Meet the Philly Food Scientists Who Can Make a Potato Chip Taste Like a Cheesesteak

Food scientists break flavor down into elements. / Photograph by Andre Rucker

Another autumn, another snack-time promotion: In November, venerable Herr’s, headquartered in Chester County’s Nottingham, announced a new potato-chip flavor contest, with $15,000 in prizes at stake. The latest “Flavored by Philly” challenge: Suggest a chip inspired by a local small business. Something cheesesteak-y, perhaps? Or soft-pretzel-esque? Did Herr’s already do crab fries? Inquiring minds throughout the region got to pondering ideas. And other inquiring minds got to wondering: How exactly do you make a potato chip taste … cheesesteak-y? Last year’s Flavored by Philly winner was a long-hots-and-provolone take on the roast pork sandwich, for which one Ryan Reigel earned $10,000 for himself and a matching $10,000 for a charity of his choice. Which … good for Ryan for brainstorming that flavor. But how the heck do you get long hots onto a potato chip?

“I don’t even know what long hots are,” Sam Tharpe confesses, laughing in a Zoom meeting set up by his professional colleague, Cathianne Leonardi, a South Jersey resident who just happens to be president of the Society of Flavor Chemists, a national confederation of flavor geeks. (Sam’s a past president.)

“It’s a kind of pepper,” Cathianne and I inform him simultaneously. And on the screen, I can almost see the gears in Sam’s head start turning as he catalogs all the different molecules that make up a pepper.

“You know,” Sam muses, “Lay’s had a Southern-gravy-and-biscuit chip once. I was surprised how good they were.”

When it comes to eating, ours is an age of unprecedented abundance. Not only do we get to snack on exotica like durian and dragon fruit on the regular (supply-chain woes notwithstanding); we get to munch Southern-gravy-and-biscuit potato chips, too! Anything you can dream up, a flavor chemist can create. But ours is also an age that fetishizes connection to the land, local foods, foraging, heirloom veggies and organic produce. In other words: We want to put as much distance between us and chemicals as we can. Sam and Cathianne say that’s impossible — and that we shouldn’t want to, anyway.

Cathianne, who grew up in an Italian American family in New Jersey, first became aware she wasn’t like the rest of her clan during the holidays. The traditional Feast of the Seven Fishes celebration was, for her, one long exercise in disgust. It turns out she and I share a sensitivity to trimethylamine, a colorless organic compound that makes fish smell awful to us instead of like an alluring foodstuff. I wrote about my aversion to trimethylamine last June in a story on Philly’s Monell Chemical Senses Center, which is what prompted Cathianne to get in touch with me.

Both Cathianne and Sam, it turns out, can cite strong sensory memories from their childhoods that they consider pivotal to their eventual career choices. For Cathianne, it was a strawberry patch at her grandparents’ house with a rose hedge growing alongside it. For Sam, it was a Florida uncle’s citrus grove and gardenia bush. He recalls collaring the gardenia blossoms with his hands as a kid: “It was the most wonderful scent I’d ever experienced.”

Most of us can point to flavors and smells that make us nostalgic; why do you think realtors plant Christmas-y scents in the houses they’re trying to sell? Most of us, however, don’t grow up to become food scientists. First off, you’d have to know such a job exists. Cathianne, who always loved cooking, remembers that in her organic chemistry class at Stockton University, the professor one day took a little packet of grape sugar — a.k.a. glucose — and hung it up in the front of the classroom. “I knew what I was studying included sugars,” she says, “but that made it real to me: This is in our food, where it had been a molecule on a page. He brought it out of the book and into my kitchen.” Sam began academic life intending to become an architect — until he happened on an article about the Norton International Flavor Company. “It said that samples come in all day, and you taste them! I thought that was the coolest job!” Today he’s principal chemist for McCormick & Co., the spice-and-flavor giant headquartered outside Baltimore. Cathianne is a staff flavorist for the Coca-Cola Company.

