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Japanese scientists claim cork taint in wine 'suppresses' sense of smell

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http://www.decanter.com/news/wine-new...

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  1. That certainly fits my experience. I can't smell TCA in low concentrations that all my other wine-geek friends can. I only know a wine is corked because it smells muted compared with a good bottle.

    1. It kills wine. How it does so is totally irrelevant IMO. The wine is still dead.

      1 Reply
      1. re: jock

        Maybe it's of no interest to you but I find it fascinating that the perceived corked smell may be a sensory illusion, like an afterimage.

      2. Here's the actual study:

        http://www.pnas.org/content/early/201...

        "We investigated the sensitivity of single olfactory receptor cells to 2,4,6-trichloroanisole (TCA), a compound known for causing cork taint in wines. Such off-flavors have been thought to originate from unpleasant odor qualities evoked by contaminants. However, we here show that TCA attenuates olfactory transduction by suppressing cyclic nucleotide-gated channels, without evoking odorant responses. Surprisingly, suppression was observed even at extremely low (i.e., attomolar) TCA concentrations."

        Attomolar is parts per quadrillion? quintillion?

        1 Reply
        1. re: Robert Lauriston

          10 to the -18. (can't do superscripts right now) = parts per quintillion

        2. Hi, Jason:

          Yet another reason not to overtrain one's olfactory recognition of TCA.

          I fully expect someone here will claim that one part per quintillion is a "flaw" in wine that makes it undrinkable. Where are you Diogenes?

          Aloha,
          Kaleo

          1. Curious.

            The findings *suggest* the smell of cork taint -- that musty, moldy, old hymnal smell -- is the smell that's revealed when other smells are suppressed.

            Would love to see the experiment/findings corroborated in another study.

            10 Replies
            1. re: maria lorraine

              Seems like there's no actual mustiness to be revealed.

              "… the smallest effective concentration of odorants known to induce responses in individual ORCs is approximately 1 μM. On the contrary, the levels of TCA that would evoke musty odors (<5 pM concentration, or 10−4 fold lower) are extremely low for receptor-mediated biological mechanisms … We did not observe any detectable ORC excitatory responses in the experiments in which very low concentrations of TCA were applied to ORCs.

              "… we propose that the reduction of CNG channel activity may induce some kind of pseudoolfactory sensation by inducing an off-response, or the suppression of ORC output may itself induce an olfactory sensation."

              1. re: Robert Lauriston

                Do you understand this?

                1. re: maria lorraine

                  In their observation the olfactory receptors are not being excited. I.e. TCA doesn't trigger the receptors for mustiness; apparently its suppression of the CNG channels somehow triggers that perception somewhere down the line.

                  It's something like an optical afterimage.

                2. re: Robert Lauriston

                  Hi, RL: "...pseudoolfactory sensation..."

                  We shoudn't be surprised, but perhaps we should be a little more humble...

                  What's the next realization? That there really is no such thing as dependable taste memory? I've made wine for years with a academic who claims to be able to perfectly remember every wine we've made. If he doesn't shut the F up soon, I swear I'm gonna burn him badly.

                  Taste the wine. Draw some general conclusions if you want--for yourself. If you like it, smile, drink more, maybe buy more. If you don't, push it away, but don't presume to know a lot more than that. Much more than that, and other things tend to get in the way. JMO.

                  Aloha,
                  Kaleo

                3. re: maria lorraine

                  Hi, ML:

                  "The findings *suggest* the smell of cork taint -- that musty, moldy, old hymnal smell -- is the smell that's revealed when other smells are suppressed."

                  I agree that's what the Decanter article (and the study author's quote) suggests. And that's an interesting theory. But there's no such suggestion in the study's abstract.

                  I find the more fascinating finding to be that truly infinitessimal levels of TCA far below even *your* trained threshold of perception can reduce flavor to an extent which IS perceptible, viz. "without evoking odorant responses."

                  Kinda freshens the perspective on the flavor "hallucinations" theory which was recently pooh-poohed here, too.

                  Aloha,
                  Kaleo

                  1. re: kaleokahu

                    It is unfortunate, as you point out, that Decanter did not report the study findings correctly.

                    Hasn't been peer-reviewed, so we'll see if what's suggested holds up.

                    1. re: maria lorraine

                      Hi, ML: "Hasn't been peer-reviewed..."

                      I'm unclear. This is a study published in the Proceedings of the National Academy of Sciences under the heading:

                      [A]ccepted by the Editorial Board August 15, 2013 (received for review January 13, 2013)."

                      Is this not peer review?

                      Aloha,
                      Kaleo

                      1. re: kaleokahu

                        You're right. I didn't catch that till I read the full text. Only saw that it was self-submitted.

                  2. re: maria lorraine

                    Yes . . . just as the absence of all color is black, apparently the absence of all odor is "musty."

