![]() I don't know if these correlate to the main genetic groupings of S.cerevisiae-eubayanus "lager" hybrids, the triploid (well, 3n-1) Saaz group which has lost much of its cerevisae-ness, and the allotetraploid Frohberg group which has lost much of its eubayanus-ness. In particular, there seems to be a group of lager yeasts that seem to ferment cleanly at ale temperatures - 34/70, S-189 and the California Common/steam yeasts. That thing about lager yeasts not growing at 37C seems like the kind of thing that's ripe for exceptions, given how we know that growth temperature is a moveable feast (qv Norwegian landraces), it's the sort of phenotype that is a prime candidate for selection through the years. Perhaps our flavour creep is connected to the different growth rates of the various strains that make them up. ![]() ![]() 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. I suspect different strains act in very different ways to simple repitching. 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. However, without proper propegation techniques, simply capturing and repitching, we have noticed some creep in the qualities of the strains. I have noticed that Wyeast products consistently do better than White Labs, including a batch of 1469 which we recently pushed to 20 uses. On the wet side, again very mixed but generally they last longer. Funny thing too about their lineup - all of their different UK strains taste exactly the same. I thought they were saying that just to shift more product, but sure enough theirs craps out earlier than anyone else's strains. I did see that Mangrove Jack specifically states that their drying technique renders the yeast unsuitable for repitching. 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. Granted it is in a homebrew setting without a lab. I have had mixed results when reusing dry and wet strains. ![]() 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. 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. What intrigues me here is your assertion that lager yeast "is unable to grow" at 37 degrees. The only really sensible way to prove any of this would be to have the strains genetically fingerprinted. 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. This is only through our experience, rather than any true scientific experiment. Brewing enzymes are often made from GM micro-organisms, but they don't need to be labeled GM. 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. Perhaps they are even genetically modified. My suspicion is that dried yeast strains are developed to stop commercial brewers having good results from normal re-pitching. ![]() It is of course possible that we have done something wrong when we have tried to propagate yeast that is a dried strain. "Wet" yeast does not do this anything like as much even after many more generations. Off flavours like phenols and unpleasant esters introduce very quickly after 2-3 generations. We now propagate up strains from "home brew" viles as well as having used lab propagated production pitchable supplies.ĭried yeast doesn't pitch on well in our experience. We have tried cropping from dried yeast fermentations. I have a hunch that dried yeast strains are cultured and cultivated so that the strain is not a regular beer yeast at all. I really should look at your blog more often. ![]()
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