What about taking gravity readings at 30 minutes then at 45 to look for a change? I've read how some feel they can get away with only a 30 minute mash. If you see the gravity increasing from 30 to 45 to 60 then you can keep going longer. If it stays the same wouldn't that be an indication you can stop? I'm facing similar issues and I'd hate to go to a 90 minute mash if I don't need to do I might try to take more readings during the mash.
Mill Gap for BIAB (Efficiency Problems)
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What about taking gravity readings at 30 minutes then at 45 to look for a change? I've read how some feel they can get away with only a 30 minute mash. If you see the gravity increasing from 30 to 45 to 60 then you can keep going longer. If it stays the same wouldn't that be an indication you can stop? I'm facing similar issues and I'd hate to go to a 90 minute mash if I don't need to do I might try to take more readings during the mash.
I've actually done this on most of the brews I've completed so far, and I do see the gravity increasing throughout the mash. For example, my last mash:
15 minutes: 1.018
30 minutes: 1.040
45 minutes: 1.041
60 minutes: 1.043
It does seem to slow down toward the end, which is why I'm hoping I can keep doing a 60 minute mash but stir better at the end and dunk the bag a couple of times to better rinse it. Like you I don't want to do a 90 minute mash if I don't have to.
Yep, taking readings of mash SG will tell you how far your conversion has progressed. You should stir well before each reading for the same reason you stir before pulling the bag. Compare your measured SG with the value in the table here to determine what your conversion efficiency is at that point in the mash. You can end the mash when your conversion efficiency gets close enough to 100% to satisfy you. If you get to a point where the SG no longer is increasing, even if significantly less than 100% conversion, your enzymes have probably completely denatured, and you are done (whether you want to be or not,)
As said above, if the gravity is still increasing between measurements, you mash is not "done." Again, use the link above to determine the actual % conversion.
Dunking the bag will not provide any benefit over just stirring adequately, unless you dunk in fresh water (then you are doing a dunk sparge, which is a version of a batch sparge.)
Brew on
Well maybe a longer mash is called for then. When I brew this weekend I'll try mashing out to 90 minutes and monitor the SG. Kind of kills some of the time savings of BIAB, but if it helps me attain better conversion efficiency then it's worth it.
Required mash time for full conversion is primarily determined by crush. Gelatinization of the starch is the rate limiting step in the conversion process. The enzymes cannot do their work until the starch is gelatinized (and they work even faster once the starch is dissolved in the wort.) Gelatinization proceeds from the surface of the grits towards the center. The larger the grit, the greater the distance from the surface to the center, and the longer it takes the grit to fully gelatinize.
If you can't reduce the crush size, you may have to accept longer mash times or lower conversion efficiency.
Brew on
If you can't reduce the crush size, you may have to accept longer mash times or lower conversion efficiency.
Brew on
Required mash time for full conversion is primarily determined by crush. Gelatinization of the starch is the rate limiting step in the conversion process. The enzymes cannot do their work until the starch is gelatinized (and they work even faster once the starch is dissolved in the wort.) Gelatinization proceeds from the surface of the grits towards the center. The larger the grit, the greater the distance from the surface to the center, and the longer it takes the grit to fully gelatinize.
If you can't reduce the crush size, you may have to accept longer mash times or lower conversion efficiency.
Brew on
Exactly. What he said.
Required mash time for full conversion is primarily determined by crush. Gelatinization of the starch is the rate limiting step in the conversion process. The enzymes cannot do their work until the starch is gelatinized (and they work even faster once the starch is dissolved in the wort.) Gelatinization proceeds from the surface of the grits towards the center. The larger the grit, the greater the distance from the surface to the center, and the longer it takes the grit to fully gelatinize.
If you can't reduce the crush size, you may have to accept longer mash times or lower conversion efficiency.
Brew on
That makes perfect sense, however I'm crushing finer than most, and seeing significantly lower conversion efficiency than most. Based on the sieve testing Monster Brewing performed, and the gap I have my mill set to, I should have really good crush. To my inexperienced eyes it looks really good, but I'll post a picture later this week when I get ready to brew my next batch.
