Carefully ascending the building’s steep staircase, I follow Tsunenori Kano to the floor of the fermentation room at Kadocho—his family’s 180-year-old soy factory.
The space is dark and eerily silent, except for the creak of my footsteps on the old wooden boards arranged between the soy sauce containers. The soy sauce was now at rest, it was late winter, but it still filled the air with an appetizing aroma.
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Around me, a thick crust of fungus covered the ceiling, falling from the rafters and growing along the walls.
“It’s the bacteria and yeasts, they have the age of construction”, says Kano, who is part of the seventh generation of the factory. According to him, “they provide the authentic flavor”.
I was in Yuasa, a quiet Japanese port located in a bay on the west coast of the Kishu Peninsula in Wakayama Prefecture, on a journey to learn about the ancient origins of the “holy grail” of Japanese cuisine: soy sauce, or shoyu
Origin dates back to the 13th century
Soy sauce is undoubtedly the most important condiment in Japanese cuisine. Its rich, deep and balanced flavor, both sweet and salty (known as “umami”), provides almost all foods with the satisfaction of a delicious taste. Its uses range from a dab of sushi to larger amounts in stewed noodles and stir-fries, as well as the characteristic flavor of bright dishes like teriyaki.
In 2017, the Japan Agency for Cultural Affairs declared Yuasa a Heritage Site of Japan, as it is the birthplace of Japanese soy sauce. Shoyu is believed to have been made there for the first time in the late 13th century.
Tsunenori Kano: seventh generation of Kadocho soy sauce factory — Photo: TOM SCHILLER/BBC
The popular condiment emerged shortly after a Japanese Buddhist monk, Shinchi Kakushin, returned from a trip to China and became abbot of Kokoku-ji Temple near Yuasa. He brought with him a recipe for kinzanji miso, a unique, full-bodied type of miso (fermented soybean paste, commonly used in soups and sauces) made from whole soybeans, a variety of other grains (such as barley and rice), and other ingredients. of plant origin.
The people of Yuasa soon realized that as the kinzanji miso ingredients were pressed with heavy stones, the liquid that accumulated in small amounts in the fermenting basins was delicious. This by-product was named tamari (a generic Japanese word meaning “to accumulate”) and became the basis of the soy sauce we know today.
Over the years, from being a stopping point on the Kumano Kodo pilgrimage route — which leads to the famous temples and shrines of nearby Mount Koya — Yuasa has developed into Japan’s most important soy-making center.
In its heyday, the tiny town of only about 1,000 homes was filled with soy sauce factories—in all, more than 90, or nearly one for every 10 homes.
To this day, kinzanji miso is a popular delicacy in the region, consumed as a snack, side dish or even as a light meal — Photo: TOM SCHILLER/BBC
Currently, the city’s historic district is protected by Japanese law. It is an extensive area that encompasses 323 houses and other hongawara-buki (traditional buildings) recognized for their immense cultural value.
Many of these buildings still retain their traditional lattice windows and curved tiles, architectural features that symbolized the prosperity of their owners to anyone who passed through the street. They include five soy sauce stores and six kinzanji miso makers that are still in business.
Visiting these buildings brings with it the remarkable history of the intertwined progress of kinzanji miso and soy sauce.
The distinctive flavor of Yuasa soy sauce reflects its ancient origins from kinzanji miso. Unlike other types of miso, which are spreads used as a condiment, kinzanji miso is a nutritious and exquisitely flavored dish.
It is a culinary relic of the Song dynasty, considered one of the great developments in the gastronomic world, at a time when new and exquisite flavors were created from common ingredients. It has remained a popular delicacy of the region over the centuries, eaten as a snack, side dish or even as a light meal, added to a bowl of rice or mixed with chagayu (porridge made from rice, water and tea).
The kinzanji miso was part of all my meals during my stay in Yuasa.
The liquid that accumulated in the kinzanji miso fermentation vats became the basis of the soy sauce we know today — Photo: TOM SCHILLER/BBC
But tamari, a by-product of kinzanji miso, was so tasty that locals wanted to find a way to produce it in larger quantities. That’s when they successfully adapted the production method of kinzanji miso to create soy sauce, which is a thinner form of tamari with a similar flavor.
Founded in 1841, Tsunenori Kano’s Kadocho is one of Yuasa’s oldest soy factories still in business. The soy sauce they produce is as close to the original as can be found in Japan today.
