From the HBD Archive
From: meyer@tcville.hac.com (Mike Meyer)
Subject: Freezing Yeast
Date: 1989-03-09 18:51:59 GMT

My original question was "Will inadvertantly freezing dried yeast (in the
packet) cause a reduction in viability?". I didn't get any responses via
E-mail, or I would have posted them to the list. I haven't come up with
any good answer yet through my own experience, either. I've pitched some
yeast from other packets that have been stored in the same refrigerator,
though a different area of the fridge that might not have frozen. This
yeast started up with no problems, but I can draw no conclusions from the
data. For now, I will assume that active dried yeast has enough moisture
in it to be damaged by freezing temperatures, and that it should be stored in
an area of the refrigerator that does not freeze, like the butter drawer.

Can anyone on the list with microbiology experience enlighten us about
the mechanism behind active dried yeast and the factors which affect
viability? ( I assume that some moisture is required in the yeast for it
to stay viable at all, hence the longer shelf life when refrigerated...)

Sorry I couldn't be more helpful, and I realize this has nothing to do with
freezing your cultures, which I have an interest in, especially with our
psychoactive batches...strictly in the service of science, of course. It
sounds like the yeast-freezing kits are a bit of a high-priced crock, and
can be easily duplicated using apparatus available from any lab supply
store. Can any one recommend a book on lab procedures for yeast culture?

Mike Meyer
meyer@tcville.HAC.COM

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