It seems like non-BIAB brewers, who have to use a coarser crush, are seeing pretty good conversion efficiency too, and other than the presence of the bag, the mash is identical.
The only other thing I can think of is to machine new bulkheads for my Monster Mill that would allow me to adjust the mill gap even finer. I could do this, it would take some work, and seems well outside the realm of what should be necessary.
I'm stumped. Will try stirring like a madman this weekend as well as extending the mash and see how things go. Otherwise I'll likely just assume 80-85% conversion efficiency moving forward. The fact that I'm getting lower conversion efficiency than I should will forever bug me, however.
I appreciate all the input. While I may not have completely solved my problem, I've seen some improvement and I've learned a lot more along the way.
Just a guess here, I'm thinking the helical slotted rollers may not free the inside of the kernel, and the kernel remains whole with the husk cracked, but not free of the kernel. This would slow conversion. The quest for husk preservation may have been taken too not allowing easy access to the inner starch portions ... idk.
Monster claims this is a first in homebrewing mills....perhaps this concept is in the developmental stages for smaller 2 roller mills.
Perhaps it works great on larger multi roller commercial mills but doesn't scale down quite so simply.
Anyways I have a hunch at the reduced gap your planning, and THOROUGH stirring, your efficiency will jump.
Milling new end plates?
OMG I would look to send it back to MM before taking on that project.
All the best!
Wilser
Monster claims this is a first in homebrewing mills....perhaps this concept is in the developmental stages for smaller 2 roller mills.
Perhaps it works great on larger multi roller commercial mills but doesn't scale down quite so simply.
Anyways I have a hunch at the reduced gap your planning, and THOROUGH stirring, your efficiency will jump.
Milling new end plates?
OMG I would look to send it back to MM before taking on that project.
All the best!
Wilser
Very interesting theory! There is obviously something going on as Monster says the mill gap setting is different than with a knurled roller. The depth of the helical cuts in the roller is substantial, so if two of the cuts were to align around a grain, the mill gap is significantly greater than if the non-cut portions of the rollers line up.
This is also possible, and I'd be a little frustrated to have spent such a large sum of money on a prototype. Monster has been a great source of information however, and their sieve testing gives me confidence that the mill *should* produce a very good grain crush. At a mill gap ~0.025" they obtained 63% of the grist in the coarse pan, which is close but not quite in the ideal range referenced in the link you posted earlier in the thread. My hope is that setting the mill to its lowest setting of 0.022" will get me there.
I already tested the reduced (smallest possible) gap on the batch I brewed with a friend, and our conversion efficiency wasn't great. That was with his process though, which doesn't involve as much stirring as mine. I've yet to try the finest gap setting with my process, so I'll reserve judgement until this weekend. I do hope you're right
As helpful as Monster Brewing has been in providing information to dial in the grain crush, they weren't willing to concede that the mill might require a finer setting than the supplied bulkheads will allow, so I'm not sure I'd get very far in requesting a return.
I've also invested a significant amount of time already in milling a base for the mill out of a block of aluminum (see attached image of almost complete base prior to filleting). On top of that I've designed a table for the mill to accommodate a direct-drive motor, construction of which is almost complete.
Thanks again, really appreciate all the input I've received here!
1MadScientist
Well-Known Member
Thanks for sharing in advance of your next brew day.
Your 9 gallons starting water is spot on, that's good.:rockin:
1.047 OG with 9# grains
34.68 L = 9.16 Gal of cold starting water
33.57 L = 8.87 Gal of boiled hot wort
32.27 L (adjusted) pre-boil to a cold temperature
34.68 L - 32.27 L = 2.41 L (difference)
9 lbs grain = 4.083 kg
4.083 kg * 0.6 L/KG (hot liquor retained by grain) = 2.45 L
Apparent grain absorption = 2.45 L / .647 Gal
pre-boil 8.87 gals @ 1.0326
evaporation in 90 mins. 2.71 gals
flame-out 6.16 gals
cooled at 5.92 gals @ 1.047
trub 0.64 gals
in fermentor 5.28 gals.
I will always recommend a 90 mins mash with enough stirring plus keeping the bag in the kettle during heating to a mashout (takes about 10+ mins to get to mashout temp) , one last stir, then lift the bag.
