Saturday, 11 October 2014

Are dried yeasts what they claim to be?

I went to a SIBA meeting on Wednesday and a bloke from Surebrew gave a brief but interesting talk. For starters it was amazing to see a question and answer session on Brettanomyces, when barely over a year ago one of my beers was wrongfully disqualified from the specialist beer section of a SIBA competition because no-one knew what Brettanomyces was.

But it was when he was asked about dried yeasts that it got really interesting. He said Safale 04 is Whitbread B, something I'd previously seen Graham Wheeler (PBUH) say over at Jim's; US 05 is apparently composed of several strains, and Nottingham Ale yeast is in fact a mix containing 70% lager yeast. I'm quite astonished by this last point, and it also seems to me that it should be relatively easy to investigate if it's correct. If I remember rightly lager yeast can ferment melibiose whereas ale yeast cannot, and ale yeast is able to grown at 42 degrees C whereas lager yeast cannot. I'll have to check the details, and see what we've got a work, but this is one I'd really like to look into...

5 comments:

  1. If this information came from the manufacturer it would be one thing, but sounds rather like folklore to me.

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    1. Yes, which is why I'm keen to investigate it myself. I've heard various bit of gossip about dried yeast over the years but it would be nice to have some evidence.

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  2. I'd thought most of these well known yeasts like Nottingham were supposed to have been isolated/propagated from single-cell level? (Or is that a myth?)

    Saw a big "family tree" of yeasts based on something like genetic analysis once. Was on t'web... but I can't find it now. (Anything just on t'web is dubious of course.)

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    1. It's absolutely routine to culture from a single cell (well, Colony Forming Unit, but that's generally taken as close enough). What's happened when the strain is repeatedly re-pitched is where difference can have occured. Contamination and/or mutation can have altered what's being cultured.

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