The Dark Art of Gastrophysics

Your palate isn’t nearly as independent as you might think.
Charles Spence (left) performing gastrophysics research.Courtesy of Kitchen Theory.

If (like me) you’re a nervy novice chef who still insists on hosting, the holiday season presents a series of opportunities to ritually humiliate yourself. Hosting a dinner party is daunting enough; the prospect of fluffing a holiday spread can keep you up at night. If you’re facing this same dread, do as I did: put aside those half-written guest lists for now, and first acquaint yourself with the dark arts of gastrophysics. This niche outgrowth of culinary psychology offers unique comforts. It shows that cooking is only a narrow sliver of the dining experience. It delineates all the surprising ways the senses intermingle and suggests new ways to trick them. Internalized sufficiently, it can help you design unfailingly pleasurable gustatory experiences against all odds.

To learn how to best deploy this sensory alchemy, consider the work of Charles Spence. The experimental psychologist has put his research on so-called cross-modal sensory integration to work for some of the world’s biggest corporations and most influential chefs. Over the past 35 years, Spence’s lab at Oxford University has studied how our senses inter-relate (from seeing to hearing, textures to taste, taste to touch); and how two senses can amplify each other in the culinary context, making a dish sing or a diner squirm. Spence has distilled all this knowledge in several excellent books, most notably Gastrophysics: The New Science of Eating. His two decades of experiments show how a subtle soundtrack playing in the background can radically transform an eater’s perception of a meal; how the shape of a snack shapes our perception of its flavor; how the aesthetic arrangement of ingredients makes them seem more or less fresh, to name but a few examples.

Gastrophysics is a skeleton key for so much. It reveals a nuance only familiar to a specific type of culinary nerd, a host of big snack companies, and some very open-minded chefs: your palate isn’t nearly as independent as you might think.

A Tantalizing Research Gap

I reach Spence via Skype at his home just outside of Bogota, Colombia, where he and his wife have spent much of the pandemic. It feels appropriate for the multi-sensory guru to tell me his story while framed by the diffuse light of a cloud forest, his voice punctuated by the chirping of tropical birds.

Two decades ago, when he first got interested in food, Spence was busy putting his research to work for large conglomerates and automotive companies. At the time, he was conducting two lines of research for Unilever, the multinational purveyor of soap and foodstuffs. In one, he varied the sound of washing machines to see if consumers would perceive the laundry as softer. In another, he tried to figure out why consumers commonly complained that their brightly colored fruit teas “didn’t taste of anything.” An idea struck him: “Why not put these two projects together? Why not think of the color and the sound of food together?”

This put him on the path that eventually led to his fateful “Sonic Chip” experiment, which won the Ig Nobel Prize, a distinction that is annually awarded to odd and improbable research, such as papers exploring the decongestant properties of orgasms, or gaming out the best ways to transport rhinos. Spence’s study demonstrated that the perceived crunchiness and freshness of slightly stale Pringles could be amplified by as much as 15 percent, merely by boosting the high-frequency sound heard when biting into a chip. The brain combines two sensory inputs—the sound of the crunch and the tactile mouthfeel—into a single synergistic, more satisfying result.

Expectations, developed over millions of years of evolution, guide (and can be used to trick) even the most refined palettes.

The provocative chip experiment brought Spence to the attention of chef Heston Blumenthal, one of the leading lights of the culinary movement then popularly (now controversially) known as “molecular gastronomy.” In the foreword to Spence’s book, The Perfect Meal: The Multisensory Science of Food and Dining, Blumenthal recalls how the experiment’s main finding sent his “mind racing, like a kid in a sweet shop.” He launched into a series of experiments to see how “sonic seasoning” could amplify different dishes. One of them resulted in the Fat Duck restaurant’s now iconic seafood offering, “The Sound of the Sea”: sashimi arrayed on a bed of sand (composed of tapioca), served to patrons alongside an iPod playing immersive seascape sounds. Research by Spence has shown that the sonic accompaniment makes participant diners think of the dish as “fresher” and “fishier.” In some cases, Blumenthal adds, patrons find the experience so affecting that they’re moved to tears. “[The research] has continued and gone on from there ever since,” he says. The two men became longtime collaborators.

An ebullient man dispensing dry wit at a rapid-fire pace, Spence recalls his early impressions of this new world. Flavor research at the time was still in its infancy, he says, and rife with misconceptions. One popular notion known as flavor pairing, for example, held that one could predict which flavors would go well together by the molecules they shared. “Like, say, ‘chocolate goes well with caviar,’” Spence recalls. “Turned out to be total nonsense.” Extra culinary inputs, like plating or cutlery, were still woefully under-researched. “There were food scientists thinking about these questions, and chefs doing these exciting things, but never had the two met really.” He had discovered a tantalizing research gap.

