79% mash efficiency on a high gravity mash?

[odie]

Just did a huge RIS and using a couple online calculators I'm getting 79% conversion which I thought was pretty high for a high gravity beer. Am I using/interpreting it wrong? I'm new at calculating mash efficiency and using the SG measurement.

BIAB 9.5 gal starting at mash in. 3 hours later and 7.9 gal after squeezing the bag.
17# 2 row pale
2# roast barley
0.625# black malt
1# American chocolate
2# flaked oats

SG was 1.080. Brewers Friend and Homebrewing.com calculators gave me 79% mash efficiency.

I was under the impression that 60% ish was normal for a very large grain bill/very thick mash. Is the longer mash time the key here?

 

[McKnuckle]

With conversion efficiency set to 100%, I get a pre-boil SG of 1.071 which represents a 78.8% mash efficiency. That rounds off to 79%.

In three hours, I'll bet you did have 100% conversion. But the actual SG is lower than you measured, probably due to stratification. Still a great job on your part (and the enzymes') it would seem.

 

[bgmac]

What was your pre-boil gallon amount of wort after you finished mash and sparge etc.. 7.9 gallons? And post boil gallon amount of wort and OG?

If 7.9 gallons before boil, a quick check online says you are right.

 

[odie]

9.5 gallons mash water then add the grain. After draining and squeeze the bag I had 7.9 gallons which took a couple hours to boil down to my “start boil” volume.

 

[odie]

Well efficiency is how much you get into the pot? Even with 100% conversion there will be sugar left behind in the grain?
Unless I sparge it. But then that’s a lot of water to boil down to your target volume

 

[odie]

Post boil OG was 1.116 but that’s including 1# lactose and 0.5# DME and 3oz cacao powder and 3oz coffee
Not sure if the cacao or coffee affect the gravity

 

[doug293cz]

Well efficiency is how much you get into the pot? Even with 100% conversion there will be sugar left behind in the grain?
Unless I sparge it. But then that’s a lot of water to boil down to your target volume

Yes, mash efficiency is the percentage of total potential sugar that you actually get in your BK. There is always sugar left in the spent grains, even if you sparge. There will be less if you sparge, but you can never get it to zero, unless you sparge with an infinite amount of water.

Your mash efficiency is the mathematical product of conversion efficiency and lauter efficiency. You can get 100% conversion efficiency, but you can never get 100% lauter efficiency.

Brew on

 

[doug293cz]

Just did a huge RIS and using a couple online calculators I'm getting 79% conversion which I thought was pretty high for a high gravity beer. Am I using/interpreting it wrong? I'm new at calculating mash efficiency and using the SG measurement.

BIAB 9.5 gal starting at mash in. 3 hours later and 7.9 gal after squeezing the bag.
17# 2 row pale
2# roast barley
0.625# black malt
1# American chocolate
2# flaked oats

SG was 1.080. Brewers Friend and Homebrewing.com calculators gave me 79% mash efficiency.

I was under the impression that 60% ish was normal for a very large grain bill/very thick mash. Is the longer mash time the key here?

What was your weighted grain potential for your 22.625 lb grain bill? I cannot make any reasonable assumptions that get to a pre-boil gravity of 1.080 using your grain bill weight, strike volume, and pre-boil volume. Your volumes and grain bill weight lead to a max lauter efficiency of about 73%, and mash efficiency is always less or equal to lauter efficiency.

Brew on