All grain recipe conversion based on BH efficiency

[nick sekerak]

I never really saw a thread on here that goes in to good detail about this. There looks like a lot of great recipes here on HBT but many have different brewhouse efficiency. How Is the correct way to convert someone’s recipe who has a 85% brew house efficiency to mine that has a 70%. I am assuming you just would add 15% more to each type of gain in the recipe. I was unsure if this was as simple and linear as I am assuming.

 

[Qhrumphf]

Getting scaling accurate requires math, and is easiest done with brewing software.

There are two most core efficiencies. One matters for scaling, the other does not.

Mash/lauter efficiency- the efficiency of getting wort sugars into the kettle- is the important one. This is what you need to scale to.

Brewhouse efficiency is what makes it into the fermenter, and takes the above but factors in losses. It has no impact on the character of the beer that isn't already factored into the above. And EVERY system will be different.

Losses can be different. Volumes might be adjusted accordingly to account. You don't use their system, so why try to account for them.

So what do you do?

Don't worry about the grain weights. Look at the *percentages*. Ex: 82% 2 row, 8.5% Crystal 60L, 4% Black Malt, 5% flaked oats.

Keep those percentages. And scale the weights so that on *your* system you hit gravity and *your* preboil volume.

THEN, scale the hop additions proportionaly to your system. I like to keep late hops (20 mins left or later) factored by an oz/gal or lb/bbl ratio, even if alpha acids of the hops change. Then I will adjust the *bittering* hops based based on my system to factor both any change in hops alphas (late hops included) as well as boil volume/boiloff changes, so that I match the IBUs.

Say they're listing a 14.5%AA Citra with 1 oz each at 60 mins, 10 mins, flameout, and hopstand, but the Citra you get is 13%AA. Assuming the same "batch size" (you unfortunately do have to make assumptions here), you'd keep the 10, flameout, and hopstand 1 oz additions, but you'd probably have to imcrease the 60 minute to match the IBUs.

Even if you get the same %AA hops, I'd still calculate the bittering additon out with your system- changes in pre boil volume and boiloff rate will change the alpha acid isomerization.

Using this, you can scale not only for efficiency but for batch size as well.

 

[Qhrumphf]

There is also the school of thought that specialty grains should be treated like late hops, and kept at the same weights, and the only thing that should be adjusted for efficiency change is the base malt.

I'm not a fan of that approach. But that's another perhaps simpler route to take.

 

[RM-MN]

Recipe efficiency is all about the conversion of starches to sugars and the extraction of those sugars from the mash. In my mind that means that the only grain that matters is the base malts. The rest will give you the color and flavor and shouldn't need adjusted.

 

[Qhrumphf]

Depends on how big of a leap you're taking I suppose. If you're taking a recipe designed for 65% efficiency and drop the base malt based on 87% efficiency, especially with something with a heavy specialty malt grain bill, you've made some big changes especially with pH and the like.

If you're going from 75% to 70%, probably not a noticeable difference.

 

[Qhrumphf]

Also there are indeed sugars, fermentable and otherwise, in specialty grains.

 

[CascadesBrewer]

I am assuming you just would add 15% more to each type of gain in the recipe.

I think the simple answer is "Yes".

I can see cases where Mash Efficiency (what percentage of available sugar you are able to extract from the grain) vs Brewhouse Efficiency (which includes lost wort in your process) could impact the ideal scaling, but you likely don't know these values for the original recipe, and you don't mention them for your system.

In this specific case, you might be able to assume that somebody with a 85% brewhouse efficiency has a pretty high mash efficiency (say 90%) and maybe you should scale up the base grain more than the specialty grains (assuming your mash efficiency is say 80%)...but I doubt a few 1 or 2 oz tweaks here and there will impact the beer much either way.

I don't see a case where you would need to change the hops unless you change the size of the recipe.

 

[Qhrumphf]

I don't see a case where you would need to change the hops unless you change the size of the recipe.

Boiloff. Someone who's starting with 7 gals and finishing with 5 will get different isomerization than someone starting at 6.5 gals and ending at 5.5 or 6.

 

[CascadesBrewer]

Boiloff. Someone who's starting with 7 gals and finishing with 5 will get different isomerization than someone starting at 6.5 gals and ending at 5.5 or 6.

I would have to look at the numbers, but I cannot imagine that even 1 gal of starting volume makes enough difference to care. It is bound to be much less than the impact of alpha acid % from one crop of hops to the next...and honestly if I have a recipe that calls for 1 oz of 6.5% hops and the bag I buy is 7%, I will just throw in the same 1 oz. If the OP is changing his batch size from 5 gal to 6 gal, then of course.

You seem to really want to complicate a simple question that has a simple answer.

The real answer is that a recipe does not scale 100% from one person's system and process to another person's system and process...but in this case multiplying the grain by 1.15 should get the OP close.

 

[Qhrumphf]

I would have to look at the numbers, but I cannot imagine that even 1 gal of starting volume makes enough difference to care. It is bound to be much less than the impact of alpha acid % from one crop of hops to the next...and honestly if I have a recipe that calls for 1 oz of 6.5% hops and the bag I buy is 7%, I will just throw in the same 1 oz. If the OP is changing his batch size from 5 gal to 6 gal, then of course.

You seem to really want to complicate a simple question that has a simple answer.

The real answer is that a recipe does not scale 100% from one person's system and process to another person's system and process...but in this case multiplying the grain by 1.15 should get the OP close.

It's all as simple or as complicated as you want to make it.

And ultimately if you're taking someone else's recipe you're not gonna be able to tell how close you are anyway.

I have done a lot of scaling between different systems of different sizes with different efficiences over the years. That allows me to keep things consistent between them.