BIAB Efficiency and Grain weight

[B1tman1ac]

New Homebrewer here...To start off with I love big beers and hate that I lose effeciency as I increase grain weight. I have a design/solutioning background so in developing my BIAB process I have been trying to increase efficiency such that I don't lose effeciency when I add more grain. What I've come to realize is that efficiency as it relates to grain weight is largely determined by grain absorption rate. More grain, more sweet wort gets left behind. Developing a process to combat this problem was my goal.

For my last homebrew, according to brewfather, I managed 84% mash efficiency (82% brew house) with a 27.5 lb grain weight (OG 1.151 wayyyy overshot even for a big beer).

My process,
1. BIAB as normal.
2. Perform a mash out at 170f ish.
3. Heat 1 gallon of sparge water for a dunk sparge.
4. Lift bag and squeeze as much as possible. Then place bag in a big cooler.
5. Using proper sanitized gloves, a 6 gallon bucket and a colander and your 1 gallon sparge water, grab a smaller mesh BIAB bag and a handful of wet grains. Then squeeze the grains in the colander in the bucket, dunk sparge in the sparge water (seperate pot) and squeeze some more in the colander.
6. Repeat step 5 until all of the grains from the cooler are processed and the wort added back to the main pot.
7. Continue brew day as normal.

Again, fairly new here so I may be way out to left field here and over engineering what is supposed to be a simple BIAB. I still need to repeat this process a few times to ensure consistency but if I can do that it might work out.

Thoughts or critiques? Anything I could do differently or in a more efficient way?

 

[DBhomebrew]

There's just no way to negate the fact that larger grain bills will have a lower lauter efficiency than small bills, given the same preboil volume. Best to concentrate on achieving 100% conversion and a predictable grain absorption ratio. With those reliably under your belt, you'll be able to regularly hit your intended recipe.

A dunk sparge can be very, very simple. Pull bag, drain fully. Maybe a squeeze if you are so inclined. Dunk drained bag into sparge water in a bucket. Open bag, give a good stir. Pull bag, drain. Pour sparge water into kettle, boil.

Targeting roughly equal volumes coming from each running will give best efficiency.

 

[madscientist451]

Looks like a total PITA from here. I'm way to lazy to do all that. I've simplified my brew day and don't do a mash out, but I do use a smaller pot for a dunk sparge. For a beer that big, how about using 3 grain bags that would hold about 9 lbs each, then pull each one and drop it in the dunk sparge? Put your colander over a bucket and as you pull each bag, place in the collander and let it drain before and after the dunk sparge. If you got 2 collanders and 2 buckets you could speed up the process.

 

[RM-MN]

I'd suggest some changes in your process.
1. Mill your grain finer. You should be able to get a mash efficiency in the mid to upper 90% range.
2. Skip the mash out. If your mash efficiency is in the upper 90%, you have nothing left to convert and a mash out does nothing but take time.
3. Use cool water for the sparge. Saves heating water in another pot, does the same thing. When you drain the sparge you will discover it to be pretty warm yet, adding little time to get to the boil.
4. Do the sparge as mentioned in post #2.
5. Drink a beer.

 

[wilserbrewer]

Interesting approach…
I suppose efficiency does increase wit multiple successive batch sparge a w/ portions of the grain bill….
Reminds me of Calculus I believe.

Sounds like too much effort to me, but if you find this soothing while you come to boil have at it….
Your efficiency seems surprisingly well for big batch

 

[Bobby_M]

and hate that I lose efficiency as I increase grain weight.

Why do you hate it?

The easiest way to deal with it is to know it happens and accommodate. In your favorite software just make several profiles tuned to how it really happens. I have three profiles: 1. Up to 1.050 2. 1.050 to 1.070 and 3. Over 1.070. Each of them are progressively set to about 4% lower efficiency.

Since you're a new brewer, I want to suggest that there are exactly nine things that are much more important than maximizing efficiency when it comes to brewing good beer.

 

[doug293cz]

Reduced lauter efficiency with increased grain weight happens will all brewing methods, not just BIAB.

As you are doing your step 5 & 6 repeat loops, some of the extract (sugar mostly) will diffuse into the clean water in the bucket, and the extract content in the bucket will increase with each repeat cycle. Sparging with less than "pure" water is less effective, so each of your individual sparge steps is a little less effective than the previous step. You might be making up for this by being able to squeeze the smaller grain mass to achieve a lower grain absorption rate. As you surmise, the lower the grain absorption rate, the higher the lauter efficiency, and thus the higher the mash efficiency (mash efficiency = conversion efficiency * lauter efficiency.)

