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Biomedicine

A Rose by Another Name

A food critic explores the synthesis of the scents in modern fragrances.

For most of my adult life, I’ve been fragrance-­free. That’s not because I don’t like scents, perfumes, eaux de cologne, and the like. I do. But I outgrew the scents I used as a teenager–Eau Sauvage and, yes, Canoe. I stopped dousing myself. Or perhaps I moved my powers of appreciation to my palate. I’m a food writer, and I try to identify and remember everything I eat.

Because I’m a food writer, I know how much industrial food depends on odorants, as molecules created for fragrance or flavors are called. And I’m interested in how the new “hypercuisine” or “molecular gastronomy” draws upon the technologies of industrial food to create new flavors: see the profile I wrote of Grant Achatz, the chef at Alinea in Chicago (“The Alchemist,” January/February 2007). But the food and fragrance industries use odorants in very different ways.

Food manufacturers buy odorants that mimic real flavors, although they goose them until they are almost unrecognizable–take truffle oil, which tastes nothing like truffles. But fragrance manufacturers mostly don’t bother to imitate nature. Perfumes are a mixture of natural essences, which are expensive because they require so many flowers, herbs, or spices (the extraction rate of flowers in an essential oil is at best 1 percent, and often closer to 0.1 percent), and synthetic odorants. The synthetics include “effect aroma chemicals” with little smell of their own, which extend and enhance other molecules, and “character impact chemicals,” which either cheaply mimic natural ingredients or do something that hypercuisine chefs envy: smell like nothing in nature. Blended, these ingredients can make a perfume modern, fresh, sexy, and fascinating. Or blaringly, nauseatingly domineering.

I like new things. I was curious whether a new perfume, particularly one made with novel scents, could appeal to me.

Things Reviewed
  • EAU SAUVAGE Christian Dior
    Created 1966 by Edmond Roudnitska. 3.4 ounces eau de toilette, $72.
  • EAU DE GUERLAIN Guerlain
    Created 1974 by Jean-Paul Guerlain. 3.4 ounces eau de toilette, $96.
  • BIGARADE CONCENTRÉE Editions de Parfums Frédéric Malle
    Created 2002 by Jean-Claude Ellena. 3.4 ounces perfume, $210.
we smell

Finding your own fragrance can be as difficult and complicated as finding the right partner in life, and a lot harder than deciding what to eat. It’s sexual in its overtones, which helps explain why $38 billion worth of perfume is sold every year. Cruising the first floor of Saks Fifth Avenue in Boston is like cruising a certain kind of bar: you get to test anything that appeals, brutally snub whatever bores or repels you, and take home whatever you find really attractive.

In perfume aisles Luca Turin is an homme aux femmes, ready to be ravished. Turin is a biophysicist, currently at MIT, who has a celebrated, notorious passion for perfume. He didn’t invent the discipline of perfume criticism, but he redefined it, opening up a new branch of aesthetic evaluation with a dazzling field of reference and punchy pungency. The English magazine Prospect called his 2008 book Perfumes: The Guide, which he wrote with Tania Sanchez, “bigoted, snarling, monomaniacal, subjective, triumphalist, and quite magnificent.” He and Sanchez are Pauline Kaels of the fragrance world, revered and reviled.

The two (who are married) are sensual in their reviews. Turin, who met me at Saks, told me that the 1971 Chanel No. 19 was a “bitch perfume, like green sharkskin pumps.” He writes of a perfume by Le Labo that after three minutes, “Oud 27 becomes properly pornographic: a wet-hair note and a couple of macrocyclic musks of the kind found near the rear end of deer take over … . Great fun, brilliant perfumery, and, for once, really raunchy.”

Any lesson in the art and history of perfumery starts at the Chanel counter, to which Turin kept returning during our pinballing tour. That’s because Chanel No. 5 is the definitively modern, composed perfume–a pretty, very sweet floral made with jasmine and rose, which are always expensive, and a surprising amount of violet, which is to the fragrance industry what vanilla is to food: the first successfully synthesized floral. But Chanel No. 5 also has a significant proportion of novel chemicals: a blend of aliphatic aldehydes that both buffer the sweetness and enhance it, giving the perfume an artificial scent. They also give it structure. The Belgian perfumer René Laruelle calls synthetics the bones of fragrance, naturals the flesh.

Artist, scientist: Luca Turin is an MIT biophysicist, a fragrance chemist, and the coauthor of Perfumes: The Guide.

