The last beer review on this site unearthed an interesting subject. Skunked beer.
This term, so loosely thrown around by pseudo beer connoisseurs everywhere deserves some attention. Let me set the scene for you…
You are at a gathering at a friend’s house. For the most part, the bud light is flowing. In walks captain cliche with a pair of Sketchers, an iPhone, and a highly sophisticated case of Heineken he just purchased at Walmart. As he esoterically asks for a bottle-opener, another, even more sophisticated attendee sipping on his Killian’s says, “whoa…keep that skunky beer away from me!” Another guy with a sweet man-purse says, “Yeah, those Dutch guys need to invest in some brown bottles!”
All three of these guys are idiots.
It never occurred to guy one that Heineken isn’t as cool as the commercials make it out to be. (Although I am impressed with Heineken‘s ingenuity–the time spent on their pressurized mini-kegs was genius marketing).
It never occurred to guy #2 he should have kept his mouth shut. I don’t believe that Heineken (or other so called skunky beers; i.e. Stella Artois, Grolsch, St. Pauli Girl…) are actually skunked beer. Beer is a science. The skunky smell and unique flavor of said beers is quite intentional. That sulfur-ish smell and flavor may result from a delicate and precise combination of grains and yeast, interacting in and changing each other in the turbulent fermentation process.
Guy #3 (who most definitelty likes the sound of his own voice) may be on to something, but is overwhelmingly wrong. Green bottles may affect the quality of beer, but most likely only marginally.
The fact is, skunked beer is not desirable. It is a flaw, not intended by the brewer. Last Friday, Mike noted that his Sierra Nevada Pale Ale had that skunked quality. The Sierra Nevada beer I drank, miles away, most likely having being born of a different batch than Mike’s was not skunky. Obviously, the brewer is going for uniformity in his beer, so something went wrong.
Beer becomes ‘skunked’ when it is unintentionally exposed to light; more specifically, UV radiation. That is why it is imperative for beer to be kept out of sunlight and fluorescent lighting, which emits far more UV radiation than an incandescent light bulb (fluorescent light bulbs don’t use a burning filament, rather excited ions resulting in plasma, the fourth state of matter, unique only to the sun and nuclear reactions…which makes me wonder…should the EPA be pushing so hard for these creepy bulbs?)
Anyway, when UV light streams through a bottle of beer, the hop compound (an acid used not just for flavor (bitter) but also for preservation), as well as sulfur compounds in the beer are chemically altered from the energy. As I said above, beer is a science. The energy transforms the acids into 3-methyl-2-butene-1-thiol (thiol indicates sulfur). As we all know, sulfur is known for having a pungent, offensive odor. Stink bombs, well water, and skunks all utilize this element to drive people away.
The myth is busted. Skunk beer is not a desirable trait, although many folks tend to think so and thus many brewers go after this effect naturally. However, they are not brewing a bunch of beer in green bottles and letting them sit out in open sunlit fields. You can avoid skunked beer by drinking your beer in the underground leaded fallout shelter in your basement like I do.
Nice article Nate. Andrew were talking about skunking a homebrewed Cervesa and a primitive scale by putting it in the sun for a bit. You are right though, industiral brewers do not do this. In fact, brewers that actively against it and can add compounds to their beer to eliminate this phenomenon.
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Sorry, Andrew and I were…
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i cannot fathom that that sierra nevada pale ale did not taste very skunky! You took two sips of it and i could smell the skunk on your breathe 50 yrds away.
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Well, it wasn’t that skunky to me. However, according to what I’ve read in Bamforth, different people are more sensitive to MBT than others (this is true for all sorts of flavors).
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Actually brewers do intentionally subject certain beers to UV radiation after bottling to initiate the chemical reaction you describe above. The American market is flooded with perfectly good beers that are then ‘skunked’ (which doesn’t necessarily mean flawed) because people either like the taste or associate the flavor with being foreign and therefore cool.
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Thanks For the feedback, Jack. As I pointed out, skunked beer, once a flaw has become a style, so I completely agree with the intentionality behind many popular brands (final paragraph). After some (not a lot) of research, I found several breweries that allowed sulfur content in their beer, and other compounds, to give it that “skunked” flavor, but I did not find any evidence that some intentionally exposed their beer to UV. Thanks for pointing out that some indeed do allow this natural phenomenon. I would be interested to know which brewers do.
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By the way, I’ve seen many people doing a search. Skunked beer will not harm you. It is hard for beer to have anything that is actually harmful to people. So, if you want to sip on your skunked beer go ahead. I don’t mind it sometimes.
