Question on Malt Effects on Mash pH

Discussion in 'Calculator Support Forum' started by Brewer #238457, Aug 17, 2019.

  1. Brewer #238457

    Brewer #238457 New Member

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    Hi. I have been using the site and am absolutely loving it - very nice program.

    I was curious as to how the program calculates mash pH, particularly for malt effects.

    Using the Brewer's Friend site, I created profiles for various individual malts at different mash thickness (in 6 gallons water - no salts).
    upload_2019-8-17_15-42-27.png

    My question is with regard to the plateauing of pH with higher rates of malt addition for the crystal and darker malts. Granted, the higher additions are ridiculous in practice, but I wanted to see what was the mathematical function/treatment. I see in the documentation that this is general based on Troester's work (excellent work), but I am wondering to what extent the plateau effect is based on measured/calculated values vs extrapolation of a model beyond what is intended for the given mathematical function (like a log or exponential fit that was never intended to be used in the plateau range).

    For comparison, I performed the same exercise for Bru'n Water as seen below. They appear to treat malt addition as a linear function and class the various malts into three groups (base, crystal, and darker roasted).

    upload_2019-8-17_15-54-3.png

    To be clear, I have used both Brewer's Friend and Bru'n Water and they have both been just fine in practice. I am just curious as to the plateau effect and the different treatments of the two programs mathematically.

    Any info is appreciated - Thanks!!
     
  2. Nosybear

    Nosybear Well-Known Member

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    Buffers handled differently, I'd guess
     
  3. J A

    J A Well-Known Member

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    I get pretty consistently lower readings that the predicted PH with BF calculator. Not drastic but definitely signicant and enough to make me suspicious.
    Interesting that the curves should flatten out that much after only a half pound or so. That doesn't follow any real logic, especially with roasted malts. OTOH, a full linear relationship means that you could conceivably have a wort that's incredibly low if you added enough extremely dark malt. I don't think you'd ever get to a PH that matches Star-San by soaking 10 lbs of Roasted Barley in a gallon of water. :)
    I'll use both next time I brew and see which prediction is closest.
     
  4. Craigerrr

    Craigerrr Well-Known Member

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    I suspect that it is not linear.
    Maybe much like adding hot water to cold, as you add more in equal amounts the resulting increase in temperature will plateau. The hotter the water gets the less the newly added water can affect the temperature to the point that it actually can't affect the temperature.
    I assume that likewise once your pH reaches a certain point on the scale, adding more acidic grains can't make the resulting pH lower than the pH of the added grains are themselves.

    Or.... I could be entirely full of Sh*t, just the first thought that popped into my head.
     
    thunderwagn likes this.

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