Any Real Science on the Effect of Crush on Extract Yield?

[Denny]

I have only the experience of 420 batches to draw on. It tells me that crush does make a difference. I came to this conclusion by brewing multiple batches of the same recipe with all other variables remaining the same...even the same bags of grain.

 

[MalFet]

I was simply taking some real world things that I've experienced and tried to explain them the best I could for the discussion. I have no scientific knowledge and it appears you are quite versed in the subject. Everything I said was pretty much assumption.

Still a new brewer trying to figure it all out still

I wanted to perform the test because (and I'm not trying to argue with you at all) I just can't see in my head that if you mashed a pound of crushed and uncrushed grain, you would end up with the same first running in gravity. Again, not arguing with you at all, I just can't seem to wrap my head around it.

Please do argue with me! That's the fun!

Anyway, I have absolutely no doubt that you would get different values between crushed and uncrushed grain...the experiments passedpawn linked seem to suggest that. The OP is asking about the difference between coarsely crushed and finely crushed. Whole kernels wouldn't work well.

 

[Northcalais40]

You're right in that I am addressing only the conversion myth. Thanks for the clarification, but, you don't think there's a general belief that crush is critical to conversion? I do.

I do agree with this point, but I don't find it really relevant or helpful to me and the way I brew.

As I understand, the news here is that a coarse crush will convert in the mash, nearly as well as a fine crush. But the lautering process will never be as successful with a coarse crush as with a fine crush, provided a suitable lauter tun.

 

[Pilgarlic]

Calais, yes, mine was a pretty specific question. I meant it to be. I didn't really expect that everyone would find it interesting.

 

[MalFet]

As I understand, the news here is that a coarse crush will convert in the mash, nearly as well as a fine crush. But the lautering process will never be as successful with a coarse crush as with a fine crush, provided a suitable lauter tun.

Never is a mighty strong word here, though. In my system, I get equivalent lauter efficiency for a coarse grind and a fine grind. That's anecdotal, of course, but it shows that generalizations about this kind of thing are tough to make.

More broadly, though, I don't really get the idea. Why would a coarser grind lauter less well? Are you saying that a coarsely grind grist absorbs more water than a finely ground grist?

 

[bottlenose]

Given that even well-modified malt has a CG/FG difference, I find it hard to come to any conclusion other than that grind makes a difference. Whether or not this is noticeable depends on how repeatable your efficiency is, or for that matter if you trust your OG measurements to 0.001.

 

[Northcalais40]

I don't really get the idea.

Ditto. I think we should join the scientists and craftspeople to help work out the best practices for homebrewing. I will continue to mill my grain as per usual.

 

[MalFet]

Ditto. I think we should join the scientists and craftspeople to help work out the best practices for homebrewing. I will continue to mill my grain as per usual.

I don't think anyone is suggesting that you should stop milling. Neither the article referenced by the OP nor the data passedpawn posted indicated that that would work out well.

 

[Bennypapa]

Just watched a "Modern Marvels" on brewing, in it Coors explained their crush as "a fine powder comparable to common wheat flour used at home for cooking" which would mean very high efficiency meaning less malt meaning normal gravity, very little malt, beer.

Common sense tells you the smaller the particle the easier it is to absorb in water. The finer the crush the easier it is absorbed in water, but who wants 90%+ effeciency?? Lower the alcohol the more you can drink!

Remember, the goal of a Coors/Miller/Budweiser is low production costs. Time is money so the less times spent in each stage of the brewing process the better. Finer crushes lead to speedier mash times. That is their goal with the fine crush/grind of their grains, speed.

 

[Pilgarlic]

Many brewers, when they experience an anomalously low efficiency or generally have inconsistent or low efficiency, assume (or are told by throngs of 'experienced' brewers here) that their efficiency problems are the result of a "poor crush". The obvious solution, then, is to spend money on a new, expensive mill. The studies offered here would suggest that new mill isn't a panacea, and that one might productively look to other aspects of their process before jumping to the conclusion that their problem is crush.

