Increased boil time does not increase color

On the design page, I had a 90 minute hop addition and realized I had my Boil Time at the top still at 60 minutes.  When I changed it from the default 60 to 90 the IBUs increased....makes sense.  However the color doesn't change.  Shouldn't extra boil time increase the color as well to some degree?

Thanks,
Donovan

In my understanding, the only time color would change in when your wort is in contact with your grain.  After the mash, there really isn't anything to change the color, other than evaporation, which wouldn't seem to make much difference at all in my experience.

The issue isn't the longer boil time crating a different hue. That's just something you observe and adjust for in your system. The SRM scale is relatively limited in what it says about color. It is simply a measure of absorption of one wavelength in the visible spectrum.

It's stated pretty well in the BeerSmith article, Understanding Beer Color

"In fact, it is not possible to specify the precise color of a beer with a single “beer darkness number” such as SRM. The subtle variations in red, brown, gold, copper and straw can’t be captured in a single dimension beer color system. Irish Red is a good example – if you do an estimate of the color for an Irish Red you will likely get something that does not look very red at all on the color card. Yet the addition of a tiny amount of roasted barley gives it the distinctive red hue that the SRM system simply can’t capture."

donovanneb said:

When I changed it from the default 60 to 90 the IBUs increased....makes sense.  However the color doesn't change.  Shouldn't extra boil time increase the color as well to some degree?

Click to expand...

I've read that DME darkens faster than an all-grain wort, and that is partially why some pale styles are tougher via extract.  But in reality, as brewfun pointed to, are the differences even perceptible by humans?  What might be the SRM difference in 30 minutes boil time?  Compared to a sloppy scale reading and the brewer has 6 oz of some 500 Lovibond roasted grain, and not 5 oz?  Or water volumes are inexact, and the whole recipe is either diluted or concentrated in much more measure-able ways.

Vikings stirred brew with a stick. 

My last brew, the s/s scrubby clogged up, so I washed my arm, Star-San'd my arm, and "Elbow Deep IPA" was born.  Tastes fine.  The harsh edge to the bitterness is my fault and probably occurred during recipe creation when I was trying to utilize a bunch of high-alpha hops...and apply things I learned at AHA NHC.  Likely had nothing to do with my Viking stick arm methods on brew day.

Maltlicker, to complete that recipe, you must add the dryhops with your armpit! 

Mtnmangh - you are correct in that it is related to evaporation rate.  The Maillard reaction takes place as wort is boiled; therefore, wort color increases with boil time.

In beersmith there's an evaporation / hr percentage.  So if you adjusted your boil time to 90 minutes vs. 60 then you would have more evaporation and the SRM would change.  SRM is calculated to the tenth on the program, so I would expect to see a change in SRM, even if slightly.

Color perception and SRM measurement don't necessarily correlate. The mechanics of wort viscosity and Maillard reaction have several variables that are not going to be picked up by SRM in a meaningful way. Someone's observation of beer color depends on turbidity, depth of the sample, light source and how close you hold it to your eye.

SRM measures one light wavelength in the deep blue spectrum (430 nanometers). A true SRM reading is 1 cm thick, free of turbidity. The number is derived from the log ratio of the light entering vs. the light exiting the sample, multiplied by 12.7. Since it uses just one wavelength, the SRM scale is not very good at detecting the difference between light orange and deep burnished gold or other colors based on subtle red shifts.

Bob Hansen at Briess spent a lot of time on the subject and created this poster for the MBAA, http://www.brewingwithbriess.com/Assets/Presentations/Briess_2010MBAA_BeerColorPoster_.ppt

To anyone without a lab, the use of SRM for color observation is a bit arbitrary and possibly useless. Most observable beer color shifts are in the red area of the spectrum. This is more typical of the wort darkening you're describing. There is a newer formula for SRM that takes more coefficients into account and may make the numbers more likely to change according to human perception, but it isn't getting much traction.

The ASBC has approved a method that uses 81 different wavelengths, which places SRM into a scale that recognizes more than just the loss of 430 nanometers. If adopted by the industry, it would change the way numbers represent the color of beer.