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White Foam on top of Starter

Discussion in 'General Brewing Techniques' started by Pik000, 7/8/18.

 

  1. Pik000

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    Posted 7/8/18
  2. MHB

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    Posted 7/8/18
    Looks like what you would get if you beat a wort with a whisk - froth!
    I hope that is vey early in the life of the starter, if so is it a bittered wort, they will al ways foam a lot more than just DME/LME.
    Mark
     
  3. Pik000

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    Posted 7/8/18
    What is a bittered wort? Its 200g of DME and a yeast I had harvested from last time I did a starter.
     
  4. MHB

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    Posted 7/8/18
    Wort with bitterness, a lot of people use a cheap kit to make starters, or they use some unfermented wort saved from the brew (strained/settled trub - whatever) but the same Iso-Alpha acids that bitter the beer make it much more prone to foaming.
    Mark
     
  5. hoppy2B

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    Posted 8/8/18
    Add some dextrose to your starters and the yeast should take off faster and have thicker cell walls.
     
  6. hoppy2B

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    Posted 8/8/18
    And I should add, some yeast nutrient wouldn't go astray.
     
  7. MHB

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    Posted 8/8/18
    Wrong, and wrong in a way that will harm the yeast.
    If you feed yeast on simple sugars it gets lazy with regard to higher sugars, these are exactly the sugars we want the yeast to consume to get the beer to fully attenuate. About the worst possible time to feed yeast on simple sugars is during the reproductive phase.
    There are a bunch of other reasons to culture yeast on wort, including sterol precursors, protein, glycogen reserves... All of which we want to maximise in a starter that is going to be sent of to work hard in a wort. None of these are supplied by "sugars" but just looking at sugar metabolism.
    Yeast will pretty much tackle sugars in order of size, so monosaccharides first (glucose, fructose), then disaccharides (Maltose and Sucrose) then higher sugars some but not all of the trisaccharide's.
    Yeasts approach to Maltose and Sucrose is quite different, it takes Maltose into the cell and breaks it down, it cant import Sucrose so it produces Invertase enzyme which is pushed into solution (and stays there for good (or bad)), it then breaks down the Sucrose into Fructose and Glucose which are taken up from solution by the yeast. Yeast will preferentially produce invertase even over other reproductive pathways, which would make using Sucrose in a starter even worse than Glucose/Dextrose (same thing).
    I suspect (cant prove) that this treatment of sucrose is strongly linked to the traditional "Kit Twang" people talk about.

    Hoppy2B, you are getting to be notorious for posting complete crap in very authoritative terms!
    When you don't know WTF you are talking about try asking a question.
    I would agree that a little yeast nutrient (a complex one not just DAP) and/or a little zinc wouldn't go astray, but if you want to make plenty of good healthy yeast, avoid sugars and use wort (DME/LME same thing).
    Mark
     
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  8. hoppy2B

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    Posted 8/8/18
    Bullshit, I'm not even going to read your post MHB. Scientific papers I've read state that dextrose will result in thick yeast cell walls early in the fermentation. Of course that results in better yeast health later on.

    I don't know what rubbish you are reading and I don't really care.
     
  9. MHB

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    Posted 8/8/18
    Why would making a semipermeable membrane, that controls what the yeast gets to eat be better for being thicker?
    Would have thought it was like a condom, the thinner and more flexible the better - well until you get to the point where it breaks (not so good).
    If you aren't hoppy2B - don't add sugars to starters.
    If you are hoppy2B - please supply one link to "scientific paper" recommending adding simple sugar to starters
    Mark

    PS
    Brülosophy isn't a scientific paper
    M
     
  10. MHB

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    Posted 8/8/18
    If anyone is interested this is a very good introduction to yeast propagation.
    It covers the basics quite well, I don't agree with everything in it (i.e. the bit about not liking air-stones…) but well worth a read and if followed will give very good results.
    Mark
     

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