Good Luck
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With due respect MS, how is a preboil of 8.9 gallons possible with a total water volume of 9 gallons?
Is that the Hercules squeeze lol?
Is that the Hercules squeeze lol?
Thanks for taking a look for me
I have an estimated pre-boil volume of 8.41 gallons followed by a 1.75 gal/hr boiloff rate.
Epos7,
Are you mashing full volume with simply a kettle and bag? Or are you using a basket or false bottom? In some instances using a FB or basket results in a large percentage of the available water outside the mash and a reduction in efficiency. An example would be a small batch, large kettle with a high percentage of liquor outside the grain bag not fully participating in the process.
Describe your set up please.....sorry if this has been done...
Are you mashing full volume with simply a kettle and bag? Or are you using a basket or false bottom? In some instances using a FB or basket results in a large percentage of the available water outside the mash and a reduction in efficiency. An example would be a small batch, large kettle with a high percentage of liquor outside the grain bag not fully participating in the process.
Describe your set up please.....sorry if this has been done...
I'm just mashing at full volume with a Spike 15 gallon kettle and one of your bags. No false bottom or basket. I made a mash paddle out of some scrap madrone I use to stir, I drilled some 1.5" holes in it to make it easier to move through the wort. I wrap the kettle in a sleeping bag during the mash.
I have found the best device for stirring the thinner mashes typical of BIAB to be one of these:
I got mine here: https://www.amazon.com/dp/B001VZ8S1Q/?tag=skimlinks_replacement-20 Great for breaking up dough balls, and provides more uniform shear thru the bulk of the mash when stirring.
Brew on
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1MadScientist
Well-Known Member
I added information in red on my post #90 << https://www.homebrewtalk.com/showpost.php?p=7729178&postcount=90 >>. Hopefully I explained it well, does this makes sense.?
With all the handy people in the forum making all kinds of devices, I'm surprised we don't see more automatic mash stirring devices.
This thread has me considering an upgrade from the Barley Crusher to a Monster Mill 3. I'm never able to spot a good crush except when you see fully in tact grains. So I start to wonder if gap settings are important if the rollers themselves aren't up to the job.
This thread has me considering an upgrade from the Barley Crusher to a Monster Mill 3. I'm never able to spot a good crush except when you see fully in tact grains. So I start to wonder if gap settings are important if the rollers themselves aren't up to the job.
I'm thinking the helical grooves on the MM are a poor design. I'm kinda tired tonight, so I will explain my theory about why I think that on Friday.
Brew on
I'll be pretty bummed if the mill turns out to be no good. If that's the case I'm hoping Monster would let me work out an exchange for the knurled MM2-Pro.
I'm going to crush some grains for this weekend tonight. I'll try to get some good pictures of the crush and post those.
I'm going to crush some grains for this weekend tonight. I'll try to get some good pictures of the crush and post those.
Magnus314
Well-Known Member
Orthogonal answer, but if you know the last runnings are high gravity, why not reserve a bit of mash water and sparge?
Mash, squeeze, sparge, squeeze.
Can't hurt (efficiency).
Mash, squeeze, sparge, squeeze.
Can't hurt (efficiency).
Kind of a crazy thought, but I'll put it out there.
Could the non drive roller be reversed end to end in the mill so that the helical grooves do not parallel to each other while milling? This would reduce or eliminate the wider gap created when the grooves align, and perhaps give a more thorough crush at similar gap.
Crazy to be thinking like this, but since you brought up changing the end plates I'm guessing your open to suggestions.
Sorry I realize it's backwards thinking.
Could the non drive roller be reversed end to end in the mill so that the helical grooves do not parallel to each other while milling? This would reduce or eliminate the wider gap created when the grooves align, and perhaps give a more thorough crush at similar gap.
Crazy to be thinking like this, but since you brought up changing the end plates I'm guessing your open to suggestions.
Sorry I realize it's backwards thinking.
I had the same thought! It would be easy to try, and shouldn't hurt anything. I'm going to keep it on the back burner as something to try.
