Recently, I tried a bag of Lay’s “New York Reuben” potato chips, one of the four finalists in the company’s “Do Us a Flavor!” contest to find its newest variety of chip. The experience was nearly hallucinatory: From within a substantial haze of salt emerged the pucker of sauerkraut, the familiar fragrant sourness of rye bread, the unctuousness of Russian dressing and Swiss cheese, and the rubbery meatiness of corned beef. It was gorgeous.

But there was also something disconcerting about this vivid mirage of an entire sandwich delivered in a mouthful of crunch. As much as I enjoyed the taste, I also felt like I was eating in the uncanny valley.

Mark Schatzker, in his recent book The Dorito Effect, defines junk food as “food that tastes like something it's not.” By that definition, munching a bag of “New York Reuben”-flavored Lay's probably represents, to some people, a kind of cheapening of human experience. But if you look at the forces that allowed the Reuben potato chip to come into being, this flavor-infused piece of starch is a marvel, representing not only the work of expert flavorists, but also the culmination of a set of technological, economic, and cultural changes that began decades ago.

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In the early 20th century, many middle-class households took their culinary cues from progressive health reformers who considered highly spiced, intensely flavored foods—the garlicky, pickled, and spicy dishes associated with immigrant cuisines—to be dangerously stimulating. The chemist Ellen Richards, one of the founders of home economics, compared the frequent consumption of strongly flavored food to a “too-frequent and violent application of the whip to a willing steed.” It was an indulgence, she believed, that was liable to “wear out the glands and the membranes” and cause lasting damage, contributing to both physiological and moral disarray.

At that time, the canned vegetables and meats, packaged crackers and cakes, and factory-baked breads were beginning to make up a significant portion of the American diet—and, in general, were pretty bland. The volatile chemicals that contribute to a food's distinctive flavor often break down the high temperatures used in industrial food production; oxidation and other chemical reactions can also introduce undesirable, though harmless, off-flavors. Other qualities that contribute to our perception of flavor, such as color and texture, are also dulled by processing. The food companies of the early 1900s didn’t have today’s tricks for restoring and enhancing flavor—as the historian Gabriella Petrick has described, they prioritized safety and cost over tastiness, aiming for flavor that was “good enough.”

By the end of the Second World War, however, “good enough” no longer cut it, as the landscape of processed foods became an increasingly competitive one. In a 1947 article in the trade journal Food Industries, A.D. Hyde, the vice president of research at General Mills, described the supermarket aisles as a sort of battleground where soups were fighting not only other soups for commercial supremacy, but all the other things that people might choose to eat instead of soup: salad, fruit cocktail, anything. For a food product to triumph in this environment, it had to catch a customer's “flavor fancy.”

But it wasn’t enough for flavor to be merely appealing. It also had to be distinctive, he wrote, adding “a new ‘note’ to the ‘symphony’ that modern families demand in their meals.” Ideally, the flavor would be recognizable and memorable, so that it could serve as “a built-in trade-mark” that would be identified with its brand name and producer.

Around the same time, a burgeoning flavor-additive industry was rising to meet the food companies’ wishes. Flavor manufacturers promised not only to create memorable signature flavors, but to restore homemade appeal to factory-made food—and, perhaps most importantly, to create chemicals that could stimulate new consumer desires.

One of these chemicals was monosodium glutamate, or MSG, which was little known in the U.S. before World War II. But between 1943 and 1961, domestic production of MSG boomed, jumping from 3 million pounds to more than 21 million pounds a year. Unlike East Asia, where a shaker of MSG was common in home kitchens, it the U.S. the vast majority of MSG went into formulation of “convenience foods”—canned and dehydrated soups, frozen foods, condiments and sauces, and baby foods. MSG seemed to have the ability to restore freshness and savoriness to meats and vegetables rendered insipid by canning. One researcher in the 1940s described the taste of MSG as “a feeling of satisfaction.”

The success of MSG spurred a search for other flavor enhancers, as food manufacturers began looking for ways to add what we now call umami into their products. (The “yeast extract” listed on the ingredient label of New York Reuben Lay's is a descendant of these efforts.) In the 1950s and 1960s, powerful new analytic instruments like the gas chromatograph and mass spectroscopy (GC-MS) transformed the chemical understanding of flavor, helping chemists to identify thousands of volatile chemicals present in foods.

