Just an FYI…we recently brewed a Kolsch, using yeast that was harvested over 5 moths ago. Yes, I was a little concerned as we normally re-use the yeast much quicker than that.
Upon stealing a one ounce sample, and doing my “Sniff 'n Taste” test, it is doing great! And the beer will be very good indeed.
So no worries if your harvested yeast is in storage for a few months! It will be just fine.
I’ve done up to 6 months with no issues.
I have done over a year with some cultures.
The oldest harvested slurry I’ve used was one month old. It was for an American lager, which turned out great. So I’m coming around to the anti-conventional-wisdom that harvested yeast can stay healthy/viable for a lot longer than commonly believed.
I usually brew Kolsch regularly. I haven’t brewed in awhile. I always use Giga021 and pulled my slurry out last week. I made a small starter to check it. It took 3 days to get going. It is going strong in the fermenter right now. It was 14 mo old by the way.
14 months…WOW! Our yeast is all very fresh, or maybe 3 months old now.
The 5 month old Wyeast Kolsch took about 3 days to get real active (no starter), but it is doing great and will produce another crowd pleasing beer.