Taste: Surprising Stories and Science About Why Food Tastes Good (14 page)

Now head of a lab at Monell Chemical Senses Center, Johan Lundström was born and raised in Sweden. He was always intrigued with smells, but it was his pet German shepherd, Ella, who was responsible for his professional path toward
olfaction. On walks, Lundström noticed that Ella would detect other dogs’ urine in places where he could not smell a thing. He knew that dogs have a more acute sense of smell than humans, but he was particularly interested in her behavior after she’d smelled another dog’s output. Sometimes her tail would go wild; sometimes she’d get anxious; at other times she’d be amorous.

“She definitely got some kind of signal from that urine,” Lundström says. Watching his dog react to the secret signals in other dogs’ urine got him interested in pheromones, the aromas that emanate from many living creatures, reportedly used as signals. Lundstrom eventually went to graduate school to earn a PhD in psychology. His team at Monell studies the science of smell in humans and how it affects our behavior.

As both a Swede and an expert in the science of olfaction, Johan Lundström told me he has never, ever, smelled anything as horrid, as putrid, as sickening as the Swedish canned fish delicacy (atrocity?),
surströmming.

“Its odor is the most foul I’ve ever experienced. And I’ve been working in olfaction for ten years,” Lundström says.

In ancient Sweden, salt was used to preserve everything, including fish, the mainstay of the Swedish diet. When the herring catch was very large and the supply of salt—expensive in ancient times—was very small, the Swedes had to get creative. Instead of curing the fish with salt, they resorted to another method to preserve an excellent harvest. They put the fish in cans along with water and just enough salt to control (but not completely halt) the growth of microorganisms, sealed the cans, and put them into storage. Because the amount of salt in the brine wasn’t high enough to completely stop all microbial growth, what happened inside the can was a type of oxygen-free—anaerobic—fermentation. In food processing we go to great lengths to avoid anaerobic fermentation. Usually, this type of spoilage gives off signals so you know not to consume the food. Sometimes the gases that develop in cans of surströmming are so strong that the cans buckle and bulge: a clear warning signal if ever there was one. Yet in Sweden this only increases the value of the putrid fish inside.

Lundström correctly refers to the above process as
rotting.
This rotten herring product is still being made in modern Sweden, although you have to be pretty committed to eat it. Swedish law prevents apartment renters from opening the putrid cans inside their homes because the stench is almost impossible to remove from a building. It’s also prohibited on some international flights. The preferred method for getting the rotted fish out of the can is to hold it under water while opening it, so the offensive aromas that escape are largely lost in the
water, as opposed to being volatized into the air. This method also acts to control the stinky contents from spraying everyone in the near vicinity of the can, as a lot of pressure builds up inside it during fermentation. Years ago, Lundström took his Canadian girlfriend to Sweden, and in an effort to share his culture with her, he and a few friends threw a surströmming party. Outside, of course. Out came the pièce de résistance: the rotted, canned, fermented herring. When the uninitiated foreigner got a whiff of it, she vomited.

Ever the curious eater, I went online to order surströmming from Sweden, but I was unsuccessful every time I tried. The U.S. Customs and Border Protection doesn’t look favorably upon bulging metal cans with foreign words on the label. So I asked Lundström to tell me what it tastes like.

“When you put it in your mouth, the odor is completely different,” says Lundström, describing the taste when surströmming is served classically, as opposed to the nauseating smell.

It’s a little bit sour. You have this very fresh taste of onion, the warm boiled potato, and the sour note of the herring on the crispy bread. That together is extremely nice. There’s this complex difference between the retronasal odor and the orthonasal smell you detect through your nose before you eat it. And no one really knows what this is.

This conundrum also fascinates Linda Bartoshuk. At her Center for Smell and Taste, Bartoshuk has experienced the same distinction between aromas that are detected outside the mouth versus inside.

“You take the same molecule. You sniff it, you like it. You put it in your mouth and you don’t like it,” she says, explaining a phenomenon that happens with some food.

