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 Home Brew Forums > Any Real Science on the Effect of Crush on Extract Yield?
05-10-2012, 09:29 PM   #51
brewski08
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discussions like this are what make me love brewing so much more. i'm getting ready to take my MCAT this saturday, and i can't tell you how much brewing/fermentation science has helped me understand both basic and advanced scientific concepts.

my hypothesis on the subject:

-finer as compared to coarse grain crushes increases the AVERAGE home brewer's brew house efficiency and sugar extraction. when i say average home brewer, i'm referring to the home brewer who mashes for the typical 60 minute period.

my logic and assumptions:

-starch to sugar conversion from malted grain occurs when amylase enzymes come into contact with starch polymers within the grain.

-finer crushes increase the surface area that clumps of crushed grain (starch) have exposed to the amylase found in the mash solution.

-increased amylase to starch interaction increases the rate of sugar conversion. the product of an increased rate to the amount of time (60 minutes) will increase sugar yield.

-an increased rate over an infinite period of time will not have an effect on your sugar yield because all sugar would be converted theoretically.

scientific set-up:

-i took 3 ice cubes. each ice cube represents my grain.

-the first ice cube i left untouched.

-the second ice cube i lightly crushed.

-the third ice cube was finely crushed.

-i then measured how long each ice cube took to melt. melting represented the conversion from starch (ice) to sugar (liquid water).

results:

-the finely crushed ice cube was converted to liquid water at the fastest rate, followed by the coarsely crushed ice cube, followed by the untouched ice cube.

-when left for an extended period of time, all ice cubes were converted to water.

discussion:

-i'm anticipating some will counter argue my results by saying that since both water and ice are the same molecule (H2O), conversion didn't take place. that's a valid argument, but i'll counter by saying ice, while it is H2O, forms a crystal lattice while liquid water does not.

-i looked at the air molecules (nitrogen, oxygen, carbon dioxide) surrounding the pieces of ice as the catalysts responsible for converting ice to water. they interacted with the larger surface area of the finely crushed ice more easily by exchanging kinetic and heat energy between the ice molecules and air molecules which acted in the conversion of ice to water.

conclusion:

-i think these results show a finer crush increases the surface area to conversion catalysts whether these catalysts be air molecules or amylase enzymes. by increasing the surface area in a finer crush, conversion rates are much higher. to the average brewer who has limited temperature control over a limited time frame of typically 60 minutes, higher conversion rates will add to an increased sugar extraction.

i would love to hear everyone else's thoughts on my logic and cheaply designed experiment

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05-10-2012, 09:36 PM   #52
AZ_IPA
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Quote:
 Originally Posted by brewski08 i would love to hear everyone else's thoughts on my logic and cheaply designed experiment
And if you recirculate the melting water onto the uncrushed chunk of ice, it will melt faster than the partially crushed chunk of ice. So, will a recirculating mash with a coarser crush be as (or more) efficienct than a static mash with a finer crush?
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05-10-2012, 09:37 PM   #53
GodsStepBrother
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There is a maelstrom of different things happening in a mash, your experiment can show there is more surface area for a cube of ice being crushed or not, but has little bearings on what is going on in something as complex as a mash.

There is no doubt more surface area on a pulverized grain, but what is important here is if that really matters. Just as Pjj2ba said, there is tons of different causes that lead up to one thing. surface area is just one aspect but most likely not the only culprit. Still nice insight very simple.

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05-10-2012, 09:52 PM   #54
brewski08
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solid points.

i designed this experiment with the assumption that surface area was the main variable affecting the starch to sugar conversion rate. while i understand that there's more going on in a mash (pH, temperature, dynamic equilibria) that contribute to efficiency, i thought surface area and mash time were the most influential efficiency factors.

perhaps i have more researching to do

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05-10-2012, 09:57 PM   #55
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Quote:
 Originally Posted by brewski08 solid points. i designed this experiment with the assumption that surface area was the main variable affecting the starch to sugar conversion rate. while i understand that there's more going on in a mash (pH, temperature, dynamic equilibria) that contribute to efficiency, i thought surface area and mash time were the most influential efficiency factors. perhaps i have more researching to do
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05-10-2012, 10:52 PM   #56
Denny
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Quote:
 Originally Posted by AZ_IPA And if you recirculate the melting water onto the uncrushed chunk of ice, it will melt faster than the partially crushed chunk of ice. So, will a recirculating mash with a coarser crush be as (or more) efficienct than a static mash with a finer crush?
Only if you mash ice cubes instead of grain.
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05-10-2012, 11:08 PM   #57
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I recently purchased a 2" grain mill from Morebeer and have been experiencing higher OG gravity readings when I am done now. No scientific evidence, just the same recipe's with different grain mills. Over shot my OG on a cream ale with the finer grain crush (1.060). I ended up adding a gallon of water to bring it down to 1.050 as I really wanted a lawnmower beer.

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05-11-2012, 02:03 AM   #58
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I just tried mashing 3 ice cubes. Sure, they all melted, but all i ended up with was crummy water! At first, i thought it was just my hydrometer reading 1.000. But, after tasting it, my worst fears were confirmed... water.

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