Few soy sauces are still made in the traditional way, using wooden barrels and long paddles — Photo: GETTY IMAGES/BBC
As we walked down from the fermentation room, Kano showed me around the factory and explained how the soy-making process was adapted from the production of kinzanji miso.
Pointing to old wooden tools and iron machines, he said that, to make soy sauce, only two types of beans are used (cooked soybeans and roasted wheat) — these are crushed to better extract their flavor and umami (while, in the case of kinzanji miso, they are left whole).
The beans are then mixed with koji kin (green spores of the Aspergillus oryzae fungus), in the same way as for kinzanji miso, and kept for three days in a closed room, called a wall, where the temperature is carefully controlled. There, the grains germinate, and their starches are converted into sugars, which favor fermentation.
This mixture is then placed in wooden barrels with massive amounts of fresh water and salt (which replace the water-rich vegetables used for kinzanji miso) and fermented for at least a year and a half to achieve the same kind of smooth flavor. and kinzanji miso complex.
A strong-looking man, Kano says that much of his work is done by hand — which includes regularly mixing the batter from his 34 large barrels with long wooden paddles and pressing the soy sauce out of the mixture when it’s done. Finally, Kano slowly heats the soy sauce in an iron cauldron for half a day to stop the fermentation, using pine wood for the fire.
— Photo: TOM SCHILLER/BBC
But only about 1% of the soy sauce produced in Japan by about 1,200 companies is still made in the traditional way, using wooden barrels, according to Keiko Kuroshima, a licensed soy sauce inspector and evaluator. A self-styled shoyu sommelier (there are only three in Japan), Kuroshima is the author of the definitive guide to soy sauce: Shoyu Hon (“The Shoyu Book”, in free translation), published in 2015.
“Most soy sauce is mass produced in stainless steel tanks to create flavor consistency in the shortest amount of time possible, often using artificial means to speed up fermentation,” she explains.
“Wooden barrels help create greater flavor diversity due to the microorganisms that live in them. They also better reflect the producer’s technique and greater dedication to the process.”
Kadocho’s soy sauce, with the characteristic flavor of the soy sauce produced in Yuasa, is full-bodied and intensely rich in flavor, yet still has a pleasant aroma and is velvety like an aged cognac. Its flavor reflects, in part, the use of a higher proportion of protein-rich soy to wheat compared to the industry standard.
Most producers, even traditional ones, use a 50:50 ratio of soy and wheat, which produces a less full-bodied, lighter-tasting soy sauce.
The Kubota soy sauce factory — another former Yuasa producer — makes two types of soy sauce. One, to my surprise, is made with 80% soy and only 20% wheat. The other, according to the matriarch of the Fumiyo Kubota family, is “light” soy sauce, made with 70% soy and 30% wheat.
When I visited her, she was busy preparing koji—the mixture of koji kin, soy, and wheat—for a new batch of soy sauce that she will leave to ferment for a year and a half to two years.
Facing the competition
The number of shoyu makers in Yuasa has dropped dramatically in the last century. The main factor is competition from mass producers, “who mainly compete on price, as the quality of their soy sauce is standardized,” according to Kuroshima.
Traditionally brewed soy sauce is about two to three times more expensive than mass-produced soy sauce.
“Competition is so intense that it is removing not only traditional producers, but even mass manufacturers in recent years,” she says.
Traditional soy sauces have a wider flavor range — Photo: GETTY IMAGES/BBC
But some producers have been challenging this trend. One of them is Toshio Shinko, who works to re-establish Yuasa’s position as a leader in shoyu making. Shinko represents the fifth generation of owners of the kinzanji Marushinhonke miso factory — a company founded by her great-great-grandmother in 1881.
In 2002, Shinko created Yuasa Soy Sauce, in a new building strategically located on a hill on the outskirts of town. He claims that he aims to “make the best shoyu in the world”, combining the best possible ingredients with ancient techniques such as wooden barrels, as well as new production methods.
And their main soy sauce, called Kuyo Murasaki, includes a special ingredient: some of the rare tamari by-product of the family’s kinzanji miso.
Shinko has also created a line of specialty products, including organic and halal soy sauce, to ensure the condiment remains on consumers’ tables for years to come.
Yuasa’s official recognition as the birthplace of soy sauce has revitalized the community, promising more variations and uses of soy sauce.
And to celebrate this fascinating future, before leaving Yuasa Soy Sauce, I stopped by the factory cafeteria and enjoyed a cone of their soy sauce ice cream — delicious.
Soy sauce is used in a wide variety of Asian dishes — Photo: GETTY IMAGES/BBC