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.
[Reply]
TheGremlyn Reply:
July 31st, 2012 at 1:28 pm
Sounds like a risky experiment. Direct exposure of beer to sunlight will result in a noticeable smell/flavour, and undrinkable beer in mere minutes! Try taking a bottle of beer, pouring it into a glass, and put it in your sunlit window to see how quick this can happen.
[Reply]
Sorry, Andrew and I were…
[Reply]
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.
[Reply]
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).
[Reply]
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.
[Reply]
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.
[Reply]
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.
[Reply]
[...]
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$$ if this is what the brewer intended (because dumb beer drinkers don’t realize the beer they’ve been drinking for 20 years task like crap and think that’s what ‘good’ beer taste like.) McDonalds makes junky burgers, and millions of people eat them (happily). But lets not suggest that McDonalds makes a really great burger.
[Reply]
Thanks for expressing your opinion on this topic. I feel that what Nate is really getting at has been a bit misconstrued. I know because we’ve spoken on this topic on several occasions.
It seems to me that the real point Nate is making is that “skunked” is unintentional. Beer with sulphur tones is quite intentional. That’s the point he is clearly making. Furthermore, he does note that brown is better at protecting the beer from becoming light struck, but is irrelevant in cases like Heineken.
He is clear that the green bottles are primarily in view on the third example while noting the the guy with brown bottle statement is “on to something,” to use his words. The point he is making is specific to the idea that the green bottles creating “skunk”, as the term is used, is actually wrong because the sulphur creation is usually intentional in that case. There is nothing in the article that says brown bottles don’t protect the beer (in fact that opposite point is made by way of concession). I think a closer reading of the article points to this and doesn’t really expatiate on brown bottles as such.
Furthermore, people do give a rat’s a$$ 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.
[Reply]
ohio_brewer Reply:
February 17th, 2013 at 10:20 am
good thoughtful reply. i would add that about ten years ago i was in Amsterdam and the Heineken we drank there was superbly clean and fresh with zero skunkiness, in contrast to the product that makes it to the US market. which is shipped here in green bottles. so either the product i drank there was actually a different product than what they export to the US, or it changed along the way. another complicating factor is that the product i had over there was served on draft, not out of a bottle. so in order to pin the skunkiness on the glass packaging, you would have to verify that 1) the racker and the bottler are fed by the same bright tanks (ie, not formulated any differently), and 2) a bottle of H served over there is not skunky and 3) the bottles filled for consumption in EU markets come from same stream as those filled for export to US market. anybody else been to the Netherlands more recently? i’d like to hear a more up-to-date second opinion.
[Reply]
Thanks for diplomatic response. Perhaps you missed the word “marginally” in regards to brown beer bottles.
[Reply]
can a beer be skunked after its out of the bottle,in a matter of minutes in the sunlight?
[Reply]
michael reinhardt Reply:
October 18th, 2011 at 6:25 am
If the UV is intense enough…absolutely.
[Reply]
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. https://www.gotskunkedbeer.com
[Reply]
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
[Reply]
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.
[Reply]
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.
https://media.libsyn.com/media/basicbrewing/bbrskunking.pdf
[Reply]
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.
[Reply]
[...] 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 [...]
“Skunk beer is not a desirable trait, although many folks tend to think so and thus many brewers go after this effect naturally.”
This sentence is completely contradicting. If many folks tend to like it and brewers go for the “skunked” effect, then it clearly is desirable to some. So I don’t really know what busted myth your talking about.
Also, I am one of the folks who love “skunked” beer…. or whatever the heck you want to call it. It never lets me down!
[Reply]
nate Reply:
July 31st, 2012 at 5:35 pm
Thanks for the input cleo…your right, my statement is somewhat paradoxical. I should have clarified further that the chemical changes that occur in ‘skunked beer’ are considered a flaw when judging a beer for the most part.
As far as you liking skunked beer, I take no issue with that. I love sour beers, and for many, bacteria doesn’t belong in beer…but not for me. Please stop back…we’re gonna start writing on this beast again.
[Reply]
zymurgistic Reply:
February 17th, 2013 at 11:29 am
the way i understand the heineken-skunk-as-flaw issue: after WWII, brown glass was in short supply in EU, so many EU brewers went to green glass. many of these beers were very high quality, and so some exporting brewers (notably Heineken) chose to stick with green for marketing reasons, even though the optical implications for green glass to hop chemistry were known by then.
FFW to the 1980s: Heineken is one of the best-recognized “quality EU imports” here in the US, and consumers have become accustomed to the skunky flavor, and since many consumers don’t mind it, or actually enjoy it (as Cleo), this aspect of the product as it is consumed in the US actually serves to reinforce the “acquired taste of a luxury good” mystique.
