Fortification calculation

Discussion in 'Tutorials, Calculators, Wine Logs & Yeast Charts' started by RiderEh, Mar 12, 2019.

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  1. Mar 12, 2019 #1

    RiderEh

    RiderEh

    RiderEh

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    Hi All,

    I thought I'd post how I calculate how much brandy to add to port to boost the alchohol:

    P=Port at start (what you made)
    a=alchohol percentage of port you made (SG-FG)*131
    b=alchohol percentage of brandy you are adding
    A=final percentage alchohol you wish to have
    B=brandy to add (what we are solving for)

    P*a+B*b=(P+B)*A
    P*a+B*b=P*A+B*A
    B*b-B*A=P*A-P*a
    B*(b-A)=P*(A-a)
    B=P*(A-a)/(b-A)

    Example:
    P=12L, a=16%, b=40%, A=20%

    B=12*(0.2-0.16)/(0.4-0.2) = 2.4L brandy to add.
     
    Rice_Guy likes this.
  2. Mar 12, 2019 #2

    sour_grapes

    sour_grapes

    sour_grapes

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    Nice.

    Or you can use a Pearson Square: https://winemakermag.com/article/the-pearson-square


    There are also times that one would like to make a port as they do in Porto (or Oporto), that is, by adding the fortifying alcohol during an active fermentation, so that the increased ABV stops the fermentation and leaves the desired amount of residual sugar (and the desired ABV). I worked out the math for that (quoted below) here: https://www.winemakingtalk.com/threads/whole-grape-port.44373/page-3#post-503223

    I also wrote up a spreadsheet that will make this calculation for you:



    Here is the calculation in all of its, ummm, glory:

     
    Rice_Guy likes this.
  3. Mar 12, 2019 #3

    RiderEh

    RiderEh

    RiderEh

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    The Pearson Square seems to go off the same type of formula's as mine (i checked and the math works out the same with both), but what I don't like is you have to know what your final quantity will be, whereas my calculation tells you the quantity to add just to boost the ABV of the batch. For some reason it confuses me as I'm better with algebra than drawing lines to perform calculations lol.
     

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