Restarting frozen yeast

mplsbrewer · June 14, 2012, 4:47pm

so earlier this year I decided to test out freezing yeast. In January I took some British Ale II and mixed it up with 50% yeast 25% glycerine and 25% water, put it in the fridge for a day and then tossed it in the freezer. I used a thick Tupperware container filled with ice to try and neutralizer the defrost on our freezer. Last night I pitched it to a small starter after letting it defrost in the fridge for a day and thus far I have no activity.

How long does this normally take? It doesn’t smell bad so I think my sanitation was good but I guess they could have died at some point during my experiment.

gregscsu · June 14, 2012, 5:01pm

How much frozen yeast and what size starter?

I know it can take a day or two to see any activity in that situation.

mplsbrewer · June 14, 2012, 7:04pm

I think it was a 40ml glass vial I froze them in so that has to be 20ml of yeast and I pitched it into a 500ml starter which seemed like a lot to me but was what the directions I printed off earlier said to do.

brwrboy69 · June 14, 2012, 9:06pm

Did you shake it good before freezing to make sure the glycerine was thoroughly mixed with the yeast? You probably have very little yeast alive or maybe even none. If no activity for 2 days, you’ll know. I just dump it in a big starter, stick it on the stir plate, and wait. Don’t see much point in stepping up starters.

baratone_brewer · June 14, 2012, 11:36pm

Any idea what what your yeast concentration was? I am typically starting with approx 10B cells in a 250ml starter.

mplsbrewer · June 14, 2012, 11:47pm

I did do a pretty good job shaking it to mix everything up. I tried to pour the least amount of trub possible into the vial because it was such a small amount. Oh yeah, guess I should mention that. It is washed yeast from a pretty successful batch. If this fails I might try and make a starter for my next batch and freeze half a vial or two and pitch the rest. I don’t know where I got these numbers from but I wrote down months ago that there should be 37.5 billion cells.

I’m starting to think failed experiment as I’m approaching 24 hours but I’ll give it another day.

mplsbrewer · June 16, 2012, 1:36pm

So 48 hours in or so I noticed a thin foam on top so I shook it up instead of dumping it and this morning it looked like it had bubbled up a bit on the sides and then died down. I’ll probably let it go a while longer and then chill, decant and maybe add to a larger starter.

While I was buying my ingredients for the beer I was planning I picked up a yeast packet because I wasn’t sure this was going to work. Looks like I might have to make two beers now…Oh the troubled life of a homebrewer…

gregscsu · June 22, 2012, 2:44pm

Just restarted a frozen vial on Wednesday, didn’t notice ferm signs until the 24 hour mark.
50 Billion cells frozen in a 60 ml vial frozen in Feb, assumed 40% viability. Pitched into a 250ml simple starter. Signs of active ferm at 24 hours, at which point I added another 650ml of starter wort and tossed it on the stir plate.

mplsbrewer · June 22, 2012, 4:32pm

Well it looks like I’ve pulled it off. After a while it started to ferment at which point I let it go for a day and a half, cooled, decanted and added to a bigger starter, stir plate for a day, cooled, decanted and pitched to a beer last night! Seems to be chuggen along nicely and the starter smell fine so I think I’m in the clear.