One example is a group of chemicals known as pyrazines, nitrogen-containing organic molecules that, at very low concentrations, can provoke a range of sensations, from the unmistakable green note of a raw bell pepper to roasted, nutty, and smoky flavors. Using GC-MS, researchers identified these compounds in a variety of foods—including coffee, cocoa, tea, roast chicken and meat, and fried and oven-roasted potatoes—and began to develop an increasing awareness of their importance in flavor. In the 1960s and 1970s, flavor companies filed numerous patents for newly synthesized pyrazines and pyrazine derivatives. By the early 1970s, synthetic methoxypyrazines were even being used to enhance the potato flavor of potato chips.

But when did chips stop tasting like potato and instead begin tasting like barbeque, salsa, and Reuben sandwiches? According to David Sprinkle, the research director of the food-industry market-research firm Packaged Facts, the rising importance of snacks in American life opened the door to bold, spicy, and distinctive flavors. Snacking became more than just sustenance; it was entertainment and self-expression. “Once you've got your own bag,” he said, “the sky's the limit.”  

As the cultural significance of the snack grew, so did Americans’ interest in “the culinary delights of other peoples,” as one 1959 flavor-additive ad put it. By the 1970s, a boom in “ethnic” fast food was well underway, with brands like Taco Bell, Totino's Pizza, and La Choy sauces marketed to a broad consumer base. Although these offerings are now derided as dumbed-down and inauthentic versions of the foods they represent, they reflected, and perhaps helped kindle, an appetite for regional American and international cuisines.

More recently, as the trend has swung toward “authenticity,” flavor intensity has come to denote realness in the cultural imagination. As Sprinkle explains, “the ideal went from haute cuisine to ethnic street food”—a rejection of exclusivity and an embrace of experimentation and adventure. Other technological innovations in production and packaging—like the shape of the polypropylene bag that keeps potato chips satisfyingly crisp—meant that unstable and volatile flavor molecules wouldn't be distorted by oxidation or lost to the wind. Together, all this has meant that processed foods can deliver their full flavor payload the moment you take a bite.

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Although a bag of chips may seem a universe away from a 12-course tasting menu, the two gastronomic worlds are inextricably intertwined. The food-trend forecasters that help guide companies like Lay’s develop their recommendations in part by analyzing the menus of trendy eateries. Flavor companies and fancy chefs might both get new ideas from the same food trucks. And like the creation of a new dish at a high-end restaurant, formulating a new flavor is a creative process—one where the masterminds aren’t chefs, but a small group of trained professionals known as flavorists. There are currently around 500 certified flavorists in the U.S., working on everything from Fritos to Fancy Feast.     

Frito-Lay declined to connect me with any flavorists who had worked on the New York Reuben chips. So I asked Jack Fastag, a senior flavor chemist at the Philadelphia-area flavor and fragrance company David Michael, how he might go about creating a “New York Reuben” flavor for a potato chip.

He said the first step would be to go out and get a sandwich—or several of them—for a small panel of expert tasters trained in sensory analysis to eat. The panel members would ruminate, debate, and identify the most desirable qualities of what they were eating before settling on what Fastag calls the “gold standard,” the target for the flavor.

“Then,” Fastag explained, “I would start looking into our palette of available flavor ingredients and try to find which combinations deliver the characteristics we are looking for.” This process involves a lot of trial and error, revising and reworking the formula to bring it closer and closer to the target. There are approximately 3,800 flavoring materials, including synthetic chemicals, oils, spices, and extracts, that are certified as GRAS— “generally regarded as safe”—and permitted for use in foods in the U.S.

But direct chemical analysis of the sandwich, Fastag says, wouldn’t necessarily helpful. There are hundreds of chemicals in foods that do not meaningfully contribute to flavor, and separating signal from noise can be burdensome. Some of the flavor chemicals present in foods may also lack FDA approval for use in flavor additives, or aren’t commercially obtainable. “For the most part,” he says, “we don't try to reproduce each one of the molecules that we find in nature.”

Instead, they try and capture the essence of a flavor, a process that’s about emotions as much as it is about chemistry. A crucial part of making an effective flavor, said Cyndie Lipka, a senior flavorist at the flavor company Prinova, is tapping into cultural associations and evoking sensory memories. As an example, Lipka described a pear flavor she once created: “Someone told me, ‘I can taste the starch granules on my tongue.’” The aroma alone had evoked the full experience of eating a pear at peak ripeness.

Unspooling the chemical components of food flavors remains important, but the science of flavor is a substrate for the art. As Fastag explained, “Ultimately, we are just trying to create something that is beautiful and pleasing to the senses.”

So which is more pleasing: the genuine Reuben sandwich or its mimic? I'm glad to live in a world where I can have both.