Ha! I would like to, but I've got to wait a couple weeks for some space to open up in my fermentation chamber. That leaves me a lot of time to ruminate, maybe too much
Mill Gap for BIAB (Efficiency Problems)
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Ha! I would like to, but I've got to wait a couple weeks for some space to open up in my fermentation chamber. That leaves me a lot of time to ruminate, maybe too much
my mill is set to 0.035" single pass and i get 78% brewhouse eff. I dont stir at all after mash in. Mash in is the only time I stir. I havent seen any change in efficiency by not stirring. I have been trying this as there was a school of thought that very very slow lifting of the bag after mash helped reduce the amount of flour and trub in the kettle. I let it hang over the kettle for the 30 min it takes my system to reach boil and I also squeeze just before i move it.
i havent sparged because i dont think i need to but then again most of my brews are below 1.060 so cant comment on need to sparge higher OG
i havent sparged because i dont think i need to but then again most of my brews are below 1.060 so cant comment on need to sparge higher OG
That leaves me a lot of time to ruminate, maybe too much
Ok than read this about crushing grain....note the "expert" didn't even use a feeler gauge but rather just by eye...Look at pics of what a good crush looks like, I believe it to be more crushed than where you are.
http://brewlikeapro.net/maltmilling.html
On another note when i set my mill i used a feeler gauge and noticed that there is a slight misalignment in the rollers com,pared to the adjustment markers on the mill ends. If I used the adjustment marks on the sides of the mill and set them the same the feeler gauge at one roller end is not the same as the other. I now ignore the markings if i move it and set using feeler gauges at each end of the mill rolls.
Wow, what a great article, and an excellent method for quantifying mill setup. I would say my crush falls in between his examples of "good" and "bad" meaning I can afford to tighten it up some more.
I noticed the same with my mill, and also elected to set it using the feeler gauge and ignore the position of the adjustment knob.
I believe he mentions wheat and rye as well....
Also notice the impressive numbers that the cheap $25 corona mill puts out lol, I just find that interesting / ironic.
BeardedBrews
Well-Known Member
There isn't really a reason you'd have to wait for a new batch to test your conversion efficiency. 2# of 2-row and a gallon of hot water are cheap, you can just dump it when you're done.
For what it's worth, I keep my Cereal Killer between the 0.025 and 0.050 marks on the side and get fairly good conversion efficiency, but I also found early on that I was putting volume numbers into Brewer's Friend "wrong" based on my BIAB approach.
"Mash Complete" Step - Enter the total strike water volume
"Pre-Boil Gravity" Step - Enter the volume after you've squeezed the grain bag
"Boil Complete" Step - Volume in the kettle after you chill it but before transferring
"Brew Day Complete" Step - Volume in the carboy
Using this approach means that each step can only have one source of "loss".
Mash - Conversion Efficiency
Pre-Boil - Lautering Losses
Boil Complete - N/A
Brew Day Complete - Transfer and Trub Losses (and any losses because it wouldn't fit in the carboy)
http://cdn.brewersfriend.com/understanding_efficiency_large.png
I included a snapshot of the brew I did Sunday morning. It was a 20 minute mash / 20 minute boil which meant my conversion efficiency wasn't great (88%), and I overshot my final volume which ended up being the biggest hit on my brew-house (BH 66%).
For my process the biggest things that have helped improve my conversion efficiency were:
1. Mind the Gap - I am more consistent with my home mill, and I keep it relatively tight.
2. Stir the Mash - Unless it's a short mash I stir every 15 minutes during the mash. It has helped out considerably.
I honestly worry less about brew-house efficiency numbers because they swing so much depending on how much trub and hops you send into the carboy. Brewer's Friend lets you pick the ending kettle volume instead of the carboy volume as your batch size target which normalizes your efficiency a bit.
For what it's worth, I keep my Cereal Killer between the 0.025 and 0.050 marks on the side and get fairly good conversion efficiency, but I also found early on that I was putting volume numbers into Brewer's Friend "wrong" based on my BIAB approach.