Bartoshuk told me about a patient who came into the Center for Smell and Taste after injuring her tongue in a cringe-inducing accident months earlier. The woman had opened a metal can, stuck her tongue into it and licked the sharp inside, slashing the nerves in her tongue in the process. (I told you it was cringe-worthy.) Bartoshuk expected her to complain of a loss of
taste
, since she’d injured her tongue, where we
taste
food. But she visited the clinic months after the accident because she was being tortured by the smell of her mother-in-law’s lasagna.

Before the accident, the patient used to love the homemade version of this Italian specialty as prepared by her husband’s mother. After the accident, she would still salivate at the heady aroma of Italian cheeses and tomato sauce bubbling
in the oven until gooey-crisp. The problem was that when she finally sat down at the table to eat it, it tasted like cardboard.

Bartoshuk’s first reaction was that this woman was lying in order to get some kind of insurance settlement. As a good practitioner of science, though, she conducted an experiment on herself to try to duplicate the injury’s effect. She ate a bite of a milk chocolate Hershey bar and noted the sensations. Delicious. Creamy. Chocolaty. A little bit sour. Roasty. Then she anesthetized her tongue—which was easy for her to do since the Center is affiliated with the school of dentistry—but didn’t do anything to alter her sense of smell, because she was trying to duplicate the medical condition of the woman who had a slashed nerve in her tongue but an intact sense of smell. With her leaden tongue, Bartoshuk then ate a piece of that same chocolate bar. She was shocked:

It wasn’t chocolate anymore. The retronasal olfaction should have been just like normal. It should have gone right up, back, and into my nose, no problem. Here’s what I think goes on. The brain looks for a cue, to tell itself whether that particular odor came in through the nostrils or from the mouth. The cue is: When you sniff, the brain knows the smell came in through your nostrils. When you’re chewing, swallowing, and getting taste and touch in your mouth, the brain knows it’s coming from your mouth. It sends that olfactory information to different parts of the brain for processing, depending on that cue.

Now what happened to this woman with the cut nerves, she didn’t get
either
cue. She wasn’t sniffing it when she put the lasagna in her mouth. But the brain wasn’t getting the clue from the mouth either, since the nerves had been cut, so it threw the information away. Somehow the brain needs the information from the taste system to process retronasal olfaction [mouth-smelling].

Normal people with functioning taste and smell senses wildly underappreciate mouth-smelling. Scientists do not. This is a hot area of research. You can experience mouth-smelling without tasting, in the exercise at the end of this chapter.

Molecular gastronomy, the high-concept trend in cooking that took off sometime after the turn of this century, uses food science to create mind-blowing food that
is visually beautiful or arresting and presented in challenging new forms, tastes, and textures. It is often also delicious. Chefs describe their dishes as being freeze-dried, foamed, or sealed under vacuum and cooked in a controlled-temperature water bath (sous vide); these are some of the same techniques that we use at Mattson. Many of the ingredients that make molecular gastronomy possible, as well as the techniques, are common to our business. For example, at Mattson we’ve been using hydrocolloids (compounds used in food to manipulate texture and viscosity) as functional ingredients for more than three decades. In professional food development, we strive to balance culinary art with science, but unlike molecular gastronomy restaurants, we try to minimize the visibility of the science. Consumers generally feel better about eating food that’s less rather than more processed, so we use the minimum amount of processing necessary. And we certainly don’t market to customers how we do it. In fact, when consumers buy groceries, the less they read about the science that makes their food safe, extends its life on the shelf, or delivers certain nutritional benefits, the better. The fact that restaurants like Alinea in Chicago and elBulli in Spain put food-processing science in the forefront makes me just the teensiest bit uncomfortable, but other restaurant diners have been eating it up.

Dining at a molecular gastronomy restaurant is a lot of work, and I don’t mean just for the chef. It’s a lot of work from the intellectual perspective of the diner. I appreciate the judicious use and application of food technology principles to restaurant food, but some of it is just too close to work for me.

