Full Volume BIAB affect efficiency?

[moreb33rplz]

I am 3 batches in my first BIAB batches. I do 2.5 gallon batches, and use a 5 gallong kettle and standard mesh bag.

First batch was about 50% efficiency, next 2 were about 60-65%. I made sure I had a super duper fine crush and squeezed/let drain the bag after mashing on the second 2.

But don't know what I can do to get higher? Ideally I'd like 70-75%. My mash temps are expected (low 150s), I stir like a mother and dont' notice doughballs, I don't measure but calcs say my pH should be OK, and my last 2 crushes have been very well crushed.

Only thing that is new for me is the mash grist ratio. I use 4 gallons for each beer to hit my pre-boil volume. So with 6'ish pounds of grain that's like 2.75-3 or something. I used to use 1.25-1.5 on my old grain system.

Does grist ratio affect efficiency?

 

[wilserbrewer]

You say “very well crushed”
I say compared to what?

Your extraction should be higher imo....if your measurements are accurate and your calculations are appropriate.

 

[moreb33rplz]

FWIW, I'm almost certain the crush isn't the issue. On my pre-BIAB system I crushed more coarsely than I have on my previous 2 BIAB brews, but had higher efficiency. I'd describe the crushes I've had recently as 'if this wasn't BIAB it would clog my filter' crushes.

 

[SteveH aka shetc]

My BIAB is producing ~84% efficiency without doing any extra crushing. I use a spreadsheet from https://biabrewer.info/index.php that is very useful.

 

[madscientist451]

I had some efficiency problems and I use a second, smaller pot for a dunk sparge and now I hit my numbers pretty consistently. Others get good results with a full volume mash, find a way that works for you. Stirring every 15-20 minutes seems to help.

 

[Oginme]

In my experience, if the issue is not the crush, then it is with the proper wetting of the grains when doughing in. I sift the grains into the strike water while stirring and then stir vigorously for at least 5 minutes; continually bringing up the grains from the bottom up to the top of the kettle and looking for dough balls or clumps of grain. I do mostly full volume BIAB and my mash/lauter efficiency is always in the mid to upper 80's.

 

[CascadesBrewer]

Do you crush your own grains? I have a mill that I dialed back to 0.025" when I moved to BIAB (standard/store crushes are in the 0.040" range to support lautering). My girlfriend has been doing small batch BIAB with grains crushed at the store (since she lives 1/2 mile from the store). I get 70% to 75%, where she is maybe in the 65% range.

I found that with a dunk sparge I was getting in the 80% to 85% range (with mash efficiency readings in the 90% range). I might move back to a dunk sparge, but full volume mash is easy enough that I don't care that much about saving $1 worth of grain.

I picked up a $18 refractometer earlier this year...best cheap addition ever! I can take a quick gravity and volume reading at the time I pull out my grain bag, and then adjust how much I need to drain/squeeze/sparge. If I am low I can gather a little more volume and adjust my boil vigor or length. Brewed a 5 gal batch today...target 1.050 at 75%...ended at 1.052...close enough for me!

 

[doug293cz]

Full volume mash will definitely reduce your mash efficiency vs. a sparged lauter, all else being equal. Mash efficiency equals conversion efficiency times lauter efficiency. Full volume mash decreases lauter efficiency vs. sparging. Full volume mashing may increase your conversion efficiency somewhat since conversion occurs faster in thinner mashes. This means that you could get more conversion during a fixed mash time, or you may need a longer mash to get complete conversion with a thicker mash. However, the largest variable affecting conversion rate is the crush size. This is because the limiting step in conversion is starch granule gelatinization (enzymes cannot act on the starch until after it is gelatinized.) Gelatinization starts at the surface of the grits, and proceeds towards the center, and the larger the grits, the longer it takes to gelatinize all the way to the center of the grits. You can't reach 100% conversion until after you get 100% gelatinization.

BIAB can make up for some of the loss in lauter efficiency with higher conversion efficiency since BIAB can use a finer crush than traditional lauter systems. In this case, the "all else being equal" condition in the first sentence of this post is violated in a beneficial way. BIAB can also get a boost in lauter efficiency over traditional lauter systems due to lower grain absorption. Traditional systems have grain absorption rates of about 0.12 gal/lb, while BIAB can achieve absorption rates down around 0.06 gal/lb with squeezing or very long drain times.

The chart below summarizes the affects of batch sparge vs. no-sparge (full volume mash), high vs. low grain absorption rate, vs. various grain bill weight to pre-boil volume ratios (bigger beers have higher ratios.)

Less than 100% conversion efficiency will make mash efficiency less than the lauter efficiency shown above.

Brew on

 

[ChaosB]

I'm also doing a full volume mash with high water to grist ratio but not BIAB. I like to think that recirculation is helping me get some back on my conversion efficiency but I understand that may not be an option with a finer crush for BIAB. I mill my own using 0.040. You're still getting higher efficiency than I do so far, not quite sure what the trade off in efficiency is between finer crush and recirculation.

