how long can you keep a yeast cake?

[domdom]

i wanted to check how long you can keep a yeast cake as long as you keep an inch or so of beer on top of it? i've tried yeast harvesting about 5 times and 4 of those times i've ended up with the yeast getting infected. i would boil jars and lids for 15 minutes and still had issue, though was not using the yeast very quickly. the one time i didn't have issues i used the yeast within a month.

i'm also wondering as i'm planning to do a really big RIS (around 12-13%) and wanted to know how much wiggle room i would have for timing a batch before the big brew.

thanks!

 

[RPh_Guy]

4 contaminations? Wow, I would have tried an alternate process after 1 or 2 contaminations.

Overbuilding a starter is in my opinion the best method to propagate yeast for multiple batches.
You should be able to store it refrigerated under beer for several months at least.

Do you live somewhere that it's difficult to get yeast locally or via mail? If not, it might be better to avoid the hassle and risk.

 

[ehk089]

Not sure I’ve ever had an infection from pitching into a cake, however, I generally keg on brew day. That way the cake sits for maybe 2-3 hours before new beer goes on top. If you don’t have time the same day, dump that cake immediately into a couple mason jars, and screw on lids loosely, then put in fridge until you’re ready. I still wouldn’t keep the jars much longer than 6 months tops

 

[magno]

I've kept a yeast cake under an inch or so of beer for about two weeks before I was ready to pitch the next batch on it. I've had to hold off this long a couple times before, and haven't had an infection from it. Like ehk089, I try to avoid this by kegging on brewing day, but this wasnt't really an option before I was kegging.

 

[CascadesBrewer]

I have been follwing this https://www.homebrewtalk.com/forum/threads/simple-yeast-storage-procedure-with-photos.579350/ process since December with very good luck. I don't wash the yeast, but just collect slurry into sanitized jars. I have used yeast that was maybe 2 months old.