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| The Marvels in Your Mouth | The Marvels in Your Mouth |
| (35 minutes later) | |
| WAGENINGEN, THE NETHERLANDS — When I told people I was traveling to Food Valley, I described it as the Silicon Valley of eating. At this cluster of universities and research facilities, nearly 15,000 scientists are dedicated to improving — or, depending on your sentiments about processed food, compromising — the quality of our meals. | |
| At the time I made the Silicon Valley comparison, I did not expect to be served actual silicone. | At the time I made the Silicon Valley comparison, I did not expect to be served actual silicone. |
| But here I am, in the Restaurant of the Future, a cafeteria at Wageningen University where hidden cameras record diners as they make decisions about what to eat. And here it is, a bowl of rubbery white cubes the size of salad croutons. Andries van der Bilt has brought them from his lab in the brusquely named Department of Head and Neck, at the nearby University Medical Center Utrecht. | But here I am, in the Restaurant of the Future, a cafeteria at Wageningen University where hidden cameras record diners as they make decisions about what to eat. And here it is, a bowl of rubbery white cubes the size of salad croutons. Andries van der Bilt has brought them from his lab in the brusquely named Department of Head and Neck, at the nearby University Medical Center Utrecht. |
| “You chew them,” he said. | “You chew them,” he said. |
| The cubes are made of a trademarked product called Comfort Putty, more typically used in its unhardened form for taking dental impressions. Dr. Van der Bilt isn’t a dentist, however. He is an oral physiologist, and he likely knows more about chewing than anyone else in the world. He uses the cubes to quantify “masticatory performance” — how effectively a person chews. | The cubes are made of a trademarked product called Comfort Putty, more typically used in its unhardened form for taking dental impressions. Dr. Van der Bilt isn’t a dentist, however. He is an oral physiologist, and he likely knows more about chewing than anyone else in the world. He uses the cubes to quantify “masticatory performance” — how effectively a person chews. |
| I take a cube from the bowl. If you ever, as a child, chewed on a whimsical pencil eraser in the shape of, say, an animal or a piece of fruit, then you have tasted this dish. | I take a cube from the bowl. If you ever, as a child, chewed on a whimsical pencil eraser in the shape of, say, an animal or a piece of fruit, then you have tasted this dish. |
| “I’m sorry.” Dr. Van der Bilt winces. “It’s quite old.” As though fresh silicone might be better. | “I’m sorry.” Dr. Van der Bilt winces. “It’s quite old.” As though fresh silicone might be better. |
| Dr. Van der Bilt and his colleagues have laid claim to a strange, occasionally repugnant patch of scientific ground. They study the mouth — more specifically, its role as the human food processor. Their findings have opened up new insights into quite a few things that most of us do every day but would rather not think about. | Dr. Van der Bilt and his colleagues have laid claim to a strange, occasionally repugnant patch of scientific ground. They study the mouth — more specifically, its role as the human food processor. Their findings have opened up new insights into quite a few things that most of us do every day but would rather not think about. |
| The way you chew, for example, is as unique and consistent as the way you walk or fold your shirts. There are fast chewers and slow chewers, long chewers and short chewers, right-chewing people and left-chewing people. Some of us chew straight up and down, and others chew side-to-side, like cows. Your oral processing habits are a physiological fingerprint. | The way you chew, for example, is as unique and consistent as the way you walk or fold your shirts. There are fast chewers and slow chewers, long chewers and short chewers, right-chewing people and left-chewing people. Some of us chew straight up and down, and others chew side-to-side, like cows. Your oral processing habits are a physiological fingerprint. |
| Dr. Van der Bilt studies the neuromuscular elements of chewing. You often hear about the impressive power of the jaw muscles. In terms of pressure per single burst of activity, these are the strongest muscles we have. But it is not the jaw’s power to destroy that fascinates Dr. Van der Bilt; it is its nuanced ability to protect. | Dr. Van der Bilt studies the neuromuscular elements of chewing. You often hear about the impressive power of the jaw muscles. In terms of pressure per single burst of activity, these are the strongest muscles we have. But it is not the jaw’s power to destroy that fascinates Dr. Van der Bilt; it is its nuanced ability to protect. |
