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Thread: Grist analysis

  1. #1
    Join Date
    Nov 2018
    Location
    Amboise, France
    Posts
    41

    Question Grist analysis

    Hello
    We are a 10 BBL brewery using Dutsche Beverage Technology brewhouse and a local (French) mill + screw auger (from Criquet). Mill is a 2 rollers crushing up to 1T / h
    We only have ~6 months of operation and ~20 batches under our belt.
    A consistent issue is a very slow transfer {2 to 2.5 hours or more}. We have had 2 fully stuck mashes and we are trying to solve the issue. We have been using ~150 liters of rice hulls per brew to help. Which it does a bit but it didn't keep us from a fully stuck mash on our last IPA (6.9% ABV)
    Looking at the grist out of the mill I feel like the flour quantity is somewhat greater than I am used to from previous brewing experience.
    We performed some analysis on the grist with lab calibrated sieves.

    One finding from adjusting the rollers was that the rollers are not perfectly flat. This will explain (potentially) some findings below.

    With the mill supplier we did several tests with difference mill gap. At ~1mm to 1.2mm (rollers are not flat so we have sections at 1mm apart and sections at 1.2mm apart) we have the following:
    74 % captured by the 1mm sieve
    12 % captured by the 0.55 mm sieve
    14% passing through the 0.55 mm sieve (of which we have 50-50 > than 0.25 mm and < than 0.25 mm)

    We did the analysis on a sample size of 9.32 KG {20.55 lbs} which we collected from the screw auger after travelling the entire way.
    We had some grain not crushed in the 74% captured by the 1mm sieve but not enough to be alarming

    Online research were not super fruitful - only finding this: beerandwinejournal.com/malt-sieves/ {Thanks Alex L.!}
    From the brewing elements series - Malt written by John Mallet we don't have any defined grist analysis. And yes, we get it - target grist depend on the brewhouse / malt / recipe / etc... - but guidelines can be useful!

    During mash we have our rakes going in alternate directions at 40% of the speed. We vorlauf during temp. increase (when we can) to have a more accurate temp reading in the MLT.

    Why do we have slow transfer and stuck mash?

    Any guidance you may have regarding:
    - process to avoid stuck mash
    - grist analysis
    - material to read
    - feedback


    Thanks

    Matt

  2. #2
    Join Date
    May 2012
    Location
    Livermore, CA
    Posts
    688
    Too much raking, you should turn them off, once your mashed an and not turn them back on until your graining out. You need some entrained air, raking will knock all that out, your bed will compact and sink, and then get stuck. You should never need rice hulls on a barley based mash. If you have a high % of wheat or oats, then maybe. Your 74% capture above the largest sieve is adequate to get a great mash. That would be my guess as to your problem. Other things to look at, make sure that your false bottom is completely submerged under water before mashing in, if you trap air under it, you will have struggles as well.
    We run our rakes at something around 20% of max speed during only mash in and grain out. During the rest, they are off, during vorlauf they are off, during run-off they are off.

  3. #3
    Join Date
    Nov 2018
    Location
    Amboise, France
    Posts
    41
    Quote Originally Posted by jebzter View Post
    Too much raking, you should turn them off, once your mashed an and not turn them back on until your graining out. You need some entrained air, raking will knock all that out, your bed will compact and sink, and then get stuck. You should never need rice hulls on a barley based mash. If you have a high % of wheat or oats, then maybe. Your 74% capture above the largest sieve is adequate to get a great mash. That would be my guess as to your problem. Other things to look at, make sure that your false bottom is completely submerged under water before mashing in, if you trap air under it, you will have struggles as well.
    We run our rakes at something around 20% of max speed during only mash in and grain out. During the rest, they are off, during vorlauf they are off, during run-off they are off.
    Thanks for your answer and guidance.
    I’ll give it a try with the racking arm off.
    We usually sit to have 1 inch of water above the false bottom before dropping the grains. We will keep this step in our process!
    Thanks again


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  4. #4
    Join Date
    Apr 2008
    Location
    Littleton, CO
    Posts
    57
    Take a look through this presentation.

    http://www.craftbrewersconference.co...ency-Havig.pdf

  5. #5
    Join Date
    Nov 2018
    Location
    Amboise, France
    Posts
    41
    Quote Originally Posted by Wayne1 View Post
    Take a look through this presentation.

    http://www.craftbrewersconference.co...ency-Havig.pdf

    Thank you so much!


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