The grooves are currently not parallel to each other in the grinding zone. And turning end for end won't change anything. To change crossed grove to parallel groves (or vice versa) you need to change one of the rollers to right hand grooves (they are currently both left hand twist.) If you turn a right hand threaded rod end for end, it is still a right hand threaded rod (same for left hand threads.)
I think you are on the right track as far as the root problem though. In the grinding zone, 25% of the length (averaged over a full rotation) is at the measured gap. 50% of the length is at the measured gap plus the groove depth, and the last 25% is at the measured gap plus two times the gap depth. With a 0.022" gap and 0.020" groove depth, the maximum gap would be 0.062", which wouldn't provide much of a crush. And, the 25/50/25 ratio of gap run lengths is misleading, as the maximum gap will have 0.062 / 0.022 = 2.8 times the volume of the minimum gap. Thus a large fraction of the grain will actually go thru the maximum gap, and be poorly crushed.
The fix for this is to make the groove pitch on the rollers less than the length of a typical barley kernel (actual optimum pitch would need to be determined experimentally, preferably by MM's engineering dept.) But, that will probably make the rollers significantly more expensive to machine.
What is the actual groove depth on the rollers? I just WAG'ed a value above, and if the grooves are much shallower than 0.020", then things might not be as bad as laid out above.
Brew on
ps: I was supposed to have written this up yesterday, but I got distracted.
Spot on as usual Doug, good analysis. Not sure why I thought the rollers were opposite spiral rather than the same....also obviously turning a roller end for end does nothing....shame on me lol.
The pic below shows the roller grooves pretty well, I'm guessing your guess of 0.02" might be a little light, IDK.
I measured the groove depth with a pair of calipers as 0.03" so as doug outlined, the maximum gap is substantial (more so than he estimated even).
I brewed yesterday. Here is a picture of my grain crush at 0.022", as low as the mill can go. I actually determined it can go down to 0.020" on one side and 0.022" on the other, but kept both sides set to 0.022" so as to keep the shafts perpendicular to the bushings.
https://dl.dropboxusercontent.com/u/16976040/DSC_1410.jpg
I still find some whole grains in the crush, but usually when I pick them out they have been cracked and fall apart in my fingers.
I modified the Munich Helles recipe slightly to fit in a 5 gallon fermenter.
6.96 lbs pilsner malt, 0.96 lbs Munich malt, 0.11 lbs Melanoidin for a total grain bill of 8.03 pounds.
I mashed in 8.25 gallons of water.
15 min: 6.3 brix (1.025 SG)
30 min: 7.1 brix (1.028 SG)
45 min: 7.2 brix (1.029 SG)
-fired up burner briefly to bring mash back up to temp-
60 min: 7.6 brix (1.030 SG)
70 min: 7.7 brix (1.031 SG)
I mashed out to 70 minutes to see what would happen. I didn't go further since I had already overshot my estimated pre-boil SG per Brewer's Friend. My mash pH was pretty far off this time around at 5.72. I added a few more salts than I usually do, and the Brewer's Friend water calc was pretty far off on the pH estimation. I added a tiny amount of table salt, which may have contributed as sodium is basic in solution, but the calculator should account for that, so I'm not sure what happened.
Pre-boil volume: 8 gallons
Post-squeeze: 7.6 brix
According to Brewer's Friend, at 7.7 brix that gives me a conversion efficiency of 92%, or 88% at 7.6 brix. I'm guessing the actual reading was right around 7.65 brix, which is what caused my refractometer to jump back and forth. Brewer's friend calculated an expected pre-boil gravity of 1.029 at 75% brewhouse efficiency, so it seems like they're assuming an 85% conversion efficiency.
My boil-off rate was lower than I estimated, so I still undershot my expected OG by quite a bit. Ended up at 10.5 brix (1.042 SG) instead of the expected 12.1 brix (1.049 SG). Still, that should be an easy fix. I had my boiloff rate set to 1.75 gallons/hour, but I've changed that to 1.5 gallons/hour moving forward. Target was 4.5 gallons into the fermenter. I ended up with 4.8, with almost a gallon of wort + trub left in the kettle.
I think the helical cutters may produce a crush that's weighted heavily toward both ends of the spectrum. I think it produces a lot of flour when the grains pass through the rollers when the non-cutter sections are lined up, but also produces a very coarse crush when the helical cutters line up over the grain. I don't think it produces much in between those two extremes.