| Think of a peanut between two molars, about to be crushed. At the precise millisecond the nut succumbs, the jaw muscles sense the yielding and reflexively let up. Without that reflex, the molars would continue to hurtle recklessly toward one another, now with no intact nut between. | Think of a peanut between two molars, about to be crushed. At the precise millisecond the nut succumbs, the jaw muscles sense the yielding and reflexively let up. Without that reflex, the molars would continue to hurtle recklessly toward one another, now with no intact nut between. |
| To keep your he-man jaw muscles from smashing your precious teeth, the only set you have, the body evolved an automated braking system faster and more sophisticated than anything on a Lexus. The jaw knows its own strength. The faster and more recklessly you close your mouth, the less force the muscles are willing to apply. Without your giving it a conscious thought. | To keep your he-man jaw muscles from smashing your precious teeth, the only set you have, the body evolved an automated braking system faster and more sophisticated than anything on a Lexus. The jaw knows its own strength. The faster and more recklessly you close your mouth, the less force the muscles are willing to apply. Without your giving it a conscious thought. |
| Teeth and jaws are impressive not for their strength but for their sensitivity, Dr. Van der Bilt has found. Chew on this: Human teeth can detect a grain of sand or grit 10 microns in diameter. A micron is 1/25,000 of an inch. If you shrank a Coke can until it was the diameter of a human hair, the letter O in the product name would be about 10 microns across. | |
| As it happens, my masticatory performance is “just fine,” Dr. Van der Bilt said. But the study of oral processing is not just about teeth. It’s about the entire “oral device” — teeth, tongue, lips, cheeks, saliva, all working together toward a singular revolting goal, bolus formation. | As it happens, my masticatory performance is “just fine,” Dr. Van der Bilt said. But the study of oral processing is not just about teeth. It’s about the entire “oral device” — teeth, tongue, lips, cheeks, saliva, all working together toward a singular revolting goal, bolus formation. |
| The word “bolus” has many applications, but we are speaking of this one: a mass of chewed, saliva-moistened food particles. Food that is in, as one researcher has put it, sounding like a license plate, “the swallowable state.” | The word “bolus” has many applications, but we are speaking of this one: a mass of chewed, saliva-moistened food particles. Food that is in, as one researcher has put it, sounding like a license plate, “the swallowable state.” |
| In Dr. Van der Bilt’s line of work, on any given day you may find yourself documenting “intraoral bolus rolling” or shooting magnified close-ups of “retained custard” with the Wageningen University tongue-camera. Should you need to employ, say, the Lucas formula for bolus cohesiveness, you will need to figure out the viscosity and surface tension of the moistening saliva as well as the average radius of the chewed food particles and the average distance between them. | In Dr. Van der Bilt’s line of work, on any given day you may find yourself documenting “intraoral bolus rolling” or shooting magnified close-ups of “retained custard” with the Wageningen University tongue-camera. Should you need to employ, say, the Lucas formula for bolus cohesiveness, you will need to figure out the viscosity and surface tension of the moistening saliva as well as the average radius of the chewed food particles and the average distance between them. |
| To do that, you’ll need a bolus. You’ll need to stop your subject on the brink of swallowing and have him, like a Siamese with a hairball, relinquish the mass. If the bolus in question is a semisolid — yogurt and custard are not chewed but “orally manipulated” and mixed with saliva — the work is yet less beautiful. | To do that, you’ll need a bolus. You’ll need to stop your subject on the brink of swallowing and have him, like a Siamese with a hairball, relinquish the mass. If the bolus in question is a semisolid — yogurt and custard are not chewed but “orally manipulated” and mixed with saliva — the work is yet less beautiful. |
