The Story of Sushi: An Unlikely Saga of Raw Fish and Rice

by Trevor Corson

  A friend tried to talk her into eating sushi; after all, the fish and seaweed contained protein and iron. At first Kate scoffed at the idea of eating raw fish, but finally she relented. Her friend took her to a neighborhood sushi bar, where Kate tried something called pepper salmon nigiri. It tasted fresh and clean. She ordered more. Then she tried albacore tuna nigiri, and next something called a crunchy roll. She stuffed herself.

  Soon Kate was eating sushi three or four times a week. She liked the food, but she also liked the fact that the sushi chefs were jocular and outgoing behind the sushi bar—just her style. She made friends with one of the chefs. She’d wait to get a seat in front of his position at the bar. She and the chef would joke with each other, and she would watch him work. He made her feel special, as if he were her buddy. Her health returned, and she gained weight.

  In Japan, there is a famous short story called “Sushi,” written in 1939 by a woman named Kanoko Okamoto, who was a poet and Buddhist scholar. It tells the story of a gentleman who eats regularly at his neighborhood sushi bar. The customers come to the sushi bar to escape themselves and the worries of their daily lives. The chef remembers what each one likes to eat and in what order, and recommends certain fish when they’re in season and especially fresh. The atmosphere of the sushi bar is relaxed, sometimes rather silly.

  The particular gentleman in the story had hated eating as a child. All foods repulsed him, especially fish. He would eat only a Japanese version of scrambled eggs. He was thin and sickly. In desperation, his mother set up an impromptu sushi bar in the house. She prepared sushi rice. As the boy sat across from her, she rolled up her sleeves and showed him her clean, empty hands. She flipped them like a magician and squeezed together a piece of sushi in her palms. She topped it with sweet fried egg cake—a common sushi topping not so different from scrambled eggs.

  Seeing his mother squeeze the sushi together especially for him made the boy want to eat it. He liked the egg and the taste of the tart, lightly vinegared sushi rice. His mother squeezed out more sushi, adding new toppings of mild white fish—flounder, then snapper. Watching her, the boy ate happily. After that he moved on to clams and squid. He grew into a strong and handsome man, and ate sushi regularly for the rest of his life.

  Kate credited sushi with her return to health. Some of her old sociability returned. She spent less time depressed and more time getting to know the people she encountered in her daily life. That made her feel better, though she still fell in and out of depression.

  She didn’t know what she wanted to do with her life. In the past she’d worked jobs in which she interacted with people—for example, as a receptionist at a hair salon, and as a hostess and cashier at a Chuck E. Cheese pizza parlor. Most recently she’d been working at a surf shop on the beach. She liked the social aspect of all these jobs, but none of them gave her the chance to get to know her customers. She wanted a career where she could build camaraderie with repeat customers over time. Better yet, one where she could joke and laugh with her customers, and help them enjoy themselves.

  One day on her way to the L.A. airport she saw a sign for the California Sushi Academy. She keyed the telephone number into her cellphone. For a year she toyed with the idea.

  Her family was skeptical. She had no cooking experience, and there was really no reason for her to leave San Diego. Her job at the surf shop was fine. She liked being near the beach, and she had started dating one of the guys who owned the shop. Still, Kate thought about it, and one day mentioned to her boyfriend that she was considering attending sushi school in L.A. He told her he didn’t want her to go.

  That didn’t sit well with Kate. She called the academy and spoke with Jay Terauchi, the coordinator for student affairs. She talked her dad into covering half of the $5,500 tuition; she would cover the other half and her living expenses. She located a tiny house she could rent month-to-month in an industrial suburb of L.A. called Torrance, near Hermosa Beach. She quit her job at the surf shop.

  A few weeks before the semester started, Kate realized she was taking a huge gamble. She stopped eating again. Right before she left, her boyfriend dumped her.

  3

  MOLD

  Later in the first week of school, Zoran piled the students into the restaurant’s old van. They drove north for an hour on a ten-lane freeway, exited near a Home Depot, and stopped at a factory that made miso. Kate thought miso was a kind of soup. What did this have to do with sushi?