His parents, however, were worried that their son was abandoning a successful path for a niche pursuit. “My parents never went to school. They were in the traveling community,” he tells me. “They’d say: Is this a real job?’ I always had to justify the use and value of this knowledge, these insights.” Luckily, his new research path yielded quick results. Unlike his work with automobile companies, where any minor innovation could easily take a decade to make it into a car, this new work was distinctly lab-to-table. “You could take the science, turn it into a delightful memorable dish, and put it on the menu next week,” he recalls. And so it was. Star chef Charles Michel visited his lab in 2013, and they came up with the ‘Kandinsky salad,’ an artfully-arranged salad with swooshes of dressing inspired by the abstract expressionist’s oeuvre. The point was simple: the eye fed the mouth. Subsequent experiments showed that diners considered the artistic salad 21% tastier than a neater counterpart composed of the same ingredients.

Spence’s lab became a pilgrimage site for award-winning chefs, with a prolific output of new food innovations and studies. These meetings often spilled out into experimental dinners at his house. These concept dinners, like the famous Surrealist one where guests dined on rabbit using knives and forks adorned with tufts of rabbit fur, were halted by the pandemic. At the same time, in the era of lockdowns, taste loss, and sourdough starters, interest in the sensory world surged. So then: what can we common cooks and diners glean from Spence’s two decades of gastrophysics research?

The Power of Expectations

Spence’s tasteless tea conundrum proved instructive. The fruit tea’s color and scent cued sippers to anticipate sweetness and fruitiness, a promise the taste couldn’t keep. This provided an important lesson in the power of expectations. Underselling yields a more pleasurable experience than its opposite.

This applies also to the language used to describe a meal or product. Spence’s longtime collaborator Heston Blumenthal presided over an instructive culinary misadventure in 1997, when he served his patrons a crab ice cream to accompany a crab risotto. Despite rigorous taste testing by his team, the ice cream that found its way to most diners delivered a disagreeable shock, as most of them thought its pinkish-red hue and label portended a fruity dessert-like sweetness.

A follow-up study in 2008 by Martin Yeomans, in collaboration with Blumenthal, found that this effect could be reversed by appropriate labeling: by calling a pink-hued food like smoked salmon ice cream a “frozen savory mousse.” Calling such a food “ice cream,” they found, led patrons to find it “intensely aversive” and perceive it as excessively savory and salty. However, calling the dish something anodyne, such as “Food 386,” led diners to perceive it as more pleasant and less intensely salty. This is but one hint of the strong subconscious factors at work when we eat. Expectations, developed over millions of years of evolution, guide (and can be used to trick) even the most refined palettes.

Form Dictates Flavor

Expectations of a meal are shaped profoundly by color. This quasi-synesthesia can be remarkably consistent, as demonstrated by an experimental dining event in 2015 by Spence’s frequent collaborator, chef Jozef Youssef. Building on research from Spence’s lab about the tastes people around the world associate with different colors, Youssef served his guests a series of amuse-bouches—four randomly arranged spoons whose frothy contents were red, white, green and deep brown. Without identifying them, he suggested they commence with the salty, and then set upon the bitter, the sour, and the sweet spoons. About 75 percent of diners began with the blue spoon, and then progressed to the green, yellow and red. Just as the chefs predicted, most diners tended to equate blueness with saltiness, green with bitterness, yellow with sourness, and red with sweetness. 

Building on this in a review paper, Spence points out that this type of visual or synesthetic sweetness might even be more potent than actual sucrose, citing a study in which people sampling a red (or as he puts it, “appropriately colored”) drink found it to taste sweeter than an “inappropriately colored” green drink—even when the latter contained as much as 11 percent more added sugar. “In other words, psychologically induced taste-enhancement is indistinguishable from the real thing, at least sometimes,” he writes.

Make sure not to play farm noises while serving seafood.

Spence points out that it isn’t just colors we tend to perceive as sweet or bitter; we also associate specific shapes with corresponding tastes and textures. A vivid illustration of this phenomenon offered itself in 2013, when the confectionery company Cadbury received a torrent of letters complaining about the excessive sweetness and creaminess of their recently reformulated Dairy Milk chocolate bar. The company responded that the formula was unchanged; all they had done was soften the bar’s previously angular corners.

The tendency of a food’s shape to intensify (if congruent) or attenuate (if incongruent) its taste also extends to the crockery on which it is served. Spence cites a study which found that a beetroot jelly, when served on a round plate, was found to taste far sweeter than when it was served on an angular plate. The color of the plate can also modulate the taste of its contents, Spence has found, noting that the same strawberry mousse was found to taste 10 percent sweeter and 15 percent more flavorful when served on a white plate, instead of a black one. In other studies, his lab has found that the effect applies to beverages, with hot chocolate tasting more intensely and pleasurably of cocoa when served in an orange cup, as compared to a white cup (which appeared to accentuate a perceived bitterness). A latte, however, is found to taste more bitter when served in clear glass than a white cup. The more one considers the subtle psychology of these arrangements, the more intuitive they become, adding a whole other secret layer to one’s personal approach to meal presentation.

Set The Tone

Since the sonic chip era, Spence’s research has delved ever deeper into the flavor-enhancing qualities of sound, which he evangelizes as the “forgotten flavor sense.” His research has consistently found that modulating the sound generated by food can dramatically alter our perception and enjoyment of its taste. Background music can also be a potent enhancer of taste, texture, and mouthfeel––but only if, aligning with the logic of “congruence,” we like the music.

