Ask The Brewmasters

  • 1.  Stout Sludge

    Posted 04-10-2023 15:54

    For the longest time we felt our imperial stout was lacking in body and after many years of recipe tweak's we now have the nice smooth profile we were looking for. 
    this was due to the addition of dextrin malt, flaked barley, mash alkalinity adjustments, and calcium chloride in the kettle.
    Sadly we just got hit with a dreaded picture of slimy sludge in a keg about 5 months old. and a year or so ago a similar picture from a bottle. 

    any thoughts on the cause and any subsequent remedies would be greatly appreciated. 
     



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    Michael Smith
    Head Brewer
    Eel River Brewing Co.
    Fortuna, CA
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  • 2.  RE: Stout Sludge

    Posted 04-11-2023 11:47

    Hi Michael,
    Have you investigated the sediment via microscopy or stains? Distinguishing among cells, proteins, dextrins, and oxalate crystals could help troubleshoot the cause.



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    Michaela Kazek
    San Diego CA
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  • 3.  RE: Stout Sludge

    Posted 04-11-2023 14:20

    Hi Michael,
    1.  I agree with Michaela.  Always a good idea to have a look a sample to help determine what is causing this.  Staining will help identify and eliminate possible causes.  You can do this in house or send it out to a lab for analysis.
    2.  You mention, Imperial stout, beer body, flaked barley, and sludge.  Without having a look at the particles, I would guess that you have beta glucans coming out of solution.  
    There is an increase in beta-glucans in the beer, coming from the flaked barley.  They do add body to the beer, and in high alcohol beers (Imperial stout), the beta-glucans can come out of solution in the package/keg, especially at cold temperatures.  Shear-stress from centirfuges can exacerbate the problem.  The slime or sludge appears afterwards. Several authors have written about this problem over the years.

    What to do?  Use of beta-glucanase in the mash will certainly help, but unfortunately, it will not help with any beer that has already been produced.  Maybe some fellow MBAA members can share their experiences?  

    Andrew   



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    Andrew Fratianni, Dipl. Brew.
    Sr. Enzyme Application Specialist
    Brewing & Distilling Enzymes
    IFF Health & Biosciences
    andrew.j.fratianni@iff.com
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  • 4.  RE: Stout Sludge

    Posted 04-14-2023 13:16

    If you could share some of the pictures, that would be helpful.  Does it at all look similar to this substance?  



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    Tyson Read
    Head Brewer
    Iron Horse Brewery
    Ellensburg WA
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  • 5.  RE: Stout Sludge

    Posted 04-17-2023 18:11
      |   view attached

    I would say it certainly does look similar 



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    Michael Smith
    Head Brewer
    Eel River Brewing Co.
    Fortuna, CA
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    Original Message


  • 6.  RE: Stout Sludge

    Posted 04-18-2023 14:12
    Tyson,

    That looks like coagulated protein/polyphenol complex to me from the dark malts.

    Harlan Coomes



    Original Message


  • 7.  RE: Stout Sludge

    Posted 04-21-2023 11:58

    We had a very similar problem about 8 years ago.    We pieced together the cause through a few scientific journal articles, some analytical testing (it was not microbial), and pure conjecture.  Or we just got lucky.   Short story is that we traced it back to running high yeast content (tank bottoms) through our centrifuge.   If I remember the articles correctly, glucans and mannans (think yeast cell walls) in the presence of high alcohol and sheer stress can create gels.  These coagulate into what we affectionately called "beer loogies".    All I know is when we started clearing up the tank bottoms  on that product before running it, the problem went away.  It could also be from the dark malt and high alcohol and the tank bottoms slowed it all down, allowing for more heat and shear in the centrifuge.  Good luck.  



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    Tyson Read
    Head Brewer
    Iron Horse Brewery
    Ellensburg WA
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    Original Message


  • 8.  RE: Stout Sludge

    Posted 04-22-2023 11:35
    Yes centifuge haze has been studied at ICBD (see Stewart, Speers,?? and Maskel and students (e.g.,?? Huismann) over a number of years.
     * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *    Former Director and Honorary Professor    Int. Cent. of Brewing and Distilling    Heriot-Watt University, Edinburgh, Scotland     Emeritus Professor, Alex Speers, B.Sc. (Agr.), M.Sc.,Ph.D., FIBD    Canadian Institute of Fermentation Technology/ PEAS       Email: Alex.Speers@Gmail.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *    Everything flows/Nothing endures but change    Heraclitus ca. 500 B.C. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *  R



    Original Message


  • 9.  RE: Stout Sludge

    Posted 04-25-2023 16:00

    Perhaps this is a similar scenario, but with a different kind of beer. We just emptied a brite tank after kegging and discovered a very similar substance that came out of the bottom drain pipe... This was a Session IPA, but we have no filter or centrifuge. We drop yeast and hops from the FV for a week before we transfer to the BT, and we transfer with a sock screen trap for the larger particles. 



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    William Kozloski Co-Founder
    Co-Founder/Head Brewer
    GearHouse Brewing Co
    Chambersburg PA
    (717) 552-2427
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    Original Message


  • 10.  RE: Stout Sludge

    Posted 04-16-2023 12:27

    Since you have changed the substrates make sure it is not microbial. Keg pasteurised?  Beta-glucans will generally dissolve with heat and ppt with shear. But they can be tricky to diagnose. See papers of M. Huismann and Y-L Jin et al. for details.

    *Disclaimer.....Great students of mine (<:)



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    Alex Speers B.Sc. (Agr.), Ph.D.,FIBD
    Kootenay Consulting
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