"Mash Complete" Step - Enter the total strike water volume
"Pre-Boil Gravity" Step - Enter the volume after you've squeezed the grain bag
"Boil Complete" Step - Volume in the kettle after you chill it but before transferring
"Brew Day Complete" Step - Volume in the carboy
Using this approach means that each step can only have one source of "loss".
Mash - Conversion Efficiency
Pre-Boil - Lautering Losses
Boil Complete - N/A
Brew Day Complete - Transfer and Trub Losses (and any losses because it wouldn't fit in the carboy)
http://cdn.brewersfriend.com/understanding_efficiency_large.png
I included a snapshot of the brew I did Sunday morning. It was a 20 minute mash / 20 minute boil which meant my conversion efficiency wasn't great (88%), and I overshot my final volume which ended up being the biggest hit on my brew-house (BH 66%).
For my process the biggest things that have helped improve my conversion efficiency were:
1. Mind the Gap - I am more consistent with my home mill, and I keep it relatively tight.
2. Stir the Mash - Unless it's a short mash I stir every 15 minutes during the mash. It has helped out considerably.
I honestly worry less about brew-house efficiency numbers because they swing so much depending on how much trub and hops you send into the carboy. Brewer's Friend lets you pick the ending kettle volume instead of the carboy volume as your batch size target which normalizes your efficiency a bit.
Fair point, and thanks for the post. It looks like I've been using a different tool than you have on Brewer's Friend. I've just been using the Brewhouse Efficiency Calculator.
brew703
Well-Known Member
Did you withhold a gallon of water from your strike water volume to pour over your grains? I don't sparge but I normally just dunk the bag in and out of the wort then squeeze using some bbq gloves to squeeze all the wort out. My brewhouse efficiency always sucks, usually under 70%. I like the idea of using a bucket and drilling holes in the bottom and may try that on my next brew to see if that improves my efficiency.
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Yes. In Beer Smith I specify whatever volume I'll rinse with as "kettle top up" so it pulls that from the strike volume and adjusts strike temps correctly. You can do the same thing without messing with the software just by holding off on a gallon.
BeardedBrews
Well-Known Member
I'm using the brew session log function to track my brews, it makes it easier for me to keep all the data in one place, although it also means I have to keep a phone or ipad nearby during the brew day.
I've set my mill to 0.025". I looks like 0.022" is as low as I can go, so hopefully 0.025" gets close to a good result. I could try mashing a couple pounds of 2-row in a gallon of water, but maintaining mash temps on that small of a volume would be challenging. I've got a friend who is going to brew soon and wants to use my mill. I'm hoping he can be my tester.
Do the test mash in a pot you can put in your oven. Will help hold temperatures.
Brew on
pricelessbrewing
Brewer's Friend Software Manager
Do the test mash in a Thermos.
I brewed again today, and with a 0.025" gap I hit 86% conversion efficiency. I think next I'll try going to 0.022", which is as low as my mill can go. 86% is a significant jump from where I was. For this brew I also fired up the burner for five minutes about 15 minutes into the mash to bring it back to 152 as it had already dropped a few degrees. This might also have aided efficiency.
ch19
Well-Known Member
Entered the numbers wrong, conversion efficiency was 82% not 86%. I'm wondering how much of that improvement was from the finer crush and how much was from reheating the mash water. Think I'll go as low as my mill can go next time - .022" and see what happens. If that doesn't get me up to 90% there's not much else I can do. Still, at least I'm moving in the right direction.
I emailed Monster Brewing and got some good info. They said the gap setting for the helical rollers is much different than for knurled rollers, and recommended starting at 0.030" and going down from there. It's good to know the setup is different, and I'm hoping I can take another big jump in conversion efficiency going down to the lowest setting 0.022".
normonster
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After that you should borrow a Corona and grind it up even further and check the diff. When I was dogging on Corona mills everyone kept saying how they're awesome for BIAB. It sure would be a ***** though if you got better results with a $50 mill vs. your Monster.
