BIAB mash efficiency low. Why?

Jayhem · Feb 27, 2012

So I've made 2 BIAB partial mashes now.

The 1st was 5.5 lbs of grain, I mashed in 2 gal at 152F for 45 min, mashed out with 2 gal at 165F by "tea-bagging" in the sparge water and then letting it sit in the sparge water for 10 min. Efficiency was only 55%

2nd batch was 7.0 lbs of grain, mash in 2.25 gal @ 152F for 60 min, mashed out in 2.5 gal @ 165F "tea-bagging" plus soak for 10 min. I let the bag drain through a colander and squeezed the bag some for 30 additional minutes and did save more wort that way. only got 54% efficiency.

What is the deal? I've heard plenty of reports of 60-70% BIAB efficiency? Could it by my crush? I noticed that most of the grains are only crushed enough that they break in half..do I need a finer mill?

NordeastBrewer77 · Feb 27, 2012

i'm wondering if it's the crush. i do a similar method of BIAB and get 80% efficiency quite regularly for PMs and 70-75% for AG doing BIAB this way.
the grains should look more crushed than just broken in half, can you set your mill rollers a bit closer? that should give you a better crush.

kh54s10 · Feb 27, 2012

With BIAB you are not worried about a stuck sparge. You can get better efficiency with a very fine crush.

I had very low efficiency on my 2 BIAB and asked about it here and came to the conclusion that I was getting more wort than predicted. I did a hard squeeze on the bag so I got a lot less grain absorption than was calculated for. I was shooting for a 3 gallon batch and got 4+ and 4.5 gallons on the 2 brews. Hence, the efficiency numbers were not right.

wilserbrewer · Feb 27, 2012

I am guessing crush as well...sounds as if you are using plenty of water for both the mash and sparge, so the grains should we well rinsed.

Jayhem · Feb 27, 2012

I have the brew shop do my milling. I guess I need to invest in a mill sooner than I had planned.

scoundrel · Feb 27, 2012

I've also found that mashing for longer helps too. I've seen a big difference since I moved to 75 min mash as opposed to 60 in the past. As mentioned previously, I also use a fine crush.

NordeastBrewer77 · Feb 27, 2012

Jayhem said:
I have the brew shop do my milling. I guess I need to invest in a mill sooner than I had planned.

i noticed a jump in my efficiency after my wonderful wife got me a mill for xmas. i was getting 70% on PMs and 60-65 on AG, jumped to my previously stated % after i started crushing my own.

Stauffbier · Feb 27, 2012

Jayhem said:
So I've made 2 BIAB partial mashes now.

The 1st was 5.5 lbs of grain, I mashed in 2 gal at 152F for 45 min, mashed out with 2 gal at 165F by "tea-bagging" in the sparge water and then letting it sit in the sparge water for 10 min. Efficiency was only 55%

2nd batch was 7.0 lbs of grain, mash in 2.25 gal @ 152F for 60 min, mashed out in 2.5 gal @ 165F "tea-bagging" plus soak for 10 min. I let the bag drain through a colander and squeezed the bag some for 30 additional minutes and did save more wort that way. only got 54% efficiency.

What is the deal? I've heard plenty of reports of 60-70% BIAB efficiency? Could it by my crush? I noticed that most of the grains are only crushed enough that they break in half..do I need a finer mill?

For BIAB, I got my best results when I did a finer crush, mashed for 90 mins (with direct heat to maintain temp), and squeezed the snot out of the bag! Like mentioned above, be careful about calculating the proper water ratio if you do a good squeeze. If you end up with too much pre-boil wort after squeezing you can boil it off prior to starting your 60 minute (hop utilization) boil..

SaevaVeritas · Feb 27, 2012

Here's a question do you have enough base malts in your partial? If not you won't get proper enzymatic break down.

DoubleAught · Feb 27, 2012

+1 on the crush. My first BIAB was a terrible 55%. I don't own a mill so I started running my grain through the blender, being careful to not turn all of it into flour. My brew I just did yesterday came in at 78% efficiency.

completenewbie · Feb 27, 2012

If you're picking the grain up at a local store just run it all through the mill twice. Works for me.

