What exactly makes foam a certain color?

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Endovelico

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Yes, i know grain has alot to do with it but that still doesn't explain why there are Stouts (assuming they use Black patent or roasted barley) who have white head and some who have darker shades of creme/pastel/tan.

At first i thought it had something to do with nitrogen since the only Stouts i could remember having white head were Murphy and Guinness. However i have now seen some traditionally carbonated Stouts with white head as well.

Any guesses?
 

davesrose

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Yes, i know grain has alot to do with it but that still doesn't explain why there are Stouts (assuming they use Black patent or roasted barley) who have white head and some who have darker shades of creme/pastel/tan.
Why wouldn't grain bill explain the difference in head color? :confused: Stouts and porters still have a wide variety of specialty grains that influence color and taste: I've found just the presence of patent doesn't add to head color so much as types of caramunich and such. I haven't gotten into beer gas for my home kegs. With just CO2, I have found that dry stouts can have a white head, while oatmeal and imperial stouts can have a tan or gray. I'm thinking it's mainly specialty grains, but perhaps hops add some too. I think the main thing nitrogen does is make the head creamier with smaller bubbles. I get some pretty gosh darn bleach white head with my lighter ales under normal CO2 at any rate.
 

steelerguy

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I would think it would depend on the grain bill also and the type of proteins that are in each grain. The proteins themselves that bind together may have a color of their own but more likely they probably bind to different pigments from the grain and carry that pigment with them in the head.

Put another way, I have seen only white and slightly off white heads on lighter beer, but dark beers can go from white to a darker brown. Must mean it is coming from the grain bill and some dark grains add dark color to the head.
 
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Endovelico

Endovelico

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I'm not saying Grain bill has nothing do to with it, that would be silly.

I am however intrigued how certain stouts have pure white heads while especially since most of them use black patent and/or roasted barley. But that caramunich bit was interesting, didn't know it played that big of a role.
 

Homercidal

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Funny, I read up on this in Charlies book a couple of weeks ago, but can't remember exactly what the different grains were. He tells which ones do which and why. Have to look that up again.
 

davesrose

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I am however intrigued how certain stouts have pure white heads while especially since most of them use black patent and/or roasted barley. But that caramunich bit was interesting, didn't know it played that big of a role.
Yeah, I'm not sure how big of a role various Caramunichs play....but I do seem to get darker/tanner heads if I have grains such as that in. It's mainly that I don't think gas adds any color, and that it's not the black patent that adds color per say. I haven't done any controlled experiments to see just what grains do what to add to the color of the head, though when I just brew a straight forward black patent/roasted barley stout it usually turns out with a white head. I would think it also has to do with ratios of specialty grains to your malt: ie if there's more specialty grains, then maybe there's more fermentables from them winding up as protein that forms the head. Almost makes me want to learn chemistry just for more beer study.....ALMOST! :) If someone finds the info on grains and head color, that would be interesting.

Oh, and speaking of Guinness stouts....don't the ones that are brewed with sorghum (in areas that ban barley) have a dark tan head? Think I've seen that in photos at least: haven't tried a sorghum beer though.
 

JuanKenobi

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Funny, I read up on this in Charlies book a couple of weeks ago, but can't remember exactly what the different grains were. He tells which ones do which and why. Have to look that up again.
I remember this from Complete Joy as well. I believe Charlie says that roasted barley adds significantly to head color and that black patent does to a lesser degree.
 

theonecynic

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So if one wanted a black and white beer, one should stick to chocolate and black malts for speciality grains? Or just black? Or maybe something else?
 
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Ditto to Charlie. I just read it this part last week. Stop by your local book store and pick up "The complete Joy of Homebrewing by Charlie Papazian. Or just flip to the section about grains. it explains which ones add to head color. I had my copy at my desk till just last week or I could have looked it up for you. sorry.
 

davesrose

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OK, I've got my copy of it that I looked up....Charlie doesn't seem to get into much detail: only does say that roasted barley adds to color of head significantly while black patent doesn't. He doesn't say anything about the other degrees of malts (crystal or caras). Maybe it does have to do with fermentability: as the main difference between black patent and roasted barley is that one is malted. I might have to do a real study of my stouts to see what grains add what....but I would think that dry stouts tend to have white heads because of less proportion of roasted barley to black patent and malt. And that my imperial stouts have a dark tan color because of quite a bit more roasted barley and specialty grains being present. It seems like its the unmalted grains that add more color to the head. I'd say even oatmeal as my current oatmeal has a dry irish stout grainbill + 1lb of oatmeal....notice the head to it is a grayer color then a dry irish stout.
 

theonecynic

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Thanks very much. I decided to brew a memorial beer for my (black and white) cat so it is for a slightly better reason than "oh I want it look like guinness" - I'll do a bit of tweaking.
 
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