Recipe Scaling - Increased efficiency?

[ratinator]

So I have been brewing on a brewzilla the past 5-6 years and have been getting 68% brewhouse efficiency. I recently bought a grainfather G40 and am getting 80+% efficiency, which is obviously a good thing.

My problem now is converting my 5 gallon recipes like I enjoy in brewfather. In a 5 gal batch I need 1-2lbs less grain. My question is should I scale the recipe down completely or just drop the amount of base malt? As I scale stuff down based on percentages I tend to get less SRM, and I would also get less of those specialty grain flavours that I have in my recipes. It obviously also sucks to have quantities such as 1lb, 8oz, 4oz, etc. and have to move to 7.2oz

 

[VikeMan]

I would scale everything proportionally. You're getting a lower computed SRM, but I very much doubt that you're actually getting lighter wort. The computed SRM is lower because the standard MCU/SRM model is naive. It's based strictly on grain weights and finished volumes, and knows nothing whatsoever about mash efficiency. When you leave wort behind in the mash tun or in transfer pumps/hoses (resulting in lower efficiency), that part of the grains' color contribution doesn't make it to the finished volume. And when you leave less wort behind, a higher percentage of the gran bill's color contribution (from an adjusted, smaller grain bill) does make it to the finished volume. IMO, if you think about color units in exactly the way you think about sugars and dextrins, you won't be far off.

The next release of BrewCipher is going to include an new (optional) experimental SRM model that is less naive. (I've already developed the model. Just need to make time to finish the rest of the release.)

 

[ratinator]

I would scale everything proportionally. You're getting a lower computed SRM, but I very much doubt that you're actually getting lighter wort. The computed SRM is lower because the standard MCU/SRM model is naive. It's based strictly on grain weights and finished volumes, and knows nothing whatsoever about mash efficiency. When you leave wort behind in the mash tun or in transfer pumps/hoses (resulting in lower efficiency), that part of the grains' color contribution doesn't make it to the finished volume. And when you leave less wort behind, a higher percentage of the gran bill's color contribution (from an adjusted, smaller grain bill) does make it to the finished volume. IMO, if you think about color units in exactly the way you think about sugars and dextrins, you won't be far off.

The next release of BrewCipher is going to include an new (optional) experimental SRM model that is less naive. (I've already developed the model. Just need to make time to finish the rest of the release.)

In an extract brewing world the speciality grains are steeped and provide colors/flavours without adding fermentable sugars. I can't see how 10-12oz of chocolate malt or roasted barley can provide the same color as a lb of it.

 

[VikeMan]

In an extract brewing world the speciality grains are steeped and provide colors/flavours without adding fermentable sugars.

Steeped specialty grains do provide some fermentable sugars and unfermentable dextrins. But I don't think that's really relevant to the discussion.

I can't see how 10-12oz of chocolate malt or roasted barley can provide the same color as a lb of it.

It's not only a matter of how much color a particular amount of malt can provide. It's also a matter of how much of that color reaches your kettle.

For illustration, and easiest math, let's say one pound of a particular malt provides 100 Color Units. When you were getting 68% mash efficiency, about 68 color units were reaching the brew kettle. The rest (32) were left behind in the mash tun and/or transfer apparatus. When your mash efficiency increases to 80%, that same pound of malt is getting 80 color units into the boil kettle (with 20 left behind). So in the kettle, you're getting 80 / 68 = ~1.18 times the previous amount of color into the kettle. To keep the amount of color reaching the kettle the same as before, you'd cut that one pound of malt back to 1 / 1.18 = ~0.85 pounds.

 

[lumpher]

In an extract brewing world the speciality grains are steeped and provide colors/flavours without adding fermentable sugars. I can't see how 10-12oz of chocolate malt or roasted barley can provide the same color as a lb of it.

In an extract world you shouldn't be seeing much efficiency difference. When you talk about efficiency, it usually refers to all-grain, not extract. Sure, there's a little difference in dme/lme quality, but not that much.