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-   -   Specialty Grains for Extract Brewing (http://www.homebrewtalk.com/f37/specialty-grains-extract-brewing-223429/)

mplsbrewer 02-06-2011 08:48 PM

Specialty Grains for Extract Brewing
 
Hello,

I have a question regarding the use of specialty grains for extract brews. Particularly, how do you calculate OG and color contributions for specialty grains? I've seen some other threads suggesting that specialty grains do not contribute to the OG, but this is incorrect since they do contain non-fermentable sugars even though there is no enzymatic activity occurring.

I've also seen some numbers that indicate steeping has an extraction efficiency on the order of 20-30%, so the formula for point contribution should be something like:

Points =

[Grain weight * Grain ppg * steeping extraction efficiency]/Boil volume

The efficiency should be a function of steep time, temp, and grain crush size, but I'm just wondering if there is any empirical data that could be used to calculate steeping efficiency as a function of these variables, or do I just assume something like 30%?

Also, this efficiency should just be in regards to sugar extraction; is there any other correlation to color contribution? Or is it assumed that the color contribution is 100% efficient? I'm using

Grain weight * Lovibond rating to get MCU, then using Morey's formula to estimate SRM.


Any help would be much appreciated!

MalFet 02-07-2011 12:16 PM

I've never seen people claiming that specialty grains don't impact gravity, but if you have they are - as you say - incorrect. Some of the sugars in them are fermentable, too. There's a good thread around here comparing the fermentability of a bunch of different crystal malts.

20-30% sounds about right to me, and I doubt you are going to find more precise numbers than that as your extraction efficiency would depend significantly on the conditions of your set up. If you'd like something more precise and specific to your system, run a quick test. It should be easy enough.

I would be very surprised if sugar contribution extracts at 30% efficiency but color contribution does at 100%. It is possible that color compounds are extracted selectively, but not to that degree. If I had to guess, I would likely assume that color contribution is more in line with the 30% extraction rate. That jibes with my anecdotal experience, at least. In any case, this too could be tested if you wanted more precise numbers.

Gavagai 02-07-2011 10:32 PM

There are some numbers on specialty grain color and ppg on CP's brew chart.

http://www.homebrewtalk.com/f14/cps-...-2-0-a-221089/

mplsbrewer 02-07-2011 11:06 PM

Thanks for the feedback. Looks like I'll need to do some testing in my kitchen, but that gives me an excuse to brew some more (not that I needed the motivation).

Do you happen to know what the actual color compounds in malt are? If they are similar to sugars in molecular weight and solubility, then yes, I agree that they would diffuse into the steeping water at a similar rate.

ASantiago 02-08-2011 01:28 AM

Trial and error can be a lot of fun, but if you want a more direct route, check out Beer Smith or similar software.

MalFet 02-08-2011 02:41 AM

Quote:

Originally Posted by mplsbrewer (Post 2623373)
Do you happen to know what the actual color compounds in malt are?

Hmm...not off hand. I read an article a while ago that listed some. I think it was by Charlie Bamforth. Two that pop into my mind would be melanoidins in some toasted malts and burnt carbon in roasted malts.

abbot555 02-08-2011 06:15 AM

Also check out Qbrew. It is a nice free software to use to start out with.

Frodo 02-08-2011 06:36 AM

The percentage you'll get from the grain will depend on the method and volumes of water you use to steep and rinse the grain. 70% should be doable using the dunk method; i.e. steep in a certain volume of water for awhile, then dunk for several minutes in a similar volume of clean 160ish water. Obviously combine the 2 volumes, then add your extract and boil as your process requires.

MalFet 02-08-2011 11:22 AM

Quote:

Originally Posted by Frodo
The percentage you'll get from the grain will depend on the method and volumes of water you use to steep and rinse the grain. 70% should be doable using the dunk method; i.e. steep in a certain volume of water for awhile, then dunk for several minutes in a similar volume of clean 160ish water. Obviously combine the 2 volumes, then add your extract and boil as your process requires.

Interesting. I've never seen anything close to 70% extraction. Do you have a source?

Frodo 02-08-2011 04:11 PM

Quote:

Originally Posted by MalFet (Post 2624634)
Interesting. I've never seen anything close to 70% extraction. Do you have a source?

Is what I described much, if any, different than batch sparging? That's where I got the 70% from.


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