Freezing yeast glycerin question

[Surly_goat]

Doing my yeast bank. Have successfully frozen and reused my yeast a few times now so happy with my process.

Have been putting my glycerin in a mason jar and doing 20 minutes at 15psi with my water.

It's USP glycerin. This isn't necessary is it?

 

[lump42]

At the concentrations that would eventually end up in the finished product, it probably doesn't matter the grade too awful much. However, I personally would stick with food or medical grade, since those are both intended for human consumption.

If you are not using the entire vial to revive the yeast, avoid fully thawing the yeast. Scraping the top bit is enough to plate out or start a small culture.

 

[Surly_goat]

I'm doing 50ml vials of yeast slurry.

So make a starter. Decant extra. Mix slurry with glycerin at 15% concentration. Put into vial. Freeze.