Turin spent the most time with me at the counters of Chanel, Guerlain, and Estée Lauder, the last of which he said was underappreciated. He wanted to smell a new Lauder perfume: Jasmine White Moss. It is a classic chypre, the French word for “cypress” and the name of a famous 1917 perfume that blended sweet amber resin, citrus, and woody, oak-moss notes in what became an endlessly varied triad. The current classic of the genre is Chanel’s Cristalle. Turin pronounced the new Lauder “as good as it gets.” I smelled both Cristalle and Jasmine White Moss at length–the “heart” and the “drydown,” after 15 minutes to an hour, are what really matters–and found Cristalle to be admirably formal and cold, as Turin said I would. By contrast, Jasmine White Moss was startlingly sweet at first but was then reined in by the sterner oak moss and wood.

Turin likes chypres, but he’s fascinated by the “wonderfully spare aesthetic” of what he calls nouvelle parfumerie, which is characterized by dry wood, smoke, tar, and the abundant use of aromas that don’t exist in nature. Landmarks include Bertrand Duchaufour’s 2004 Timbuktu for L’Artisan Parfumeur and Comme des Garçons’ 2 Woman, “rasping and caressing,” designed in 1999 by ­Duchaufour’s colleague Mark Buxton. At Saks, Turin gave me a whiff of another fragrance he guesses is 80 percent synthetic–the same proportion he estimates in the Lauder, but this one designed to be new and strange: Rush, by Gucci. He loves it. “This creature may be from outer space,” says The Guide, “but its blood is warm.” I found it like a neon sign as bloody red as its box–impossibly strange, and frankly emetic.

it’s chemistry

How do chemists find these chemicals that mimic natural fragrances, enhance aromas, or smell completely new? By trial and error. Fragrance chemists can build the molecules that produce a smell, and then test variants. But they have never been able to design odorants without weeks or months of labor and expensive trials. Turin says he has found a way to do just that, guided by a different theory of how molecules stimulate smell perception. It is not his reviews, however brilliant, but The Secret of Scent (2006), describing the molecular-vibration theory of olfaction, that he hopes will be his legacy.

For decades the guiding theory was that a molecule’s shape determined smell: in lock-and-key fashion, a molecule would bind to a receptor site in the nose, ultimately sending signals to the brain that result in the experience of a smell. The lock-and-key model had proved widely applicable in biochemistry, and it seemed natural to extend it to olfaction, as Linus Pauling did in 1946. But 50 years of fragrance chemistry has shown little correlation between molecular shape and odor. Musks, for example, have very similar shapes and very different odors; tiny changes to the molecule of, say, an elusive floral fragrance can wreck its smell. Turin revived a theory, originated in the 1920s, that posited a correlation between molecular vibrations and smells. The English chemist Malcolm Dyson formally proposed it in 1938, and Robert H. Wright, a Canadian chemist and physicist, advanced it in a 1977 paper. But they both lacked an explanatory mechanism.

Any mechanism would have to explain how the nose can do the work of a spectrometer, without infrared beams to excite vibration. Since humans have only 347 smell receptors, a discovery announced in 1991 by Linda Buck and Richard Axel, each receptor must somehow recognize thousands of smells. In Turin’s theory, an odorant molecule that fits into a receptor’s binding site can switch on the receptor only if the molecule has a particular vibration, a quantum of energy matching the difference between two energy levels in the receptor. Once the sluiceway is open, electrons can travel through the molecule across the receptor, which recognizes the smell in much the way that cone cells in the retina recognize color by frequencies, or hair cells in the cochlea recognize sound vibrations.

Turin published his electron-tunneling mechanism in 1996 in Chemical Senses. Some parts of the theory were, and remain, unproved. Isotopes, for example, are identical in shape but should smell different from one another because their slightly different weights should produce slightly different vibrations. Turin reported that they did. But his finding proved hard to reproduce in studies involving naïve subjects: differences in smell are subtle, and perception varies from subject to subject. The failure to confirm odor differences between isotopes, which seemed to disprove the theory, was reported in a paper in a 2004 issue of Nature Neuroscience, accompanied by a harsh editorial. But recent studies are turning the tide Turin’s way. A 2007 paper in Physical Review Letters showed that his mechanism was physically plausible; and Greek researchers are preparing to publish a paper showing that fruit flies can, in fact, smell the difference between isotopes. (In 2003, Turin’s trials in forwarding his theory were the subject of The Emperor of Scent by Chandler Burr, who now writes about perfume for the New York Times.)

While his theory was under attack, Turin consoled himself, as Noël Coward would say, with the bitter palliative of commercial success. From 2000 to 2007 he was chief scientist for Flexitral, whose main business was creating replacements for 26 fragrances that the European Union had restricted or banned as possible allergens. He was using vibrational theory to design molecules every day “and getting a tremendously high success rate,” he says. “I could calculate whether a smell would be right or not.”