My approach is to crush my grain as fine as I can while maintaining a whole husk. To me, maintaining the whole husk is more important (to facilitate sparging) than the particle size of the crush (with its negligible effect on yield). I'm able to accomplish this just fine, thanks, with my hand cranked Corona corn mill!

 

[Denny]

When I brewed at Rogue earlier this week I took a good look at the crush they use. Very fine, not an intact husk in 1200 lb. of grain. Lautered perfectly.

 

[passedpawn]

When I brewed at Rogue earlier this week I took a good look at the crush they use. Very fine, not an intact husk in 1200 lb. of grain. Lautered perfectly.

Yep, I mill the crap out of mine also. No sparge problems here, and I never use rice hulls either! (nor do I "condition" the grain).

 

[pjj2ba]

I've been mulling this subject over in my head. Yes, I can see how the crush is not important for conversion. However that is only part of the process. On the other hand, I can see where are fine crush can lead to greater reproducibility as the particle sizes will be more uniform. With a more coarse crush, you are more likely to get batch to batch differences which can make it more difficult to exactly reproduce a brew.

For the record, I use a fine crush. I do step mashes, so the times at the different temperatures are important and a fine crush ensures that what I expect to happen in the time interval does happen.

 

[MalFet]

I've been mulling this subject over in my head. Yes, I can see how the crush is not important for conversion. However that is only part of the process. On the other hand, I can see where are fine crush can lead to greater reproducibility as the particle sizes will be more uniform. With a more coarse crush, you are more likely to get batch to batch differences which can make it more difficult to exactly reproduce a brew.

For the record, I use a fine crush. I do step mashes, so the times at the different temperatures are important and a fine crush ensures that what I expect to happen in the time interval does happen.

Can you say more about what you mean? Why would a finer crush lead to more consistency? What kind of effects would be less consistent with a coarser crush?

 

[pjj2ba]

With a finer crush, you are going to have better exposure of more of the enzymes and more of the starch all at once. Basically all of the component for conversion will be available quickly

With a coarse crush, there will be enzymes and starches tied up in that chunks that will not be solubilized and available for conversion until the already soluble enzymes have an chance to dissolve into and break down the chunks. Basically some of the enzymes are temporarily trapped. Since the crush size is so variable from crush to crush, it is harder to predict how fast the mash will proceed. Now if you are doing single infusion mashes and are not in a hurry, this makes no difference.

By analogy, a course crush is like a Dogfish head 60 min IPA. A little bit of enzyme and starch is continually added (solubilized) over a longer period of time as opposed to dumping it all in at once.

Does this make sense?

 

[MalFet]

With a finer crush, you are going to have better exposure of more of the enzymes and more of the starch all at once. Basically all of the component for conversion will be available quickly

With a coarse crush, there will be enzymes and starches tied up in that chunks that will not be solubilized and available for conversion until the already soluble enzymes have an chance to dissolve into and break down the chunks. Basically some of the enzymes are temporarily trapped. Since the crush size is so variable from crush to crush, it is harder to predict how fast the mash will proceed. Now if you are doing single infusion mashes and are not in a hurry, this makes no difference.

By analogy, a course crush is like a Dogfish head 60 min IPA. A little bit of enzyme and starch is continually added (solubilized) over a longer period of time as opposed to dumping it all in at once.

Does this make sense?

Sure, and I have no doubt that a finer crush will lead to quicker conversion. As you said, this probably doesn't matter much for a simple infusion mash, since we tend to mash longer than is strictly necessary in any case.

But why would a coarser mash lead to inconsistent results? It seems like you're comparing a highly variable coarse crush to a consistent fine crush, which obviously will make the fine crush look more consistent. Wouldn't a consistently coarse crush produce consistent results, even if slightly different consistent results than a fine crush?