I brewed yesterday. Here is a picture of my grain crush at 0.022", as low as the mill can go. I actually determined it can go down to 0.020" on one side and 0.022" on the other, but kept both sides set to 0.022" so as to keep the shafts perpendicular to the bushings.
https://dl.dropboxusercontent.com/u/16976040/DSC_1410.jpg
I still find some whole grains in the crush, but usually when I pick them out they have been cracked and fall apart in my fingers.
I modified the Munich Helles recipe slightly to fit in a 5 gallon fermenter.
6.96 lbs pilsner malt, 0.96 lbs Munich malt, 0.11 lbs Melanoidin for a total grain bill of 8.03 pounds.
I mashed in 8.25 gallons of water.
15 min: 6.3 brix (1.025 SG)
30 min: 7.1 brix (1.028 SG)
45 min: 7.2 brix (1.029 SG)
-fired up burner briefly to bring mash back up to temp-
60 min: 7.6 brix (1.030 SG)
70 min: 7.7 brix (1.031 SG)
I mashed out to 70 minutes to see what would happen. I didn't go further since I had already overshot my estimated pre-boil SG per Brewer's Friend. My mash pH was pretty far off this time around at 5.72. I added a few more salts than I usually do, and the Brewer's Friend water calc was pretty far off on the pH estimation. I added a tiny amount of table salt, which may have contributed as sodium is basic in solution, but the calculator should account for that, so I'm not sure what happened.
Pre-boil volume: 8 gallons
Post-squeeze: 7.6 brix
According to Brewer's Friend, at 7.7 brix that gives me a conversion efficiency of 92%, or 88% at 7.6 brix. I'm guessing the actual reading was right around 7.65 brix, which is what caused my refractometer to jump back and forth. Brewer's friend calculated an expected pre-boil gravity of 1.029 at 75% brewhouse efficiency, so it seems like they're assuming an 85% conversion efficiency.
My boil-off rate was lower than I estimated, so I still undershot my expected OG by quite a bit. Ended up at 10.5 brix (1.042 SG) instead of the expected 12.1 brix (1.049 SG). Still, that should be an easy fix. I had my boiloff rate set to 1.75 gallons/hour, but I've changed that to 1.5 gallons/hour moving forward. Target was 4.5 gallons into the fermenter. I ended up with 4.8, with almost a gallon of wort + trub left in the kettle.
I think the helical cutters may produce a crush that's weighted heavily toward both ends of the spectrum. I think it produces a lot of flour when the grains pass through the rollers when the non-cutter sections are lined up, but also produces a very coarse crush when the helical cutters line up over the grain. I don't think it produces much in between those two extremes.
By my calculations, using the correction factor of 1.04 from Sean Terrill's brix to gravity conversion (http://seanterrill.com/2012/01/06/refractometer-calculator/comment-page-1/), you actually achieved the expected 1.029 pre-boil which means you might have gotten 75% brewhouse (BEFORE the boil) and 85% conversion. Then after the boil you had not 1.042 but rather 1.040, which is 9 points lower than the desired 1.049, with a final brewhouse efficiency of about 62% instead of the 75% that you might have gotten had you not left behind 3-4 quarts in the kettle.
I would strongly encourage you not to waste the kettle trub if you care about efficiency. Just go ahead and dump it all into your fermenter.
Bottom line is that you used too much strike water, 8.25 gallons instead of the proper amount which would have been about 7.5 gallons, and this is most likely because you did not accurately account for the boiloff rate of 1.5 gal/hour instead of 1.75 gal/hour, plus you left a lot of sugar in the kettle. Had you used just 7.5 gallons strike water, and kept most of the kettle trub, then your conversion efficiency would have been higher, and your final brewhouse should have been closer to 75%, respectively, ballpark figures.
So, this whole thing, in my opinion, has more to do with volume measurements, boiloff rates, and kettle waste, than anything else.
Mash pH probably also played a role, but a minor one IMHO.
We're getting closer now.
I would strongly encourage you not to waste the kettle trub if you care about efficiency. Just go ahead and dump it all into your fermenter.