All very practical, and potentially very profitable–but not madly artistic. “One would like to invent new smells, but business is business,” Turin says. Yet at the company he did achieve what he calls a long-held dream: a “drop-dead lily of the valley.” Muguet, the lovely French word for the flower, is the mountain any fragrance chemist hopes to scale. There has been no truly accurate rendition of its all-white scent, which combines soapy rose and cut grass. Edmond ­Roudnitska’s Diorissimo, created in 1956, came the closest; it established Roudnitska, Turin writes, as the “Mozart of postwar French perfumery.” Two of the chemicals Roudnitska discovered to be key components were later identified as potential allergens, and their use has been restricted. On a mountain on a skiing holiday, Turin got the idea for a molecule he guessed would smell right. That night he faxed a sketch of it to chemists at his lab and asked if they could make it. Two days later, they reported that the whole laboratory smelled of lily of the valley. It was “an epiphany,” Turin says. “Like a Roman emperor, I can die now.”

Instead, he left the business for what he calls a “science break”: at MIT he is working on an artificial nose.

a matter of taste

Could I outgrow Eau Sauvage and embrace the new? In a long smelling session at the New York offices of Robertet, an international fragrance firm, I discovered one reason I used Eau Sauvage in the first place: it contains a novel synthetic, and one I like. To historians of fragrance, Eau Sauvage is famous because it was the first perfume to use hedione, an “effect aroma” that, Turin says, “lubricates” a fragrance, as if one were licking one’s lips. Discovered in 1961 and put to use by Roudnitska five years later, hedione gives Eau Sauvage what Turin describes as a “strange, glittering freshness.” The fragrance could cut through a 1960s smoke-filled room (cigarette smoke has become the great missing ingredient in older perfumes) with its mixture of citrus, pine, and rosemary.

Jérôme Epinette, the proper, precise fragrance chemist at Robertet, let me smell hedione in his shiny, glass-walled, glass-bottle-lined lab on Fifth Avenue. Robertet designs fragrances for many U.S. designers and brands, and it is Epinette who translates vague ideas into samples sent off for evaluation and, if approved, production. I loved hedione, not because it reminded me of Eau Sauvage but because it smells a little like concentrated peony petals after a spring rain. Indeed, Epinette told me that he describes it to clients as “petal-ly” and “transparent.”

“Transparent,” “fresh”: these are the qualities that became popular after the complex, big fragrances of the 1980s, and they can be found in many fruity, food-y fragrances, as Paul Austin, an Australian-born fragrance consultant who was a longtime top executive for Quest International, the large fragrance firm since bought out by rival Givaudan, told me. Unchallenging, foodlike fragrances now appeal to more sophisticated European noses, too, he said, though Europeans once preferred the “intellectual” chypre genre.

And yet … Eau Sauvage, dépassé as it may be, is still admired for its structure, and ­Austin says it had more character than many of the mainstream scents “we in the industry produce today.” In his guide Turin writes, “I always forget how good this darned thing is. Part of the reason I don’t wear it is that it reminds me of my youth.” He embraces the new!

Then, in our madcap Saks round, Turin randomly sprayed on a Guerlain eau de toilette that, he said, was the only thing he wore for years. I loved it. Eau de Guerlain is pure, unsweet citrus, with a lingering light verbena scent on the drydown. “If you want citrus, there is simply nothing better out there,” his review says. Bergamot and citrus, also the dominant notes in Eau Sauvage, are apparently what I want. It makes sense. Verbena was the scent of my childhood: my mother ordered boxes of specially milled lemon verbena soap for every bathroom.

Eau de Guerlain it is, then. Well … there was one new perfume that I kept returning to with an almost physical craving, even after smelling dozens: Bigarade Concentrée, sold by Malle and created by Jean-Claude Ellena, now the house fragrance designer for Hermès, where he designed Eau de Pamplemousse Rose, another citrus I liked. Bigarade Concentrée smells powerfully of bitter Seville oranges, with nothing sweet or false about it; Turin likes the “interesting mixture of citrus friendliness and resinous austerity.” But I wouldn’t pay the $210 for the 3.4-ounce bottle (the same size bottle of Eau de Guerlain costs less than $100).

Maybe my simple taste marks me as a cook. “All chefs like citrus,” Lev Glazman, who creates bespoke scents as head of fragrances for the Boston-based firm Fresh, told me. “It doesn’t interfere with what they’re cooking.” So sue me. My search for the new resumes–with flavors.

Corby Kummer is a senior editor at the Atlantic, where he writes about food.

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