Here's a chart that shows how lauter efficiency drops as the grain weight to pre-boil volume ratio increases for various numbers of batch sparge steps and two grain absorption rates (for sparge cases, absorption rate is assumed equal for all drain steps.)

The only way to maintain constant lauter efficiency as the grain bill weight increases is to increase the pre-boil volume proportionately, which for large beers would lead to some very large boil-off requirements.

Brew on

 

[B1tman1ac]

Why do you hate it?

Cost being one, I've reduced my grain bill cost by 50% in the last batch but that's coming from ~55% efficiency to ~84% on similar large grain bills. Simply chasing efficiency is another but I realize there are more important things in brewing but I'm getting to those too Tying efficiencies to separate profiles is a good idea, thank you!

Looks like a total PITA from here.

You are correct, it is a bit of a pain That's a good idea, never thought of that. Figuring out how to mash in 3 grain bags in one kettle would be interesting and how to stir them without getting them tied together to ensure full conversion would be another interesting problem to solve.

There's just no way to negate the fact that larger grain bills will have a lower lauter efficiency than small bills, given the same preboil volume. Best to concentrate on achieving 100% conversion and a predictable grain absorption ratio. With those reliably under your belt, you'll be able to regularly hit your intended recipe.

A dunk sparge can be very, very simple. Pull bag, drain fully. Maybe a squeeze if you are so inclined. Dunk drained bag into sparge water in a bucket. Open bag, give a good stir. Pull bag, drain. Pour sparge water into kettle, boil.

Targeting roughly equal volumes coming from each running will give best efficiency.

I don't disagree with the fact that larger grain bills have lower lauter efficiency (given the same pre-boil volume) I believe one of the reasons why that happens (happy to be corrected here), is due to the grain absorption rate increasing. Given the same process, more grain will hold onto more liquid. However if you were to reduce the size of your grain bill artificially by say squeezing it in smaller bags, you end up with the same absorption rate as if you had a smaller grain bill.

Equal volumes and a single or even two or three dunk sparges will definitely increase lauter efficiency. There has been a lot of good work demonstrated on that by people here. What I struggle with is how to do that in a single vessel BIAB system. You either need a separate Mash Tun (MIAB) then dunk sparge in your pot or another pot and burner (two BIAB setups). But even if you could do that you remove some of the benefits of the single vessel BIAB system cause now your transferring a lot of wort from one pot to another and back. All that aside, say I can work out the process and equipment needed. What would be the expected efficiency?

I'd suggest some changes in your process.
1. Mill your grain finer. You should be able to get a mash efficiency in the mid to upper 90% range.
2. Skip the mash out. If your mash efficiency is in the upper 90%, you have nothing left to convert and a mash out does nothing but take time.
3. Use cool water for the sparge. Saves heating water in another pot, does the same thing. When you drain the sparge you will discover it to be pretty warm yet, adding little time to get to the boil.
4. Do the sparge as mentioned in post #2.
5. Drink a beer.

Ok, here we go . . .
1. Great idea, currently the LHBS mills my grain to 0.025" and double crush, or at least that's what I ask for and it seems to be accurate based on pictures I've seen. I have plans to buy my own mill, but its not high on my list of homebrew wants. Fermentation chamber probably being #1.
2. I might do this just to compare as I've heard this a lot. Only reason why I included it was because I thought sugar flows more easily out of wet grain at higher temperatures. Perhaps the benefits of which are not as much as expected.
3. This is a great idea that allows one to combine the benefits of equal volumes batch sparging with the single vessel BIAB system. Like you said, not needing another pot and burner is a huge process improvement imho.
4. Agreed
5.

Here's a chart that shows how lauter efficiency drops as the grain weight to pre-boil volume ratio increases for various numbers of batch sparge steps and two grain absorption rates (for sparge cases, absorption rate is assumed equal for all drain steps.)

View attachment 756626

The only way to maintain constant lauter efficiency as the grain bill weight increases is to increase the pre-boil volume proportionately, which for large beers would lead to some very large boil-off requirements.