If you’re interested in becoming a flavor chemist, you start by studying biology and (duh) chemistry. Then, Sam says, you have to learn the language of flavor science and how it describes things: “As you work on a project, you become an expert on that flavor profile. You home in on the nuances — oh, there are dried apricot notes! There’s a nuance of cooling — a touch of menthol, perhaps? You’re figuring out nature’s puzzle.” What we read as “taste” is composed of both scent and flavor; if you hold your nose and eat a jellybean, all you taste is sweet, Sam points out. Open your nose, though, and via the smell of cherry or lime or grape, the full flavor comes through.

Cathianne recalls working on a cheesecake project and presenting samples to a panel of tasters. “Cheesecake isn’t just one flavor,” she explains. “You have vanilla, creaminess, citrus … so we’re gauging what combination works best.” One offering emphasized cheesiness, and a female taster who’d just had a baby announced, “It smells like baby vomit.” Cathianne laughs at the memory. “At different times of life, we have different sensitivities,” she explains. “When I was a child, I loved milk chocolate and hated dark chocolate. Now, it’s the other way around.” The point, she says, is this: “You want the broadest, most pleasing taste — and an experience that sticks in the memory.”

So say somebody wanted that long-hots-and-provolone potato chip. Where would a flavor scientist start? “The first thing I’d do,” Sam says, “is go out and buy some long hots and provolone and eat them.” McCormick has professional chefs who create what its scientists call a “gold ­standard” — the ultimate exemplar of the taste they’re seeking to create. “You break the flavor down into pieces. And then you have to get the flavor in there. In this case, it’s a chip, so you’ll want a seasoning blend.” For a soda or juice product, you would use a liquid blend instead. There are flavorists who specialize in different product types — ­beverages or snack foods or spice blends.

And there are myriad ways to stir up a given flavor. Perusing the advertisements in industry journal Perfumer & Flavorist is like stumbling onto a newfound land. “Bring bold flavors to the snacking trend craze by using Sigma-Aldrich aroma chemicals!” one cajoles. “Our EU Natural Vanillin ex Ferulic Acid adds a sweet, creamy aroma for your food needs — a ‘cream’ come true!” a company called Oqema promises. There are so-called “flavor houses” all over the world that specialize in various tastes and blends. Sensapure, headquartered in Salt Lake City, offers five different apple flavors, from apple pie to Red Delicious, and seven strawberry variations, from “creamy” to “jammy” to “tart.” (Speaking of vanilla, Cathianne says it’s the most popular flavor all around the world because it has the same chemical notes as breast milk. Who knew?)

There are multiple elements to any flavor, Cathianne tells me — aroma, bitterness, saltiness, even texture: “That last is important. It’s hard to get chocolate flavor, for instance, into things that don’t contain fat.” One more quality makes chocolate tricky: “It melts at body temperature. If you’re missing that element, you can’t always quite get the taste.” And there’s a chemical reason why chocolate yogurt is hard to come by, Sam explains: “The acid in the yogurt makes chocolate difficult to translate.”

Food scientists concoct flavors from extracts, from essential oils, from blends sold by flavor houses, and from beakers of chemicals. Some are easier to stir up than others. Some scents contain molecules that are unstable over time, like coffee, tea and cheese; that’s why your leftover coffee from yesterday’s pot doesn’t taste as good as it did fresh. They’re an example, Cathianne says, of “parameters that fit into taste that we can’t completely control.”

For the most part, though, flavor scientists have taste down to … a science. “What we create at the bench” — scientist-speak for the workspace where they ply their trade — “uses the tools of nature,” Sam says stoutly. “Life is carbon. It’s carbon chains. We’re all carbon chains.” That’s why he and Cathianne get a bit snippy when people talk about “natural” vs. “unnatural” flavors. “‘Chemistry’ has negative connotations,” Cathianne sighs. It’s one reason she and Sam put on educational programs at schools, presenting high-school students with scent strips that smell like gym socks, or green grass, or cantaloupe — to make chemistry more relatable. Smells, they explain, are nothing but molecules floating in the air.