It's a little strange that the Monster can't go lower than 0.022" as it says it can go down to 0 on their website. Still, if I can get good results I'll be happy. I mostly bought the Monster Mill because it should last forever. I'm pretty confident the rest of my process is sound, but I'm still pretty new to this and it's certainly possible I'm overlooking something obvious that is hurting my conversion efficiency.
normonster
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I have the MM2 (I think it is) and it looks like it goes to 0.
One tip that helped me that may or may not help you is this: when you set the gap, make sure the roller is on it's way closed when you tighten the thumb screws, as opposed to on it's way wide open.
Mine slipped a little on the first batch I used it with and when I called concerned that the thumbscrews weren't locking it down right they told me that and it hasn't slipped since.
I had the same thought as you and basically set the gap by rotating the rollers to find the smallest possible distance. The 2" mills hold their settings a little differently than the 1.5" mills, and it seems to be pretty solid.
Monster said they did some sieve testing around 0.025" gap on the mill I have, and found 63% of the grist in the coarse pan, with 9% flour in the bottom pan. Based on the link posted earlier in this thread by wilserbrewer, that's pretty close to an ideal crush, but could be adjusted to bring the coarse pan down below 60%. I'm hoping dropping the gap to 0.022" will do just that, although I'll have no way of testing.
Couple of questions just to clarify -
It looks like you are taking a gravity reading to measure your conversion efficiency after you have squeezed the bag and taken any additional sparge steps, is that right? I've been taking a reading before squeezing the bag, which is probably making my mash/conversion efficiency appear lower than it is. Any sugars left in the bag represent starches that have already been converted to sugars and should therefore be included in the conversion efficiency. It's a little confusing applying these measurements to BIAB, but I think I have my head wrapped around it now.
Mash efficiency = conversion efficiency, if I'm understanding correctly. For example, I just brewed a batch with a friend on his system, using my mill. We set the mill gap to 0.022". His grain bill was 32lbs 2 Row and 2lbs Munich, and we mashed in 16 gallons of water.
That grain bill gives a total of 1222 points / 16 gallons = 76.375 points per gallon, or a potential gravity at 100% efficiency of 1.076.
Our refractometer reading after squeezing the bag was 14 brix, or a gravity of 1.0568 (56.8 points).
56.8 points / 76.375 points gives us a mash efficiency of ~74%.
Now you're confusing me. Here's my understanding, based on science (FYI, I have an engineering degree):
Squeezing the bag will help your overall brewhouse efficiency, but this overall improvement is due to lauter efficiency, not conversion efficiency. Conversion has to do with starches turning into sugars. Conversion does not improve from squeezing the bag; the conversion efficiency is a measurement of the effectiveness of a chemical reaction which is affected by crush, enzymatic content, temperature, time, pH, etc. You can't just squeeze a starch to turn it into sugar. The concentration of sugars is the same both inside and outside of the grain bag. In other words...
After the mash is complete, any specific gravity readings taken before and/or after squeezing the bag should be identical. However, after squeezing the bag, even though the concentration stays the same, you will indeed have more total mass of sugar collected -- this sugar is not wasted by being soaked up into the spent grains. This extraction of total sugar describes lauter efficiency, which is more based on physical separation than the chemical reaction. You can subsequently concentrate the sugars down in the boil as much or as little as you want, as the total amount of sugar stays the same, while evaporation only affects the water content / volume.
Maybe I'm just rambling, I don't know. I'm trying to make sure you don't think you'll get different readings before and after squeezing a bag, because you won't -- concentration stays the same before and after. However the boil will definitely change the concentration, and so will the mash... at least, for the first 30 minutes or so until conversion nears completion.
"Mash efficiency" ("Pre-Boil Efficiency" in BrewersFriend's terminology) is made up of two components: "Conversion Efficiency" - the percentage of starch in the grain converted to sugar during the mash, and "Lauter Efficiency" - the percentage of the sugar actually created in the mash that makes it into the boil kettle.
