Beer Color measurement needs a serious overhaul

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Edcculus

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Excuse the extreme geeking out in this thread. I feel like I am excused since this is the "brew science" section.

I'm suprised I haven't read through this material before. After all, I am a Color Management Specialist at a printing company.

When I first heard about SRM, I immediately realized what the links in this thread (especially the second one) say abou the limitations of SRM. In printing terms, SRM most closely resembles how we measure the whiteness of paper. Whiteness is a measure of the reflectance of light at 457nm by a spectrophotometer. In these terms, SRM is merely a factor of how light passes through a beer.

In the printing industry, we have color viewing and measurement standards. We obviously have a much wider range of colors to describe. In general, a three value system is used to quantify numbers. Most people and programs use L*a*b* color space. I find the CIE LCH system more intuitive. Basically it describes color according to lightness, chroma and hue. Lightness is how light or dark a color is. Chroma is how saturated it is. Hue is the actual color.

To measure beer color correctly one would need to do a flow cell analysis. Sorry no link. I forget what the instrument is called since I haven't used one since my Junior year in college. This instrument is used to measure the pure color of ink. You dillute the ink at a certain rate. You pour it into a system that feeds it into a very thin clear tube. A spectrophotometer then reads the spectral data.

I believe the very same instrument and software could be used to very accurately measure the color of beer. I am willing to bet that a certain large brewery uses a very similar method so their extremely pale lagers all come out the same color. If not, I need to put in my resume!
 

david_42

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True, measuring all beers at one frequency doesn't make much sense. On the other hand, only people that make pale beers care about color. And the occasional person that wants a bright red beer.
 

menschmaschine

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Ed, would the turbidity of beer affect the measurements produced by the flow cell analysis? If so, perhaps the beer could be filtered to a certain micron as a standard of the measurement.
 
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Edcculus

Edcculus

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True, measuring all beers at one frequency doesn't make much sense. On the other hand, only people that make pale beers care about color. And the occasional person that wants a bright red beer.
Thats true. Although the current measurement system can't account for hue shift if the same amount of light passes through.

Ed, would the turbidity of beer affect the measurements produced by the flow cell analysis? If so, perhaps the beer could be filtered to a certain micron as a standard of the measurement.
You know I'm not too sure. Excess yeast or protein haze would impede light's ability to pass through the sample. I've never torn the instrument apart, but I'm assuming it shines a 500K light through the sample and reads the light with a spectrophotometer.
 

Absolut_Ninja

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Figure my Hue Heffner (hee hee) is about a PMS 109; though I don't have a 100K bulb to check it anyway. Have you brought any brew to work and checked it on the light table? Wonder if it looks weird.
 
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Edcculus

Edcculus

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Ha, I think they would frown on me examining my beer on a light table against a Pantone book. I do have an extra spectro I was going to take home. I just don't have any software I can use to run it from home. All the stuff we use here requires hardware keys to work.
 

Dr Malt

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The color method for beer or wort can be found in the American Society of Brewing Chemist Standard Methods of Analysis. Yes, haze does cause problems and needs to be removed before doing accurate color determinations. Ther single wavelength measurement of color for beer is not ideal, but it is simple and very reproducible within and between labs. It can be run on a relatively inexpensive spectrophotometer. Before a method becomes part of ASBC procedures it is tested by numerous labs in the brewing industry for it's accuracy and reproducibility of results.

Dr Malt :mug:
 

mrkristofo

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I was reading a method last year in the ASBC regarding this very thing. They were attempting to convert quantification of color into this 3D color space you're describing.
Have a look at the JASBC, and I think you'll be pleased.

Downside is you need a spectrophotometer.
 
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Edcculus

Edcculus

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look for a crack whats the software called
There are several. Most you have to buy through a vendor and require a hardware key to work. They come with a little USB device that has to be in the computer for the software to run. There is probably free software out there that will just calculate the color into a 3D color space though.

I was reading a method last year in the ASBC regarding this very thing. They were attempting to convert quantification of color into this 3D color space you're describing.
Have a look at the JASBC, and I think you'll be pleased.

Downside is you need a spectrophotometer.
Very cool!

I think that in the end, the reason the beer industry has gotten away with single wavelenght measurement is that there is a very limited gamut of hue achievable in beer.
 
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