Big Food spends millions and millions of dollars creating new flavors. You know açai? I mean — you’ve seen the word, though you may not be sure how to pronounce it. (Sam says “ah-sah-EE.”) To get consumers acquainted with this fruit of a South American palm tree, a company might mingle it with a more familiar flavor — in blueberry açai yogurt or juice drink, say. Cathianne recalls finding a tropical grass called pandan, used in Asian cooking, at a local farmers’ market. “I’d been reading up on it,” she says, so she bought a bunch: “It was like a little bouquet. I put it in my car and drove around and did another errand, and when I came back to the car — it stinks! It was like vanilla at first, then green, then like dirt. It was an aroma that was new to me. I was hotboxing my car with it!” She wound up concocting two versions of a pandan flavor for a client: “I made one with more vanilla, so it would be more familiar, and the other was more authentic. I suggested we introduce the one with more vanilla first and then expand.”

And the delivery method matters, too: The scent of fresh-cut grass is stronger than that of uncut grass. Slicing the stem, Sam explains, separates the enzymes from the vacuoles, which then release more chemicals into the air. For school presentations, Sam demonstrates the chemical compound we read as “fresh-cut grass” by snapping a string bean in half.

Food scientists talk about flavors being “forward” or coming on later. You can think of our sense of taste as a chemical parfait; some layers are more prominent, while others recede. Cathianne remembers stirring up different samples of a raspberry tea blend for a client. Some emphasized the raspberry; others focused on the tea. “They had a specific kind of outer packaging they were going to use,” she says, “that had brown and red fading into each other. I told them they needed the taste profile to match the packaging: The two flavors had to mesh into each other.” The client agreed.

She’s even been asked to create flavors that don’t exist: “What does unicorn taste like?” she muses. “What does mermaid taste like? Or a party? When you have a flavor like ‘party,’ that means a special occasion. It should bring joy, whether it’s for ice cream or popcorn or whatever.”

Tastes tend to become trendy in waves, according to Sam; the food world will jump on caffeinated energy drinks, or hard seltzers, or green-apple everything. Large corporations that see a flavor trend building often depend on entrepreneurs to do the developing and then snatch their companies up. Think how many foods you’ve seen flavored with McCormick’s iconic Old Bay. One recent Old Bay project for the company was vodka: “That was difficult to translate because of the clarity.” I think Sam means the taste was muddled, but he’s being literal: “People are used to vodka being clear.”

Marketing, of course, is a huge part of the flavor business, just as it is with everything else. And sometimes … well, sometimes the best-laid plans go awry. “The classic flavor disaster is Crystal Pepsi in the 1990s,” says Sam, referring to the so-called “Clear Craze” marketing fad back then that emphasized product purity. “They did consumer testing, but they didn’t test the right consumers, which is critical for product development.” If you want to visit a fun house of flavor disasters, just stop by a Big Lots. Sam says the closeout retailer is a graveyard for unsuccessful flavor ideas.

On the 300 block of Chestnut Street in Philly is a museum you’ve likely never been to: the Science History Institute. It was founded in 1982 as a joint project of the University of Pennsylvania and the American Chemical Society to promote the history of science and chemistry and provide research fellowships. It’s here that the Society of Flavor Chemists is setting up a research library and an archive of its members’ writings and work — an effort Sam’s in charge of. As part of that task, he recently made a trip to the Canton, Georgia, home of the late John C. Leffingwell, a giant in the flavor industry.

Leffingwell, who died in 2020 at the age of 82, got his PhD in organic chemistry from Emory and worked for three decades for companies including Häagen-Dazs, where he created flavors like Macadamia Nut Brittle ice cream, which USA Today declared the best new ice cream of 1985; Sunkist, whose signature orange soda he helped develop; and Canada Dry. Sam went to Canton to meet Leffingwell’s widow and children and take stock of the chemist’s vast catalog of papers and memorabilia, to be included in the library’s holdings.

The past half-century, Sam says, has been a period of tremendous growth in the flavor industry. (Believe it or not, when I was a kid, there was one flavor of potato chip — potato.) That’s why it’s so important to document the work that was done, the scientists who performed it, and the marketers who promoted it — people like Pamela Low, creator of the flavor coating for Cap’n Crunch cereal; William A. Mitchell, inventor of Pop Rocks and Cool Whip; and Frito-Lay’s Arch West, whose enjoyment of a deep-fried tortilla chip resulted in Doritos. “We’re so lucky to have this place to store things,” Sam says of SHI, “and for people to explore and do research.” There’s a practical reason to maintain an archive, too, Cathianne notes: “I texted Sam once to ask if we had a book on the history of essential oils. We did. We have historical data on the chemical components of essential oils.” Climate change, for instance, could affect the chemical makeup of citrus fruit, or lemongrass, or oregano. “We’d only know that,” she says, “because of the data we have.”