Mash Efficiency = Conversion Efficiency * Lauter Efficiency
Conversion efficiency can be as high as 100%, meaning you converted all of the available starch. Lauter efficiency is alway less than 100% because of the sugar content of the wort remaining in the wet grain.It turns out in practice that for typical grain bills, the maximum potential wort SG in the mash, at 100% conversion efficiency, depends only on the water to grain ratio in the mash (ref: http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency#Measuring_conversion_efficiency.) So, conversion efficiency can be measured by measuring the SG of the wort in the mash, and then dividing the measured value by the maximum possible for the water/grain ratio used. A table of maximum SG's is provided in the reference linked above.
Since you mashed 34 lbs of grain in 64 qts (16 gal) of water, your water/grain ratio was 64 qt / 34 lb = 1.88 qt/lb. From the reference, your maximum possible wort SG was about 1.067. Since your measured SG was 1.0568, your conversion efficiency was:
56.8 / 67 = 0.8478 = ~85%
This is not a very good conversion efficiency.Your potential max SG calculation is in error because the PPG is defined by wort volume not water volume. The wort volume is higher than the water volume due to the volume added by the dissolved sugar. For 16 gal of strike water with 34 lbs of grain @ 100% conversion efficiency, the actual volume of wort in the mash would be 17.785 gal. So, the sugars make up 1.785 gal of the wort volume.
Brew on
BeardedBrews
Well-Known Member
Whew, I waited long enough for Doug to take care of the math. That was a close one!
All I can add is that it seems much easier to get good consistent beer by adjusting the consistency, quality, and quantity of raw materials instead of adjusting your entire brewing process.
Thanks for taking the time to respond.
Agreed.
It's not though. At least not in my experience. Brewing this batch with my friend we did a little experiment.
First we measured the wort at the end of the 60 minute mash: 9.25 brix
Next we squeezed the bag into the kettle and took another wort sample: 14.0 brix
Finally we squeezed some of the wort remaining in the bag into a sample cup and measured that: 25.0 brix
Clearly the wort left in the bag has a higher concentration of sugars than the wort in the kettle. Those sugars have already been converted from starch - squeezing the bag isn't converting anything, but it is adding more of the sugars you converted to your kettle (and at a higher concentration than the sugars already in the kettle). Since those sugars have already been converted, my contention is that squeezing the bag should be included in calculating conversion efficiency.
I have also observed the brix/gravity of my wort rising after I have squeezed the bag on my previous brews.
Agreed.
It's not though. At least not in my experience. Brewing this batch with my friend we did a little experiment.
First we measured the wort at the end of the 60 minute mash: 9.25 brix
Next we squeezed the bag into the kettle and took another wort sample: 14.0 brix
Finally we squeezed some of the wort remaining in the bag into a sample cup and measured that: 25.0 brix
Clearly the wort left in the bag has a higher concentration of sugars than the wort in the kettle. Those sugars have already been converted from starch - squeezing the bag isn't converting anything, but it is adding more of the sugars you converted to your kettle (and at a higher concentration than the sugars already in the kettle). Since those sugars have already been converted, my contention is that squeezing the bag should be included in calculating conversion efficiency.
I have also observed the brix/gravity of my wort rising after I have squeezed the bag on my previous brews.
Since you mashed 34 lbs of grain in 64 qts (16 gal) of water, your water/grain ratio was 64 qt / 34 lb = 1.88 qt/lb. From the reference, your maximum possible wort SG was about 1.067. Since your measured SG was 1.0568, your conversion efficiency was:56.8 / 67 = 0.8478 = ~85%This is not a very good conversion efficiency.
Your potential max SG calculation is in error because the PPG is defined by wort volume not water volume. The wort volume is higher than the water volume due to the volume added by the dissolved sugar. For 16 gal of strike water with 34 lbs of grain @ 100% conversion efficiency, the actual volume of wort in the mash would be 17.785 gal. So, the sugars make up 1.785 gal of the wort volume.
