What the Nose Knows - Avery Gilbert [5]
THE APPEAL OF aroma wheels is that they organize product-specific smells into a few, easily recognized categories. As a result, food lobbies around the world have come up with their own versions. There is a chocolate aroma wheel from Switzerland and a Flavour Wheel for Maple Products, courtesy of Canada. There is a pan-European wheel for Unifloral Honey, and another for cheese (although with seventy-five different aromas it doesn’t really simplify things for cheese fans). There is a South African brandy wheel, and the Berkeley-based perfumer Mandy Aftel has created a Natural Perfume Wheel. Recently, some guys in the Philadelphia Water Department came up with a wheel for identifying the odors found in sewage. (Anyone who’s lingered on the banks of the Schuylkill River knows that wastewater offers a particularly rich olfactory experience.) The world has gone wheel crazy, and we can expect to see more of them in the future.
The Perfumer’s Problem
Odor space is an imaginary mathematical realm containing all possible odors. The aromas of wine and beer occupy only a small fraction of odor space—not nearly the full range of smells detectable by the human nose. Can smell classification work on a larger scale? Perfumes and colognes take up a bigger chunk of odor space: There are at least 1,000 currently on the market, with new ones added at a rate of about two hundred per year. Each has anywhere from 50 to 250 ingredients. If anyone has a lot of smells to keep track of, it is the perfumers who create them.
At its core, the practice of perfumery hasn’t changed much since it came to full flower in Renaissance Italy. In those days there were no more than 200 commonly available ingredients, all derived from natural sources, either botanical (essential oils, gums, spices, and barks) or animal (musk and civet). By the late nineteenth century, discoveries in organic and synthetic chemistry created a host of new materials. Some were novel, man-made molecules; others were pure chemicals isolated from the complex mixtures found in nature. The result is that the modern perfumer’s palette is far larger than his predecessor’s. Learning these materials is a correspondingly bigger task. How does a perfumer keep it all straight?
The professional perfumers Robert Calkin and Stephan Jellinek explain: “The novice perfumer may well feel daunted by the hundreds of bottles containing strange and often unpleasant smelling materials that line the laboratory shelves. But for the talented student the task of learning to identify them is in fact less difficult than it may seem at first.” The trick, according to these experts, lies in honing specific cognitive skills, namely learning new mental categories and how to fit new smells into them. To become a perfumer you don’t learn to smell like one—you learn to think like one.
The first step in training is to learn the smell of the available ingredients. The leading teaching technique—the Givaudan method, created by the French perfumer Jean Carles—introduces students to the major ingredients using a matrix approach. Imagine a grid of rows and columns. Each row is a fragrance family: citrus, woody, spicy, and so on. Each column is a training session. In the first session, students smell column-wise one material from each family: lemon oil, sandalwood oil, and clove bud oil, for example. In the second session, the students smell new examples: bergamot oil, cedarwood oil, and cinnamon bark oil. This process continues for about nine lessons, by which time the students are familiar with the olfactory differences between families. Now comes the hard part—learning the “contrasts” within a family. Each subsequent session traverses one row of the matrix. In the citrus lesson, for example, students smell lemon, bergamot, tangerine, mandarin orange, blood orange, grapefruit, and lime. The goal, according to master perfumer and teacher René Morgenthaler, is for the student to create