Calculating projected OG when adding fruit during active fermentation

Discussion in 'Homebrewing' started by DVoors, Sep 17, 2021.

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  1. DVoors

    DVoors Zealot (627) Jan 6, 2014 Indiana

    Good afternoon. I’m looking for suggestions on the best way to calculate the potential impact on OG/ABV of adding fruit/juice/purée to the fermenter during active fermentation. I plan to add 6 gallons of 1.091 wine must to 38 gallons of actively fermenting wort that had an original gravity of 1.063. Would you please confirm what formula should be used to arrive at an approximate “OG” for the full volume of beer? Thank you in advance for any suggestions.
     
    #1 DVoors, Sep 17, 2021
  2. VikeMan

    VikeMan Grand Pooh-Bah (3,067) Jul 12, 2009 Pennsylvania
    Pooh-Bah

    The effective combined OG would be a weighted (by volume) average of the base beer's OG and the wine must's OG.

    (Gb × Vb) + (Gm × Vm)
    ------------------------------- = Combined Gravity
    Vb + Vm

    Where:
    · Gb = Gravity of beer
    · Vb = Volume of beer
    · Gm = Gravity of must
    · Vf = Volume of must
     
    #2 VikeMan, Sep 17, 2021
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  3. DVoors

    DVoors Zealot (627) Jan 6, 2014 Indiana

    this is EXACTLY what I was looking for. Thank you for the quick response and help! And thank you for brew cypher btw. I’ve been using it for about 5 years now and it is the best!
     
    #3 DVoors, Sep 17, 2021
    GormBrewhouse and VikeMan like this.
  4. VikeMan

    VikeMan Grand Pooh-Bah (3,067) Jul 12, 2009 Pennsylvania
    Pooh-Bah

    Just realized, way to late to edit, that the last line of the abbreviation definitions should say...

    · Vm = Volume of must

    But I'm sure you figured that out.
     
    #4 VikeMan, Sep 17, 2021
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