  They walked through a large garage door. The company, Miyako Oriental Foods, could trace its roots back to the oldest miso-making operations in the United States, begun by Japanese immigrants in California before World War II. The factory currently made several brands of miso. A Japanese man showed the students a jar of green powder.

  ‘This is mold,’ he said.

  Without this mold, sushi as we know it wouldn’t exist. The mold’s Japanese name was kji.

  Scientists call it Aspergillus oryzae. Like all molds, it’s a form of fungus. Out in the wild, it has family who are killers. One of its closest cousins, a vicious carcinogen, doomed 100,000 turkeys and ducks in England in 1960, simply by sitting around on a pile of peanuts. Some of its other relatives are less exciting. They’re known as mildew.

  A handful of small shops in Japan are in charge of most of the good mold. Mold experts manage mold as though they are breeding racehorses. Some of the shops have been selling the best strains for centuries. They keep backup jars of mold in high-security vaults or hidden in caves. The green powder in the man’s jar consisted of mold spores—around a trillion of them.

  Mold has to eat. The spores are dormant, but when you give them something to munch on, they germinate and grow into white fuzz like the type you see on old bread.

  The man led Kate and her classmates onto the factory floor. Kate saw machines two stories tall, with conveyor belts, catwalks, and pipes going everywhere. Once a week, the Japanese man said, he pours a little mold into a funnel on one of the big machines—just enough to infect a batch of 6,600 pounds of rice. Once the rice is properly infected, he shoots it through a high-pressure pipe into an incubator the size of a house.

  The big incubator looked like a nuclear reactor. The man explained that inside, it was like a warm, moist cave. The machine cost several million dollars and was equipped with a control panel the size of a vending machine. In the old days, miso makers had simply used a box lined with a blanket.

  In the incubator, the mold gobbles away at the rice and grows at tremendous speed, sending out feelers like ivy until it has ensnared every grain of the 6,600 pounds of rice in a web. The mold eats so fast that the incubator, like a nuclear reactor, would overheat if it weren’t properly controlled. In two days, the fuzzy web has eaten so much rice that some 500 pounds of it has simply vanished.

  At that point, the man cooks 5,000 pounds of soybeans. The moldy rice rides a conveyor belt into a computerized meat grinder that churns it up with the soybeans, along with a dose of sea salt, bacteria, and yeast.

  Then the process turns low-tech. From the meat grinder, Mexican laborers shovel 1,300 pounds of the mush at a time into tubs the size of a Jacuzzi. They cover the tubs with tarps and drive them with a forklift into a temperature-controlled garage. Then the process gets really low-tech—the tubs just sit around. For months.

  Molds don’t have stomachs, but they do manufacture digestive enzymes. Enzymes are like robots in a chemical factory where the assembly line can run forward or backward; they put different molecules together or, just as often, take them apart. And they work fast. There’s an enzyme that shortens a certain chemical reaction from 78 million years to 25 milliseconds. That’s the kind of speed you want when you’re a hungry mold.

  From the mold’s point of view, the rice and soybean plants have spent their lives soaking up sunlight and building it into giant molecules that are much too complicated. The digestive enzymes take those molecules apart. The enzymes split the proteins into useful building blocks called amino acids.
They split the carbohydrates down into little energy bars in the form of simple sugars. In fact, this is just what you do with your food. Humans would not survive without the digestive assistance of enzymes. Mold and man think alike.

  Which is what makes the subsequent betrayal so tragic. After the tarp goes over the Jacuzzi tubs, the mold in the miso suffocates and dies before it has even had a chance to have sex. Or rather, since mold produces spores asexually, before it has had a chance to have non-sex. The man wants the mold just for its enzymes. The mold might need air, but the enzymes don’t. They keep right on digesting.

  Soybeans contain a lot of protein, and most of that protein is a type called glycinin. The enzymes tear it apart, leaving behind an amino acid called glutamate. Humans love glutamate. It tastes fantastic. Glutamate is also crucial for human functioning. It is the most abundant fast excitatory neurotransmitter in our brains and spinal cords; it is believed to be important for thought and memory. In addition, it is the most frequently used building block in the proteins throughout our bodies.

  The enzymes tear apart the carbohydrates in the rice as well, leaving behind glucose and other sugars—also yummy to humans.

  The process still isn’t finished. Next, the bacteria go to town. The same bacteria that make yogurt and cheese are the life of the party in miso. Cows never caught on in Japan; miso is, in a sense, Japan’s cheese.

  Like mold, the bacteria manufacture digestive enzymes, but their enzymes gobble up sugars. They leave behind lactic acid and acetic acid, some of the substances that give yogurt its pleasant tartness and prevent it—and miso—from spoiling.

  Finally, the yeasts join the party. Put crudely, yeasts eat sugar and pee alcohol. In the miso, the alcohols produced by the yeasts then react with the acids made by the bacteria. The result is a group of fruity-smelling compounds called esters, which are also present in the complex aromas of fine wine.

  When the contents of the Jacuzzi tubs have finished fermenting, the Mexican forklift operators move the tubs back out of the garage and into a refrigerated room for packaging. Now, the miso possesses just about every attribute you could want in a food: savory amino flavors, sugary sweetness, acidic tartness, salty tang, and fragrant smells, along with nutritious proteins, sugars, fats, helpful digestive enzymes, and friendly bacteria.

  It’s got something else as well. And that’s where the connection to sushi comes in. Around the edges of the tarp, a brown liquid has oozed out. It contains many elements of the miso, especially the tasty glutamate.

  Possibly as early as 1,200 years ago, discerning chefs who cooked for the Japanese aristocracy decided that plain miso, with its bumpy texture, wasn’t refined enough for the delicate tongues of their lords and ladies. They noticed the brown liquid oozing out. Instead of flavoring their dinner with miso, they drizzled the new liquid over it.

  Other, similar products were probably discovered in different places at different times in different ways, in both China and Japan. Historians don’t agree on the details. But one thing is clear: soy sauce originated as a by-product of making miso.

  Like miso and soy sauce, cured ham is rich in glutamate. Parmesan cheese is, too. So are tomatoes. Because of glutamate, a serving of sushi with soy sauce actually has taste elements in common with a plate of pasta covered with tomato sauce, anchovies, and Parmesan cheese.

  Before soy sauce, the Japanese, like the Chinese and Southeast Asians, had preferred fermented fish sauce. Vegetarianism became popular when Buddhist monks arrived in Japan in the sixth century. As in America today, Buddhist food manufacturers in ancient Japan racked their brains for ways to make soybeans taste like meat. Miso and then soy sauce were the results.

  For a long time, soy sauce remained a luxury. Japanese commoners made do with miso. Then, about 500 years ago, Japanese food companies built the first soy-sauce factories, and soy sauce became commonplace. About the same time, the makers of soy sauce added wheat to the mold fermentation process to make the sauce sweeter.

  The man at the miso factory explained to the students that Japanese companies now use mold and incubators to make soy sauce in their modern manufacturing plants.

  The same kind of mold and the same kind of incubator are also used to produce the initial stage of Japanese rice vinegar. In the case of rice vinegar, the fermentation process produces acetic acid, which is what gives vinegar its tangy sourness. And rice vinegar is what sushi chefs add to cooked rice, along with sugar and a little salt, to make it tangy and sweet.

  Kate and her classmates had been under the impression that what made sushi delicious was the fresh ingredients. In fact, the fundamental flavors of sushi—soy sauce and rice vinegar—depend on infecting certain foods with fungus and letting them get moldy.

  Kate enjoyed the field trip. It was a welcome diversion from the routine. Back in the classroom, Zoran made the students practice cutting cucumbers every day. Then he started them cutting giant white radishes using the same technique.

  Zoran continued to yell at Kate, close beside him at the head of the table. When he wasn’t yelling at her, he treated her like some sort of special-needs student, giving her extra help while the rest of the class watched or moved ahead. Kate had always prided herself on pulling her own weight in a group, on being “one of the guys.” But here, she was certain her classmates had already written her off as a total flake. At the end of every day she considered quitting.

