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New research on dry yeast

Discussion in 'Yeast' started by nosco, 13/5/18.

 

  1. MHB

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    Posted 1/6/18
    The reason for washing is to remove the alcohol and other fermentation products, these can cause problems from two directions
    First Mutations are accelerated by contact with fermentation biproducts.
    Second Reducing the osmotic pressure on the yeast helps to stop it loosing minerals water and other cellular products that it will need next time you use the yeast. Ideally use mineralised water (very similar to what's in the wort you will by using when you next ferment)

    Acid washing is to reduce bacteria, by acidifying to around 2-2.2pH you can kill off most beer spoilage bacteria (if you think a multi generational culture contains just the yeast you want you seriously mistaken (probably)).

    For short term storage (days) the risk of getting an infection by water washing probably increases the risk of infection just through handling and exposure to air, for longer term (weeks) storage water/acid washing has distinct and measurable benefits in terms of strain purity, contamination counts, yeast health...
    For very long term storage (months+) you really need to be thinking about plates/slants/freezing... followed by stepwise re-culturing up to pitchable populations.
    Mark
     
  2. Byran

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    Posted 2/6/18

    Im with you mate. Why make an easy job less easy.
     
  3. snails07

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    Posted 2/6/18
    So that you can make better beer, perhaps?
     
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  4. Byran

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    Posted 4/6/18
    If you think rehydrating makes better beer then go for it. I dont.
     
  5. TheSumOfAllBeers

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    Posted 4/6/18
    You lose a lot of the cells when you pitch dry. This can result in under-pitching.

    Hydration doesn’t automatically improve the beer, it just ensures more cells survive the pitch, and helps you avoid any yeast stress issues if you are cutting it fine with the pitch rate
     
  6. MHB

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    Posted 4/6/18
    Going to agree - with some qualifications
    Most home brewers are under-pitching or pitching at the low end of the range. More is better (up to what sounds ridiculous)
    Hard to tell how many cells just die during drying and how many are killed on re-hydrating/pitching
    If you pitch into wort at the right temperature you get enough live/healthy cells
    If you re-hydrate at the right temperature you get enough live/healthy cells (temperature, mineral content, aeration...)
    If you don't temporise (adjust yeast and wort to same temp) you will have another kill event, further reducing he population.

    Either way done under the right conditions you will get good results, follow the instructions on the yeast carefully, depending on the time of cropping, type of yeast, drying method... there will be optimum methods for activating the dry yeast that will be yeast specific - there isn't a on size fits all method.

    I'm sticking with what I've been saying for years - "follow the manufacturers instructions"
    Mark
     
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  7. Rocker1986

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    Posted 4/6/18
    I harvest yeast from starters by making them a bit bigger than needed, then just stir it all up after it ferments out and tip the excess into a mason jar and stick it in the fridge. It sits in there until I need it next, usually somewhere between 1 and 2 months. While there most likely are other organisms in there with it, I have taken a few strains past ten generations without noticing any difference in the resultant beers. I've got a 1469 that I've been re-using for two years up to 14 generations currently. Interested to see how much further I can take it actually.

    I had also done some stain testing with trypan blue on a separate sample that was also stored under the starter beer (in a smaller jar). After two months it was still 80% viable. I know that viability testing doesn't tell you if the live cells are healthy or not, but without any fermentation or off flavor problems in the beers, the method can't be working too badly.

    On the odd occasions I use dry yeast these days, I always re-hydrate it in water first.
     
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  8. theSeekerr

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    Posted 14/6/18 at 3:40 AM
    So it looks like Fermentis have finally gotten around to publishing some of this stuff: https://fermentis.com/news-from-fermentis/technical-reviews/e2u-direct-pitching/

    E2U is the branding they use on pretty much all their dry yeast, so this is applicable to US-05, S04, Saflager etc
     
    Last edited: 14/6/18 at 4:08 AM
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  9. MHB

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    Posted 14/6/18 at 4:02 AM
    Good spot, be worth keeping an eye on over the next little while.
    Mark
     
  10. jackgym

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    Posted 14/6/18 at 9:08 PM
    I've never bothered to rehydrate yeast, it seemed to be an unnecessary step. Seems I've been proven correct.
     