Brew on

Great Post! Thank you! I've seen and used your charts a lot to estimate some of my variables. This one clearly shows the variables at play here. For the batch in question,

grain weight = 27.5lbs
pre-boil volume = 11.25gal
Grain Weight (lb) / Pre-boil Volume (gal) = ~2.4
Actual grain absorption rate = 12 gal total water (includes 11gal strike + 1 gal sparge) - 11.25gal pre-boil volume / 27.5lbs = ~0.027 gal/lb grain absorption rate
Expected Efficiency with a single equal volume batch sparge @ 0.06 grain absorption rate and a 2.4 grain weight to pre-boil volume= ~87%

So it would seem, if I switched my process over to this, AND I could achieve a 0.06 gal/lb grain absorption rate on 27.5lb of grain I could possible improve my efficiency without the need for the separate smaller squeezes. However doing equal volume on 27.5lb of grain with a pre-boil volume of 11.25 gallon would be an initial mash thickness of 0.81 qt/lb (0.20 gal/lb), which is a very thick mash indeed. Probably wouldn't need exactly equal to get this efficiency.

I'll have to go to work to redesign my equipment profiles and recipe for the next attempt to compare. Thank you everyone!!!

 

[B1tman1ac]

The only way to maintain constant lauter efficiency as the grain bill weight increases is to increase the pre-boil volume proportionately, which for large beers would lead to some very large boil-off requirements.

Brew on

Wanted to add that this is a great observation. I feel this batch I made is a prime example of your statement. Considering my pre-boil volume of 11.25 gallons and a boil off rate of 1 gallon per hour, I boiled for ~5 and a half hours to put ~5.5 gallons into the fermenter.

 

[bikerbred]

New Homebrewer here...To start off with I love big beers and hate that I lose effeciency as I increase grain weight. I have a design/solutioning background so in developing my BIAB process I have been trying to increase efficiency such that I don't lose effeciency when I add more grain. What I've come to realize is that efficiency as it relates to grain weight is largely determined by grain absorption rate. More grain, more sweet wort gets left behind. Developing a process to combat this problem was my goal.

For my last homebrew, according to brewfather, I managed 84% mash efficiency (82% brew house) with a 27.5 lb grain weight (OG 1.151 wayyyy overshot even for a big beer).

My process,
1. BIAB as normal.
2. Perform a mash out at 170f ish.
3. Heat 1 gallon of sparge water for a dunk sparge.
4. Lift bag and squeeze as much as possible. Then place bag in a big cooler.
5. Using proper sanitized gloves, a 6 gallon bucket and a colander and your 1 gallon sparge water, grab a smaller mesh BIAB bag and a handful of wet grains. Then squeeze the grains in the colander in the bucket, dunk sparge in the sparge water (seperate pot) and squeeze some more in the colander.
6. Repeat step 5 until all of the grains from the cooler are processed and the wort added back to the main pot.
7. Continue brew day as normal.

Again, fairly new here so I may be way out to left field here and over engineering what is supposed to be a simple BIAB. I still need to repeat this process a few times to ensure consistency but if I can do that it might work out.

Thoughts or critiques? Anything I could do differently or in a more efficient way?

My friend is taking a brewmaster class at Penn State. He suggested doing a step mash and my efficiency boosted significantly. I did 120f/15min, 140f/15min, 154f/30min, mashout 170f/10 min pull bag rinse with 1 -3 gallons@ 170f depending on grain bill.

 

[Bobby_M]

My friend is taking a brewmaster class at Penn State. He suggested doing a step mash and my efficiency boosted significantly. I did 120f/15min, 140f/15min, 154f/30min, mashout 170f/10 min pull bag rinse with 1 -3 gallons@ 170f depending on grain bill.

But only do this if you want low protein and high fermentability

 

[B1tman1ac]

But only do this if you want low protein and high fermentability

Agreed, and with normal beers you probably don't want to do this, however, in the context of "big beers" you're usually running into other problems such as hitting the yeast's alcohol tolerance rather then worrying about the beer drying out too much or not having enough haze. In fact, the batch in question is currently sitting at 1.064sg (1.151og) (11.4%abv) (after ~40 days and still going) I had to add amylase enzyme, beano (which both did nothing) and now amylo 300 (glucoamylase) and a fresh starter of us-05 which is sloooooowly bringing the gravity down. I have another starter of escarpment labs French saison ( French Saison ) (wyeast 3711 clone I'm thinking but listed at 14-16% alcohol tolerance?) to hopefully bring the FG down a bit quicker. I've also got a packet of Horndail Kviek (rated to 16%) if that doesn't work.

