Help with some math, and a question...

Discussion in 'Homebrewing' started by Lukass, Jul 3, 2018.

  1. Lukass

    Lukass Savant (936) Dec 16, 2012 Ohio

    I need some help figuring out what my OG is gonna be on a saison/wine hybrid that I’ll be brewing this coming weekend.

    I suck at math, so I’d love it if someone could take a stab at figuring this out for me. Here are the specifics:

    1. I am using 1 L of white grape concentrate, that when mixed with 3.2 L of water, has a gravity of anywhere from 1.082-1.092. I plan on using it as is, and not mixing it with water.

    2. The target OG for the saison wort will be around 1.053 post-boil, and I plan on having around 5.5 gal into the fermenter.

    Any idea what the combined OG would be if I mixed this white grape concentrate with my chilled saison wort before fermentation? And, is this a good idea to do, or should I add the grape juice to the saison as fermentation begins to slow (Like I would with a sugar addition)? I really don’t want to do a secondary on this one, hence my questions about using the juice in primary. Thanks in advance.
  2. VikeMan

    VikeMan Meyvn (1,470) Jul 12, 2009 Pennsylvania

    Let's say the water/grape mix comes in at 1.087, then:

    ((1.087 - 1) x 1.10952) + ((1.053 - 1) x 5.5)
    ---------------------------------------------------------- +1 = 1.059
    1.10952 + 5.5

    In a hurry. Someone can correct my math if needed. Brewpub calling.
    Lukass likes this.
  3. NeroFiddled

    NeroFiddled Poo-Bah (10,359) Jul 8, 2002 Pennsylvania
    Premium Trader

    @VikeMan seems to have the numbers down. Looks right to me. As for adding it prior to fermentation starting or later on I would suggest going later on, once fermentation starts to slow a bit but certainly before it stops.
    Lukass likes this.
  4. KeyWestGator

    KeyWestGator Devotee (492) Jan 21, 2013 Florida

    In his hurry, I think Vike missed that you were not going to dilute the concentrate. I just tried to fix it and came up with an obviously wrong answer. And I too am running to begin the festivities, so will tag somebody else in!
    Lukass likes this.
  5. Lukass

    Lukass Savant (936) Dec 16, 2012 Ohio

    You guys are awesome, thanks. @VikeMan and @KeyWestGator yea, I was not planning on diluting the concentrate with water, so would probably be a much higher og for the juice, but also at a less amount. I would guess that the og you calculated (1.059) shouldn’t move too much if I diluted or didn’t dilute the concentrate though, right? Since it’s the same amount of sugars being added either way.
  6. Push_the_limits

    Push_the_limits Initiate (30) Feb 8, 2018 Antarctica

    ((3.2 / 3.78) X .087)) / (5.5) = .0134

    1.053 + .0134 = FG = 1.066

    However, I wasn't totally sure if you will have 5.5 gal before you add the grape concentrate, or after. Since 1 L is more than a 1/4 gal, it is significant. This math assumes you have a 5.235 gal wort that would become 1.053 if you added just water up to 5.5 gal. However, you add 1L of your grape stuff to to get 5.5 gal @ 1.066.
    #6 Push_the_limits, Jul 3, 2018
    Last edited: Jul 3, 2018
    Lukass likes this.
  7. VikeMan

    VikeMan Meyvn (1,470) Jul 12, 2009 Pennsylvania

    Crap. Reading is FUNdamental. With undiluted grape concentrate (where 1.087 in 4.2 liters = 1.3654 in 1 liter (0.264172 gallons)...

    ((1.3654 - 1) x 0.264172) + ((1.053 - 1) x 5.5)
    0.264172 + 5.5

    + 1 = 1.067

    ETA: This assumes 5.5 gallons of just the saison wort portion. And the grape concentrate adds 1 liter.
    ssam and Lukass like this.
  8. Lukass

    Lukass Savant (936) Dec 16, 2012 Ohio

    TooHopTooHandle likes this.
  9. Lukass

    Lukass Savant (936) Dec 16, 2012 Ohio

    Thanks man. I was thinking this as well, will probably add as an addition during high krausen, or as ferment begins to slow.
    TooHopTooHandle likes this.
  10. Lukass

    Lukass Savant (936) Dec 16, 2012 Ohio

  11. dmtaylor

    dmtaylor Aspirant (205) Dec 30, 2003 Wisconsin

    I would say yes I think it's okay. I'd be more concerned about sorbate.
    Lukass likes this.
  12. VikeMan

    VikeMan Meyvn (1,470) Jul 12, 2009 Pennsylvania

    I suspect it won't hurt anything. Wine makers add K-Meta to their must to kill wild yeast before pitching their wine yeast.
    Lukass likes this.
  13. Lukass

    Lukass Savant (936) Dec 16, 2012 Ohio

    Description says it can be added to wine to boost alcohol so I didn’t ‘think’ it’d be a problem, but this is good to know. Thanks man

    Ok, thanks. I assume it would be a problem if used in high amounts, but as a preservative for the must it’s probably not a high dosage that I’ll be adding.

    Appreciate your guys’ feedback, once again!