There’s plenty of confusion when it comes to decanting: what to decant, how long to decant it (we’ll get to that), why to decant. Recently we asked the question “should you decant white wine?” (Answer, sometimes.) And that led us to the, well, provocative concept proffered here: wine “farts.” Yes, your $13 bottle of wine might do to you at the dinner table what your 13 year-old brother used to do to you at the dinner table.
As ever, when farts temporarily spoil something awesome, there’s one specific chemical to blame: sulfur. Volatile sulfur compounds, to be more precise. According to California wine analysis outfit ETS Laboratories, the basic outline starts with yeast metabolism, which, as we all know, yields delightful alcohol and CO2. It also yields Hydrogen Sulfide, or H2S, the same stuff found (in tiny, but potent, concentrations in human flatulence). Typically, H2S “volatilizes” with the C02, but when it doesn’t, trouble arises. On its own, H2S can impart “rotten egg, sewage like” aromas at just .9 to 1.5 parts per billion. Just like when that lady in front of you at the movies breaks wind, it doesn’t take a lot to go a long way.
And it doesn’t stop there. Your wine also contains something called “mercaptans,” compounds “probably formed during fermentation by reactions [that] involve H2S or breakdown of sulfur-containing amino acids.” The most common mercaptan is methyl mercaptan, perceptible at 1.5 ppb and reminiscent of “rotten cabbage” and “burnt rubber.” Remind you of anything? A dude’s locker room, maybe?
Bear in mind, not every bottle of wine is crop-dusting you with mercaptans. If they were, we’d all know to stand back after popping a cork. As W. Blake Gray notes on Wine-Searcher, they actually tend to happen in younger white wines sealed with screwcaps, since those are better at keeping oxygen out, and an anaerobic environment may be at least one contributing factor to wine farts. For this reason–and although it may seem counterintuitive, since they are among the cheapest–decanting screwcapped bottles is wise.
It’s interesting we don’t hear more about this, and not just because it allows us to finally, legitimately couple the sophisticated world of wine with the word “fart.” It’s interesting because it’s an issue in winemaking. Again, according to ETS Laboratories, “sulfide formation in wine has been a persistent problem.” Not only that, but “corrective options are limited and current winemaking techniques often include risks for sulfide formation”—including, we assume, the use of screwcaps.
Decanting can help fix the issue, of course. And there’s an unexpected silver lining: hydrogen sulfide may smell nasty, but according to a study by Exeter University, inhaling it might also be really, really good for you—in small, ahem, doses.