So, the buzz in the wine writing world the past few days has been the "surprising new research" that suggested 2, 4, 6-trichloroanisole (TCA) doesn't actually smell like anything, let alone musty. The authors of the acclaimed study suggested that their data show TCA actually suppresses odors. Is that really new news? If you actually read the article (I conducted the arduous Google search for you...), you might come to a different conclusion than some of the people writing about the article.
I can't be the only person that knows low levels of TCA will kill a wine’s aroma and flavor. In fact, I know I'm not as Ray Isle wrote the last eleven words of the previous sentence over four years ago in Food & Wine. Yet, over the last couple days, Steve Heimoff, Wine Spectator and Decanter all wrote about the research seemingly without actually reading the paper.
If you read the article with a critical eye (I know, that's a pain to do sometimes...) you will see two things that should make you question all the lazy pundits. First, the study was conducted on newts (Cynops pyrrhogaster), not humans (Homo sapiens). They clearly stated, "functional olfactory receptor genes is different between amphibians and mammals, so we cannot rule out the expression of receptors with very high TCA sensitivity in humans." Hmmm. That changes the conclusion a bit. Human olfactory receptors could interact with TCA differently than those of newts! Additionally, the authors stated that, "we cannot assume that we surveyed all possible olfactory receptors in the newt." Might there be other olfactory receptors that transduct musty odors? Humans have around 400 functional genes coding for olfactory receptors. The picture just got a bit more complicated...
[note: the following paragraph was re-added after my original post was published to better reflect the full content of the PNAS study]
The authors did in fact conduct an experiment on on human perception of TCA (and TBA) in wine. They investigated the concentration levels at which "the reduction of original odor and the extrinsic musty smell from TCA were discriminated." So, in fact, the authors were able to show that humans do sense musty odors in wine caused by TCA and TBA. The levels varied person to person and the musty odor was recognizable in red wine at a lower concentration than white wine. So why the media blitz about an article that basically supports what we all knew about TCA? I know PNAS isn't hoping to increase its advertising levels! [end revision]
I don't have any answers to the question of why olfactory receptor cells removed from a decapitated newt did not trigger a musty odor, but I think the idea that this research is somehow earth-shattering is a bit hyperbolic. It is interesting to know how TCA (and don't forget the often neglected 2,4,6-tribromoanisole, or TBA) interacts with neurons, but to borrow something I saw in a tweet from my chemical engineering buddy Tom Mansell: