Philadelphia’s Monell Center Is Solving the Mysteries Behind the Science of Taste and Smell


A computerized smell-generating machine.

This feature was produced in collaboration between Vox Creative and Infiniti. Vox Media editorial staff was not involved in the creation or production of this content.

When the Museum of Food and Drink set out to create an exhibit about flavor, it turned to the Monell Chemical Senses Center in Philadelphia, which researches two of our most fundamental and most mysterious senses. The center inspired MOFAD Lab's interactive Smell Synth, but its work goes well beyond that. Here's a look.

In a sprawling, drab building in the middle of the University of Pennsylvania, a diverse collection of scientists — from chemists to psychologists to molecular biologists — are hard at work figuring out the hows and the whys behind taste and smell. In floor after floor and row after row of fluorescent-lit labs, they're sniffing scents puffed out of tiny tubes attached to giant machines, searching for tastes that don't yet have a name, and trying to make something that tastes just like salt but isn't. In windowless testing rooms, they're studying children's built-in love of sugar, and finding out whether smells can trigger emotions. This is the Monell Chemical Senses Center, the biggest independent, non-profit, and interdisciplinary hub for this kind of research in the world.

The Monell Chemical Senses Center

A tour of just a fraction of the work going on in this vast complex starts with Gary Beauchamp, who spent 24 years as the center's director before retiring from that post (but not from his research) last year. To demonstrate one of his biggest discoveries, he conducts a tasting of a fine Spanish olive oil. A small shot of the vibrant chartreuse oil is smooth, fresh, and grassy on the tongue, but as it goes down the throat burns so suddenly and so sharply that at least one person in the room starts coughing. That sensation, which you'll get from any good olive oil, is something that Beauchamp has been studying for years.

As it turns out, that sensation is identical to the burn in the throat you'd feel if you ever chewed up ibuprofen and swallowed it. Beauchamp realized this in 1999, while tasting olive oil at one of the first conferences on molecular gastronomy. He had been working with a company trying to make a drink with ibuprofen in it, who had been stymied by that unpleasant burn, and so he was one of the few people in the world equipped to recognize the sensation in olive oil. Six years later, he had isolated the compound responsible, oleocanthol, and proven that it was an anti-inflammatory a lot like ibuprofen. Eating a diet heavy on the olive oil was the equivalent of taking a dose of baby aspirin every day, with the benefit of reducing the risk of diseases like cancer and Alzheimer's. In other words, the already touted "Mediterranean diet" had — at least in part — a very real chemical basis for increasing health. To this day the research on oleocanthol continues, now focused on finding ways of extracting it for concentrated use.

Michael Tordoff doles out sips of calcium chloride, an indescribable taste.

In another lab, Michael Tordoff, a Monell faculty member — like a university lab, the center has faculty, adjunct faculty, research associates, and postdoc fellows — conducts a tasting of a flavor you've never tasted (at least not consciously): calcium. A sip of calcium chloride dissolved in water (pure calcium wouldn't be stable) tastes undeniably unplaceable. There's something bitter about it but also something other. Tordoff explains that just because we don't have a name for something doesn't mean that it's not a taste. He believes that there are many more basic tastes than just the five we talk about, sweet, sour, salty, bitter, and umami, but that we haven't distinguished them yet because they're not as obvious. And for that matter, he points out, we're not even sure how to define a basic taste. Do we have to have specific receptors on our tongue for it? Because we're far from finding all of those. Does it have to activate a particular part of the brain? Because we still haven't found an area of the brain devoted to tasting sour.

It may be that our ability to taste minerals like calcium — even unconsciously — is put into use when we're deficient in those minerals. That is to say, when we need calcium, we prefer food that has the taste of calcium in it. This is one of the questions Tordoff focuses on, and he's already demonstrated it to be true in rats. If true in humans, it wouldn't be so different from our preference for other tastes, like sugar. Sweetness is the flavor of readily available energy, so biologically it makes sense for us to love sweet foods as an energy source.

Cubicles for volunteer taste-testers.

The study of those sorts of human preferences is happening on another floor. The human test subjects are all volunteers who get paid, a little or a lot, depending on how involved the test is, to sit in rooms with researchers, or alone, or at weird little carrels with built in sinks for spitting and rinsing, like at the dentist. They taste solutions or smell smells and then answer questions, give ratings.

A whole section of this floor is devoted to kids, from newborn up, and looks like a pediatrician's office: baby scales, high chairs, play tables, a stuffed Big Bird. Nuala Bobowski, a postdoc, is one of many there studying childhood preferences, which are sometimes vastly different than those of adults. This shouldn't be surprising to anyone who as ever watched a kid eat. Kids hate vegetables, and they love and consume candy at a level unfathomable to a grown-up. Kids need energy to grow, and before the time when food was readily and easily available, this meant that they had to really crave it — in the form of sugar — or else they would starve. Their desire for salt, which is historically linked to high mineral content, is similar — it's biologically programmed. Likewise a sensitivity to bitterness, which in nature is often a sign of poison. An aversion to bitter keeps kids, who will put anything into their mouth, from eating something poisonous, but it also makes them think broccoli is disgusting.

Bobowski presents two shots of sugar water, one at the average concentration preferred by adults, and one at the concentration preferred by kids. The latter is unpleasantly cloying to an adult. Bobowski explains that the adult sweetness preference is about equivalent to a soda. The kid preference is a can of soda plus another 28 grams of sugar. Bobowski's research focuses on how this preference relates to actual food consumption, which could (and has) become a problem for some kids in today's world of readily available junk food. Her hope is to help develop ways to keep kids, vulnerable as they are to the lures of candy and chips, from overeating.

Joel Mainland sniffs the scent of artificial strawberry from his computerized smell machine.

Meanwhile, in an upstairs lab, Joel Mainland fiddles with sliders on his iPhone screen. They're linked to a computer, which is linked a contraption on the countertop with thin plastic tubes sprouting out of it like vines. The contraption houses 40 glass jars, each with a different chemical scent, and with a few swipes across the screen, Mainland can get one of those tubes to blow out the scent of cut grass or strawberry, or supposedly 85 percent of all the food scents out there. This is the machine that MOFAD Lab based its interactive Smell Synth on, though it's more complicated and less user friendly. Its purpose, besides impressing visitors, is to help develop a code to digitize odor, the scent equivalent of the six-digit HTML color code. This would give scientists, perfumists, and flavorists a universal way to describe odors, making for less tinkering, less memorizing, and more precision. But odor is much more complicated than color, and it would take many more digits than color to codify. Odor (which, don't forget, is essential to flavor) is so complicated that we can't even predict how its chemical structure relates to how our brain perceives it, though we know the chemical structures of many, many odors.

Figuring out that key to recognizing odor by its shape is another one of Mainland's projects — one that shows, maybe more than any other, just how many mysteries the Monell Center still has to piece together.

This feature was produced in collaboration between Vox Creative and Infiniti. Vox Media editorial staff was not involved in the creation or production of this content.

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