A recent thread on the board here mentioned freezing yeast slurry as a longer-term alretnative to refrigeration. Additionally, I recently heard about adding glycerin to the yeast before freezing.
Anyone have any experience with freezing yeast? Pros, Cons? Recommendations for or against?
This is the process I use when freezing yeast.
I’ve frozen small 10ml aliquots in 10% glycerol. You can get the glycerol from NB’s winemaking section, its a finishing chemical for wine.
I kept yeast alive for over a year this way. It was a pain to restart this small of an amount though. Any more I just keep cake and use a yeast a half dozen times, then buy new.
Does it save money in the long run? Is it worth the effort? I am always looking for ways to reduce cost & improve beer (at a reasonable cost of time).
You can pick up the glycerin at your local pharmacy, or look for USP.
I keep a frozen yeast bank of my favorite PC strains and a few that I have harvested from bottles. To me it is worth it for those strains. But, I do not recommend it for anyone who questions their sanitation or doesn’t want to put in a little extra work. You will have to step up your starters.
For my usual strains I just save slurry in the fridge.
I’m tempted to employ tom sawyer’s approach above…save the cakes, maybe wash a few times and re-use. Then spend a few bucks on new yeast when needed.
I recently racked a batch to secondary that I had put right on top of a used cake in the carboy for the first time…that seemed to work really well, and couldn’t be easier.
On a related note…I’ve read that using the same yeast much more than 4 times is risky for a variety of reasons…do others agree/disagree?
Also…If you took a single cake and washed and stored the yeast in multiple jars…could you not use the yeast from each jar 4 times…presuming that you make a starter each time and that generates a new cake…which you then split into multiple jars…etc, etc, etc…?
As long as your sanitation is good then there’s no real risk. You do have to worry about flavor carryover if you’re repitching from a very hoppy beer, but even that can be mitigated by discarding the trub and collecting clean yeast. (Not as easy in a flat-bottomed fermenter, admittedly).
