OUCH! Frozen Yeast

[badhabit]

When I got home last night I found that 4 bottles of yeast that I had washed and stuck in the back of my refrigerator had frozen. They were not frozen solid but most of the wort covering the yeast was frozen, some more than others. I had not intended to freeze the yeast and had not prepared it to be frozen. My question is if it is worth a try to see if the yeast is still good. I thought That I just might make a starter and see if the yeast started growing. Then I wonder if it does start will the yeast be good or will it have been so stressed that it will not produce as it has or should. The biggest pain is that the yeast that froze wipes me out of two strains. Anyway do I try and save it or just pitch it, spend the bucks on new yeast and start over?

 

[Poobah58]

Decant and make a starter. What do you have to loose but a few ml of wort starter?

 

[badhabit]

I did some more checking around and reading and even ended up calling White Labs. They said give it a try even if I thought I Froze it solid. Evaluate how viable the yeast is after 24 hours in a starter. They also said, and to me this is the good stuff, that I will not segregate out a mutant freeze resistant strain by trying to propate the yeast. If it froze it won't work, if it didn't freeze it will start growing. If I have something worth keeping I should see a 10 fold increase in the yeast in the first 24 hours, if I did not I should think about just getting new. They were very helpful and said this was not an uncommon problem in cold winters. Bottom line is I threw the yeast in the starter and got good activity in less than 6 hours. I am waiting 48 hours and will decant and refrigerate. I am sure that the yeast will be fine, just lost one generation.

 

[badhabit]

Just wanted to give a final follow up on this thread. I used the frozen yeast this past weekend in a brew. Made a 1 L starter before and had good activity in the fermenter in less than 6 hours with very active fermentation complete in about 72 hours. I would say that everything worked out well.

 

[jeremydgreat]

Thank you for the followup badhabit. Same thing just happened to me and it was very assuring seeing it worked out!

 

[badhabit]

Just an FYI on this yeast in as much as you brought it back to life for at least a moment. I made three different batches of APA's and IPA's with that yeast. Opened the last of those three after conditioning this past weekend. All three of them turned out well, no off flavor. Interestingly there is another thread in the beginners section right now that froze some yeast. I have responded to that thread with this same info from the yeast lab.