Brew on
I am finding a lot of conflicting information on what constitutes good or typical conversion efficiency. Some say 95% or higher should be easily attainable, others such as BeerSmith say typical mash efficiency is in the 80% range:
http://beersmith.com/blog/2014/11/0...vs-mash-efficiency-in-all-grain-beer-brewing/
I lean toward believing what you and the Braukaiser wiki you linked to say, which is that something around 95% should be easy to attain. Given that I'm way off, I'd like to figure out what I'm doing wrong, but that's proving very difficult
Aha, that makes sense. So to sidetrack a little bit, how is grain absorption determined?
Is it [strike water volume] - [pre-boil volume]
or
[strike water volume] - [pre-boil volume] - [volume of sugars dissolved into mash]
It seems like most are just using the first formula, but that's not really taking into account the sugars added back into the wort, which is dependent on conversion efficiency. If the second formula is correct, then grain absorption is also dependent to a small degree on conversion efficiency.
1MadScientist
Well-Known Member
Isn't a 14 brix equal to a 1.0592
I used the Brewer's Friend calculator, it spits out 1.0568.
1MadScientist
Well-Known Member
Sorry, I was thinking of a Brix hydrometer.
Wow. This seems scientifically improbable to me. The only explanation that I can think of is that you're not stirring the mash enough to force the concentration to be equal everywhere, AND there is still some active conversion going on inside the grains. If conversion is still happening then yes I would expect a lot more sugars in the grains, but if it is complete or very near complete then I would expect very little difference in concentration -- maybe a couple points Brix if conversion is like 90% or so complete but not a huge difference like you're seeing. Besides stirring to even out the concentration, this also makes me wonder if the crush is inadequate. If it's not then you essentially have millions of starchy "sponges" holding sugars that can't get out into the liquid portion of the mash, and even with a lot of stirring and even squeezing you can't get the majority of it out.
Bottom line from what I can tell is that if you crush very well and stir very well, then the concentrations should be the same inside and out. If you're not seeing that, then improvements are needed in the crush and or the stirring.
I'm crushing at 0.022" which is as low as my mill can go. The crush looks pretty good to me, but I'll post a picture when I brew again this weekend.
My process it to stir for 2 minutes at the start of the mash and break up any dough balls, then stir at 15 minute intervals for 30-60 seconds until the mash is complete. I'll definitely try stirring more next time, although there is a balancing act between how long I stir for and how much heat I lose from my mash tun as it's un-insulated when I'm stirring.
Based on my theoretical discussion above, the only time we really should ensure we stir well is at the very end of the mash right before pulling the bag, or maybe 3-5 minutes before pulling the bag. Doing that should make a big difference. I'll have to ensure I do this from now on as well -- maybe I learned something from this thought-experiment!
1MadScientist
Well-Known Member
Could you share your recipe with us before you brew? The total grain bill weight, target OG, batch size, starting water, etc. etc. With an efficiency problem and a refractometer handy, why don't you monitor readings past the 60 mins. mash and go out to 90 mins. + ?. What size kettle do you have? Can you do a full volume mash?
A SG measurement right before and after pulling the bag at the end of the mash could be a useful indicator for whether the mash has been stirred well enough. I think next time around I'll try dunking the bag a few times at the end of the mash as well. Most of my stirring has been at the beginning of the mash, maybe stirring at the end is all I need to do!
Pretty much my thoughts as well. Saved me some typing
OP's estimated conversion efficiency was only 85%, so I think the continued conversion during the post-initial drain steps is definitely playing a role. Concentration gradients at the grit surfaces is also likely to be in play.
Agree, a good stir prior to pulling the bag is essential.
Brew on
I'm going to try brewing Brulosophy's Munich Helles recipe.
Total grain bill: 9.375 lbs
8.125 lbs Belgian Pilsner
1.125 lbs Munich Light
0.125 lbs Melanoidin
- Target OG: 1.047
- Total mash water: 9 gallons
- Strike temp 155F
- 60 minute mash at 150F
- Est pre-boil volume: 8.41 gallons
- 90 minute boil
- Shooting for 5.25 gallons into the fermenter
I have a 15 gallon kettle and have been doing a full volume mash for every batch so far. Depending on how my SG looks at the end of 60 minutes, I may prolong the mash and see what happens. That's a good thought.
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