Declining Efficiency at Higher OG

http://beerandwinejournal.com/efficiency-gravity/

Excellent article on the subject. This is a concept I've experienced and have been aware of, but had only accepted and never thought about the reasoning. After reading the first paragraph, it hit me, because it makes perfect sense. If you want consistent extract efficiency, your total water volume has to be in the same proportion to the size of the grain bill.

[EDIT] You'd think this would be an easy thing for brewing software to take into account...

 

It looks like there's going to be a follow up article on how to account for that. I think that will be helpful to a lot of people.

 

Bump up the grain bill & conduct multiple sparges.

 

I mean actually calculate it, so that you're not just shooting in the dark, which is what I've been doing. Typically, for my beers over 1.075, I just adjust my recipe for 65% efficiency. The closer I am to 1.075, I usually over shoot my gravity, the further away I am, I end up under shooting.

 

That would be nice. I am sure there are enough resources out there to estimate how to bump up your grain bill using a baseline efficiency at say 1.050 SG. It would be nice for BeerSmith to get that incorporated in some fashion, or at least have it in the "Tools" section.

Maybe the relationship is linear, and you can take your efficiency at 1.050 and at 1.100 and simply scale up based on where you land in that window, assuming the same starting volume of wort. Have you tried doing that? If you have a bunch of data from past brew sessions, you could look at the total mash + sparge water, specific gravity pre-boil, and your calculated efficiency, then toss it in a simple model. Or maybe just SG and efficiency?

If I have some free time this weekend, maybe I'll try to find some resources to start putting a spreadsheet together. Unfortunately, I rarely brew beers over 1.065-1.070, so my empirical data is lacking. I use Avangard malt sometimes as well, which seems to have higher extraction efficiency...

 

Nice information. Am waiting for the follow up so I can get more consistent with my process.

 

Hrrrm, interesting read. I'm very curious to see the follow up as well.

 

http://beerandwinejournal.com/estimating-ee-gravity/

Here's the followup, but I'll admit I was very disappointed. He basically says, "Take good notes over a number of batches, and use the data to predict what your future extract efficiency will be." I was really thinking he was going to give a formula for calculating extract efficiency based on total water to grain ratio.

That formula must exist, right? I would think if you know your efficiency at a given point, say 1.040, you should be able to predict your efficiency at any other point, if you know what your total water to grain ratio is.

Then again, it might not be that simple, since my efficiency doesn't start declining until I start to get over 1.075 or so. So my 1.040 batch will have a higher water to grain ratio than my 1.070, but the extract efficiency is still basically the same...

Guess I better start taking better notes.

 

I have always tried to get to full boil volume (~7 gallons) since I've been able to do so, but my boil vessel isn't able to handle larger volumes. I guess I'll need to upgrade at some point, but my efficiency has never been so low that it caused me great distress. Also, boils longer than 90 minutes grind my biscuits! Lol

 

I'm the same way, I just want to be able to accurately predict what my efficiency will be at any given gravity so that I can compensate, adjust my recipe, and hit the target numbers. I don't want to be shooting for 1.105 and hit 1.090.