What colors do hops impart to beer?

When I make a starter using Pilsner or Extra Light DME (no hops) and put it in the fridge for decanting, it always turns an orange color. Sometimes a brown orange; sometimes more of a fuller brilliant orange.

Beer is usually yellow to black with browns and amber hues in between (SRM scale etc..) so my guess is that hops (added during the boil) impart green and yellow hues to the wort which would take the orange to the yellow brown range.

Never thought of this before... Although I have to say that it is strange that you put hops in your starter...
You could scale your starter way down to 8 ounces or so and add the appropriate amount of hops, then observe the color change, if any.
I am guessing it will turn a light yellow, and maybe darken a little like when a tea bag steeps for too long...

Interesting question. I would guess it adds a slight green hue, but we could find out pretty easily. Someone should scale down a standard pale ale recipe to 1 gallon or so, but remove everything but the hops - no grain. Boil just the hops in water, but follow the hop additions. You could drink it as hop tea, and you'd be able to easily see the color.

@hopdoc - No hops in starter; didn't mean to imply that in post.

@andycr - I was thinking along the same lines with the hop tea experiment... maybe when I get some free time.

ShootsNRoots said:

Beer is usually yellow to black with browns and amber hues in between (SRM scale etc..) so my guess is that hops (added during the boil) impart green and yellow hues to the wort which would take the orange to the yellow brown range.

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Hops will add zero perceivable color to beer, the green pigment is not that water soluble in the first place plus the amount of sugar you have in wort makes it next to impossible to extract it. As of the yellow/brown of the oils, before you get any noticeable color change the beer will become undrinkable, the flavor threshold is just way to high. The amount of hops you add per unit of water is also very small.

As for the color profiles, SRM Levibond etc, are just a measure of opacity. There is no simple way to judge color of wort, however there are complex ways that no one uses.

If you want to test it for your self, get 1/2 gallon of water add 6.5oz of table sugar (should be about 40 points if i did my math right) and add 1/10 of what you use in a 5 gallon batch of beer of hops (so if you use 1 oz use 1/10 of an oz) and boil for 60 mins, remove hop matter and compare vs pure water with a white back drop (piece of printer paper) in sunlight.

The interesting thing about beer color is that all beers have an absorption spectrum that is essentially the same. It starts high at the blue end, drops precipitously and levels in the green region to become essentially flat at the red end. This is why most (about 90%) of the information about a beer's color is contained in the SRM (which is derived from a single absorption measurement taken at the blue end (430 nm). It also explains why beer is essentially red. Shine a flashlight through a carboy of fermenting light beer. Do the same for a quarter inch of stout in the bottom of a glass.

Anything in the beer that absorbs light will have an influence on the color including hops. But they don't add colors - they take them away. Thus if hops derived materials make beer look more yellow they are actually absorbing blue light. If they make it look more green they are actually absorbing blue and red light.

To see what the effects of hops are on color you would have to make some wort and ferment part of it unhopped (fermentation changes color) and the other part hopped. You could then look at the two beers if a visual comparison was enough for you. To quantify the color differences you would have to go to a lab that does the ASBC tristimulus color measurments or get a lab to report the absorption spectra (1 cm path, 5 nm steps 380 - 780 nm) to you which you can then stick into a spreadsheet available at my website (wetnewf.org). This will convert the spectra into R,G,B or L,a,b color values (the latter are what the ASBC method determines but only at one wavelength and one light source quality - yes, color depends on the nature of the light illuminating the beer).

As for the color profiles, SRM Levibond etc, are just a measure of opacity. There is no simple way to judge color of wort, however there are complex ways that no one uses.

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The SRM and EBC color measurements are based on optical absorption of light at a single wavelength (430 nm). The Lovibond measurement is based either on visual comparison of a sample of the beer to colored glass discs or on measurement of the entire absorption spectrum of the beer and mathematical comparison of that spectrum to the absorption spectrum of the sample discs done in the computer in the instrument.

If you happen to have a spectrophotometer SRM and EBC measurements are simple. If your instrument happens to be capable of recording the entire spectrum (as most modern ones do) then the tristimulus and augmented SRM methods are simple (the math may be complex but that's all hidden in a spreadsheet or the spectrophotometer).

When I introduced the augmented SRM method at an ASBC conference I asked how many people in the audience were using the Tristimulus method. I'd say about 40% of them raised their hands. So quite a few people do use that 'complex' method. No one uses the augmented SRM method except me AFAIK.

ajdelange said:

SRM (which is derived from a single absorption measurement taken at the blue end (430 nm). It also explains why beer is essentially red. Shine a flashlight through a carboy of fermenting light beer. Do the same for a quarter inch of stout in the bottom of a glass.

Anything in the beer that absorbs light will have an influence on the color including hops. But they don't add colors - they take them away. Thus if hops derived materials make beer look more yellow they are actually absorbing blue light. If they make it look more green they are actually absorbing blue and red light.

When I introduced the augmented SRM method at an ASBC conference I asked how many people in the audience were using the Tristimulus method. I'd say about 40% of them raised their hands. So quite a few people do use that 'complex' method. No one uses the augmented SRM method except me AFAIK.

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I agree 100% I guess the point I was trying to make was that to the human eye there really isn't an effect.

