Monday, June 10, 2013

Individual tastes differ: About 10% of drinkers prefer corked wines

Quality control at Amorim's cork factory in Portugal
The cork industry is always sending me interesting data on how bad screwcaps are for wine. Recently I got an even more interesting study: that some consumers prefer corked wines.

Granted, this study, published in Food Quality and Preference journal,
was commissioned by the cork industry. But I don't doubt it.***(see update below) Peoples' tastes differ, dramatically so. Do you like your neighbors' music? If so, you're lucky, or you live next to radio host Dennis The Menace.

Update: This study was paid for by Hanzell Vineyards, not the cork industry. More details at bottom of post.

What the study was trying to establish is the threshold of TCA, the chemical that causes "cork taint,"* that would cause consumers to notice and reject the wine. A 1995 study estimated that tainted corks cost the wine industry $10 billion, so a data point like that is worth having.

* That's "cork deliciousness" for you 10-percenters

In an irony that New Zealand winemakers will smile at, the scientists used New Zealand Chardonnay bottled under screwcap and they added TCA dissolved in ethanol at different concentrations.

In one experiment, the scientists* were surprised to learn that no matter how much TCA they added, more than 10% of consumers would not reject the wine. They posited that perhaps the consumers' noses had become accustomed to TCA. So they designed a second experiment to check the finding.

* John Prescott from James Cook University in Cairns, Australia; Leslie Norris from Flavor Sense in San Rafael, California; and Madeleine Kunst and Sandra Kim from University of Otago, New Zealand

In the second experiment, 30 consumers were given pairs of wine, one with and one without TCA. They were given just four wines a day, for two days, and rinsed their mouths before and after each sample pair.

The study concluded that 3.7 parts per trillion of TCA is the critical tipping point where more consumers will reject it than not. That's interesting if you're a chemist, but it means nothing to me.

People preferring no TCA in wine never reaches 100%
Here's the interesting point: one sample wine had 32 ppt of TCA added -- nearly 9 times the threshold amount, enough to send most sommeliers gagging out the back door of a restaurant.

And 10% of consumers not only didn't reject that wine -- they preferred it.

If you think about it, 10% of consumers is a huge market. Maybe some savvy wine company can come up with a new niche product: Corkin' Cabernet, now with extra TCA!

About the funding for this TCA study: Two of the scientists reached out to me to say the cork industry did not fund it. 

Here's what Leslie Norris, president of Flavor Sense, told me by email:

The  Consumer Rejection threshold study was NOT sponsored by the cork industry, but arose from a "real world problem" at Hanzell Vineyards.  The Wine Spectator wrote an article "exposing" that Hanzell had a TCA problem in their wines.  Hanzell paid ETS to measure the amounts of TCA actually in their wines.  Hanzell then hired FlavorSense to intepret the analytical data.  With Hanzell, we defined the objective of the study as: "at what level of TCA can Hanzell no longer sell the wine?"  FlavorSense and John Prescott came up with a protocol to determine the consumer rejection threshold (CRT), and we dosed the wines at a range of concentrations.  Based on the results of the CRT and the fact that Hanzell's ppm of TCA were under the CRT,  we recommended that Hanzell could offer the wines for sale to the public. They did and sold out their entire stock for that year!  Still one of my prouder moments!  Good question, good science!

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mountainstirrer said...

Having just thrown out a bottle of French wine with very noticeable cork taint I say long live the screwcap!

Unknown said...

Could it be that 10% of these tasters just happened to have little or no sense of smell?

W. Blake Gray said...

Kent: I think 10% is too high for that. Even as an estimate for non-tasters (the opposite of super-tasters), it's too high.

rapopoda said...

I don't think "super tasting" has any impact here. The perception of TCA is based on aroma and, as a result, its interpretation into a flavor. As far as I understand, super tasting has to do with the ability to *taste* certain compounds. This heightened perception, from what I can tell, has little to do with perception of aromas/flavors.
I would imagine its quite possible for a "super taster" to have anosmia for the aroma of TCA

Patrick Frank said...

Great post, outside the normal realms of thought. This is why I keep coming back to this blog.

