people use/store their yeast and how long are they willing to use yeast after it was "fresh"?

I just started making oversized starters/harvesting and growing a fresh starter.

Right now I am kind of brewing all over the map, but I know that a good US west coast and an English strain I'll use every couple of months, so that will always be fresh. Other stuff, not so often.

Ideally I've love a US West coast, a UK, a Belgian Trapist and a couple of lager strains. Maybe a Heffe strain too.

However, with some of those, I might only be brewing it twice a year. Should I expect I'll need to buy a new vial if I am pushing past 3-4 months of fridge storage? Or are some of you culturing up a starter from yeast that is 6,8, 12 months old? I don't mind low viability, because a lot of times I am only making a 2.5 gallon batch, so if I am culturing up from only a billion cells, I can have a right sized pitch with a simple 1000ml starter and a stir plate in 3-4 days. Or a 2 gallon starter for lagers.

Thanks!

 

[dhutchings]

Last Monday I started an Aventinus clone brew. I harvested some WLP351 from my last Weissbier batch in August that I used for this batch. Washed the yeast and stored it in the fridge since then. I was worried about its viability but in a 2L starter the yeast woke up and reproduced like you wouldn't believe. That was after 8 months.

How well will it turn out? Too early to say. It's only been in the fermenter 1 week so far. But it fermented very aggressively for the first 4 days.

 

[Calder]

I save a sample from my starters. I use half pint mason jars.

I reuse slurry for consecutive batches, so the starter sample sits a while. After 3 to 6 months in the fridge I usually decant the beer and replace with distilled water. I figure the yeast is well asleep.

I try not to let the samples go longer than 2 years, but have sucessfully revived several after about 30 months. I have never failed to revive a sample.

 

[brewprint]

I've gone 6 months from WL Kolsch. That was harvested from a starter. Absolutely no issue.

I believe that yeast will last a long long time in the fridge.

 

[desabat]

I have a mini wine cooler that chills down to 45 Farenheit? Is that too warm to store washed yeast?

 

[Calder]

I have a mini wine cooler that chills down to 45 Farenheit? Is that too warm to store washed yeast?

Yes, and no.

Sure you can store it at 45 F! But it will will deteriorate much faster than if stored around 35 F.

 

[WoodlandBrew]

Over the last few months I've been collecting fermentation metrics of yeast stored in water, beer, and frozen. I have data out 65 days and so far there is not a discernible trend in viability, lag time, growth rate, attenuation or biomass yield in the fermentation after storage.

How long the yeast is good for is much more dependent on cleanliness when preparing the samples for storage than it is on the time that it is in storage.

If you not sure of the quality of your yeast you can make a liter or two of beer as a test batch and then use the slurry to pitch your next beer. (Here is how to make beer in 15 minutes:https://www.homebrewtalk.com/15-minute-brew-process.html )

 

[azazel1024]

Thanks all. Maybe I'll try worrying about it a little less. Doesn't cost a whole lot to experiment by just doing oversized starters and filling a vial. Then a week out, I can try to make a starter from the vial, even if the vial is 6-12 months old. I guess worst comes to worse, I can re-vivify it and I need to run to my LHBS and buy a new vial.

Probably my "big" experiment will this fall when I do my annual Oktoberfests, since it'll probably be a full year before I brew them again (actually, Saison will be first, since I like the Belle Saison yeast, I'll probably pitch a tiny bit of slurry and make a clean starter from that and bottle a vial for next summer and see how it goes).

Saison and Oktoberfest are probably the two that I only brew 1-2 times a year and only every 10-12 months. Most of the others, Belgian, German Lager/German Bock, English Ale and West Coast Ale I tend to brew more often than every 6-8 months.

I guess I should stop worrying and learn to love the home brew