BIAB mashing efficiency help?

I've done two brews with BIAB, and ended up with low mash efficiencies for both (~50%). I ran an experiment today with a small amount of milled 2-row to see whether sparging the grains would increase my yield. It did not increase it by much. I was hoping for some help trouble-shooting my process from you fine folks. Here's my set-up:

3 gallon cooler (pre-heated before mashing in)
Voile grain bag (home made)
The temperature of this set-up drops by 1-2F over 60 mins
The mash pH was calculated to be 5.55 using ezcalculator (after adding CaSO4 to the mash/sparge water)

Here are the results:

Step 1: 5L water with 3.33 lbs 2-row (1.5:1); mashed at 150F for 60min
Step 2: drained and sparged with 3.5L at 150F for 10min
Step 3: drained and sparged with 3.5L at 150F for 10min

Mash efficiencies:
Step 1 = 35%
Step 2 = 15%
Step 3 = 10%
Total = 60%

Total volume recovered = 10.5L

So, even after three sparge rinses, I'm only getting 60% yield. I'm squeezing the bag between each rinse. The grains are milled using an electric coffee mill at my LHBS, so they are medium-finely ground. Any suggestions to improve my efficiency? Much appreciated!

*edit: recovered 10.5L, not 13.5L

Do you stir your mash at all? I stir mine 2-4x during the 60 min mash. I get 70-75% efficiency.

Other than that - I'd check the crush. I got higher efficiency when I used grains from a different store which crushed differently.

Also - how long are you storing the crushed grain before using?

Hi jigidyjim - thanks for your reply. I did not stir the mash during the 60mins. The grains were stored for between 3-10 days after crushed before I used them. I have a grain mill coming in the mail this week, so I plan to test how milling impacts my efficiency (unfortunately, there's only one LHBS in Vancouver, so I can't move between shops). How long can crushed grains be stored before use?

nufad said:

Step 1: 5L water with 3.33 lbs 2-row (1.5:1); mashed at 150F for 60min
Step 2: drained and sparged with 3.5L at 150F for 10min
Step 3: drained and sparged with 3.5L at 150F for 10min


Total volume recovered = 13.5L

Click to expand...

just doing the math here 5L + 3.5L + 3.5L = 12L

Crush is hugely important.
When using BIAB you want a tighter crush, (or a double crush if they wont do that).
Its time consuming but you can do that yourself with a rolling pin.

(make sure you stir occasionally)

You might try adding a mash out step as well as stirring.

I do full volume, no sparge BIAB. Once my saccharification rest is complete, I'll heat it up to about 168 and hold it there for about 6-8 minutes before removing the grains. The higher temperatures increase the solubility of the sugar and also makes the wort a bit more fluid and able to drain better.

Buna_Bere: yes, your math is correct. In an earlier version of this post, I had included a fourth step with 3L rinse (hence the 13.5L value), and forgot to change the final volume to reflect this. I decided to take that step out of this post for various reasons (it was done about 45mins after I had finished the third step, it was a low-temp rinse, and it only yielded about 3%).

gmcastil: thanks for the tip - for my next test-run, I will mash out at 170 after my first soak. I'm running my BIAB inside a cooler to maintain a constant temperature (it drops by 1-2F over 60min), so I won't be able to mash out with the same water with which I mash. How fine should the grain be milled? There is some powder in the grain, but also plenty of larger grain pieces (the coffee mill isn't consistent at my LHBS).

I do BIAB and had some efficiency issues, I was able to trace these to:

1. Mashout. Having one at 170 for 10 minutes completely resolved my issues; and,

2. Grain crush. When I switched to Northern Brewer I had some issues until I began requesting a double crush. After that I was dead on 70% efficiency. Today I brewed using grains from my LHBS and my efficiency shot way up as they do a mean crush on the grains.

It does help to stir. It also helps to take your grain bag and do a sort of fly sparg with 175 F water and/or dunk your grain bag in a separate container with 175 (or thereabouts) water and use that water to top off your mash to compensate for boil off.

Hope that helps.

maltoftheearth said:

I do BIAB and had some efficiency issues, I was able to trace these to:

1. Mashout. Having one at 170 for 10 minutes completely resolved my issues; and,

2. Grain crush. When I switched to Northern Brewer I had some issues until I began requesting a double crush. After that I was dead on 70% efficiency. Today I brewed using grains from my LHBS and my efficiency shot way up as they do a mean crush on the grains.

It does help to stir. It also helps to take your grain bag and do a sort of fly sparg with 175 F water and/or dunk your grain bag in a separate container with 175 (or thereabouts) water and use that water to top off your mash to compensate for boil off.

Hope that helps.

Click to expand...

Absolutely my experience as well. I crushed my already pre-crushed grains in a hand cranked Corona, made sure I stirred the mash at least three times, mashed out (dunk sparged) at 168F for 10 minutes (stirring constantly the last two minutes), and went from 60% to 89% brewhouse efficiency.

Thanks for all the advice!

Doing pretty much what Befus is doing and went from low 60s to 70s on high specific gravity worts. Never got 89% but have gotten in the low 80s with a low gravity wort. Would love to get to 80 on my typical 1.080 worts. But I'm happy at 70-75%.

ArcLight said:

Crush is hugely important.
When using BIAB you want a tighter crush, (or a double crush if they wont do that).
Its time consuming but you can do that yourself with a rolling pin.

(make sure you stir occasionally)

Click to expand...

What is different about BIAB that requires a different crush? Is it the dunk sparge?

Update! I picked up another 2lb of 2-row to test my modified procedure (finer grain, mashing out at 175F for 10 mins).

First squeeze efficiency = 79%
Mashing-out = 12%
Total = 91%

Is there any drawback to having such a high efficiency?

Also, there was a large amount of trub in the wort - around 2 inches settled in my hydrometer jar over 45 minutes. Have any of you tried a pre-boil rest to allow the trub to settle out and siphon the clearer wort instead of removing all the trub post-boil?

Part of that added efficiency are sugars that are less fermentable (due to mash out) and you will have a sweeter beer. No problem with slightly higher efficiency except alcohol flavors might be more predominant. I like that you experimented!

nufad said:

Update! I picked up another 2lb of 2-row to test my modified procedure (finer grain, mashing out at 175F for 10 mins).

First squeeze efficiency = 79%
Mashing-out = 12%
Total = 91%

Also, there was a large amount of trub in the wort - around 2 inches settled in my hydrometer jar over 45 minutes. Have any of you tried a pre-boil rest to allow the trub to settle out and siphon the clearer wort instead of removing all the trub post-boil?

Click to expand...

Had almost the same results when I jumped to 89%. Beer is still in the fermenter so I can't say what the end result will be. Planning on bottling Sunday and I'll let you know it the trub and other solids are a problem at bottling time.