Preboil Gravity Uniformity Importance (across multiple boil kettles on same batch)

Discussion in 'Homebrewing' started by koopa, Mar 20, 2014.

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  1. koopa

    koopa Initiate (0) Apr 20, 2008 New Jersey

    I've brewed a couple of big 20 gallon batches recently that required me to split the wort into two boil vessels. What I've been doing to ensure uniformity is recirculating the wort collected in those two vessels via 2 pumps until it was uniform (both gravity wise and volume wise). Then I boil in each vessel, chill one vessel first and fill it into 2 carboys (5 gallons in each), then chill the other vessel next and fill it into 2 more carboys (5 gallons in each). Got me thinking, is there any difference between that approach and the following alternative?

    1. Run off the first 1/2 (volume wise) of my total runnings into boil vessel #1
    2. Run off the second 1/2 (volume wise) of my total runnings into boil vessel #2 (obviously the gravity will be lower)
    3. Boil the worts in these two separate vessels (no recirculating the worts first)
    4. Chill and collect the wort from boil vessel #1 by splitting the cooled wort evenly across the 4 carboys
    5. Chill and collect the wort from boil vessel #2 by splitting the cooled wort evenly across the 4 carboys

    In other words, will the final product be any different if I opt to mix the wort post-boil (and chill) in the fermenters vs. pre-boil (in the boil vessels)?
     
    #1 koopa, Mar 20, 2014
  2. ericj551

    ericj551 Pooh-Bah (1,638) Apr 29, 2004 Canada (AB)
    Pooh-Bah

    I wouldn't expect a huge difference, but you'll get different hop utilization between the worts. I imagine it would mostly balance out, but you would probably lose a small amount of IBUs.
     
    #2 ericj551, Mar 20, 2014
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  3. koopa

    koopa Initiate (0) Apr 20, 2008 New Jersey

    Yeah I was thinking possibly some hop utilization difference and possibly a difference in wort caramelization if anything.
     
    #3 koopa, Mar 20, 2014
  4. VikeMan

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

    I'd guess a couple impacts might be in wort darkening and maybe hop tannin extraction as a result of different pH's. I don't know that the two semi-batches would add up/average to the whole.
     
    #4 VikeMan, Mar 20, 2014
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  5. ChinaskiDog

    ChinaskiDog Initiate (0) Mar 19, 2014 Massachusetts

    You would essentially be doing a 50/50, big beer/small beer parti-gyle and then blending it all back together. I agree with Vikeman, the result won't be a predictable average.

    Rather than doing a full recirc blend during your runoff, which I imagine is a pain in the neck, perhaps you could simply alternate running off a gallon into each kettle. They won't be identical, but they'll likely be pretty close, and it may be easier to manage?
     
    #5 ChinaskiDog, Mar 20, 2014
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