Stirring the Mash: Could it affect Mash Extraction?

Discussion in 'Homebrewing' started by koopa, Jan 8, 2013.

Thread Status:
Not open for further replies.
  1. koopa

    koopa Initiate (0) Apr 20, 2008 New Jersey

    I brewed over the weekend and hit 86% extraction efficiency with my 3 kettle single tier (batch sparge) system. Typically I always hit 78-79% so a jump that large surprised me. I've narrowed the cause down to 2 possible variables:

    1. I adjusted my mash ph to 5.30 (usually its 5.45) and I do believe I've read that 5.2 - 5.3 is best for peak extraction.

    2. I used an insulated mash jacket that held my mash temperature so well that I decided not to stir.

    Usually I need to keep direct firing from time to time (say every 15 minutes) throughout the mash to combat temperature loss. When I do, I usually direct fire for a few minutes, lift the lid, stir the mash to bring that heat trapped at the bottom up through the kettle, and put the lid on / watch the temperature equalize back to my original target mash temperature. My original thought was that the stirring would actually help extraction / conversion by making sure that all of the grain was thoroughly exposed to the mash water. Of course I've heard claims that both stratification and stirring is bad as it can impede replication of a batch (Sabco website) so I never was really sure.
     
  2. evantwomey

    evantwomey Initiate (0) Jan 1, 2008 North Carolina

    Unless someone can provide a reasonable mechanism how stirring a mash could restrict extraction efficiency, it is probably reasonable to assume that it does not, and your extraction increase came from something else.

    Getting your pH right probably helped but 8% is a lot. By chance were you wearing no pants?
     
    Gonzoillini likes this.
  3. AlCaponeJunior

    AlCaponeJunior Grand Pooh-Bah (3,452) May 21, 2010 Texas
    Society Pooh-Bah

    That's the only thing I could see that would produce such results. :rolling_eyes:
     
  4. hopsandmalt

    hopsandmalt Initiate (0) Dec 14, 2006 Michigan

    I think that you were denaturing a portion of the enzymes in your mash by direct firing your kettle. not firing the kettle allowed for more enzymatic activity in the tun. That combined with a more desirable mash PH could account for an 8% efficiency gain.
     
    koopa, Gonzoillini and AlCaponeJunior like this.
  5. Patrick

    Patrick Initiate (0) Aug 13, 2007 Massachusetts

    How accurate is your volume measurement?
     
    inchrisin likes this.
  6. koopa

    koopa Initiate (0) Apr 20, 2008 New Jersey

    Blichmann Boilermaker kettle with site glass.... 48th all grain batch.... in other words, dead accurate, as was my preboil gravity reading (2 different refractometer readings...one 10 minutes after combining both runnings, the other 20 minutes after combining both runnings)
     
  7. FeDUBBELFIST

    FeDUBBELFIST Pooh-Bah (1,765) Oct 31, 2009 Pennsylvania
    Pooh-Bah

    Did anything else change in your process/recipe? Grain crush, mash thickness, mash temp, stepped mash?
     
  8. koopa

    koopa Initiate (0) Apr 20, 2008 New Jersey

    Nope.
     
  9. mattbk

    mattbk Savant (1,111) Dec 12, 2011 New York

    I agree that your probable root causes are in fact, the root causes. My guess is that temperature gradients can drastically affect your extraction - even if you think the temp is constant, those areas that are very warm / very cold will not have the same efficiency as other parts of your mash. A well insulated mash tun is the way to go. The act of stirring alone didn't cause the reduction I don't think - unless you were over heating, then overcooling when removing the lid to stir, etc etc. I was never very happy with my mash setup until I was well insulated. Now, I usually overshoot my target by a degree or two, then add back a bit of cold water until I nail it. It stays constant with no adjustments/stirring for 90 minutes no problem.

    And yes, pH will affect your efficiency too...
     
  10. hopfenunmaltz

    hopfenunmaltz Pooh-Bah (2,635) Jun 8, 2005 Michigan
    Pooh-Bah

    Without repeating with every thing the same, including grains from the same bag, and only do the stir/not stir as the variable it is not conclusive.

    Production breweries have mash tun rakes to make sure every thing is wetted, well mixed, and uniform. Some homebrewers use motorized set ups to stir the mash continuously.
     
Thread Status:
Not open for further replies.