Formed in the early 1950s, the Society of Flavor Chemists functions like a sort of medieval guild, with new members assigned to mentors who guide them through levels of testing. “The society serves as a platform to provide credibility for those going through training,” Sam explains. “Companies have their own trainings, but if you’re certified by us, it means you’ve been tested by a body of experts and deemed qualified.” The society shares research, sponsors scholarships, holds regional meetings, and recognizes and celebrates members’ honors and achievements. Sam recently was awarded his 25-year pin.

Mentorship helps with one of the knottier aspects of flavor chemistry: There’s an enormous safety component to this science. “You have to understand the regulatory nuances, which are complicated,” Sam points out, “and the application — how a flavor will be used.” The Flavor and Extract Manufacturers Association, or FEMA, keeps a list of safe raw materials used for products marketed in the U.S. But hey, this is chemistry, remember? Sometimes, shit happens. A chemical used in a lot of orange-flavored products, Cathianne mentions, has a low flashpoint when heated. “There are a lot of stories,” Sam adds, “about explosions when Tang was headed for the moon.”

To Cathianne and Sam, whether you mix carbon, hydrogen and oxygen in a beaker to get gamma-nonalactone — the flavor we read as coconut — or extract it from an actual coconut doesn’t make much difference. Carbon is carbon; hydrogen is hydrogen. Plus, there are practical considerations in producing flavors. “Say you want a roasted chicken flavor,” Sam posits. “Do you really want to roast a bunch of ­chickens” — with all the ensuant chicken feed and feathers and guano — “when there’s a concentrated flavor you could use?” Vanilla comes from hand-pollinated orchid flowers that are labor-intensive and expensive to grow; the plants are at the mercy of weather, insects, climate ­damage — and the industry is rife with child labor. Vanillin, vanilla’s chief chemical compound, can be synthesized from wood chips or pine sap. How much of a stickler for the real thing do you want to be?

Ethics and sustainability are hot topics in the flavor-science field. So is evolving tech. Cathianne wrote an article for Perfumer & Flavorist recently on CRISPR, called “Tailoring Genes to Taste.” In it, she explores how gene editing could improve the taste of tomatoes, eliminate the pits in cherries, or keep apples from browning when sliced. Then there’s the whole evolving world of faux meat. “This is what we’re talking about!” she says excitedly. “Making new protein materials that don’t come from animals — that do our bodies good and engage our senses. You create a reaction in an amino acid with an enzyme, apply a little heat, add a little water — ”

“That’s the great food-scientist challenge,” Sam agrees. “The artistry of creating something the consumer will accept and love.”

“Think of the possibilities for space exploration, or for future drought,” Cathianne suggests. She offers a distinction between CRISPR tech and GMOs: “In a GMO, the genes come from different species. In CRISPR, you’re only using what’s already there. It’s the difference between something we haven’t seen in nature and something that has happened in nature through hybridization.”

Sam begs to differ. “You know what GMO is? It’s Mendel and the peas! It’s what you learn the first day in biology class.” Sometimes, he adds, “Technology that’s polarizing now becomes uniting later. That’s what happened with Ancestry.com, right? Someone captured and preserved information that turns out to be important later on.”

That’s the whole idea behind the library and archive at the Science History Institute. Flavor science is generally a costly, secretive, highly competitive industry. But its practitioners know their work is like chemistry itself: It depends on interactions — between an acid and ethanol, a pepper and a cheese, nostalgia and our yearning for what’s new. And also between the flavor chemists and us, the audience they’re playing to. “In my mind,” Cathianne says, “we’re making magical moments by engaging with the senses of other people. Chemistry and biology are social!” Scent and taste are gateways between the past and present, conjuring up Mom’s meatballs or the lemonade in Grandma’s backyard — or even John’s roast pork, in a potato chip.

Published as “Better Eating Through Chemistry” in the January 2023 issue of Philadelphia magazine.