 

[Pilgarlic]

The article originally cited would suggest that from the standpoint of conversion the consistency of the crush matters not, so long as gelatinization temps are reached and given a sufficient (60 min) sach rest. PJJ2ba, are you suggesting a difference not in conversion but in lautering efficiency?

 

[pjj2ba]

Sure, and I have no doubt that a finer crush will lead to quicker conversion. As you said, this probably doesn't matter much for a simple infusion mash, since we tend to mash longer than is strictly necessary in any case.

But why would a coarser mash lead to inconsistent results? It seems like you're comparing a highly variable coarse crush to a consistent fine crush, which obviously will make the fine crush look more consistent. Wouldn't a consistently coarse crush produce consistent results, even if slightly different consistent results than a fine crush?

I'm not talking major differences (trying to balance what the pros want out of a mash versus the hobbyist). I guess it boils down to, do you get the same distribution of particles every time you crush? I suspect for the most part this is probably true, but is probably a little "more true" in the case of the finer crush

The article originally cited would suggest that from the standpoint of conversion the consistency of the crush matters not, so long as gelatinization temps are reached and given a sufficient (60 min) sach rest. PJJ2ba, are you suggesting a difference not in conversion but in lautering efficiency?

I'm talking about conversion. A point here though is the standard lab analysis simply looks at whether or not the starch is converted. It does not involve any sort of analysis of the resultant sugars. If you are doing single infusions, then this is valid. However, one can take a given amount of grain and subject to an infinite number of mash temperatures profiles and WITH FULL CONVERSION, get an infinite range of sugar profiles. This is where I think a finer crush can result in better reproducibility.

This is also why I like to do step mashes. It gives me more opportunity to play with my gear and the flavors/body in the finished product. Or by analogy, I could just juggle with two balls, but I'd prefer to juggle with 10! (If I could juggle). Either way, one is still juggling

 

[MalFet]

I'm not talking major differences (trying to balance what the pros want out of a mash versus the hobbyist). I guess it boils down to, do you get the same distribution of particles every time you crush? I suspect for the most part this is probably true, but is probably a little "more true" in the case of the finer crush

That sounds plausible, and god only knows I've spent scads of time and energy chasing down variability less significant than crush size.

But, I think it's interesting crush seems to be impacting some people significantly and other people almost not at all. It makes me think there's something else going on. The punchline, I think, is that any attempt to troubleshoot efficiency needs to start by separating conversion from lautering efficiency. When people are noticing big spikes from changes in milling, I wonder which half is getting the boost.

 

[pjj2ba]

That sounds plausible, and god only knows I've spent scads of time and energy chasing down variability less significant than crush size.

But, I think it's interesting crush seems to be impacting some people significantly and other people almost not at all. It makes me think there's something else going on. The punchline, I think, is that any attempt to troubleshoot efficiency needs to start by separating conversion from lautering efficiency. When people are noticing big spikes from changes in milling, I wonder which half is getting the boost.

Agreed. Conversion and lautering are two different but related things and need to be addressed both individually and together. I can see where lautering efficiency can be a lot more variable than any crush. The geometry of the lauter filter has a lot more impact on that process then an insulated container has on starch conversion.

I think there are lots of mis-assumptions out there. People will be following a routine and then perhaps suddenly they see a boost in something, be it efficiency, flavor or something else. Then they go AHAH!, it must be X that led to this. Sometimes this may in fact be the case. Fairly often though, they in fact changed several things at once and then associated the wrong change with the boost. Plus we all seem to forget the role practice plays in any improvements we see. It can't possibly be that I've slowly but surely improved my skills and now it is simply easier to make better beer - It must have been some single thing I changed that led to this

 

[brewski08]

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

 

[bob1852]

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?

 

[GodsStepBrother]

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.

 

[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

 

[GodsStepBrother]

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

 

[Denny]

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.

 

[exels]

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.

 

[SouthBay]

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.