TCA Has No Smell..

Rather interesting article in which I find out that TCA has no smell:
https://www.acsh.org/news/2019/03/29/does-your-wine-smell-wet-dog-polluted-corks-microbiology-are-blame-13912

A rather interesting, if surprising, article.

I have a sample of a few crystals of TCA, compliments of a friend at ScottLabs, that is soaking in vodka. The small jar
is enclosed in two ZipLok, placed in a jar that has a tight clamp on the top, w/ a piece of SaranWrap sealing the
opening. Yet I can pick up the jar, thru all the seals, and smell the musty/wet newspapers when I hold it close
to my nose. Wonder what actual thing I'm smelling that the TCA is subducting?

Anyway, a nice read for the chemists on the Board.
Tom

Yes, I remember reading a paper a few years ago describing an experiment with newts (apparently commonly used to study smell as they have a convenient anatomy). There, TCA was found to supress other aromas, but had no smell itself. The newt study did seem very interesting to me, but of course just because newt olfaction works like that does not means that it is the same for humans.

I am not sure if that is the research being relied on in the article that you linked to, but it does seem that the article is rather definite about the way TCA fabricates a musty smell that does not exist (whatever that means). I was wondering at the time if what happened was that TCA removes many aromas, but leaves behind the nasty musty smells that were previously masked - though I must say it seems unlikely to me as the smell of a corked wine can be so dominant.

If anyone else can shed light on this I would be very interested.

Edit: Ah, just noticed the article "2,4,6-Trichloroanisole is a potent suppressor of olfactory signal transduction" linked to by the article. I missed it on first glance. I see it was another paper based on newts, and about the suppression of aromas - with only some brief speculation about how the musty aroma might be generated.

Interesting! But does this matter much to average wine lover? I once met a scholar who claimed that the Iliad was not written by Homer but by another man of the same name. So what?

[Robin Garr]

Interesting! But does this matter much to average wine lover? I once met a scholar who claimed that the Iliad was not written by Homer but by another man of the same name. So what?

Maybe it's akin to the ability to detect the scent of asparagus in one's urine, which is said to be based on a genetic component in one's makeup? Or an innate love/hate for leafy cilantro? Or I may simply be on the wrong base on this pre-caffeination Saturday morning?

Wonder what actual thing I'm smelling that the TCA is subducting?

I wouldn't be surprised if it turned out that it's our own saliva and/or mucus.

I suppose it all depends on how you define "smell". The physiological mechanism of the sense of smell is that chemical compounds (or parts thereof) trigger various receptors on cell membranes of olfactory cells, leading eventually to nerve pulses that are interpreted by the brain as odors. Very commonly the trigger results in cyclic nucleotide cascades (a popular signalling mechanism in cells), but the opposite--suppressing some of the cascades--could also result in the nerve impulses. Whatever the mechanism, TCA is detectable by most people in parts-per-billion concentrations.

One should also be cautious about applying results of a newt model to humans. [There's a joke in here somewhere about TCA in wine and being "pissed as a newt", as the Brits say.]

There's genetic variation in play as well. Just as there are "tasters" and "non-tasters" for PTC, and some people who can't smell asparagus metabolites in urine, there are some people who can't smell TCA. Lucky them.

-Paul W.