how long to keep harvested yeast

[BierStreet]

is there a rule of thumb on how long yeast lasts in the fridge after being harvested from a previous batch?

 

[PoppinCaps]

I doubt you'll get a rule of thumb here, but I hear the general consensus is under a month, you can pitch it directly, up to a year or so and use a starter. I've done both just fine.

 

[BierStreet]

cool, Have a bunch of different strains in bottles in the fridge but not planning to brew for a while, gotta get the kegs up and working first

 

[Sacdan]

I have had success keeping yeast for several months, if not longer. I just make a starter.

 

[Revvy]

If you make a starter, then the age of a yeast isn't really an issue. When you make a starter, and grow it, you're replicating more yeast to make up for any loss. You're making new, fresh yeast.

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And my LHBS cells outdated tubes and packs of yeast dirt cheap 2-3 dollars each and I usually grab a couple tubes of belgian or other interesting yeast when I am there and shove it in my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.
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.

 

[mrbunn]

I had a slow start on yeast that had been in the fridge for 3 months here... Wyeast 3787 if i got my numbers right. It took a little under 24 hours to get any activity in the bubbler and I was kicking myself for not doing a starter, but I changed plans last minute and went Belgian rather than BIPA.

That said, it did go and blew yeast out the top of the bubbler after a few days.

 

[jonmohno]

Depends how you are harvesting too are you just scooping the slurry,or are you washing?this would be my question how long can you keep slurry that is in water? I have different sets of washed or slurry that i harvested, basically im using the slurry i have to jars of ,2 batches in 2 weeks, then i have a more of not less washed yeast that i plan on saving and using after 2 wks.Finally i have a double washed yeast wich has just a thin layer on the bottom which i plan to make a starter with.

 

[BierStreet]

The last few times we've harvested yeast, we just pour the yeast from the carboy directly into a bottle using a sanitized funnel. Keep it in the fridge then pour the beer on top off and make a starter a day or two before brewing, always has taken off fast in the next batch.

 

[jonmohno]

Yes, i have noticed from doing this i actually had some fermentation,maybe a krausen ring and a pft when opening the jar of slurry i used after a week. Im shure it would take off but i just use the slurry and go by oz amounts.

 

[ReverseApacheMaster]

I've used six month old washed yeast without a problem. A little slow to kick off but no off flavors or stuck fermentations. Right now I have a starter of brett and saison yeast chugging away on some leftover stout wort. It smells very...different.

 

[mux]

I'm experimenting with the residual yeast left in a white labs vial after pitching. I poured a little cooled wort into the vial and let it sit for 24 hours at room temp. I then pitched that into a proper starter. Worked pretty good I decanted and it'd in the fridge now. Im going to try grow it one more time than pitch it into a lower gravity wort.

 

[mux]

This is the cake after 48 hours.