P.S. I've already got Nottingham and WLP099 in there too.

 

[doug293cz]

I don't disagree with the fact that larger grain bills have lower lauter efficiency (given the same pre-boil volume) I believe one of the reasons why that happens (happy to be corrected here), is due to the grain absorption rate increasing. Given the same process, more grain will hold onto more liquid. However if you were to reduce the size of your grain bill artificially by say squeezing it in smaller bags, you end up with the same absorption rate as if you had a smaller grain bill.

Increased grain absorption with larger grain bills occurs even with the grain absorption rate constant. If you are squeezing to reduce the absorption rate, then larger grain masses may be more difficult to squeeze as well, so the absorption rate might increase. This would give you a double whammy to your lauter efficiency, with lauter efficiency being even lower than for constant grain absorption rate.

Equal volumes and a single or even two or three dunk sparges will definitely increase lauter efficiency. There has been a lot of good work demonstrated on that by people here. What I struggle with is how to do that in a single vessel BIAB system. You either need a separate Mash Tun (MIAB) then dunk sparge in your pot or another pot and burner (two BIAB setups). But even if you could do that you remove some of the benefits of the single vessel BIAB system cause now your transferring a lot of wort from one pot to another and back. All that aside, say I can work out the process and equipment needed. What would be the expected efficiency?

You don't need hot water to sparge. All you need to do a dunk sparge is a bucket that is large enough to hold your grain bag with the amount of grain that you mashed.



Ok, here we go . . .
1. Great idea, currently the LHBS mills my grain to 0.025" and double crush, or at least that's what I ask for and it seems to be accurate based on pictures I've seen. I have plans to buy my own mill, but its not high on my list of homebrew wants. Fermentation chamber probably being #1.
If you are really getting 0.025", double crushed, you don't need your own mill. Most LHBSs won't grind this fine, which is why brewers need their own mill.
2. I might do this just to compare as I've heard this a lot. Only reason why I included it was because I thought sugar flows more easily out of wet grain at higher temperatures. Perhaps the benefits of which are not as much as expected.
The viscosity of wort only decreases by about 16% when the temp is raised from 150°F to 170°F, so not a huge deal. It's more important to insure that you have achieved 100% conversion before you end the mash. If you haven't achieved 100% conversion, then a mash out extends your mash time, allowing more conversion.

So it would seem, if I switched my process over to this, AND I could achieve a 0.06 gal/lb grain absorption rate on 27.5lb of grain I could possible improve my efficiency without the need for the separate smaller squeezes. However doing equal volume on 27.5lb of grain with a pre-boil volume of 11.25 gallon would be an initial mash thickness of 0.81 qt/lb (0.20 gal/lb), which is a very thick mash indeed. Probably wouldn't need exactly equal to get this efficiency.

The charts were made with the constraint that mash thickness would be limited to no thicker than 0.9 qt/lb. If equal volume run-offs would have caused the mash to be thicker than this, water was shifted to the strike to maintain the mash thickness limit. The balance of the water was then split evenly among all the sparge steps. It was also assumed that the grain absorption rate was the same for all run-offs, meaning that the bag would need to be squeezed equally as after each draining.

Responses in blue above (expand to see.)

Brew on

 

[odie]

just sparge more. but be prepared to boil down longer.

 

[marc1]

just sparge more. but be prepared to boil down longer.

That's what OP did, he boiled for 5.5 hours to get the volume back down...

 

[Bobby_M]

It occurred to me that there are probably less labor intensive ways to get alcohol poisoning but that's none of my business. If really big beers are your thing, I think a 3 vessel fly sparge system is a better solution. Spending an hour fly sparging will get you better efficiency than a 2+ hour boil.

 

[hottpeper13]

I do high grav brewing with 4-15 gal vessels ,2 being BK's. 34 lbs in a BIAB with 9 gal of brewing liquor,end up with ~7 gal first runnings. I then dunk sparge in 9 gal and use that for mashing in another 34 lbs of grain and run that into the first running kettle. I then sparge that with 8-9 gal and boil separately. The first runnings are 1.134-1.154 depending on % of base malt. The second runnings are around 1.040 without capping. I mainly do this to get 15 gal parti gyle into a barrel at 1.110 or so. I know it is a 2 BK process but I upgraded to a Spike 15 gal when they were induction capable so I have 2,and went induction but still have the propane burner for gypsy brews and this.

 

[odie]

My last RIS (normally a 25# grain bill)...I mashed with about 2 gallons less water and a couple pounds less grain...