  11. hoppy2B

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    Posted 15/6/18 at 12:47 AM
    That confirms what I have thought all along, homebrewers on here professing to know everything and belittling anyone who disagrees with them, are basically full of it. Which is to say, you don't know unless you do the tests.
     
  12. EmptyB

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    Posted 15/6/18 at 1:44 AM
    Good advice. Baseless advice is to be taken with two tablespoons of Bunnings gypsum - sorry, I meant salt.
     
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  13. Rocker1986

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    Posted 15/6/18 at 4:31 AM
    Bullshit. The science, at least what I'd seen of it, suggested that re-hydrating dry yeast in water first was better for the overall health of the yeast than pitching it straight into wort, as pitching it straight into wort kills/killed a greater percentage of the cells. I would rather trust the science than some random on a brewing forum who's too lazy to add an extra minor step for my information on yeast health. To say someone is full of it because they haven't got a fucking lab to be able to properly do the tests themselves, is just dumb. That's why we have scientific studies in the first place, so we don't have to do it ourselves.

    If that theory ends up being disproven then great, re-hydration isn't as important as once thought, and there's nothing wrong with that. Science is always changing, and the people who follow it are always changing their views in line with what new evidence shows. Until now, there was no evidence, at least that I was aware of, other than randoms on forums proudly proclaiming that they just "chuck it in and it works fine".
     
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  14. hoppy2B

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    Posted 15/6/18 at 5:48 AM
    The claims about attenuation and so on I don't accept. And by that I am referring to the claims people make about needing to chuck in a large amount of yeast for the wort to fully attenuate. Quantity of yeast is insignificant when considered alongside factors such as nutritional content of the wort, when fermenting worts of high gravity.. The above link posted by Seekerr confirms that, for the average beer, chucking in more yeast won't make any difference.

    Or to put things more simply, there is at least 1 commercial website that I am aware of that sells yeast, and they recommend pitching 1 gram of dry ale yeast to ten litres for home brewers, and 1 gram for 25 litres on a commercial scale. The amount for lagers is double that. Seems a bit low even to me. :eek:
     
  15. MHB

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    Posted 15/6/18 at 7:21 AM
    I don't think it confirms any sort of information about pitch rates at all, the results are for the same beer (15oP or 1.060) pitched at a rate of 50g/hl (0.5g/L) or about 11.5g/23L "standard" brew. The test is examining 3 different ways of managing the yeast - not how much yeast was added.
    You really cant take a study saying one thing and say it means somethin else just to keep your opinion on its rather shaky foundations. Well you can, its just your future posts wont get taken very seriously.
    Mark
     
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  16. hoppy2B

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    Posted 15/6/18 at 9:04 AM
    If you believe that half the yeast dies when pitching into a fermenter rather than hydrating in water, then the link proves exactly what I said.
     
  17. MHB

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    Posted 15/6/18 at 12:16 PM
    To you maybe - not I suspect to anyone else!
    Mark
     
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  18. GalBrew

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    Posted 15/6/18 at 1:53 PM
    It says nothing of the sort.
     
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  19. Jack of all biers

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    Posted 15/6/18 at 4:22 PM
    Not only does it say nothing of the sort, they haven't even released the study yet. Is that because it hasn't been peer reviewed? Potentially, or because the PhD holder who wrote the release (yes it's a media type release) is the Technical Sales Manager for Fermentis. Not what one would call an unbiased source in the scientific or any other field. Anyone remember all those Doctors studies that proclaimed that Cigarettes caused no harm.... Who paid for them again?

    I would wait for the release of the study, before making any claim about their methods or results. For example, from what they've released so far and the recommendations for rehydration (yes Fermentis still recommend rehydration of their yeasts) the only thing that has been added is this newly trademarked E2U method, which doesn't appear to have been used as part of their study. So why is it the new recommendation?

    Chill Winston and wait for the facts. Not flashy news releases that match your opinion.
     
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  20. hoppy2B

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    Posted 16/6/18 at 1:06 AM
    I really don't care. :D
     

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