As far as my comment about measure or opacity, it was a gross generalization which I should have been more clear about. I was more alluding to the fact that you can have 3 beers all with the same absorbance value at 430nm and be 3 completely different colors. (obviously as you pointed out its only one wave langth)

As for the Tristimulus method, I was under the impression it was really only something the big guys used. I guess you learn something every day!

You only boil starter wort a few minutes. You boil beer wort a full 60-90 minutes in most cases. This probably has an impact. I am also guessing that even though you decant in fridge for 24 or so hours, that there is still plenty of yeast in suspension. The yeast/beer ratio is much much greater in a starter than in wort and does not have several weeks to drop out.

Also we (some of us) do our best as brewers to get the break out of beer wort, hard full boil, clearing agents such as whirfloc, Irish Moss, and Gelatin, fast cooling, etc. You probably don't go through all that trouble on a starter that turns around in several days. You probably have tons of proteins and chill haze effecting the color.

I, over course, am just guessing in throwing out thoughts. All hypothetical.

boomernintysix said:

I was more alluding to the fact that you can have 3 beers all with the same absorbance value at 430nm and be 3 completely different colors.

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I suppose that depends on what you mean by 'completely different'. Sticking with all malt beers (i.e. no Krieks or Framboises) I'm guessing beers with the same SRM probably wouldn't be more than 10 units apart in Lab space.

boomernintysix said:

As for the Tristimulus method, I was under the impression it was really only something the big guys used.

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It was an ASBC meeting so all the big guys were there but there were lots of craft brewers too. I was surprised there were so many who used it (because, IMO, it isn't a very good method - too restrictive: 1 path, one observer, one illuminant).

ajdelange said:

I suppose that depends on what you mean by 'completely different'. Sticking with all malt beers (i.e. no Krieks or Framboises) I'm guessing beers with the same SRM probably wouldn't be more than 10 units apart in Lab space.

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I have seen it once with bud/miller/coors vs Guinness. As you would expect the big three are pale yellow and Guinness is this beautiful pale-ish red color (all at 430). I have no idea how the would compare to l.a.b. I honestly have never used it (I think that's obvious now).

I need to read up on Tristimulus more but most the texts I have found are either "who really cares" or its just way over my head. I feel like accurate color assessment is one of those "arts" in brewing where science leaves us lacking.

boomernintysix said:

I have seen it once with bud/miller/coors vs Guinness. As you would expect the big three are pale yellow and Guinness is this beautiful pale-ish red color (all at 430).

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I'm not sure what it is that you are describing but Bud and Guiness are actually pretty similar in color if you adjust the paths so that the absorption at 430 nm is about the same. As I said in an earlier post a couple of feet of Bud and a mm or so if Guiness would look pretty similar. I've put a graph of the normalized absorption spectra of Guiness, Bud, Tsing Tao and Lindeman's Kriek below. The blue curve is the average normalized spectrum of an ensemble of 99 beers. As you can see the three 'normal' beers have spectra quite close to the average spectrum. The Kriek does not.

The amount of deviation from the average spectrum can be quantified. This is the basis for the Augmented SRM method. Instead of just saying that Bud has an SRM of 2.40 you also add the Spectrum Deviation Coefficients (SDC): -0.911, + 0.19 and -0.04. That's a complete (if not 100% accurate) spec for the color of Bud. Guiness has an SRM of 51.88 but its SDCs are 0.551 -0.153 and 0.054. Lindemans Kriek has SRM 15.27 with SDCs +1.784, 0.788 and -0.074. Thus the color characteristics, expressed in terms of the difference from the color characteristics of an average beer, are small except in the case of fruit beers. A typical all malt beer has a first SDC of about -0.6. Thus Bud and Tsing Tao are typical but Guiness, with it's first SDC of + 0.55 is more Kriek like than Tsing Tao and Bud.

If you had a normal malt beer at 15.27 SRM (same as Lindeman's Kriek) but with first SDC of around - 0.6 it's obviously going to look quite different from Kriek with a first SDC of +1.78. OTOH any other beer with an SRM of 15.27 with first SDC near -0.7 (all malt beers) is going to look pretty similar with the actual distance in color space depending on the path, the full set of SDC's, the chosen color space, the illuminant and the 'observer' (one of 2 promulgated by the CIE).

boomernintysix said:

I need to read up on Tristimulus more but most the texts I have found are either "who really cares" or its just way over my head. I feel like accurate color assessment is one of those "arts" in brewing where science leaves us lacking.

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Commercial brewers care about it a great deal because, especially in the case of beers like Bud, the very light color is hard to get and is very much a part of the brand. Were the color perceptibly different from batch to batch consumers would notice. Craft brewers don't seem to care so much. Most home brewers don't but some, i.e. those with a geeky bent, find it a fascinating subject.

It is true that to understand what Tristimulus tells you you need to know more about color than what your kindergarten teacher taught you about color wheels and it is also true that the math can get pretty hairy.

The science is thus there but it is not fully appreciated. I proposed the Augmented SRM method to ASBC as it gives full color information about a beer under any viewing conditions and requires math very similar to the math required by the tristimulus method. A guy who was present when the committe considered it told me that no there understood what was involved. These things take time.