 

[LittleRiver]

I'm getting low 80's brewhouse efficiency with a full volume no sparge no squeeze single vessel process, which lines up with Doug's simulation chart. I use a .025" mill gap. I let the bag drain into the kettle during the entire boil, I don't squeeze it.

I can consistently hit or exceed recipe targets without modifying the recipe. I only sparge if I'm doing a big beer.

I sometimes don't get why people want to complicate the brewing process with re-circulation pumps and such things, but then I have to remember that for some people messing around with hardware is as much fun to them as is my joy of making beer on such a simple rig, so it's all good (but the additional gear is still not necessary to make great beer).

 

[Silver_Is_Money]

All else being equal (and I can't emphasize this enough), no sparge is about 9% less efficient than batch sparge.

 

[CascadesBrewer]

I sometimes don't get why people want to complicate the brewing process with re-circulation pumps and such things

Honestly, if you asked me a year ago I would have been positive that a recirculating system was higher efficiency than a fly sparge system which was higher efficiency than a batch sparge system which was higher efficiency than BIAB. It really is mind blowing to me that BIAB requires less equipment, is easier, is faster, produces great beer, AND can easily produce efficiency numbers that are at or above any other brewing system. I am sure glad I made the switch!

 

[doug293cz]

I'm also doing a full volume mash with high water to grist ratio but not BIAB. I like to think that recirculation is helping me get some back on my conversion efficiency but I understand that may not be an option with a finer crush for BIAB. I mill my own using 0.040. You're still getting higher efficiency than I do so far, not quite sure what the trade off in efficiency is between finer crush and recirculation.

You can you can calculate your conversion efficiency (independent of mash or lauter efficiency) by knowing the grain bill weight, the weighted extract potential of the grain bill, the strike water volume, and the wort SG at the end of mash (before any sparge.) The method is here.You can also use my spreadsheet (available here) to calculate the first wort SG @ 100% efficiency based on your weight and volume measurements. And, if you know how to use "Goal Seek," you can use it to calculate your conversion efficiency. It also predicts your lauter and mash efficiencies based on your batch inputs.

Brew on

 

[doug293cz]

Honestly, if you asked me a year ago I would have been positive that a recirculating system was higher efficiency than a fly sparge system which was higher efficiency than a batch sparge system which was higher efficiency than BIAB. It really is mind blowing to me that BIAB requires less equipment, is easier, is faster, produces great beer, AND can easily produce efficiency numbers that are at or above any other brewing system. I am sure glad I made the switch!

A well conducted fly sparge can achieve about 2 - 3 percentage points higher lauter efficiency than a triple batch sparge @ 0.12 gal/lb absorption rate. A poorly done fly sparge can be lower efficiency than a full volume, no-sparge lauter. It's all about the channeling, and giving diffusion enough time to let the sugar diffuse from the grits to the sparge water (don't go to fast, even if you could do it without channeling.)

Recirc can speed up conversion a bit (which will give you better conversion efficiency for a fixed mash time) but can't beat finer crush for improving conversion. The speed up is due to the flow taking well gelatinized starch away from the grit surfaces, allowing for water to more easily gelatinize more of the starch.

Brew on

 

[Ninoid]

I full volume BIAB, no sparge, grain milled at the store, sift the grains into the strike water while stirring and then stir continually bringing up the grains from the bottom up to the top of the kettle and looking for dough balls or clumps of grain, 60 minute mash, 10 minute mash out.
Efficiency is 75% and above.

Efficiency is a somewhat smaller if top up with few liters of water or use more unfermentable grains.

Bolded is crucial.

 

[WhiteRhyno]

sift the grains into the strike water while stirring.

How do you manage to do this with only two hands

 

[Oginme]

How do you manage to do this with only two hands

I grind my grains into a 5-gal pail. I hold the handle and cradle the bucket in the crook of my arm so that the handle is on the bottom. With the other hand stirring vigorously, I slowly shake the bucket to allow a curtain of grain to fall, nearly continuously into the water. Usually, the first rush of grain falling is pretty quick, but as it hits only water, it disperses OK. As the mash thickens, it becomes more critical to sift slower. I do about 3 kg of grains into 15 liters of water and it takes me about 2 to 3 minutes to fully sift in the grain. I then stir for another 5 to 6 minutes and stop if I don't see any dough balls (which I rarely do).

 

[geoffm33]

I use a big wire whisk for when I dough in and stir. Cuts right through any dough balls.

 

[LittleRiver]

How do you manage to do this with only two hands

I clip the handle of the grain bucket to the pulley I use to raise my bag, and position it at a convenient height. It holds the weight while I slowly tip it with one hand, while whisking with the other. I've never had a dough ball.

 

[Ninoid]

How do you manage to do this with only two hands

Grain in bucket, bucket on the edge of mash kettle, hold bucket with left hand and easy sift, stirring with right hand.