Questions about color

[Labmonkey]

For gravity purposes it can be calculated how much sugar a given grain can contribute per pound per gallon of water at 60*F. In various information sources, SRM associated with a grain is given as a range, like CaraMunich ranges 53-75 SRM, for example.

Is the range of color a function of different varieties of CaraMunich from different manufacturers, or is it a function of conditions that the grain is mashed in which results from more/less color from being added to the wort?

What quantities are these color measurements based off of? It makes sense to me that if I have a recipe that i brew up exactly the same and change the quantity of CaraMunich in it e.g. one has 1/2 lbs of CaraMunich and one has a 1/2 oz. of CaraMunich the color will be different.

We can predict IBU's or HBU's to get an appropriate bitterness for our beer. We can predict OG and FG to get appropriate measurements of alcohol and malt content for the finished product. Is there anyway to calculate approximate SRM per gallon based on quantities of grains added, or is it just a trial and process to get the desired color?

Is there a quantitative way to measure color like running a sample through a spectrophotometer and checking an absorbance at specific wavelength or across the visible spectrum, or is color determination done by looking at the color chart and mulling over whether it is a SRM of 17 or 18, or 50 vs. 51 (good luck with the last one)?

A lot to chew on here, HBT please enlighten me.

 

[McGarnigle]

I don't have the book in front of me right now, but I think Palmer's How to Brew has an index section on predicting beer color. I do think that most people are casual about color, not trying to target it as closely as other elements.

Also, it's not necessarily true that we can predict IBUs accurately. The various formulae used vary greatly.

 

[Labmonkey]

Yes, Palmer. I need to get that book. Normally color isn't a big deal for me but I am in the process of making and amber ale recipe and so I am taking some amount of time in trying to calculate what I need to add to get a color that's appropriate for what I want, and in general I am into predicting things. More specifically, I was thinking about using some roasted barley because in smaller quantities it produces a red color, but I don't know what "smaller" quantities are compared to "larger" quantities for a 5 gallon batch.

And you're right in that we can't accurately predict IBU's, but we can ballpark it based on formulas available. The one I used is from "The Brewmaster's Bible" (snyder 1997) on page 353. It incorporates % alpha-acid extraction as a function boil time, which is good enough for me. It also lists other factors that increase/decrease hop extraction rates...

But i digress, I will purchase Palmer's book, that'll be a good place to start. Thank's for the input.