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  • Lactic Acid

    I am wondering about the growth of lactic acid bacteria in the bright tanks. I am wondering where it mainly comes from and how to take care of it. Thanks.

  • #2
    Lactobacillus lives on barley, and returnns after malting. You introduce it at mash in.
    The acid rest that some brewers use is a rest at ideal growing temperature for lactobacillus to generate lactic acid in the mash.
    Avoiding any kind of resting (damp or wet) at those temperatures will reduce lactic acid growth in the brew. Once the acid is created, it stays. You can kill the bacteria by heating, but you cannot lose the acid once formed (unless you buffer it with base).
    Many German brewers use the acid rest to give a better balance to what might otherwise be a somewhat flabby beer.

    (Edited to change "remains after malting" to "returns after malting" which is what I originally meant. Thanks for pointing that out, Wired.)
    Last edited by beerking1; 07-09-2009, 05:27 PM.
    -Lyle C. Brown
    Brewer
    Camelot Brewing Co.

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    • #3
      Thank you.

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      • #4
        Beerking1, I can't look at this

        Lacto bugs are destroyed by kilning, but they often find their way back to the malt. Myriad other bugs do too (which is why a sour mash with malt is a very "iffy" proposition).

        Sauermalz is not yet kilned and hosts higher concentrations of lacto bugs from the field. It's moistened and held at the right temperature so that the bugs work and produce lactic acid, before (further) malting and kilning are done. The acid residue remains, and this is how you get sourness in your mash, at *any* mash temp.

        An acid rest is an enzyme reaction (phytase) during which mash pH is lowered chemically, not metabolically.

        Now, I am guessing that KSbrew is more concerned with why lactic acid is turning up in his brites, and I will assume that his wort pH is fine going in. Lacto can be very slow to work in competition with yeast, so the inoculation could be happening at any point post-boil. There are scores of potential sources ranging from malt dust to contaminated surfaces, and a whole lot of swabbing is in order. Lines, valves, seals and gaskets, you name it -- pretty much any surface, enclosure, or object that could come into contact with the beer post boil. You will find it, eventually.

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        • #5
          Originally posted by wiredgourmet
          Beerking1, I can't look at this

          Lacto bugs are destroyed by kilning, but they often find their way back to the malt. Myriad other bugs do too (which is why a sour mash with malt is a very "iffy" proposition).

          Sauermalz is not yet kilned and hosts higher concentrations of lacto bugs from the field. It's moistened and held at the right temperature so that the bugs work and produce lactic acid, before (further) malting and kilning are done. The acid residue remains, and this is how you get sourness in your mash, at *any* mash temp.

          An acid rest is an enzyme reaction (phytase) during which mash pH is lowered chemically, not metabolically.

          Now, I am guessing that KSbrew is more concerned with why lactic acid is turning up in his brites, and I will assume that his wort pH is fine going in. Lacto can be very slow to work in competition with yeast, so the inoculation could be happening at any point post-boil. There are scores of potential sources ranging from malt dust to contaminated surfaces, and a whole lot of swabbing is in order. Lines, valves, seals and gaskets, you name it -- pretty much any surface, enclosure, or object that could come into contact with the beer post boil. You will find it, eventually.
          You are right about lacto after kilning. I had meant to say "returns."
          As for the phytase during acid rest, I believe you are also right there, and that what I meant to refer to is more properly called a Lactic rest.
          Last edited by beerking1; 07-13-2009, 06:44 AM.
          -Lyle C. Brown
          Brewer
          Camelot Brewing Co.

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          • #6
            You just had a Joe Biden moment

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            • #7
              I am of the belief that most cellar lactic bugs benefit from autolysed yeast for their nutrition. Hence, keep your yeast healthy so as not to lyse early. Avoid yeast heaps that get warm from the heat of the room through the tank walls. Leaving extra unfermentables in the wort/beer is perfect for these critters, too, as many/most can break down starches that the yeast couldn't. (Just as unmalted grain or flour is favored in the mash or kettle for intentional lactic beers.)

              Where they come from initially...could be anywhere (malt dust is a favorite), but more important is preventing a handful that will sneak in from growing into something you can taste. When you have a blatant contamination, it usually didn't happen just in that brew, it likely has been festering, waiting for conditions to be perfect to reproduce like crazy.

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