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What’s you’re point? You say the guy who suggest that a brown bottle will help protect the beer from being “skunked” is an idiot, then go on to say “Beer becomes ’skunked’ when it is unintentionally exposed to light”. A brown bottle DOES help protect the beer from light better than a green or clear bottle. And most if not all green and clear bottled beer has a “Skunked” taste. Who give a rats a$$ if this is what the brewer intended (because dumb beer drinkers don’t realize the beer they’ve been drinking for 20 years task like crap and think that’s what ‘good’ beer taste like.) McDonalds makes junky burgers, and millions of people eat them (happily). But lets not suggest that McDonalds makes a really great burger.
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Thanks for expressing your opinion on this topic. I feel that what Nate is really getting at has been a bit misconstrued. I know because we’ve spoken on this topic on several occasions.
It seems to me that the real point Nate is making is that “skunked” is unintentional. Beer with sulphur tones is quite intentional. That’s the point he is clearly making. Furthermore, he does note that brown is better at protecting the beer from becoming light struck, but is irrelevant in cases like Heineken.
He is clear that the green bottles are primarily in view on the third example while noting the the guy with brown bottle statement is “on to something,” to use his words. The point he is making is specific to the idea that the green bottles creating “skunk”, as the term is used, is actually wrong because the sulphur creation is usually intentional in that case. There is nothing in the article that says brown bottles don’t protect the beer (in fact that opposite point is made by way of concession). I think a closer reading of the article points to this and doesn’t really expatiate on brown bottles as such.
Furthermore, people do give a rat’s a$$ if it is intentional in beer because sulphur, to varying degrees, is desirable and even preferred in certain types of lager…and some very good ones at that.
Agreed that McDonalds makes junky hamburgers and they aren’t starting from quality but that analogy doesn’t carry over in the case of desirable sulfur traits.
Thanks again for your comments and we happy to say that we welcome your comments.
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Thanks for diplomatic response. Perhaps you missed the word “marginally” in regards to brown beer bottles.
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can a beer be skunked after its out of the bottle,in a matter of minutes in the sunlight?
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michael reinhardt Reply:
October 18th, 2011 at 6:25 am
If the UV is intense enough…absolutely.
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There is a way to have clear or green bottled beer and keep the “skunk” out. Just buy beer that bottle their beer in bottles coated in SPF 2000. It blocks 99% of UV Rays that skunk beer. http://www.gotskunkedbeer.com
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I randomly started researching the effect that skunks beer today because my usual store has had a few bad batches as of late and I’d like to add on this….
The skunking reffered to in this article (generally the term skunked is used to simple imply its “off” of its normal intended flavor) Is about the UV radiation affecting the chemical compositions inside the beer. There is however certain flavor changes that take place when a beer is cooled, warmed and cooled again. upon researching this I found it affects the oxidation in the beer and changes the flavor. therefore if a beer that starts cold at the factory (a lot dont) gets heating during transport, then cooled again before sale might end up being a off flavored batch.
personally I have a few beers that I tend towards, yuengling, guiness, smithwicks, elephant, a few sam adams styles and when im going cheap I tend to drink original coors gold can or natural ice, so I do have a varied palate and appreciate different flavors. That being said I’d like the heating and recooling comment to be considered
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beer_scientist Reply:
December 19th, 2011 at 2:07 am
Kain,
Thanks for leaving a response. You are right about climactic changes having a serious effect on beer. In fact, I’ve written elsewhere about keg freshness versus bottle freshness of beer based on that idea. Generally speaking, the term skunked can be widened to encapsulate off beers as well.
We didn’t include it in this post because the specific question being addressed is sulphur (or the perception thereof) production in beer via an intentional byproduct of yeast activity or ultraviolet exposure.
Again, I think beer that has become off due to shipping and storage procedures can be called skunked as well…and you are right to point it out.
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actually, it’s not just UV light. it includes near-UV wavelengths in the blue part of the spectrum. this is why even incandescent lighting will eventually spoil green/blue/clear-bottled beer as well.
http://media.libsyn.com/media/basicbrewing/bbrskunking.pdf
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Thanks for leaving a comment. Allow me to restate what I think you mean by the comment above.
It isn’t simply UV light as a whole that is responsible for skunking. Rather, near-UV wavelengths in the blue spectrum are the specific ones that cause the reaction. Even incandescent light will skunk a beer due to the fact that it too contains the near-UV wavelengths that can penetrate green, blue, and clear bottles.
If I’m reading your response correctly, that is what I think you are saying. That being the case, the article has been clarified in the sense that it covers that specifics. I wouldn’t say that article is necessarily wrong…as the word actually seems to imply. Doesn’t UV, as a whole contain all its parts. In other words, the blue is in there whether we specify it or not.
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[...] sunlight, since if you expose beer to sunlight it creates a chemical reaction that actually creates 3-methyl-2-butene-1-thiol, which is what actual skunks use as odor defense. So Corona packages its beer in a manner to make [...]