BIAB efficiency all over the place

[popsicleian]

I've now brewed 7 batches of beer, all BIAB. My first 5 had pretty similar efficiency ~60-65%, depending on whether I did no sparge or a dunk sparge. For my last two batches, I've experimented with overnight mashing. I use a 5 gallon Igloo cooler wrapped in a sleeping bag, and both times my temp ended up around 135 by the time I was ready to start brewing the next day. I removed the bag from the cooler, squeezed a fair amount of the liquid from the grain, and did a dunk sparge in my remaining water for about 15 minutes. My first overnight mash (a saison with 46% Pils, 42% Unmalted Wheat, 12% Flaked Oats) gave me about 70% efficiency.

I did my second this weekend (an APA with 90% MO, 6% Caravienne, and 4% Caramel 20) and was very surprised to see that my efficiency ended up at 82%.

I really like the convenience of the overnight mash, but I'd like to have a better idea of the efficiency I can expect in future batches so I can plan my recipes accordingly. The only thing I can think of is that the extended mash wasn't able to pull as many sugars out of the unmalted wheat and oats as it was for the all-barley batch. Does that sound plausible? If so, should I expect efficiencies closer to 80% on future all-barley batches?

 

[doug293cz]

Your saison may have had insufficient diastatic power to completely convert the unmalted adjuncts. Out of curiosity, why did you not use malted wheat?

Do you have any idea what your crush size is? Sounds like with your first 5 batches you had poor conversion efficiency, which is often due to too coarse a crush. The overnight mashing would allow more conversion with the larger grits, thus improving your mash efficiency (except when there is an enzyme deficit.)

Brew on

 

[popsicleian]

Your saison may have had insufficient diastatic power to completely convert the unmalted adjuncts. Out of curiosity, why did you not use malted wheat?

Do you have any idea what your crush size is? Sounds like with your first 5 batches you had poor conversion efficiency, which is often due to too coarse a crush. The overnight mashing would allow more conversion with the larger grits, thus improving your mash efficiency (except when there is an enzyme deficit.)

Brew on

I decided to use unmalted wheat because I was going for the grain bill and spicing of a wit, but with the flavor of saison yeast. That may have been a poor choice, it seems. Other than incomplete conversion of adjuncts, are there any consequences to having insufficient diastatic power?

I buy all my grains from the Northern Brewer retail location, so my crush is whatever they have their mills set for, which seems pretty coarse to me. If there's no one waiting to use the mills I'll run it through 2-3 times, but I'm not sure if the extra passes make a difference.

 

[popsicleian]

I also did a protein rest as part of the mash, for whatever that's worth.

 

[doug293cz]

I decided to use unmalted wheat because I was going for the grain bill and spicing of a wit, but with the flavor of saison yeast. That may have been a poor choice, it seems. Other than incomplete conversion of adjuncts, are there any consequences to having insufficient diastatic power?

I buy all my grains from the Northern Brewer retail location, so my crush is whatever they have their mills set for, which seems pretty coarse to me. If there's no one waiting to use the mills I'll run it through 2-3 times, but I'm not sure if the extra passes make a difference.

I'm not aware of any issues, other than incomplete conversion, that can result from insufficient enzyme availability. If you got a lot of soluble starch that didn't convert, it will probably make the beer very hazy.

The extra crushes may have a small effect, but a single crush at a narrower setting works better. Coarse crushes are even more problematic for wheat, as the kernels are smaller than barley, so there may be a lot of uncrushed wheat kernels. Uncrushed kernels have terrible convertibility.

Brew on :mug

 

[Magnus314]

The first batch had 54% goopy, un-modified grains. I'd bet if you weighed it, that bag probably had an extra gallon or so of wort trapped in it.

Deadspace is the number one killer of efficiency. Also, I've never gotten very good efficiency with unmalted wheat.

Try another all-barley batch, and compare.

 

[petrolSpice]

Any downsides to mashing overnight? I'm intrigued. Nice was to shorten a brew day. And the cooler grains would be easier to squeeze.

FWIW, I was consistently getting 65-70% efficiency. On my last batch I got 82%, the only thing I did differently was mash a bit lower than usual (at 154F rather than 158F) and double crush the grains at the LHBS.

 

[popsicleian]

The first batch had 54% goopy, un-modified grains. I'd bet if you weighed it, that bag probably had an extra gallon or so of wort trapped in it.

I used the same assumption for absorption that I'd been using for my previous batches (about .08 gal/lb), and that was pretty much spot on--I had about .7 gallons of absorption for my 4 gallon batch with 8.4 lbs of grain.

Any downsides to mashing overnight? I'm intrigued. Nice was to shorten a brew day. And the cooler grains would be easier to squeeze.

Time will tell! Both batches are fermenting right now, but the unfermented wort for both were really delicious (probably the best of all my batches so far). There seems to be some disagreement online about whether an extended match can lead to overattenuation.

