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Thread: 2 step infusion calculation

  1. #1
    Join Date
    Mar 2003
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    2 step infusion calculation

    I am trying to calculate the temp of a secondary infusion for a 2d step. I am using a mash tun w/ no heating so all the heat must come from the water and would like rests at 144 and 154 with a ratio of .25 and .33 gl/pnd respectively for each rest. Recipe uses 430 pds malt and 1bbl water under the plates.
    I keep plugging at the formula in Malting & Brewing Science but keep coming up with T 2nd infusion =T 2nd rest. Empirically I know that the water has to be hotter than the desired rest temp. Am I doing the math wrong or what? Anyone got another formula?

    Thanks in advance, Ted

  2. #2
    Join Date
    Dec 2003
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    53
    The basic mixing formula should do the trick. When dealing with mashes you need to work in Mass not volume, so in this case:
    Aa+Bb=(A+B)c

    A mass of mash
    B mass of added water
    a temp of mash
    b temp of added water
    c final water

    if you solve for c you should find *206.5Fwrong* as the answer. **Please see edit below**

    (1290lbs*144F) + (275.2lbs*b) = (1290lbs+275.2lbs) * 155F

    So after heat loss during transfer you are probably talking about boiling water.

    FYI the new MBAA Handbook of Basic Brewing Calculations is a great resource for this kind of stuff. Cheap too.

    Good Luck

    * My apologies! I made a mistake in the use of this equation! The basic mixing equation only works if the materials being mixed have an equal impact. In the situation being considered a pound of water has a different impact than a pound of malt. This is defined by the heat capacity which water happens to be 1 and mash is approximately .4 (depending on moisture levels). So you will need to calculate the overall mash heat capacity first.

    To find the mash heat capacity:
    ((.4*grain wt)+current water weight)/total weight
    so
    ((.4*430lbs)+860lbs)/1290 = .8

    and then use

    added water lbs = ((mash heat cap.*mash wt) * (goal temp-present temp))/added water temp-goal temp

    so
    275.2lbs=((.8*1290)*(154-144))/X-154

    solving for X gives you 191.5F

    Hope that works a little better!
    Last edited by Tbrew; 05-04-2004 at 05:34 PM.

  3. #3
    Join Date
    Oct 2002
    Posts
    64
    Originally posted by Tbrew
    The basic mixing formula should do the trick. When dealing with mashes you need to work in Mass not volume, so in this case:
    Aa+Bb=(A+B)c

    A mass of mash
    B mass of added water
    a temp of mash
    b temp of added water
    c final water

    if you solve for c you should find 206.5F as the answer.

    (1290lbs*144F) + (275.2lbs*b) = (1290lbs+275.2lbs) * 155F

    So after heat loss during transfer you are probably talking about boiling water.

    FYI the new MBAA Handbook of Basic Brewing Calculations is a great resource for this kind of stuff. Cheap too.

    Good Luck
    By adding boiling water to already hydrated mash,...aren't you de-naturizing a substantial percentage of conversion enzymes?
    (affecting potential carbo loss?)

    Is there a cross calculation accounting for this maybe?

  4. #4
    Join Date
    Dec 2003
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    53
    Yes, you will be denaturing some enzyme. If you are an all malt brewer this should not be a problem. In all malt mashes you have roughly 3 times the enzyme you would need (especially if using N. American malts) and thus ruining up to 2/3rds is not a problem. Same situation with decoction mashing and the end result is A'OK there too.

    Affect would be less the better your mixing.

  5. #5
    Join Date
    Mar 2003
    Location
    Baton Rouge, LA
    Posts
    618

    2nd Infusion problems

    Thanks for your help
    After further work I came up w/ the same thing- boiling water from the kettle.
    As for enzyme loss that is a concern. The whole reason for this is to get a more fermentable wort thus drier beer. I hope that my plan to underlet the 2nd infusion and stir like crazy will off set this.
    Ted

  6. #6
    Join Date
    Oct 2002
    Location
    Sweden
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    If the aim is to get a higher attenuation, why not experiment with a yeast with a high attenuation. If it is ale brewing my experience with Lallemand nottingham dry yeast is that with pale ale malt and single step infusion between 63 and 69 degrees celsius you will reach an attenuation between 79 and 82 %, with a OG up to 1056.

  7. #7
    Join Date
    Oct 2002
    Location
    Tadcaster, Yorkshire, UK
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    If you want a more fermentable wort, mash in at a slightly lower temperature until you achieve the profile, but probably not less than 64 deg C initial mash temperature. Try dropping the mash temperature ).5 deg C at a time, by dropping mash liquor temperature, probably by 1 deg C.

    Check you yeast viablility, wort oxgenation and yeast food, particularly zinc. Low viability yeast will ferment poorly.

    Cheers
    dick

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