viernes, 22 de junio de 2012

La predisposición a la cata de vino viene determinada por los genes


LA PREDISPOSICIÓN A LA CATA DE VINO VIENE DETERMINADA POR LOS GENES

Una investigación publicada en el American Journal for Enology and Viticulture sugiere que la predisposición de la cata de vinos viene determinada por los genes y no por el aprendizaje, según las pesquisas realizadas por los profesores John Hayes, del Departamento de Ciencia de los Alimentos de Pensilvania y Gary Pickering, de la Universidad de Enología e Instituto de Viticultura de esa ciudad.

La investigación la realizaron sobre una muestra de 330 personas en las que figuraban críticos de vino y legos en la materia y les dieron a probar el compuesto químico 6-n-proplicuacil, con el que se testa la disposición genética a la percepción del gusto.

Solo los habituados a catar, alrededor de un 25%, percibieron el ligero amargor que ofrece esa sustancia, circunstancia que no fue percibida por el resto de los participantes en la prueba.

IS WINE EXPERTISE GENETIC?

Fuente: Ben O'Donnell. Posted: April 23, 2012 in "Wine Spectator"

A controversial new study finds that wine professionals taste wine differently than consumers, but others call the research off-target.

When it comes to tasting wine, does our ability lie in our DNA, or is it learned? A controversial new study concludes that taste sensitivity to wine comes from our genes, but other experts question the findings and their implications.

"Wine Expertise Predicts Taste Phenotype," by Profs. John Hayes and Gary Pickering, at Penn State's Dept. of Food Science and the Brock University Cool Climate Oenology and Viticulture Institute, respectively, appeared in the American Journal for Enology and Viticulture in March. The study separated 330 participants into two groups—"wine experts," defined as professionals in the wine industry, and consumers—and gave them a paper disk treated with some drops of the chemical 6-n-propylrhioueacil (PROP) and asked them to taste it.

Some people find PROP tasteless, and others mildly or extremely bitter. Hayes and Pickering wrote that PROP testing "has been widely adopted as a marker of genetic variation in taste" and that some recent studies showed “those who experience PROP as being intensely bitter not only experience heightened overall oral sensation, but also may be more acute tasters, with the ability to discriminate smaller differences between oral stimuli.”

PROP sensitivity is an expression of the TAS2R38 gene; about 25 percent of people find PROP bitter, though only 10 percent of men.

Based on participants’ reactions to PROP, the researchers labeled them as "nontasters," "medium-tasters" or "supertasters." The study authors found that when comparing wine experts with nonexperts, “there was a significant effect for PROP bitterness … with experts experiencing higher bitterness than nonexperts." Experts were "overrepresented among both the medium and supertasters."

Hayes and Pickering conclude that the differences in PROP sensitivities between wine experts and nonexperts "may suggest a possible discordance in judgments of quality and value between the two groups”—that wine experts have a naturally different sense of taste than the consumers they serve. Because of this, “wine consumers may wish to apply additional caution in adopting wine expert endorsements," the authors wrote.

Pickering further speculated on the results in an interview with Wine Spectator. "Just how much influence should wine experts have on Joe Consumer’s purchase behavior, if in fact our [professionals'] palates are significantly different not just because of our experience but because of biology? If we’re more likely to be supertasters, does that mean our wine columns and wine recommendations are more mismatched than what we might think and perhaps more apt for other wine experts rather than the consumer?”

But other sensory scientists and wine professionals cautioned that the study's conclusions may be overstated. "There's a lot of wine experts who are not PROP tasters," said Prof. Hildegarde Heymann of U.C. Davis' Department of Viticulture and Enology. PROP reflects "taste sensitivity for bitterness, not necessarily for every other taste."

François Chartier, author of Taste Buds and Molecules: The Art and Science of Food, Wine and Flavor, was blunter: The test "only means that some [experts] are potential supertasters of PROP, nothing more. Everyone has a nose and a tongue. If you work hard on aroma recognition and on taste, you will become a good taster, " he said. "Was I born with a 'supertaster' gene? I don’t buy that." (For another take on the research, see Wine Spectator editor at large Harvey Steiman's blog.)

