Frozen Yeast Starter

Doh!

So I made a beautiful 5.25L starter of Budejovice yeast. Pitched in 3 vials of yeast. 2 were close to their due date and one was past it's due date. Got great activity in 24 hours and was super stoked to brew my lager tonight. Just went to the fridge where I had it cold crashing to see how clear it had dropped and...

Well, I guess that fridge cabinet gets colder then I realized.

Sorry to hear that. As you probably already know, freezing yeast kills it.

Say a few kind words and dump it.

andy6026 said:

Sorry to hear that. As you probably already know, freezing yeast kills it.

Say a few kind words and dump it.

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Yup. Gotta go to LHBS (45 minute drive) to get replacement yeast...just gotta laugh sometimes.

I made the mistake of using thawed yeast (after I was told by a local brew shop it would be ok) and ended up dumping the whole 5 gallons.

No way would I dump it!

While this freezing will have killed some of the yeast, it won't have killed them all. If it was me, I'd thaw and throw on fresh wort and pitch at about 12 hours when krausen is high. I've accidently done the same as you and the rescued lager was fine.

Quadrupled said:

No way would I dump it!

While this freezing will have killed some of the yeast, it won't have killed them all. If it was me, I'd thaw and throw on fresh wort and pitch at about 12 hours when krausen is high. I've accidently done the same as you and the rescued lager was fine.

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Thanks for the feedback, but I'm concerned about cell counts and how much would have survived. It froze pretty good. And I needed this 5L starter to get the count I needed. I don't really have time to step it up again, although if I was certain I had enough cells I could do a 1L starter and pitch it at high krausen...I'm just skeptical that's the case.

This is going to be a Czech Lager, so decanting before pitching is kind of important if I do anything larger then a 1L starter....and that also means more time.

For what it's worth, my frozen yeast experience was for 10 gallons of Classic American Pilsner so I too had something which could really let flaws stick out. I split this into two 5 gallon vessels for my two starters; one of which was fine and the other froze.

I couldn't tell a difference in flavor and the final gravity of each was similar. Not sure how similar the two would be judged if Gordon Strong or Jamil were doing the assessing of them, but it worked out well for home consumption.

Good luck with however you go forward.

Thanks Quad. Much appreciated.

White Labs says that you should expect a 10% drop in viability if a vial is frozen. I'd imagine a frozen starter would be similar.

Reviving this ancient thread to give my two cents. I just accidentally froze a 3L starter of WLP029. I'd planned to pitch 2L and save 1L for next time. This thing was a solid block of ice after a sub-zero night in the fridge. I gently thawed it over a few hours and pitched into my wort, and 8 hours later had pretty active fermentation. I'm sure a few cells kicked the bucket but it seems to be rocking along nicely. I do have an emergency pack of US-05 on hand but doesn't look like it will be needed.

As to the remaining 1L, it's back in the fridge and I'll spin it up for my next brew. Sure it will be fine.