Bottom line is that you used too much strike water, 8.25 gallons instead of the proper amount which would have been about 7.5 gallons, and this is most likely because you did not accurately account for the boiloff rate of 1.5 gal/hour instead of 1.75 gal/hour, plus you left a lot of sugar in the kettle. Had you used just 7.5 gallons strike water, and kept most of the kettle trub, then your conversion efficiency would have been higher, and your final brewhouse should have been closer to 75%, respectively, ballpark figures.
So, this whole thing, in my opinion, has more to do with volume measurements, boiloff rates, and kettle waste, than anything else.
Mash pH probably also played a role, but a minor one IMHO.
We're getting closer now.
P.S. Err... ignore the part above where I said "then your conversion efficiency would have been higher". (I'm unable to edit posts from my browser at work for some reason.) Conversion efficiency should stay pretty much the same regardless of water to grist ratio, however it might indeed have been improved with lower mash pH. Did you use baking soda? If so, you shouldn't add that until the boil kettle. Don't ever use it in your mash as a general rule. I don't think the sodium from salt does very much at all to affect pH.
Hmm.... also just from a high level review standpoint, 8 lb in 4.5 gallons of brew just simply does not seem like it's enough to produce a 1.049 beer. So just from that aspect alone, I am not at all surprised that you only hit 1.040. As a general rule, you'd need at least like 10-11 lb for a standard strength beer at about 5 gallons, or okay 4.5 or 4.8. Just 8 lbs seems like a pretty small grist, gut feel.
Hmm.... also just from a high level review standpoint, 8 lb in 4.5 gallons of brew just simply does not seem like it's enough to produce a 1.049 beer. So just from that aspect alone, I am not at all surprised that you only hit 1.040. As a general rule, you'd need at least like 10-11 lb for a standard strength beer at about 5 gallons, or okay 4.5 or 4.8. Just 8 lbs seems like a pretty small grist, gut feel.
Thanks for clarifying, I was going to ask you about the conversion efficiency changing.
I didn't use baking soda. The Brewer's friend water chemistry calculator has been spot on for pH estimations in my first couple of batches with domestic grains. I'm thinking it's the Belgian pilsner grains that must be contributing to a higher than normal pH.
As far as kettle trub I've just been siphoning everything out of the kettle until the wort/trub mixture becomes too thick to move through my autosiphon, or until I hit my desired fermenter volume, whichever comes first. The wort/trub mixture usually becomes too thick when there's about half a gallon left in my kettle.
I managed to get a late night brew in yesterday. Same Munich Helles recipe, but scaled for a target of 5.25 gallons into the fermenter. I also made some adjustments to my equipment profile this time around to try to better nail the starting water volume.
I overshot my estimated pre-boil SG again, by even more than last time. And I ended up with a little more pre-boil water than predicted, but I'm not entirely clear on whether Brewer's Friend takes wort expansion into account, ie is the estimated pre-boil volume the estimated volume at mash temp, or at room temp? I think I also need to check the volume markings on my kettle to make sure they're accurate.
Despite overshooting my pre-boil SG, I nailed my OG (almost) - 1.048 vs expected 1.049. Somehow I ended up with less wort in my fermenter than I was targeting, and I'm not sure how that could happen given that I overshot my pre-boil SG.
I'll post some more detailed notes about the brew later today. My mash pH this time around was just over 5.4, still higher than Brewer's Friend was predicting, but in an acceptable range. I significantly increased the amount of lactic acid I added to the mash.
I think the wort correction factor on my refractometer is damn near 1. I've checked it against a hydrometer before, but I'm going to make up some wort with DME after work to double check that. Most people who own this specific refractometer report a wort correction factor between 0.95-1.
Cool, glad you're seeing improvements.
Interesting about the correction factor. I suppose I should calibrate my own refractometer to see how close it relates to Terrill's experience. I do believe it's within a couple gravity points assuming the factor of 1.04, but I suppose I don't have the experience yet to really know it for a fact -- I just got mine a few months ago and so far it seems really close with a hydrometer using the 1.04 factor.
stever1000
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My mill gap is set to the factory setting of 0.039" on my barleycrusher. Does the crush look okay? This is my first time using it, and from observation is looks quite fine already...I am going to adjust it to .030" next time.