| Bolus formation and swallowing depend on a highly coordinated sequence of neuromuscular events and reflexes, researchers here and elsewhere have found. Disable any one of these — via stroke, degenerative neurological condition, tumor irradiation — and the seamless, moist ballet begins to fall apart. The umbrella term is dysphagia (from the Greek for “disordered eating,” which may or may not explain flaming Greek cheese appetizers). | Bolus formation and swallowing depend on a highly coordinated sequence of neuromuscular events and reflexes, researchers here and elsewhere have found. Disable any one of these — via stroke, degenerative neurological condition, tumor irradiation — and the seamless, moist ballet begins to fall apart. The umbrella term is dysphagia (from the Greek for “disordered eating,” which may or may not explain flaming Greek cheese appetizers). |
| Most of the time, while you’re just breathing and not swallowing, the larynx (voice box) blocks the entrance to the esophagus. When a mouthful of food or drink is ready to be swallowed, the larynx has to rise out of the way, both to allow access to the esophagus and to close off the windpipe and prevent the food from “going down the wrong way.” | Most of the time, while you’re just breathing and not swallowing, the larynx (voice box) blocks the entrance to the esophagus. When a mouthful of food or drink is ready to be swallowed, the larynx has to rise out of the way, both to allow access to the esophagus and to close off the windpipe and prevent the food from “going down the wrong way.” |
| To allow this to happen, the bolus is held momentarily at the back of the tongue, a sort of anatomical metering light. If, as a result of dysphagia, the larynx doesn’t move quickly enough, the food can head down the windpipe instead. This is, obviously, a choking hazard. More sinisterly, inhaled food and drink can deliver a troublesome load of bacteria. Infection can set in and progress to pneumonia. | To allow this to happen, the bolus is held momentarily at the back of the tongue, a sort of anatomical metering light. If, as a result of dysphagia, the larynx doesn’t move quickly enough, the food can head down the windpipe instead. This is, obviously, a choking hazard. More sinisterly, inhaled food and drink can deliver a troublesome load of bacteria. Infection can set in and progress to pneumonia. |
| A less lethal and more entertaining swallowing misstep is nasal regurgitation. Here the soft palate — home turf of the uvula, that queer little oral stalactite — fails to seal the opening to the nasal cavity. This leaves milk, say, or chewed peas in peril of being horked out the nostrils. Nasal regurgitation is more common with children, because they are often laughing while eating and because their swallowing mechanism isn’t fully developed. | A less lethal and more entertaining swallowing misstep is nasal regurgitation. Here the soft palate — home turf of the uvula, that queer little oral stalactite — fails to seal the opening to the nasal cavity. This leaves milk, say, or chewed peas in peril of being horked out the nostrils. Nasal regurgitation is more common with children, because they are often laughing while eating and because their swallowing mechanism isn’t fully developed. |
| “Immature swallowing coordination” is the reason 90 percent of food-related choking deaths befall children under 5. Also contributing: immature dentition. Children grow incisors before they have molars; for a brief span of time they can bite off pieces of food but cannot chew them. | “Immature swallowing coordination” is the reason 90 percent of food-related choking deaths befall children under 5. Also contributing: immature dentition. Children grow incisors before they have molars; for a brief span of time they can bite off pieces of food but cannot chew them. |
| Round foods are particularly treacherous because they match the shape of the trachea. If a grape goes down the wrong way, it blocks the tube so completely that no breath can be drawn around it. Hot dogs, grapes and round candies take the top three slots in a list of killer foods published in the July 2008 issue of The International Journal of Pediatric Otorhinolaryngology (itself a calamitous mouthful). A candy called Lychee Mini Fruity Gels has killed enough times for the Food and Drug Administration to have banned its import. | |
| The safest foods, of course, are those that arrive on the plate pre-moistened and machine-masticated, leaving little for your own built-in processor to do. They are also, generally speaking, the least popular. Mushy food is a form of sensory deprivation. In the same way that a dark, silent room will eventually drive you to hallucinate, the mind rebels against bland, single-texture foods, edibles that do not engage the oral device. | The safest foods, of course, are those that arrive on the plate pre-moistened and machine-masticated, leaving little for your own built-in processor to do. They are also, generally speaking, the least popular. Mushy food is a form of sensory deprivation. In the same way that a dark, silent room will eventually drive you to hallucinate, the mind rebels against bland, single-texture foods, edibles that do not engage the oral device. |
