BIAB Crush Experiment

Discussion in 'General Brewing Discussions' started by Megary, Dec 9, 2019.

  1. Megary

    Megary Well-Known Member

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    I decided to run a little experiment today to determine how grain crush might affect mash efficiency for a BIAB set up. I think this was more to prove what is considered common knowledge: for BIAB, a finer crush will lead to better extraction.

    The basic setup:
    I crushed a Pils malt on 6 different settings on my Kitchen Aid grain mill.
    I added 2oz of each crush into hop bags and placed them in 6 coffee cups. (Color coordinated so I wouldn't forget which was which!)
    I heated a strike water to 155.
    "Mashed in" and placed the coffee cups in the oven at 155.
    Mashed for 90 minutes.
    Removed the bags, squeezed whatever wort I could get, and discarded the grains.
    Cooled to 68 and took gravity readings.

    Crushed grains from coarsest grind (top left) to finest (bottom right).
    IMG_0009.JPG

    Mash In
    IMG_0010.JPG

    Post Mash
    IMG_0011.JPG

    Gravity readings from coarsest grind to finest:
    Blue cup:1.040
    Red: 1.044
    Green: 1.046
    Yellow: 1.046
    Gray: 1.049
    White: 1.050

    Yellow reading:
    IMG_0013.JPG

    White reading: Blurry, but it was 1.050.
    IMG_0017.JPG

    I suspect there is a trade-off here at some point. The finer the crush, the more extraction and the more solids that will pass through the bag. Maybe that means more trub left behind in the kettle or in the fermenter?? Maybe water volumes would need to be adjusted to hit batch volumes?? Are there tannin issues to consider??

    It's a process. But for me, the crush/extraction question is settled. Now to make some sense of it.
     
  2. Mase

    Mase Well-Known Member

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    Very nice demonstration. Others here have far more experience/knowledge than I that will offer great feedback. The only downside I see is getting through a stuck sparge with all the fines and dust.

    On a side note, as this isn’t a commercial operation, efficiency shouldn’t be a big deal (so long as you are at least in the mid/upper 60’s percentage), rather a consistent efficiency as part of a reproducible brew.

    again.... great experiment.
     
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  3. Megary

    Megary Well-Known Member

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    I agree 100% that consistency is the key. I've been +/- 70% with my BIAB set up. And I'm happy with that because it makes designing recipes and hitting numbers much less of a worry.
    Still, if I can be consistent at 75% or above, I'll take it. And if I can get above that...well, you get the idea. I'm in it for the long haul!
     
  4. thunderwagn

    thunderwagn Well-Known Member

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    Wow. Nice little presentation/experiment. I give kudos to the time spent, nice pictures, and information you gathered and posted here! Thanks man.
    I think it was on a podcast of Brew Strong with Jamil Zainasheff and John Palmer where they talked about efficiency, saying best mouthfeel and flavor, etc. was between 70-75% if memory serves. One recent episode of Brulosophy is also devoted to efficiency. We all say go for consistency, but there are also number geeks out there who strive on not only consistency, but hitting those high numbers as well. Nothing wrong with that either. It's a hobby and it's yours to do with as you want.

    I'm curious about this Kitchen Aid grain mill you used. Is it an attachment for a stand mixer?
     
  5. Trialben

    Trialben Well-Known Member

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    LOVE IT MEGARY!
    Very sexy spread there man and pretty cool findings which I can only assume supported your hypothesis that a courser crush would =less extraction opposed to finer.

    I mill all my batches of a Thermomix reverse speed ten for ten seconds in about 4 cup increments . It's not far off flour well a bit but there is plenty of flour in there. My mash efficiencies are always high my brewhouse teaters around 80 87% being higher than expected.
    The beers I've been making mashing fine Biab Style have been pretty bloody delish. I cant say I experience tannin extraction but some beers can come off a bit thin I suppose but that may be down to low mash temp.

    Loved it Megary thanks for taking the time to write it up. Cheers!
     
  6. Group W

    Group W Well-Known Member

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    Nice experiment Megary. I know my efficiency improved when I tightened the gap on my mill. Like thunderwagn, I didn’t know there was a Kitchen Aid grain mill (or attachment). Is it a crusher with rollers, or more of a grinder. It looks like the husks are mostly intact.
     
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  7. Zambezi Special

    Zambezi Special Well-Known Member

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    Interesting!
    Curious to see if there would be a big difference in taste/flavour between the finished beers, depending on the crush...
     
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  8. Megary

    Megary Well-Known Member

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    It's funny because I thought I would be able to taste a difference in the wort between the lowest and highest gravity samples. Unfortunately, after sampling six (from low to high) I couldn't remember what the first one tasted like! I should have ONLY tasted the low reading and the high reading.
     
  9. Megary

    Megary Well-Known Member

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    Very interesting on the 70-75% findings. I am going to try and track down that podcast.

    The grain mill I have is an attachment for a stand mixer. The mill is an old, discontinued KA model GMA. It doesn't crush the grain like a typical roller mill, rather the grain passes through a hopper, into a worm gear type thing and dropped out the bottom. I would say shredded or torn might be a better description than ground or milled. Not suitable for a standard mash/sparge/run off operation, but useful for BIAB.

    I use it because it's convenient for me and easily repeatable. I brew 2.5 gal batches and typically use anywhere from 5-7 pounds of grain. The attachment wouldnt be practical and would take took long to mill grains for 5+gal batches.

    The dial on the front manually sets the "crush" by turning clockwise (finer) or counter-clockwise (coarser). I could probably fit about 1-1.5 # grain in the hopper at a time, but I usually just slowly pour them in.


    IMG_0019.JPG
     
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  10. Bubba Wade

    Bubba Wade Well-Known Member

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    Providing that the grain crush does not shred the husks to powder, a fine grain crush should not present an issue with tannins.
     
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  11. FedoraDave

    FedoraDave Member

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    I agree with thunderwagn. For myself, the numbers matter up to a point. I take a gravity reading just before I pitch the yeast, because it's a good measure of where I started and where I should end up. Same with the FG reading; I have to know if there was a stuck fermentation and I like to know what my ABV is for each batch. But that's where it ends. I do get pretty good consistency when I repeat recipes, which I do a lot. But I'm not a numbers guy; it's that simple.

    I used to use a false bottom and mash with two sparges, but I switched to BIAB, and I'm getting pretty much the same efficiency as before. Got ribbons using both techniques, so po-TAY-to/po-TAH-to.

    Very interesting experiment, though.
     
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  12. BOB357

    BOB357 Well-Known Member

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    Tannin extraction shouldn't be a problem as long as pH is within range.
     
  13. Nosybear

    Nosybear Well-Known Member

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    Have someone set us a triangle test for you. Only way I know to be sure of difference or not.
     
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