Like Pablo Picasso, who was classically trained in fine arts, most molecular gastronomy chefs are classically trained but branch out into abstractions, stretching the meaning of art and food. While Picasso’s paintings are obviously works of art, I find some of them disturbing and I certainly wouldn’t want to look at
Guernica
on my wall every day. I feel the same way about molecular gastronomy. I can appreciate the creativity and mastery of ingredient and technique, but I can’t imagine craving it the way I do a plate of perfectly cooked tagliatelle from Delfina, my neighborhood go-to Italian restaurant. When it comes to food, the higher the concept, the lower the crave-ability. What I do love about molecular gastronomy is the way it pushes boundaries to make you slow down and more carefully and thoughtfully consider the plate of food in front of you—and perhaps other meals you eat from that point forward.

Years ago, I enjoyed a twenty-three-course meal at Alinea restaurant with some girlfriends. At about course number seven, twelve, or maybe even seventeen, our servers brought three small pillows to our table, gingerly put one in
front of each of us where our place mats should have been, and instructed us not to touch. Food runners from the kitchen arrived shortly thereafter with three piping-hot plates of lamb, which they set carefully atop our pillows. The waiter explained, “Your places are set with pillows filled with coffee-scented air. As you cut the lamb into bites, the pressure on the plate will force air out of the pillow, surrounding you in the aroma of coffee, which we’ve paired with the lamb for a totally new taste experience. Enjoy.”

The three of us looked at each other and burst into giggles. When we recovered, we attempted to eat the course. I later heard Achatz interviewed about this technique, explaining that his goal was to add another sensory counterpoint to the table. I’m all in favor of this, but his technique gave an additional aroma to the environment, not the food. The difference is nose-smelling versus mouth-smelling.

When I tell Bartoshuk about this high-concept dish she cracks up, too. She says that we humans are extremely good at separating aroma in the environment from what we experience internally through mouth-smelling. As an example, she cites a big holiday meal at a table that someone has graced with a fragrant bouquet of flowers. The floral aroma that wafts from the flowers doesn’t interfere with your experience of eating, she says. In other words, the flowers don’t make the turkey taste like roses, or the mashed potatoes taste like calla lilies. That’s because we only nose-smell the flowers. The turkey flavor we get from both nose-and mouth-smelling. In other words, we smell the flowers, but we savor the food. The coffee-scented air didn’t change the flavor of the food, because we are too good at distinguishing aromas that stay outside our body from those that we experience inside the body. The fusion of taste and aroma is hard to separate, but artificially adding nose-smelling while eating food is not the same as mixing taste and aroma together in your mouth.

Still, the smell of calla lilies on a table can dredge up memories, emotions, and associations with the fragrant flower, as Achatz was trying to do with the coffee-scented air to evoke a Fragrant Flashback. He’s also done this by burning oak leaves to evoke the crisp air of autumn that smells of fragrant, fallen-leaf bonfires.

Nose-smelling something that’s not supposed to be part of a dish can interfere with, rather than enhance, our ability to experience its flavor, which combines both nose-and mouth-smelling with taste and touch. That’s why food labs like ours at Mattson frown upon heavy use of cologne. While you may be able to differentiate which way a smell came in (via the nose or mouth), it certainly
helps to have a neutral environment when you’re trying to evaluate food. Scenting the air around the food you eat can change the way you perceive a dish even though you may be unaware of it.

Humans are spectacularly sensitive to smell. In some ways, it is our most finely tuned sense. We can detect some smells at the level of parts per billion—this is akin to a few drops of liquid in an Olympic-size swimming pool. If you set up an experiment where two pools were sealed off from each other, one containing three drops of the chemical ethyl mercaptan, the other without, most people would be able to tell which pool had the chemical in it solely by the skunky smell that the chemical gives off. Ethyl mercaptan is so strong that it is often used as a warning agent in gases such as butane and propane so that we are alerted to even tiny gas leaks. Obviously, not every aroma is this strong, but the example does illustrate the sensitivity of our sense of smell. In contrast, our sense of taste is only sensitive down to a few parts per hundred.