| Those who can chew want to chew. We especially enjoy crunch. A colleague of Dr. Van der Bilt, Ton van Vliet, has spent the past seven years figuring out just how crunch works. | Those who can chew want to chew. We especially enjoy crunch. A colleague of Dr. Van der Bilt, Ton van Vliet, has spent the past seven years figuring out just how crunch works. |
| Back at the Restaurant of the Future, he stops by to instruct me in the basics of crispy-crunchy. We begin with nature’s version, a fresh apple or carrot. | Back at the Restaurant of the Future, he stops by to instruct me in the basics of crispy-crunchy. We begin with nature’s version, a fresh apple or carrot. |
| “It’s all bubbles and beams,” he said, sketching networks of water-filled cells and cell walls on a sheet of my notepad paper. When you bite into an apple, the flesh deforms and at a certain moment the cell walls burst. And there is your crunch. (Ditto crispy snack foods, but there the bubbles are filled with air.) | “It’s all bubbles and beams,” he said, sketching networks of water-filled cells and cell walls on a sheet of my notepad paper. When you bite into an apple, the flesh deforms and at a certain moment the cell walls burst. And there is your crunch. (Ditto crispy snack foods, but there the bubbles are filled with air.) |
| As a piece of produce begins to decay, the cell walls break down and water leaks out. Now nothing bursts. Your fruit is no longer crisp. It is mealy or limp or mushy. The same thing happens with a snack food degraded by moisture: Cell walls dissolve, air leaks out. The staler the chip, the quieter. | As a piece of produce begins to decay, the cell walls break down and water leaks out. Now nothing bursts. Your fruit is no longer crisp. It is mealy or limp or mushy. The same thing happens with a snack food degraded by moisture: Cell walls dissolve, air leaks out. The staler the chip, the quieter. |
| For a food to make an audible noise when it breaks, there must be what’s called a brittle fracture: a sudden, high-speed crack. Dr. Van Vliet takes a puffed cassava chip from a bag and snaps it in two. | For a food to make an audible noise when it breaks, there must be what’s called a brittle fracture: a sudden, high-speed crack. Dr. Van Vliet takes a puffed cassava chip from a bag and snaps it in two. |
| “To get this noise, you need crack speeds of 300 meters per second,” he said. The speed of sound. The crunch of a chip is a tiny sonic boom inside your mouth. | “To get this noise, you need crack speeds of 300 meters per second,” he said. The speed of sound. The crunch of a chip is a tiny sonic boom inside your mouth. |
| Crispiness and crunchiness appeal to us because they signal freshness, Dr. Van Vliet said. Old, rotting, mushy produce can make you ill. At the very least, it has lost much of its nutritional vim. To a certain extent, we eat with our ears. | Crispiness and crunchiness appeal to us because they signal freshness, Dr. Van Vliet said. Old, rotting, mushy produce can make you ill. At the very least, it has lost much of its nutritional vim. To a certain extent, we eat with our ears. |
| “People eat physics,” said Dr. Van Vliet. “You eat physical properties with a little bit of taste and aroma. And if the physics is not good, then you don’t eat it.” During this discussion, I have been working my way through our props. I tilt a bag of cassava chips toward Dr. Van Vliet, who waves it off. | “People eat physics,” said Dr. Van Vliet. “You eat physical properties with a little bit of taste and aroma. And if the physics is not good, then you don’t eat it.” During this discussion, I have been working my way through our props. I tilt a bag of cassava chips toward Dr. Van Vliet, who waves it off. |
| “I don’t like chips and things.” | “I don’t like chips and things.” |
| In his eight years at Wageningen University, in fact, he has never tried any of the food in the Restaurant of the Future. | In his eight years at Wageningen University, in fact, he has never tried any of the food in the Restaurant of the Future. |
Mary Roach is the author of the new book “Gulp: Adventures on the Alimentary Canal,” from which this article is excerpted. | Mary Roach is the author of the new book “Gulp: Adventures on the Alimentary Canal,” from which this article is excerpted. |