Man About Wine said...

Would like to see a bigger study. Results here suggest a diff. between random group of people vs. random group of known wine drinkers.

John Prescott, PhD said...

Thanks for your interest in our study.
I think the key to understanding this lies in the data we collected - reported in the paper - that rejection of added TCA was, to some extent, related to what you knew about cork taint. This suggests that if you didn't know too much about it, you perhaps felt that it was part of the wine flavour. To me, this seems odd especially in a white wine, but the group was selected only on the basis that they were regular wine drinkers, not that they knew anything about wine.

Unknown said...

Everyone needs to drink more and drink more widely (geographical sampling) and this may help identify both flaws and perfection.

Anatoli said...

I agree with Hugh - people need to drink more wine, so they will actually trust their senses more and not think that they are doing something wrong. I remember my first encounters with the corked wines long time ago, where I was thinking "this is strange, but I guess this is how this wine is supposed to smell and taste"...
But to say that 10% of people prefer corked wines - I can only wish for those scientists to drink only corked wines from now on...

Bob Henry said...


According to the Anosmia Foundation, some 2 to 3 million Americans [circa 10+ years ago] were thought to suffer from this affliction.


If a consumer is unfamiliar with the smell of cork taint, then s/he would have no "internalized" reference standard to identify that defect.

Similarly, if a consumer has no vocabulary for describing cork taint, then s/he would have no words to articulate the experience.

The smell would be perceived as intrinsic to the varietal grape or the style of the wine.

First aside: In certain professional wine circles, it is believed that Mourvèdre has an intrinsic smell akin to brettanomyces -- separate from any consideration if a particular Mourvèdre-based wine is actually contaminated by that spoilage yeast.


Consider some of the words used by the wine press to describe TCA: moldy, meldewy, wet concrete, wet cardboard.

These are smells and words outside of the normal vocabulary of most wine consumers.

Second aside: Consider the words used to describe brett in a wine: band-aids, barnyard, horse stable, antiseptic, bacon, spice, cloves, smoky, sweaty saddle, cheese, rancidity.


How many of these words are found in the lexicon of most wine consumers?

~~ Bob

Bob Henry said...

Postscript on Mourvèdre: Forgive me for what some might consider to be a gratuitous “genuflection” to our blog moderator/host . . .

Excerpts from the Los Angeles Times “Food” Section
(February 10, 2011, Page Unknown):

“Mourvèdre Grape a Paso Robles Specialty”


By W. Blake Gray
Special to the Los Angeles Times

It's hard to pronounce, and it can make wines that smell GAMY. But Mourvèdre just might be the best grape grown in Paso Robles, one of California's hottest wine regions. [Capitalization used for emphasis. ~~ Bob]

. . .

But Mourvèdre is not a grape for novice winemakers. It's prone to oxidation and contamination with brettanomyces, a type of yeast that makes wines FUNKY. "Brett" lives on grape skins and in used wooden barrels and can develop in any untreated wine, giving it aromas described as "BARNYARD" or "BAND-AID." Most winemakers call brett a flaw, but its connection with Mourvèdre is so long-established in France that such a classification remains controversial. [Capitalization used for emphasis. ~~ Bob]

"Mourvèdre has a really bad reputation in the States because so many Mediterranean wines have brett that people think they're synonymous," [Saxum owner-winemaker Justin] Smith says. "I don't know why it's so prone to brett, but whenever I leave a barrel of pure Mourvèdre, those are the only barrels that ever get brett. For so long, people thought that is the nature of Mourvèdre, it just has that ANIMAL STINKINESS. I've never tasted a clean Mourvèdre that has that." [Capitalization used for emphasis. ~~ Bob]

. . .

Smith says a brett-free Mourvèdre is best described as red-fruited, like pomegranate. "It's on the earthier side," he says. "It's not a fruit you can easily identify."

When told that wines containing Mourvèdre often seem to have a "low note" – GAMY and SAVORY -- instead of the "high notes" of bright fruit brought by Grenache, Smith nods. "Definitely bass. Mourvèdre brings the bass." [Capitalization used for emphasis. ~~ Bob]

. . .