Skelator · Feb 27, 2012

Do you tie the bag off so the grain is a giant ball or do you keep the bag open so you can stir? Be sure to leave your bag open so you can stir and throughly mix the water and grain.

Jayhem · Feb 27, 2012

Thanks to all for the replies.

SaevaVeritas said:
Here's a question do you have enough base malts in your partial? If not you won't get proper enzymatic break down.

I'm using 50% of 2-row base malt ~30% Vienna Malt and at most 20% total of crystal/caramel malts in both the batches I did with 55% efficiency.

KaiserBierMann said:
+1 on the crush. My first BIAB was a terrible 55%. I don't own a mill so I started running my grain through the blender, being careful to not turn all of it into flour. My brew I just did yesterday came in at 78% efficiency.

Interesting idea! :mug:

Skelator said:
Do you tie the bag off so the grain is a giant ball or do you keep the bag open so you can stir? Be sure to leave your bag open so you can stir and throughly mix the water and grain.

I leave the bag open, stir well when the grain is poured in, making sure there are no dough balls and I stir again every 15 min, keeping the mash in a warm oven to maintain my 152F mash temp.

I'm convinced it's the crush of the grain causing my low efficiency.

I'm going to be ordering a Barley Crusher Mill this week.

rhamilton · Feb 27, 2012

Jayhem said:
I have the brew shop do my milling. I guess I need to invest in a mill sooner than I had planned.

My LBHS will crush extra fine if you tell them it's for a BIAB

And don't feel bad either -- my first three BIAB all-grains were in the low 60% ranges. Start with doing the extra crush, and I ended up moving to 90 minute mashes after my iodine tests didn't pass until the 70-80 minute mark.

Jayhem · Feb 27, 2012

rhamilton said:
My LBHS will crush extra fine if you tell them it's for a BIAB

Mine probably would too but I'm going to start ordering my grain unmilled online, it's actually cheaper to order online then to buy it from my LHBS since my LHBS is not really local (40 min drive).

scoundrel · Feb 27, 2012

KaiserBierMann said:
+1 on the crush. My first BIAB was a terrible 55%. I don't own a mill so I started running my grain through the blender, being careful to not turn all of it into flour. My brew I just did yesterday came in at 78% efficiency.

A blender is a good idea. Before I got a mill, I would run it though the mill at my LHBS twice. That also seemed to work well.

Kealia · Feb 27, 2012

I run close to 80% on my BIAB efficiency. I run the grains through twice at my LHBS.

But I also use a lot more water in my mash. I use about 3.75 gallons for a 5.5lb grain bill. I 'sparge' by pouring about 2 qts of water over the grain bag after I've squeezed the living hell out of it.

Jayhem · Feb 27, 2012

Kealia said:
I run close to 80% on my BIAB efficiency. I run the grains through twice at my LHBS.

But I also use a lot more water in my mash. I use about 3.75 gallons for a 5.5lb grain bill. I 'sparge' by pouring about 2 qts of water over the grain bag after I've squeezed the living hell out of it.

Once I get my grain mill in I'll try using more water in the mash. I have 2, 5 gal brew pots so if I have to I can do a full boil by splitting into two pots.

Looking forward to getting 75% efficiency from BIAB! :rockin:

daksin · Feb 27, 2012

I started out with a fine crush for my BIAB batches, but was getting TOO high efficiency (gravities were way off-style), so I went to a regular .035 crush and get about 80%. I think the reason my efficiencies are high is that I'm a CRAZY bag-squeezer. I squeeze out the "first runnings" hard for a few minutes (if BIAB has such a thing) then dunk-sparge for 10 minutes, and then give another few minutes of squeezing to collect the sparge.

Crush may still be a factor though, with really low efficiencies- I would make sure the mill where your grain is crushed is properly gapped.

Jayhem · Mar 19, 2012

UPDATE:

I wanted to update this thread. I got myself a Barley Crusher malt mill and with the rollers set to the factory gap (0.037") I was able to get 80% and 83% efficiency from the 2 partial mash batches we brewed this weekend! The most impressive thing is that the first 80% we got was on 3 lbs of white wheat malt and 1 lb of flaked oats! Awesome!

It's all in the grain crush!

BIAB mash efficiency low. Why?

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