At the heart of the debate is the question of whether PROP sensitivity predicts the ability to pick up nuance in a wine. According to Pickering, "if you experience PROP intensely it means that the sensations wine elicits—heat from the alcohol, bitterness from the tannins, sweetness, sourness—are also experienced more intensely in wine." In another study, Pickering's lab also linked PROP sensitivity to odor perception in certain compounds. For the curious, Pickering's company Picksen International also sells sets of PROP disks through its website.

Heymann and Chartier, however, believe PROP sensitivity is limited to the sensations of the tongue—taste—and mouthfeel, rather than the flavors picked up by the nose. "Taste—what happens in the mouth—for wine, is really only sweet, sour, bitter, and the mouthfeel, astringency, the hotness of alcohol. Maybe tingling with Champagne or sparkling wines,” said Heymann. “That's a very, very small portion of what wine is about. It's mostly about what happens in the nose."

"It’s impossible to 'taste' (to use the same vocabulary) when you have a cold," said Chartier.

"There's a genetic aspect to every one of our senses," said Heymann. "PROP tasting happens to be the one thing in the taste sensation that has been studied quite extensively, but my guess is that there are other taste sensations that are as different as PROP tasting is. We just haven't studied them yet. The part about this that really bothers me is that people find that they're not PROP tasters and then they think, oh I can't be a good wine taster. And that is just bullshit."

Part of Hayes’ and Pickering’s study included a questionnaire that has not yet been published asking respondents to identify favorite styles of wine. "As you might expect, it looks quite clear that PROP supertasters prefer different wine styles to PROP nontasters," said Pickering.

If at least certain elements of a wine's flavor profile are often perceived differently by wine professionals, whether because of genetics or just experience, where does that leave sommeliers and critics who may experience wine on different terms than most consumers?

"I learned some of the greatest ways to describe wine from customers," said Rajat Parr, wine director of the Michael Mina group, based in San Francisco. "Sommeliers have a very short window to satisfy a guest's needs in a restaurant situation, so when the guest describes something, we have to immediately take him somewhere. Basically, fruit, earthiness, acidity and tannins are the four basic components when I'm talking to a guest to describe a bottle of wine. For a young sommelier they think, 'What does it mean [when a guest asks for] sweet or juicy or tannic or dry?' and say, 'I'll just serve them what I want to serve them.' But these words help me understand what the guest wants. That's something I've learned over the years."

Chartier chalks the communication gap up to experience: "Wine experts don’t use the same vocabulary as the general population to express senses of aromas/taste. Just as scientists don’t have same vocabulary as the rest of us. Are they genetically different? I don’t think so."

In Parr’s experience, much of wine preference is actually age-based. "I think as you get older your palate definitely gets … your senses get a little slower or not as sharp.”

The study also solicited demographic and consumption amount data from participants, and Pickering plans to examine and publish the data correlating these factors with PROP sensitivity as well. Many people with high PROP sensitivity tend not to like alcohol at all, because of its heat and astringency. Pickering cited a hypothesis that there is "a protective effect of supertasting against alcoholism" for this reason.

The Hayes and Pickering study did examine some data relating to the "nurture" side of wine habits. Respondents were evaluated for "wine adventurousness" and "food adventurousness," by answering a survey of how often they try new foods and wines. Wine experts and the food adventurous tended to be wine-adventurous, but food adventurousness did not equal PROP sensitivity. Nor were wine experts more likely than anyone else to try new foods.

"Adventurousness is part of the nurture part in terms of personality factors. You’ve got experience, you’ve got expectations, those things drive purchase behavior with things like wine as well [as biology]," said Pickering. "It would be absolutely incorrect to suggest that we think that nature rules when it comes to what we taste and what we choose to buy."

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