                    1. re: zin1953

                      My understanding of the text is that the degree of odor suppression was the same as the human detection of cork taint. TCA exudes its characteristic odor, but also masks other odors. But again, the study needs to be peer-reviewed and corroborated. Pretty interesting. Would love to see studies on other olfactory mechanisms/cells.

                  3. Could I ask a simple question? If TCA is really perceived as muted flavors/aromas (if I got that right) ..... how is it distinguished from merely 'less flavorful' wine? I've been aware of mustiness and that 'wet cardboard' smell but an not usually totally sure it'sbTCA. I'm co-mingling flavor and aroma here because they are so inextricably tied together. To my sensitivity the aroma often dissipates, leaving just muted flavors.

                    14 Replies
                    1. re: Midlife

                      Well, clearly, nothing is simple after this Japanese study, BUT . . . can I ignore it for a moment to answer the question? ;^)

                      Cork taint / TCA / whatever *has* a distinct moldy / wet dog / mildew / dank cellar sort of smell . . . EXCEPT in extremely low concentrations¹. When present in these very low / threshold levels, the "smell of TCA itself"² will be absent, but its effect upon the wine is to mute the fruit in the aroma and/or flavor (but, for *me*, it's almost always the aroma that is affected most).

                      When that happens, I find the only way to know if the wine is flawed (i.e.: affected by TCA) is to open a second bottle. Generally, the difference between the two will be dramatic.

                      I have never (that I recall) confused a low-level TCA contamination with a "less flavorful" (or "less aromatic") wine. Rather, think of a wine that is closed / backward / in a "dumb stage." That is more like it -- the wine is somewhat disjointed, and nothing is "as it should be."

                      In contract, a "less flavorful wine" -- to me -- is still sound, still drinkable, still enjoyable, but is simply "light" or "less intense" in aromatics and flavor . . . think Txakolina versus Viognier; Valdigué versus Pinot Noir.

                      Anyway, that's how *I* think of it . . .

                      / / / / /

                      ¹ Obviously with TCA/TCB, we are always speaking of extremely low levels, but where each individual's sensitivity "cuts out" varies, so one person's "obviously corked" may be another taster's "muted aromatics."

                      ² Again, the Japanese study raises the question of what the smell of TCA / TCB actually is, but -- like I said in the beginning -- let's set that aside for a moment.

                      1. re: zin1953

                        Hi, Jason:

                        "I have never (that I recall) confused a low-level TCA contamination with a "less flavorful" (or "less aromatic") wine."

                        Well, isn't a main thrust of the study that people *are* confused in precisely this way? I doubt that 1 part per quintillion TCA in a given wine is going to render it "nothing is as it should be" to you or anyone else. Rather, that wine will be universally judged sound, and the taster will merely be left to wonder if her less-than-perfect judgment was caused by below-threshold TCA. A lower score may be the only result.

                        Another unstated result of the study is that the olfactory suppression/hallucination must persist for a finite time. Obviously, measuring that duration should have huge implications for wine tasting and judging.

                        Aloha,
                        Kaleo

                        1. re: kaleokahu

                          The part of the study involving chemical analysis of the olfactory epithelia of newts found that the suppression was measurable even at 1 aM (one part per quintillion?).

                          The part involving humans is confusing.

                      2. re: Midlife

                        " If TCA is really perceived as muted flavors/aromas (if I got that right) ..... how is it distinguished from merely 'less flavorful' wine?"

                        I need much higher concentrations of TCA than most other wine geeks I know before I perceive the musty / wet cardboard smell. At lower concentrations, I know a wine is corked only because it's muted compared with other bottles, which of course means that I have to have had the wine before to make such a judgment.

                        Often I've suspected that an unfamiliar wine was corked and asked the sommelier or whoever to confirm. Sometimes it is, sometimes it's just an understated or peculiar wine. In the latter case, the wine will sometimes open up in the glass.

                        1. re: Robert Lauriston

                          Hi, RL: "At lower concentrations, I know a wine is corked only because it's muted compared with other bottles [tasted at an earlier time]."

                          I think we're safe in assuming that for each of us there is a *range* of "muting", e.g. from DOA down to the threshold of perception, just as there's a range and a threshold for actually perceiving the "smell" of corked wine. As the study intriguingly and strongly suggests, the former may be an (or just an) extension of the latter.

                          But let's be clear: below one's threshold of actually "smelling" the TCA, all we have is an *association*.

                          Color me cynical that anyone (except perhaps a cellarmaster who regularly tastes all the wines) can be a good judge of small-to-moderate differences in muting of the same wine on different days. I think Jason is right that opening additional bottles then and there would be a logical starting point.

                          This study opens some other theoretical doors, too. It causes me to ponder again why some denigrate what the Wine Key-type gizmos do as "scalping", when others (including me) have found them useful in ways.

