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Pulling a decoction

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  • Pulling a decoction

    Can anyone advise how the commercial breweries pull a decoction from the mash tun? For example, if you have a 20BBL Mash Tun and you want to pull 1/3, how do they:

    1. get it out of the mash tun?

    2. know when they have 1/3 of it out?

    I have seen some used breweries for sale that say the can pull a decoction but I can't figure out how from the descriptions of the equipment.

    Thanks much.

  • #2
    Pulling a Decoction

    I worked in a Lager brewer for a couple years. The way I did decoctions at that brewery was to pull anywhere from 33%-40% of the mash to raise my temps. varying degrees. I had a Mash pump which has an impeller capable of handling that sort of stuff. If you are looking to be able to do decoction mashes then your in for a long day. But if 12 hour brewdays are ok then you will also need to have a few other equipment parts. You will need to boil the decoction most likely in the kettle which will need a mixer or agitator. You will need the pump obviously to move the mash back and forth between the Mash tun and the kettle. You will need most likely rakes in the Mash tun/Lauter tun for even mixing when adding the decoction back. you will also want to have your brewery well vented because you will be boiling for a better part of the brewday and it will make the area very hot and humid. The brewery I worked at would get upto 130F at the highest point and only around 100 at the lowest which would heat up the restaurant and that get rid of customers pretty fast especially on a hot day. Hope the info help.

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    • #3
      A low shear pump that will keep the grain hulls intact is important. I will suggest a flexible impeller pump on a variable frequency drive. This type of pump is very gentle on the mash, can be run either direction, and is positive displacement. This means that you can have your variable frequency drive programmed to transfer a known amount of mash based on pump rotations. Just reverse the drive to add back to the mash while raking/stirring. Good luck!
      Phillip Kelm--Palau Brewing Company Manager--

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      • #4
        Thank you very much for the information. Helps a lot!

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        • #5
          Lots of really good tips here already. Here are a few more:

          1. Until you really get comfortable and know your system, boil 40-45% of thick mash. What's "thick"? Grains in just enough liquid to cover them + an inch or so. Add the boiled mash in gradually and stop when you're just short of your strike temp. Worst case scenario, you have to let some of the boiled mash cool a little before adding it to main mash. The first couple of times you do this is will always take longer than you think and you don't want to come up short or overshoot on your strike temp (you've got less enzymes left to play with)

          2. Make sure to check temperature in multiple locations if possible. Really thick mashes can have large temp differentials in diff parts of the vessel.

          3. Think twice before you do decoctions in a direct fired system. At the very least, make sure your mixing/ agitation is really good and covers ALL of the heated areas. Otherwise you'll have a really crusty mess to clean up on your heating surfaces.

          4. Decoction mashes stick more easily than infusion. The don't float and tend to compact easily. Make sure you're ready for this when lautering. Maybe do a smaller mash to start to create a thinner lauter bed and see how it goes.

          5. Start with a higher enzyme malt that gives you more room for mistakes until you get the hang of it.

          It's good to have volume calibrated equipment. If you don't, no sweat. Get a 10 foot length of copper pipe and calibrate it to your vessel. It's harder to read than a sight glass, but it works in a pinch.

          Hope this helps.

          CT

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