Saturday, 1 November 2014

The truth about Nottingham Ale Yeast

My first investigations into what exactly Lallemand's Nottigham Ale Yeast is have been completed and the results are surprising.

First I rehydrated some yeast and plated it out on WLN agar. In the main the colonies where very white, though a few colonies with a green tinge were in there too. The white colonies looked very much like lager yeast, so it appeared the man from Surebrew was right. I was after better evidence than just the look of the colonies though, so I separated out the different strains as best I could and incubated them at 37 degrees C. Lager yeast is unable to grow at this temperature so if the white coloured strain didn't grow the results would be confirmed.

That's not how it worked out though, as two days later I found both strains had grown well at 37, though for some reason they'd both developed more colour.


So I've found no evidence that there is lager yeast present. Nottingham Ale Yeast is indeed ale yeast, though it does appear to be a mixed culture. My investigations continue.







11 comments:

  1. I really should look at your blog more often. Yeast is such fascinating stuff.

    I have a hunch that dried yeast strains are cultured and cultivated so that the strain is not a regular beer yeast at all. We have tried cropping from dried yeast fermentations. We now propagate up strains from "home brew" viles as well as having used lab propagated production pitchable supplies.

    Dried yeast doesn't pitch on well in our experience. Off flavours like phenols and unpleasant esters introduce very quickly after 2-3 generations.

    "Wet" yeast does not do this anything like as much even after many more generations. At least, this is our experience. It is of course possible that we have done something wrong when we have tried to propagate yeast that is a dried strain.

    My suspicion is that dried yeast strains are developed to stop commercial brewers having good results from normal re-pitching. Perhaps they are even genetically modified. Would we be able to know? I know GM food stuffs should be marked as such, but yeast might class as a "food processing aid" and it seems it might not need to be labeled as GM. Brewing enzymes are often made from GM micro-organisms, but they don't need to be labeled GM.

    This is only through our experience, rather than any true scientific experiment. We are a commercial brewer and therefore when something didn't go quite right we stop doing it and try something else, rather than carry on the experiment to get to the bottom of it. The only really sensible way to prove any of this would be to have the strains genetically fingerprinted.

    What intrigues me here is your assertion that lager yeast "is unable to grow" at 37 degrees. Now, I know you are far more knowledgable than me on this subject, but I'd like to question if proving it does grow at 37 degrees proves it isn't lager. Could it not be that case that it is indeed derived from a lager strain but modified or cultivated to be able to sustain higher temperatures? I honestly don't know, but it's all a very interesting subject.

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  2. GROWTH OF SACCHAROMYCES CEREVISIAE AND SACCHAROMYCES UVARUM IN A TEMPERATURE GRADIENT INCUBATOR

    http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1977.tb06813.x/abstract

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  4. I have had mixed results when reusing dry and wet strains. Granted it is in a homebrew setting without a lab. I have found that most dried yeasts crap out after just three or four uses, but I have repeatedly gotten Safale's S-04 to go to 10 or higher. I did see that Mangrove Jack specifically states that their drying technique renders the yeast unsuitable for repitching. I thought they were saying that just to shift more product, but sure enough theirs craps out earlier than anyone else's strains. Funny thing too about their lineup - all of their different UK strains taste exactly the same.

    On the wet side, again very mixed but generally they last longer. I have noticed that Wyeast products consistently do better than White Labs, including a batch of 1469 which we recently pushed to 20 uses. However, without proper propegation techniques, simply capturing and repitching, we have noticed some creep in the qualities of the strains. For example, towards the end of those 20, the lovely stone-fruit esters 1469 is famous for had faded to a more neutral flavour, and my fiancée who among other things taste tests production batches for Dogfish Head, insisted I chuck it at that point as she no longer liked its performance. I suspect different strains act in very different ways to simple repitching. I know a lot of these are actually multistrains that are kept in balance, and we've all heard of breweries who struggle to maintain the correct balance between the constituent parts of their house multistrains. Perhaps our flavour creep is connected to the different growth rates of the various strains that make them up...

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  5. Moaneschien, Interesting article. It seems, in summary, to show that all the brewing strains of S. Uvarium that were TESTED indeed have a Tmax lower than 37deg. However, some other, non-brewing strains could have a Tmax of 40deg.

    My point is do we know that all brewing strains have this lower Tmax? or might there be strains that behave differently? I certainly know there are significant differences between the temperature performance of various S. Cerevisiae strains, so why not lager yeast too?

    I know, I'm being pedantic, as we know that most regular lager strains respond at lower temperatures, so it's a good indicator. However, is temperature of incubation an absolute proof of the strain being lager or not?

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    1. Growth at 37 degrees C is a standard way of distinguishing ale yeast from lager yeast, see e.g. The IBD Blue Book on Yeast: http://www.ibd.org.uk/learning/learning-resources/reading-list/42/reading-list/?groupID=51

      I don't know if anyone has done any work since the paper Moaneschien linked to, or if the non-brewing S.uvarum transferred to S.pastorianus with lager yeast or if they stayed as uvarum. Knowing what microorganisms are like I'm loathe to say anything is an absolute so I'll just stick with staying it's a standard test for now!

      I am hoping to do some further work in the Nottingham yeast strains so I'll keep you posted.

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    2. Good stuff. It's all very interesting so I'm keenly waiting the results of your investigation.

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  6. Edd, I think your comment about mixed strains being a reason for flavour creep is as good an explanation as mine. Possibly better, even.

    I think most good brewers would consider 20 generations to be quite a good use of a propagation. Once at this point the cropping regime, cleanliness, length of time between cropping and pitching, yeast growth due to nutrients, O2 etc will be the limiting factors I suspect. Fullers, I know for a fact, only go to about 6 generations. This is partly because they maintain their own strain and have a lab that can culture up easily. Why risk beer on older generations when you don't have to?

    We find that our diverse brewing schedule occasionally puts too much time between cropping and pitching to be reliable so have never got to 20 generations. And anyway, we have worked out how to reliably culture up in 3 days form a tiny £6 batch of White Labs to pitch into 16hl.

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    1. It's quite possible dried yeasts are multi-strain. The Surebrew bloke said he'd found five strains in US 05, and it looks to me like there's at least two in Notthingham.

      Another possibility about why they don't take well to repeated re-pitiching is they've adapted to being pampered in the lab when they're propagated and don't do as well in breweries. They won't be GM though, as GM yeasts haven't made it out of the laboratory so far.

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  7. I suppose it depends what the bloke meant by "lager yeast". A strain used to brew lager, or just some sort of S. pastorianus (or whatever the eggheads are calling it this week).

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