After the mash I lifted my basket, drained and then sparged with the "missing" water until I reached my "usual" pre boil starting kettle volume target.

My OG at the end/fermenter was higher with less grain used than the exact same recipe using more grain with the full volume/no sparge BIAB mash

 

[jambop]

Wanted to add that this is a great observation. I feel this batch I made is a prime example of your statement. Considering my pre-boil volume of 11.25 gallons and a boil off rate of 1 gallon per hour, I boiled for ~5 and a half hours to put ~5.5 gallons into the fermenter.

Talk about laws of diminishing returns... you wasted how much energy boiling of nearly six gallons of water getting a minimal return on efficiency hate to say it but its baffling to say the least

edit sounds like the brews you are making are crying out for a extract addition to boost gravity?

 

[BrewnWKopperKat]

[...] a extract addition to boost gravity [...]

FWIW, I brewed the "same" recipe using either a double mash or a late addition of extract. The result was two noticeably beers. I preferred the all-grain beer (and I understand why the other one beer had a noticeably different flavor).

I have also read that multi-hour boils produce desirable flavors that are may not be possible to duplicate using other methods or ingredients.

 

[ScrewyBrewer]

During a two to three-hour boil, the wort caramelizes or darkens as the sugar molecules change, causing them to reflect light differently. The extended boil time also increases the Malliard reaction to produce complex flavors that would not have time to develop any other way in a shorter boil. While not recommended for all styles, I always do an extended boil for my favorite Wee Heavy recipe.

 

[jambop]

I can only assume that energy is free in the US ... no wonder the world is in the mess its in.

 

[Beermeister32]

Anyone who has pushed up into Tier 4 electricity pricing with Southern California Edison will have a new love of propane. Maybe you can rig your electric kettle into your Tesla or Prius charger…

 

[jambop]

Anyone who has pushed up into Tier 4 electricity pricing with Southern California Edison will have a new love of propane. Maybe you can rig your electric kettle into your Tesla or Prius charger…

My car is 100% oil powered but come on boiling off 5.5US gallons is just daft in my book. Why not accept that you can over do sparging to the point where you are wasting time and energy. I take the point about the caramelisation flavours etc but that is not going to occur until the wort has almost become a syrup anyway so less sparge means less boil but still getting the flavours and quicker. The **** has already hit the fan here in Europe with energy costs... it must impact on beer prices soon as beer needs hot and boiling water that part of the process is an absolute must and prices have shot up exponentially very recently.
I do have a butane cooking ring that will be used for pre heating mash water and sparge water as I really do want to keep electricity use to a minimum. I do take your point though BIAB has the potential for slightly cheaper brewing... if possibly a little less convenient ?

 

[odie]

Talk about laws of diminishing returns... you wasted how much energy boiling of nearly six gallons of water getting a minimal return on efficiency hate to say it but its baffling to say the least

edit sounds like the brews you are making are crying out for a extract addition to boost gravity?

depends on if your kettle is electric or propane. The electricity for a several hours boil is likely less than the cost of one pound of grain. Say it's 10 cents a kilowatt hour...my 115V single water heater element system would use about 15 cents an hour to run full blast.

How long will a 20# propane tank will run a burner...IDK. But it costs $15-20 a fill...more if you exchange. But that's a whole 'nother discussion about consumer fleecing.

 

[jambop]

depends on if your kettle is electric or propane. The electricity for a several hours boil is likely less than the cost of one pound of grain. Say it's 10 cents a kilowatt hour...my 115V single water heater element system would use about 15 cents an hour to run full blast.

How long will a 20# propane tank will run a burner...IDK. But it costs $15-20 a fill...more if you exchange. But that's a whole 'nother discussion about consumer fleecing.

To be honest I do not know anywhere at all that energy is that cheap! A 13kg bottle refill of propane costs 53 USD here ! Electricity is 0.21 USD per kWhr

 

[odie]

well your profile doesn't list location...you could be in any state or country.

I'm paying 10 cents under my current contract in Texas. I'm sure that will change.

Last week it was just under 20 bucks to fill my propane. We are not on the metric system (13kg bottle) so I will assume you are not in the US....

 

[odie]

My car is 100% oil powered but come on boiling off 5.5US gallons is just daft in my book.

"daft"...I'm guessing UK or some crown territory...I've only heard one person in my life use that term...she was Polish but grew up in England.