In terms of convenience, I'm a big fan of the overnight mash. I have a one year old, so it's really hard to find 4 hour uninterrupted chunks for brewing. I can prepare the mash after he goes to bed, and then do the boil first thing in the morning (and even if he wakes up before I'm done, my wife doesn't mind so much if she knows I'm not going to be unavailable for the next few hours).

It makes a lot of sense that the crush could explain the difference given the large amount of wheat and the size difference between the wheat and the barley. Unfortunately, I can't adjust the crush on the mills at Northern Brewer. I don't really mind the low efficiency that much, as long as it's predictable. My batches aren't big enough for the efficiency to make too much of a cost difference.

 

[FatDragon]

The first batch had 54% goopy, un-modified grains. I'd bet if you weighed it, that bag probably had an extra gallon or so of wort trapped in it.

Deadspace is the number one killer of efficiency. Also, I've never gotten very good efficiency with unmalted wheat.

Try another all-barley batch, and compare.

I do a porter with two pounds (900g) of flaked oats and I get 8-10% lower efficiency versus my typical batches. In fact, a 12% barleywine that maxed out my kettle got 15% better efficiency than my last oatmeal porter that I mashed with a third of the grainbill. As Magnus314 suggested, a goopy mash can be a lot harder to drain. We may have way more surface area for draining than traditional mash tuns, but a goopy mash high in proteins or fine floury grain (my worst was a Black IPA with 2kg of unmalted rye flour) still has the potential to stop up the bag pretty well. A BIAB "stuck sparge" is a rare problem but a clogged up bag that takes forever to drain and nerfs your efficiency is far from unheard of.

 

[Magnus314]

And it's not just that there might be more trapped water, "goopy" partially gelatinized grains won't releae all of there starches into the wort to be converted by the enzymes.

So "goopy" often leads to "poor efficiency" from the lost potential wort sugars that never got to meet an enzyme.

 

[FatDragon]

In terms of convenience, I'm a big fan of the overnight mash. I have a one year old, so it's really hard to find 4 hour uninterrupted chunks for brewing. I can prepare the mash after he goes to bed, and then do the boil first thing in the morning (and even if he wakes up before I'm done, my wife doesn't mind so much if she knows I'm not going to be unavailable for the next few hours).

I'll be joining the "homebrew dads" club this winter if all goes well and I've thought about getting on the long mash bandwagon myself, but I'm not sure if it'll make much of a difference. It doesn't take me any time at all to get my strike water up to temp because I pull from an adjustable hot tap so I can mash in pretty much as quickly as I can draw water from the tap - about three minutes at the hot tap's flow rate (yes, I know I should be doing water chemistry and RO water - one of these days). However, it takes 45 minutes to an hour to reach a boil after pulling the bag. If I mash in advance and have to start the boil from room temperature, it takes another 30-45 minutes to reach a boil, so I don't really save much brewday time by mashing overnight.

 

[GQT]

I'll be joining the dads club

Did I miss anything about your becoming a dad?

 

[FatDragon]

Did I miss anything about your becoming a dad?

Not yet, but if the pee-stick didn't lie we'll be getting a Christmas gift with an endless retroactive price tag this year. You'll know for sure when I start a bunch of frantic threads about building up the pipeline sometime after I return from a US trip in mid-August.

...or maybe I'll just add a new entry to the "Primary" line in my signature...

 

[popsicleian]

And it's not just that there might be more trapped water, "goopy" partially gelatinized grains won't releae all of there starches into the wort to be converted by the enzymes.

So "goopy" often leads to "poor efficiency" from the lost potential wort sugars that never got to meet an enzyme.

I get it. I guess it was a lucky coincidence that I did the extended mash--If I had only mashed for an hour, my efficiency probably would have been pretty bad.

I'll be joining the "homebrew dads" club this winter if all goes well and I've thought about getting on the long mash bandwagon myself, but I'm not sure if it'll make much of a difference. It doesn't take me any time at all to get my strike water up to temp because I pull from an adjustable hot tap so I can mash in pretty much as quickly as I can draw water from the tap - about three minutes at the hot tap's flow rate (yes, I know I should be doing water chemistry and RO water - one of these days). However, it takes 45 minutes to an hour to reach a boil after pulling the bag. If I mash in advance and have to start the boil from room temperature, it takes another 30-45 minutes to reach a boil, so I don't really save much brewday time by mashing overnight.

Congrats! I've found that I have to try a lot harder to fit my hobbies into my schedule, but it's an amazing experience. It sounds like the extended mash might not be as much of an advantage for you. I've read that you have to keep the temp above 130ish in order to avoid lactobacillus, so I did my long mashes in a cooler mash tun. Both times it was about 135-140 by the time I restarted the brew process, so getting to a boil took a little bit longer, but not nearly as long as if I had been starting from room temp.