That looks really good. I have a Barley Crusher as well. I set mine just a hair tighter than the recommended factory setting, and I have been very pleased with the results.
stever1000
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Do you ever double crush? I have been thinking of trying that to make sure more grains are cracked/crushed
1MadScientist
Well-Known Member
My mill gap is set to the factory setting of 0.039" on my barleycrusher. Does the crush look okay? This is my first time using it, and from observation is looks quite fine already...I am going to adjust it to .030" next time.
That's good for a Barley Crusher. I have one set at .039" and it's easy to get 80% into boil efficiency, ymmv I go with a 90 mins. mash and a mash out. For BIAB, the Barley Crusher is good within the range .030 to .039, imo.
stever1000
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Thanks for the info - I will try a mashout and see how that helps me
Personally, no. In fact I have actually opened the gap on my mill with the theory that if you crush too hard, you might be missing out on malt flavor. On the other hand, I recently ran a blind triangle experiment that essentially disproved that theory -- a high efficiency beer tasted no better and no worse than a low efficiency beer. So maybe I'll tighten the gap once again. In the past I had averaged about 90-92% efficiency. After opening the gap, I have been getting 80-82% on every batch. I'll admit, I'm still undecided, even after running my experiment. I think I might just leave it alone. I'm fine with 80-82%.
Chasing efficiency is all well and good, but the most important thing is to be consistent and predictable so that you can design your recipes around it. Personally I think when you can hit at least 75% efficiency consistently on every batch, you're doing "good enough" and should be happy with it. But even a lower efficiency is not necessarily a bad thing at all, as long as it's consistent. It's just that it's easy enough to crush just a little harder and get into the 70s. Anyone should be able to hit >70% easily. If not, it's almost always because of the crush.
My 3 cents.
I set out to determine the wort correction factor yesterday. I was planning to check my refractometer against my hydrometer, which I know reads about one point high. I realized pretty quickly my hydrometer has too wide of a range to be accurate for this purpose. A 0-12 brix hydrometer would be ideal.
On the other hand, I made some wort using 48g of DME in 500ml of water (I weighed this out - 500g by mass) then let it mix well on my stir plate for an hour. This should produce wort with a gravity of 1.036. Since DME is pretty homogeneous I would expect this calculation to be accurate. My refractometer read 8.8 brix on that wort, which results in a wort correction factor of 0.97 - 0.98.
The trouble with this is that DME is produced not consistently, but could be in a pretty broad range of anywhere between 40-45 PPG, so your calculations could be off. Do you know for a fact what the PPG rating is for your particular batch of DME? If not then your above result may not be valid. Following is what I calculate for specific gravity for the different PPGs of different DME batches, using 48g in 500g(ml):
PPG=40, SG=1.032
PPG=41, SG=1.033
PPG=42, SG=1.034
PPG=43, SG=1.034
PPG=44, SG=1.035
PPG=45, SG=1.036
So, if your actual PPG of this particular batch of DME that you have actually is 42 PPG rather than the apparently assumed maximum of 45 PPG, then your correction factor is actually 1.04 as others reported.
So, who's to say which value is correct unless you have the inside scoop from your DME manufacturer.
Trying to help.
Fair point. I'll take a look at the packaging for my DME when I get home today to see if there is any indication. I used the Brewer's Friend calculator, which must be assuming 45 PPG. I was under the impression that it must be pretty standardized, but it sounds like that may not be the case. Maybe I'll look into a 0-12 brix hydrometer, as that seems like it might be the only way to arrive at a reasonably accurate number.
DME is also hygroscopic, and is likely to have absorbed some moisture since the bag was opened over a week ago. So that would throw an additional wrench in my attempt to produce wort of a specific gravity as the sugars per a given weight would gradually decrease as the DME absorbs moisture.
Excellent point, hygroscopic / hydrophilic. If you're going to go the route of laboratory experimentation, you'd have to somehow warm the extract in an oven without melting it (probably impossible) or place in a vacuum to remove water vapor. Also might need to account for changes in water density at different temperatures. Not easy.
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