  Week 2

  4

  TASTE OF THE SEA

  ‘These are bonito flakes,’ Zoran explained, showing the students a bag of fluffy beige flakes. He was teaching them to make a broth called dashi. Dashi is highly flavorful, and it is a cornerstone of Japanese cuisine. Dashi is the soup base to which miso is added to make miso soup. Like soy sauce, dashi plays a supporting role in sushi, but the method for making dashi is very different.

  First, Zoran had simmered slabs of kelp, a type of seaweed with broad leaves. Now he switched off the heat and sprinkled the bonito flakes into the pot. Kate watched the flakes melt into the steaming water. She gathered that bonito was a kind of fish. She’d seen those flakes before, sprinkled on food at Japanese restaurants. She’d always thought they were bacon. After a few minutes, Zoran removed the kelp and bonito flakes with a strainer. The remaining broth was dashi.

  Kelp—like miso, soy sauce, cured ham, Parmesan cheese, and tomatoes—is loaded with tasty glutamate. Called konbu in Japanese, kelp is the first half of what makes dashi delicious.

  The second half of dashi’s magic is the bonito flakes. Bonito are a type of tuna, also called skipjack tuna. Like their larger tuna cousins, they swim fast, sometimes in bursts that reach 40 miles an hour. They accomplish this feat by loading their muscles with high-energy power pellets that provide fuel to their cells. These power pellets are called ATP—adenosine triphosphate.

  The manufacturers of bonito flakes simmer fillets of bonito before smoking the fish for ten or twenty days. Like the makers of miso, they infect the fish with mold and lock up the fillets in a box. After two weeks they pull out the moldy fillets and lay them in the sun. They scrape off the old mold, add new mold, and lock them back in the box. They repeat this procedure three or four times.

  Just as with miso and soy sauce, digestive enzymes break down the proteins in the fish into tasty amino acids. The ATP gets broken down into a series of other molecules, resulting in a delicious compound called inosine monophosphate, or IMP, which the human tongue savors nearly as much as glutamate.

  After a few months of molding and drying, the bonito fillets are hard, like pieces of wood. To make the flakes, the fillets are shaved with a tool like a carpenter’s plane.

  Dashi’s role in sushi usually goes unnoticed, particularly in the United States. Most Americans think they are supposed to dunk all their sushi in soy sauce. But full-strength soy sauce overpowers the delicate flavors of raw fish. A good sushi chef adds all the flavoring the sushi needs before he hands it to the customer. He mixes his own sauce and uses it behind the
sushi bar. This sauce is called nikiri. Each chef has his own secret formula. Most are a variation on a standard recipe, and dashi is a key supporting actor. To 100 parts soy sauce, the chef adds twenty parts dashi, ten parts sake, and ten parts mirin, a sweet rice liquor used in cooking. The mixture is heated and reduced briefly, and is then ready to use. Nikiri is a kinder, gentler, and more complex soy sauce, with a broad array of flavor compounds appropriate for enhancing sushi.

  The Hama Hermosa restaurant attached to the California Sushi Academy provided its customers with straight soy sauce. But at the sushi bar, Toshi and the other chefs frequently painted a sheen of nikiri across the top of pieces of sushi with a basting brush. This was the traditional method of seasoning sushi. The chefs were forever handing sushi to customers and admonishing them, “No soy sauce!” Most sushi chefs in America don’t make this effort.

  The deliciousness of dashi and soy sauce intrigued a Japanese chemist named Kikunae Ikeda, who in 1908 figured out that glutamate is what makes kelp broth so delicious. He realized that the stuff could be manufactured. The product was called monosodium glutamate, or MSG.

  A few years later, a colleague figured out what made bonito broth so tasty. It was the IMP. Much of what makes all fish delicious is IMP, created when the ATP in the fish’s muscles breaks down after the fish’s death. Scientists discovered that IMP could be manufactured, too, and like MSG used as a flavor additive.

  Western scientists believed that the human tongue could taste only four fundamental flavors: sweet, salty, sour, and bitter. The Japanese scientists argued that there was a fifth fundamental flavor, triggered by amino acids like glutamate and compounds like IMP, and epitomized by foods such as dashi and nikiri. They called this fifth flavor “tastiness,” or in Japanese, umami.