I have access to a spectrophotometer at work and would like to imperically determine the color of my brews. I know that SRM is calculated using absorbance at 430nm, but when? As pre-fermented wort or as final, out of the bottle beer? does it matter?
Analyzing color
- Thread starter JLem
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menschmaschine
Well-Known Member
SRM is predicte by calculating the Lovibond of the malt and the final beer volume, like this...
((MaltA°L * lbsMaltA) + (MaltB°L * lbsMaltB) + (MaltC°L * lbsMaltC)...etc.)/Pre-boil Volume
...I think... I wanted to say it's divided by final kettle volume, but I just tested this calculation compared to Beersmith and it worked out much closer using pre-boil volume.
So you have predicted SRM and real SRM. I'm fairly sure the SRM of the boiled wort is the same as the SRM of the beer.
((MaltA°L * lbsMaltA) + (MaltB°L * lbsMaltB) + (MaltC°L * lbsMaltC)...etc.)/Pre-boil Volume
...I think... I wanted to say it's divided by final kettle volume, but I just tested this calculation compared to Beersmith and it worked out much closer using pre-boil volume.
So you have predicted SRM and real SRM. I'm fairly sure the SRM of the boiled wort is the same as the SRM of the beer.
Edcculus
Well-Known Member
I'd say fermented beer would be the best. Probably crash cooled and degassed too.
What method are you using. I have access to a crapload of spectrophotomers too. I have all of the programs to use them at work for measuring ink colors. That info doesn't translate very well to beer though.
I know people cite the usual "measured at 430nm through a 1cm cuvette" bla bla bla. Is this backed by a standardized white substrate? Backed by nothing?
What do people normally use for this? I'm using an Xrite i1 Pro (UV cut). I also have an Xrite 530 Spectrodensitometer. I don't think that would work well for this application though.
What method are you using. I have access to a crapload of spectrophotomers too. I have all of the programs to use them at work for measuring ink colors. That info doesn't translate very well to beer though.
I know people cite the usual "measured at 430nm through a 1cm cuvette" bla bla bla. Is this backed by a standardized white substrate? Backed by nothing?
What do people normally use for this? I'm using an Xrite i1 Pro (UV cut). I also have an Xrite 530 Spectrodensitometer. I don't think that would work well for this application though.
OP
OP
JLem
Well-Known Member
Yeah, that's what I was thinking too - I'll have to save a few sips from my next bottle!
I'll calibrate the spectrophotometer with a blank - probably just H2O, though to be more accurate it should be a 5% ethanol solution (or whatever the ABV% of the beer is). The machine I have access to is a simple biology lab instrument - nothing fancy - just set the wavelength, zero the machine with the blank, insert sample, get reading. The machine I have is similar to this model - Spectrophotometers - HACH - Spectrophotometer. I'm not familiar with the machines you listed (BTW, the links didn't really work)