Heineken is one of the world’s biggest brewers. they are modern, technically advanced, and they certainly know their brewing science. but for all the reasons noted above, it never made any sense from a business perspective for them to “fix” the flavor of a product which enjoyed such a long-standing premium-product niche in the world’s most lucrative beer market. all that notwithstanding, palettes, tastes, and econoics are shifting, so it wouldn’t be inconceivable to see Heineken make some effort to dial out the skunk as a way of transitioning their sales into other market segments.
another thing: Nate is correct that skunk is considered a flaw by tasting panels. i’ve never heard of skunkiness (chemically called mercaptans) being an officially desirable flavor/smell in any free-standing beer style. however, as nate pointed out, some sulfur compounds actually are. DMS, or dimethyl sulfide, is the smell you detect upon opening a can of corn. your nose tells you it is in the same zip code as skunk smell, but much less unpleasant. a hint of DMS is often considered by style guides to be a requisite for many lager styles, and a total absence of detectable DMS is sometimes considered a flaw for a light-bodied, light-colored lager.
note for homebrewers: if you are experiencing excessive amounts of DMS (cooked/creamed corn flavor/aroma), the primary suspect is the vigor of your boil. most DMS is driven off during the boil, so if your boil is actually a weak simmer, you’re probably retaining the DMS at that point. if that doesn’t fix, then change your yeast strain. the yeast can metabolize precursor to DMS during the fermentation. factors that favor DMS production during ferm are lower temps and slower ferments. a less vigorous ferm retains more DMS in beer for same reason as boil vigor.
a hint of DMS (dimethyl sulfide) is
[Reply]
brown bottles are much more than marginally better at blocking the UV light, almost 98% of UV light is stopped by the brown bottles, hence why you almost never find a brown bottle of skunky beer even if left outside all day!
Temperature change has to have an * now however, it used to be that only Extreme, and I mean extreme temperature changes would affect a bottle of beer, however with so many breweries opening some with very little start up money, lack of really good filtration, and lack of heat pasteurization has made it so that yes, temperature change can very easily spoil some beers now.
I would argue however that the skunk is done intentionally since it is a well known fact what causes it and that the bottles the brewery is using are not sufficient to protect the brew. I think in all honesty to bust the myths only a few things need to be known, !. your skunked beer is light struck. 2. if your in a green or clear bottle your much more likely to be light struck. 3. it isn’t going to kill you so if you like that taste drink it anyway.
[Reply]
Sulphur compounds are by products of the fermentation cycle and low levels are acceptable in various styles of beer, such as IPAs brewed with high sulphate water.
The presence of sulphur in a beer, however misidentified it may be by people, does not cause the characteristic ‘skunky’ flavour alone. The only way to get that flavour in a beer is to expose it to UV radiation and initiate the chemical reaction. All beer contains some amount of sulphate, whether you can detect it or not.
And as albino rhino said, the colour of the bottle absolutely matters. All you need to do is look at a colour wheel to figure it out. Blue is across from orange (or amber, like the ‘brown’ bottles actually are), and this means that those bottles will filter the vast majority of blue light out. Blue bottles will not, clear bottles will not, and green bottles will not. Only amber.
Try comparing a Heineken from a bottle to that of the beer in the can or minikeg, or better yet a real keg. The taste is quite different, mainly in that the green botle variety tastes lightly skunky, whereas the others don’t.
[Reply]
Thanks for the comment. Please refer to the my response to MICHEAL ARSENAULT if you want to see that I basically said the same thing (minus the undrinkable part).
[Reply]
I agree with Mike…thanks for the interaction guys
[Reply]
Miller MGD is clear bottle and never skunky
[Reply]
[...] Of Montreal was “established” in 1998 and for the bulk of its decade-and-a-half existence, has been carried by Kevin Barnes (the voice of OM) alone. Daughter of Cloud is an interesting ride since of Montreal is an amoebic being — it’s constantly shifting. Some of the tracks are from a more lo-fi era and others include bizarre narratives, and catchy pop melodies abound. It’s really a different experience for me. I was first introduced to of Montreal with albums like Bird who Continues to Eat the Rabbit’s Flower and tracks off of Cherry Peel and Hissing Fauna, Are You the Destroyer?. I have to admit I really love early of Montreal, it brings back good memories of late night-drives to Austin, TX and that weird phase where I really liked Heineken. [...]
This entire article is debunked by this fact. I got online tonight to see if skunk beer is bad for you and found this site. I am drinking keg beer that was left out in my basement (keg + basement= no light exposure) for a week and after I chilled it again it is skunky. Again, no light exposure…still gross…still drinking it.
[Reply]
The artical and following discussion I found interesting thanks!! I only drink larger when wishing to get hammered, I’d much rather have a cask ale or if not some kind of dark ale. The first time I really noticed the aforementioned skunk taste was when Sol beer came to the UK at that time I was a youth and I actually liked it. I suspect as I’d been drinking larger mostly from a can. I was happy that it actually had any flavor at all, after reading this I went out and bought a Heineken and yep skunky, but as larger goes it was a welcome flavor.
[Reply]
Love your answer… I have a couple of theories on dark glass vs clear glass on my blog that is worth checking out. Now as for Heineken… you might want to read my take on its market segment. Pretty safe to say we see eye to eye.
Thanks,
Stephan, the Beergonaut
[Reply]