Synesthetic correspondences subliminally shape the way we behave. This knowledge has been profitably exploited by retailers and restaurants, who spritz the air with coffee and cookie scents—and play the kind of rhythms that keep us shopping at a steady clip. Music might even influence our decision-making. Spence cites a study that found shoppers switched their choice of wine depending on the background music they heard, buying French wine to the strains of the French accordion, and German wine to the sound of stereotypical Alpine bierkeller music.

Spence and Blumenthal demonstrated the persuasive power of atmospherics in 2007, when they had subjects dine on oysters, accompanied either by sounds of the sea or the sounds of a barn. Others ate bacon and egg ice cream to a soundtrack of clucking hens or the sizzling of bacon fat on a skillet. Diners rated the oysters more highly when the meal was accompanied by a seascape than when they were listening to farm sounds. Meanwhile, those who ate the bacon and egg ice cream found it to taste redolent of the sound they’d heard; eggier when accompanied by hens clucking, and more bacon-forward when they heard the sizzle.

Keeping this in mind might influence your dinner party playlist. Just make sure not to play farm noises while serving seafood.

Get That Heavy Cutlery

Some of Spence’s most intriguing research touches on the tactile quality of culinary experience. In various studies, he has found that the use of heavier cutlery or dishes amplifies one’s enjoyment of food, and one’s willingness to pay more for it—whether it’s a yogurt cup or a main course at a high-end restaurant. The texture of our plates and cutlery rubs off on what we eat in a number of ways.

A study involving recomposed pretzels with two differently textured halves—one soggy and the other fresh—found that the tactile sensation of the soggy half attenuated the crunchiness of the perfectly crisp half that the subject bit into. Spence calls this type of sensation transference “affective ventriloquism,” when a texture readily prompts a specific feeling.

We may derive a certain comfort from this, too: scientifically speaking, you simply cannot please everyone.

Smooth consistencies associate with comfort and less smooth textures correspond to warmth and spiciness. One study found that those who ate ginger cookies off a rough plate considered them spicier, when compared to those who ate them off smooth plates. Spence also discovered that food scooped out of a heavier bowl can leave us feeling more satiated, compared to eating it off a plate. Holding a bowl of food in one’s hands, sensing its warmth and “reassuring roundness,” can even make us feel that those who surround us seem friendlier.

These takeaways are worth keeping in mind for those of us used to serving on a spectrum of discolored Ikea beige.

Quotidian Mysteries

Spence’s research is interesting far beyond its actionable advice. He demystifies the popularity of tomato juice on airplanes, to name one compelling example. Turns out, TJ’s creamy umami taste is the only flavor that is not just unaffected but enhanced by the high levels of background noise onboard the aircraft. (Sweetness, on the other hand, is suppressed.)

In recent years, his gastronomic research has taken a turn toward the lofty. In a quest to deliver new heights of “edible magic,” Spence is currently working with chefs and even magicians on a host of projects: an edible light bulb (made of spun sugar) that shatters on the diner’s plate; a “shocking” edible heart whose red oozy appearance owes itself to rhubarb and beetroot juice; deploying ASMR alongside whiskey or beer to evoke an intense emotional reaction.

Sometimes these machinations can be used for the common good. He is currently trying to get to the bottom of people’s aversion to eating insects and jellyfish—two highly sustainable foods—with the help of a philosopher. “Virtuous campaigns, like saying ‘do what’s good for the planet,’ don’t work,” Spence says. “What works better is to deliver sensory qualities, like crunch, which Colombia’s crispy flying ants have.” Once you’ve heard Spence talk up the powerful crunch of gnats and feel the sudden urge to explore your insectivorous side, you’re well on your way to appreciating the full power of his approach.

After all the palavering, the taste of whatever ends up on the plate still matters somewhat. Luckily, the subjective experience of flavor is so variable that a definitive delineation of tasty food is impossible. As Spence demonstrates exhaustively, we all inhabit distinct “taste worlds” due to our genes and environments. Much of what we consider “flavor” is half-constituted by “smells” of two kinds: orthonasal, or a direct anticipatory whiff of what’s before us, and retronasal, which refers to the volatile organic molecules released from the back of our mouth into our nose when we’re swallowing what we drink or eat. This explains why even the most carefully prepared meal turns into inesculent pap when we have a cold. It also explains one of Spence’s biggest gastrophysical pet peeves: the frustrating design of takeaway coffee cups, whose spill-proof lids obscure the smell and with it, some of the taste of their delicious contents.

While some of us are “supertasters,” with hyper-sensitive tongues bristling with exponentially more papillae, many more of us turn out to be totally “anosmic,” or smell-blind to specific volatile organic compounds in what we consume. Due to this vast spectrum of taste, and consequent “hedonic ratings,” or levels of relish we’re able to experience, the same dish of pork, garnished with coriander and served with a bottle of corked wine, might variously taste passable, tasty, or wildly unpleasant.

We may derive a certain comfort from this, too: scientifically speaking, you simply cannot please everyone. ♦

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