Freezing yeast -- Sterilization

So, I'm going to do the yeast freezing that the article mentions with glycerine, etc., and I'm going to make a starter and build up some 1318 London Ale III yeast.

I bought the Karter Scientific plastic centrifuge containers (50 ml), and though they are autoclavable, I don't have a pressure cooker. My question is this: Can I just pour 70% Isopropyl in them for a few minutes, wipe the tops/threads down, dump that out and keep moving? Can I use StarSan?

Any thoughts and help would be much appreciated.

Glycerin is a necessary addition for the recovery of healthy yeast.

If the tubes come pre-sterilized, use them as is, being very careful of course but still spraying everything down with starsan.

If not, alcohol or starsan will work fine. Alcohol is most effective when it evaporates, starsan can be left wet in the tube.

I have been using Starsan and have revived frozen yeast that I have stored for over a year. The current one is 1056 second generation frozen on January 17, 2012. It will be going into my Pumpkin Ale tomorrow.

I use 20 ml vials with 5 ml yeast, 5 ml glycerin and 10 ml sterile water.

Next up will be a Belgian Blond using 3787 Trappist High Gravity.

Thanks so much. I'm probably going to buy a pressure cooker, but I already have this yeast, etc, so I figured I'd give 'er a shot.

Yeah, I got the Food Grade Glycerine. I'm ready, willing, and now, hopefully, able! Haha.

This forum is a great resource, and I appreciate the quick responses.

for my slants (using glass vials) I will sanitize, then spray with rubbing alcohol, then put them upside down on a sanitized and well-boiled steamer basket in a stock pot to steam for about 10 minutes. I'm aware this doesn't get me to the temperatures needed for true sterilization, but its as close as I'll get without a pressure cooker. Steaming basket costs a couple bucks.

BlackGoat...thanks for the suggestion. I thought about using a steam basket, but then, I was worried about not getting to 240*F. Plus, these are plastic centrifuge containers...not glass slants.

Well, the first attempt at this post got erased so, I'll try again.

I also wanted to touch on storing the yeast in a "frost free freezer". Many of us don't have access to a non-frost-free freezer, and we probably don't have the room for a container full of an isopropyl bath, but I had a thought.

As an architect and a furniture designer/builder, I was wondering why it wouldn't be okay to use two layers for 2" rigid foam insulation (glued together) and drill holes with a forstner bit that would allow the 50 mL centrifuge tubes (or whatever someone else is using) to fit tightly in the holes. Freeze the tubes in an isopropyl bath, and then put them in the tight holes to protect from freeze/thaw. Would this not work?

Any thoughts???

^ Brilliant. Sub'd for further info on this.

Lost_Arkitekt said:

use two layers for 2" rigid foam insulation (glued together) and drill holes with a forstner bit Any thoughts???

Click to expand...

Exactly what I do, except with 4" foam. I do it for slow-freezing, but I don't see why it wouldn't work for storage too.