                          Aloha,
                          Kaleo

                          1. re: kaleokahu

                            TCA muting is quite different from any variation I've experienced in the same wine wine between one good bottle and another good bottle.

                            If a bottle seems muted, the standard test is to open another to compare. Usually that confirms that the first bottle was corked.

                            1. re: Robert Lauriston

                              What I've tasted is that wines can be muted in different ways: TCA has a particular muting profile, Brett has another, aging devices another. All seem quite different from a thin wine.

                              1. re: Robert Lauriston

                                Hi, RL: "TCA muting is quite different from any variation I've experienced in the same wine wine between one good bottle and another good bottle."

                                Well, that's the question, isn't it? I think this study suggests (among other things) that what has been treated as a difference in *kind* is a difference in *degree*.

                                Question for Maria: Is current wine laboratory equipment and technology able to identify TCA in parts-per-quintillion concentrations? If so, it would be interesting to test sample all of a large restaurant's pourings for a month. I wonder what % would be totally TCA-free.

                                Aloha,
                                Kaleo

                                1. re: kaleokahu

                                  TCA, and the family of haloanisoles (TCA, TBA, TeCA and so forth) are measured by ETS Labs in ng/l or ppt (parts per trillion).

                                  When dealing with individual human olfactory cells in testing, the solution of TCA/haloanisoles is even more dilute, parts per quintillion.

                                  TCA itself has a very distinctive odor, but it also suppresses the perception of smells and aromas in wine. Those smells/aromas are still in the wine, but TCA blocks our perception of them. (This has been known awhile, even before this recent study.) The recent paper says the degree to which we smell TCA is the same degree to which the wine's smells and aromas are not perceived.

                                  What I'm guessing is that TCA blocks odor perception by reducing the olfactory receptor cell's ability to synthesize a particular protein molecule, or group of them. The new study may go into that, but I haven't read it closely yet.

                                  An individual's inability to smell a particular smell (anosmia) may have a similar basis: a particular protein molecule needed for perception cannot by synthesized.

                                  *Over-exposure* to TCA/TBA/etc. can also cause a person to lose the ability to perceive it. This is akin to someone who can no longer smell the perfume or cologne they wear often (and often wear too much of it because of that). Few wine-tasting memories are more distinct than the times I've walked into a barrel room that reeked of TCA/TBA and was then served a glass of obviously corked wine by the winemaker, who could not perceive it was corked.

                                  1. re: maria lorraine

                                    Hi ML: *Over-exposure* to TCA/TBA/etc. can also cause a person to lose the ability to perceive it. This is akin to someone who can no longer smell the perfume or cologne they wear often (and often wear too much of it because of that)...."

                                    The groundwater of Hanford in the central SJV is "entrained" with hydrogen sulfide gas that occurs naturally. I recall vividly some 40 years or so ago when my nose got to within a couple of feet of the city park's stream of water from a drinking fountain repelling me immediately.

                                    I have to wonder if that may be what you're describing since I've spoken with a number of locals that all say that they don't even notice it.

                                    1. re: PolarBear

                                      Similar experience long ago when I visited a "vacation" home on a lake in Kentucky with a pervasive sulfur smell. I couldn't stand it, and was astounded that its owners and friends couldn't smell it.

                                      Also, my mother, dear beautiful woman, so stylish in so many ways, wore too much of her favorite perfume. She was utterly unaware.

                                      1. re: PolarBear

                                        Hi, PB: "*Over-exposure* to TCA/TBA/etc. can also cause a person to lose the ability to perceive it."

                                        I dispute this statement. Unless one is *continually* exposed to it, it has the opposite effect, IMO. In fact, I consider over-*sensitivity* to TCA to be a problem.

                                        Aloha,
                                        Kaleo

                                    2. re: kaleokahu

                                      The study used dilution techniques to test concentrations far smaller than current lab tests can detect.

                                      "I think this study suggests (among other things) that what has been treated as a difference in *kind* is a difference in *degree*."

                                      I don't know what you mean by that.

                                      1. re: Robert Lauriston

                                        <The study used dilution techniques to test concentrations far smaller than current lab tests can detect.>

                                        Yes. However, keep in mind, that the actual concentration in the wine in order to produce suppression is higher. These aM concentration mentioned is the actual concentration reaching the cell. The aM is also the concentration barely able to detect the onset. I don't think it is efficacy level.

                            2. Nice. Thanks for the article.

                              1. So..... My feeling that a lot of what is taken as gospel in the aficionado-land of wine might just be partly "hallucination" for some people ....... begins to surface again.

                                1 Reply
                                1. re: Midlife

                                  Ha ha ha. A lot of people are very opininated, and do not have a good understand of the fundamental of mechanism. Of course, this article also appear to be very narrowly focus. Only read about 2 pages, and I have to get back to reading other stuffs. So far, it seems to be a carefully conducted experiment.