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Question about skunking

Discussion in 'Beer Talk' started by draheim, Feb 15, 2013.

  1. draheim

    draheim Poobah (1,015) Washington Sep 18, 2010

    The thread about brown glassware and skunking reminded me of this question I wanted to ask.

    Saison Dupont is one of my all-time favorite beers. It's largely responsible for getting me to start exploring beers outside of the Pacific Northwest craft beers I'd been drinking almost exclusively for the previous 20-odd years. I know that in some places, Saison Dupont is packaged in brown bottles. But out here it only comes in green bottles—both 750mL and smaller ones, probably 330mL. The bottles I buy are always refrigerated and kept away from UV light, but they are in green bottles.

    Anyway. Sometimes when I open a Saison Dupont I definitely catch a strong whiff of skunk smell. It smells exactly like when you're driving through a rural area and encounter a patch of air where a skunk has either been run over or otherwise emitted its skunky foulness. But after 30 seconds or so after opening the bottle and pouring a glass, the smell is gone and the beer tastes just as fresh and wonderful as ever. So I guess what I'm trying to figure out is, is this beer technically skunked? Is there a middle zone where the air in the headspace can get skunky (and thus the aroma upon opening), but the taste of the beer remains unaffected? Or could it be that I just don't mind or particularly notice skunkiness in the taste of a beer that others would find objectionable?

    This is something I've been wondering about for a while, thanks. Cheers!
  2. I have never heard of a skunk taste/smell dissipating in a beer. Hopefully somebody will know whether this is genuinely possible. I am not an Organic Chemist but my guess would be that once MBT (3-Methyl-2-butene-1-thiol) is formed (the compound that produces the skunky taste) it will not just vent away.

    I can get Saison Dupont in small brown bottles. I personally refuse to buy Saison Dupont in green bottles; that beer is just too damn expensive to risk buying a skunked bottle.

    Cheers!
  3. Skunk odor can definitely dissipate a bit after a few minutes in the glass.
    DuPont and Chouffe beers that I've bought have been skunked, I tried maybe 2 or 3 times and then gave up on them.
  4. This has happened to me too but I couldn't explain it. Science.
  5. Both good volatiles (like hop aromas) and bad ones (like DMS) can be scrubbed by the carbon dioxide coming out of solution. This is one reason why you shouldn't dry hop in a primary fermenter, with all of that CO2 action going on; also, lagers that are cool-fermented and don't have such an active primary fermentation tend to not have that additional way of driving off DMS, so are more susceptible than ales in that regard.

    I have also had experiences with the skunky 'thiol' type aroma that dissipates with time and swirling- I assume it is being 'scrubbed', but haven't really read anything definitive on the matter. In a practical sense, though, it does go away.
  6. - note that it isn't just UV light, but also near-UV wavelengths in the blue part of the visible spectrum.

    - the 330ml bottles, offered in 4-pks, are brown glass with standard bottle cap. the 375ml bottles are green glass with cork-and-cage.

    - the aroma can dissipate slightly, but i think (and i've experienced it as well) that it's a combination of dissipation and simply becoming acclimated or "numb"/desensitized to the aroma. THE tell-tale sign is burping it up 20 minutes later and it's all skunk. i've had the displeasure of this way too many times...
  7. drtth

    drtth Advocate (690) Pennsylvania Nov 25, 2007

    Skunking should have an effect on the smell but not the taste. However since smell contributes to flavor, which is a combined effect of smell and taste...

    However, the olfactory sense adapts over time (just as the sense of taste does) so some of what you are experiencing may be related to the "fatigue" of the receptors as they adapt to the smell and become less responsive to it.
    tai4ji2x likes this.
  8. loafinaround

    loafinaround Savant (360) New York Jul 16, 2011

    I looked-up what is produced when a beer is skunked:
    3-methyl-2-butene-1-thiol
    methyl (3-methyl-2-butenyl)-disulfide
    3rd compound with an unidentified structure
    MBT is apparently readily oxidizable... meaning when it hits air, a chemical reaction will turn it into something else (presumably w/ a new aroma). No information is available on the stability of the other 2 compounds. So, it could be due to olfactory response downregulation (as drtth suggested) or merely to the dissipation of the original offending stinky compound(s).
    The burping experience sounds awful. Virtually everything I buy is in a brown bottle, so I have yet to experience that fun.

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