(Accidentally) frozen dried yeast still viable?

Share your experiences of using brewing yeast.
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JamesF
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(Accidentally) frozen dried yeast still viable?

Post by JamesF » Sat Aug 01, 2020 5:57 pm

A few weeks back when I was making my last batch of beer I brought a packet of S-04 into the kitchen to make into a starter after which point I was completely unable to find it again and nor could anyone else. In the end I put it down to having a "senior moment" and hadn't actually got the yeast in the first place, so used another pack.

This weekend my son and I have been making a batch of Brewdog Punk IPA (his request). Whilst we were getting the hops out of the freezer I found a little blue packet :) It must have got caught up with the hops I was putting back into the freezer last time and I didn't notice. So perhaps I'm not going as senile as I thought.

Anyhow, now I have it, any thoughts on the viability of the yeast having spent three weeks at -18C? I can make the pack up into a starter a few days before I want to use it to see what happens and give me time to use another batch if they're dead as a dodo, but if they're highly unlikely to have made it anyhow then I shan't bother.

James

guypettigrew
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Re: (Accidentally) frozen dried yeast still viable?

Post by guypettigrew » Sat Aug 01, 2020 8:11 pm

Worth trying a starter. Dried yeast might just make it through a -18°C storage for three weeks.

Guy

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Re: (Accidentally) frozen dried yeast still viable?

Post by vacant » Sat Aug 01, 2020 8:57 pm

Bread yeast can be frozen. I tried this dividing up a 500g block a few years ago, the viability of a defrosted yeast/flour bag was noticeably less than fresh but it was economical.
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WalesAles
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Re: (Accidentally) frozen dried yeast still viable?

Post by WalesAles » Sat Aug 01, 2020 9:36 pm

JamesF wrote:
Sat Aug 01, 2020 5:57 pm
A few weeks back when I was making my last batch of beer
James,
Does this mean you have stopped brewing? [-X [-X

WA

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Trefoyl
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Re: (Accidentally) frozen dried yeast still viable?

Post by Trefoyl » Sun Aug 02, 2020 2:24 am

I keep all my dried yeast in the freezer, it lasts for at least 2 years. I take it out a few hours ahead and always rehydrate in warm (sterile) water before using.
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ned
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Re: (Accidentally) frozen dried yeast still viable?

Post by ned » Wed Aug 05, 2020 5:22 pm

Kal at the electric brewery has an interesting page on repacking and freezing dry yeast. He says no problem freezing it.
https://shop.theelectricbrewery.com/pag ... -dry-yeast

guypettigrew
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Re: (Accidentally) frozen dried yeast still viable?

Post by guypettigrew » Wed Aug 05, 2020 6:59 pm

Interesting thought about using a non-frost free freezer. The hot and cold cycling would possibly harm the yeast if it's on the freezer bars.

In a home freezer the best way would probably be to sit it on top of something else already in the freezer to avoid this.

Guy

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