Help me understand BIAB efficiency/OG

[kh54s10]

I Brewed my second BIAB. Both ended up low on OG but decent efficiency.

hopville homebrew recipe
Floored IPA

Beer Style
Imperial IPA
Recipe Type
All Grain BIAB

malt & fermentables
% LB OZ MALT OR FERMENTABLE PPG °L
52% 5 0 Warminster Floor-Malted Maris Otter
42% 4 0 American Two-row Pale
4% 0 6 American Crystal 60L
3% 0 4 Cara-Pils/Dextrine
Batch size: 3.0 gallons
Original Gravity
1.081 / 19.6° Plato
(1.072 to 1.084)
Final Gravity
1.020 / 5.1° Plato
(1.018 to 1.022)
Color
11° SRM / 21° EBC
(Copper to Red/Lt. Brown)
Mash Efficiency
70%
hops
USE TIME OZ VARIETY FORM AA
boil 45 mins 1.0 Galena pellet 11.1
boil 15 mins 0.5 Tettnang pellet 4.8
boil 5 mins 0.5 Liberty leaf 4.0
Boil: 4.0 avg gallons for 60 minutes
Bitterness
67.1 IBU / 11 HBU
ƒ: Tinseth
BU:GU
0.83

Wyeast American Ale (1056)

Wyeast Trappist High Gravity (3787)

Alcohol
8.1% ABV / 6% ABW
Calories
267 per 12 oz.
misc
USE TIME AMOUNT INGREDIENT
boil 15 min 1 tsp Irish Moss
boil 10 min 0.1 liquid ozs Yeast Nutrient

I input for 70% efficiency and by Brewer's Friend's calculator it looks like I got 72.42% efficiency. What puzzles me is the recipe calls for an OG of 1.081. I measured 1.065. It does not worry me as far as the beer goes, but what I don't understand is that if I got the right efficiency why is the OG so low?

I got a good fine crush, fresh ingredients, 75 minute mash starting at 156 and ending at 151 degrees.

I also put the recipe in Brewer's Friend's recipe maker at 75% efficiency and it called for 1.090

Thanks in advance for your help

 

[kh54s10]

Any ideas?

 

[iaefebs]

If I remember right Brewers Friend calculates efficiency at pre boil gravity.

 

[kh54s10]

The directions say either pre-boil and pre=boil volume or OG and batch volume.

With pre-boil it calls for 1.050 OG at 75% and calculates 87.24% brewhouse efficiency on my brew.

It also says 1.066 efficiency at 100%

Yet the recipe calls for 1.081 OG?

 

[kh54s10]

Another thought is my efficiency for my all grain with batch sparging has been in the mid 70s to low 80s% and my OGs have been within a few points.

 

[gypsyhead]

How did your volumes compare between expected and actual? Your batch size says 3 gal, but your boil volume says 4 gal, so which volumes are you inputting to the calculator?

 

[BobC]

I agree with gypsyhead, If your overall batch size is 4 gal then you got a 71% efficiency. If it was 3 gal then I'm afraid you only got a 53% efficiency. So make sure your using the right amount gallons in your calculator.

 

[kh54s10]

The worst case number I can run is 67% the best is 74%. And the calculator says the best I could achieve is 1.064 at 75% and the recipe set for 70% calls for 1.081. Brewer's Friend recipe calculator was even worse saying 75% would give 1.090

This is my best guess:
Batch Data:
Wort Volume:4.2 (gallons)
Gravity Measurement: 1.058

Gravity at 100% Efficiency: 1.085 - max
Gravity at 75% Efficiency: 1.064
Brew House Efficiency: 67.86%
Points / Pound / Gallon (ppg): 25.3

So I got pretty close to what this says, but still, the recipe calculators predicted way higher OG

 

[kh54s10]

So no one has an opinion other than I calculated my efficiency wrong?

I still cannot make any sense of this.

 

[BobC]

Did you sparge? How did you get some of those sugars left behind in the bag? You had a sufficient mash time so the only thing I can think of is that you didn't get all the sugars out of the bag.

With my calculator I can only get a predicted OG of 1.081 with this recipe as a 3 gallon batch. When I bump it up to 4 gal, which is where you took your measurement, I get a predicted OG of 1.063.

Your recipe calls for a mash of 3 gallons and a boil of 4 gallons. After the boil you should have ended with about 3 gallons of beer to ferment. But you ended up with 4.2 watering down your OG.

 

[kh54s10]

Did you sparge? How did you get some of those sugars left behind in the bag? You had a sufficient mash time so the only thing I can think of is that you didn't get all the sugars out of the bag.

With my calculator I can only get a predicted OG of 1.081 with this recipe as a 3 gallon batch. When I bump it up to 4 gal, which is where you took your measurement, I get a predicted OG of 1.063.

Your recipe calls for a mash of 3 gallons and a boil of 4 gallons. After the boil you should have ended with about 3 gallons of beer to ferment. But you ended up with 4.2 watering down your OG.

I think that you led me to my problem. Using the BIAB calculator after creating the recipe I mashed with 5.4 gallons to allow for boil off and grain absorption. I squeezed the crap out of the bag (no sparge). I think this threw off the absorption amount and I ended up with a lot more pre-boil volume than was accounted for.

Now for some adjustments and another try to dial in things. I was about to give up BIAB and wait for warmer weather and batch sparge brewing.

In the mean time the worst that has happened is that this one is a session IPA.

Thanks again:rockin:

 

[gypsyhead]

still likely a tasty brew bud. rdwhahb

 

[Seven]

This was your second BIAB so I wouldn't focus so much on efficiency this early on. I'd recommend getting your process down (starting volumes, ending volumes, grain absorption, squeezing, sparge, no-sparge, grain crush, mash temps, mashout, etc.) and hitting your target OG first. Once you have these nailed, then start looking at your brewhouse efficiency. I know that I get at least 75 to 80% efficiency with my process so I don't bother calculating it any more.

Good luck.

 

[kh54s10]

As I said in my post I was not really worried about the beer, I was just wondering why my calculated efficiency and OG did not match what was predicted.

Thanks for the responses.

I think I now have a better handle on what to do differently to get closer to the recipe predictions. I also anticipate that I will have a very good beer, just not quite what I was aiming for.

We should aim for the bullseye, shouldn't we.