Cautiously climbing the building’s steep stairs, I follow Tsunenori Kano to the fermentation floor of Kadocho, his family’s 180-year-old soy factory.
The room is dark and eerily quiet, except for the creak of my footsteps on the old wooden boards placed between the soy sauce containers. The soy sauce was already 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, fell from the rafters, and grew along the walls.
“These are bacteria and yeast, they are of construction age,” says Kano, a member of the seventh generation of the factory. According to him, “they provide an authentic taste.”
I was in Yuasa, a quiet Japanese port nestled 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.
The origin goes back to the 13th century.
Soy sauce is undoubtedly the most important condiment in Japanese cuisine. Its rich, deep and balanced taste, both sweet and salty (known as “umami”), makes almost all foods delicious. Its use ranges from small amounts of sushi to large amounts in noodle stews and stir-fries, and to add a distinctive flavor to colorful dishes such as teriyaki.
In 2017, the Japan Cultural Affairs Agency declared Yuasu a Japanese heritage site as it is the birthplace of Japanese soy sauce. It is believed that Shoyu was first made here at the end of the 13th century.
Tsunenori Kano: The seventh generation of the Kadocho soy sauce plant — Photo: TOM SHILLER/BBC
The popular condiment appeared shortly after the Japanese Buddhist monk Shinchi Kakushin returned from a trip to China and became the abbot of the Kokoku-ji temple near Yuasa. He brought with him a recipe for kinzanji miso, a unique, rich type of miso (a fermented soy paste commonly used in soups and sauces) made from whole soybeans, various other grains (such as barley and rice), and other plant-derived ingredients.
The people of Yuasa soon realized that because the miso kinzanji ingredients were pressed with heavy stones, the liquid that accumulated in small amounts in the fermentation bowls was delicious. This by-product was named tamari (a common Japanese word meaning “to accumulate”) and became the basis for the soy sauce we know today.
Over the years, Yuasa has evolved from a stop on the Kumano Kodo Pilgrimage Route, which leads to famous temples and shrines on nearby Mount Koya, to Japan’s most important soybean production center.
In its heyday, the tiny town of only about 1,000 houses was filled with soy sauce factories—more than 90 in all, or almost one in every 10 houses.
To this day, cilantro miso is a popular delicacy in the region, eaten as an appetizer, side dish or even as a light meal — Photo: TOM SCHILLER/BBC
Currently, the city’s historic district is protected by Japanese law. This is a vast area that includes 323 houses and other Hongawara-buki (traditional buildings) known for their great cultural value.
Many of these buildings still retain their traditional barred windows and curved tiles, architectural features that symbolized the prosperity of their owners to anyone who walked down the street. These include five soy sauce shops and six miso kinzanji makers still in operation.
A visit to these buildings brings with it a wonderful history of the intertwining development of miso and soy sauce.
The distinctive taste of Yuasa soy sauce reflects its ancient origins from kinzanji miso. Unlike other types of miso that are used as a condiment, kinzanji miso is a nutritious dish with an exquisite taste.
It is a culinary heirloom from the Song Dynasty, considered one of the greatest achievements in the gastronomic world at a time when new and exquisite tastes were created from ordinary ingredients. For centuries, it has remained a popular delicacy in the region, eaten as an appetizer, side dish, or even as a light snack, added to a bowl of rice or mixed with chagai (a porridge made from rice, water, and tea).
Miso kinzanji was part of all my meals during my stay in Yuasa.
The liquid accumulated in kinzanji’s miso fermentation vats became the basis of the soy sauce we know today — Photo: TOM SHILLER/BBC
But tamari, a by-product of kinzanji miso, was so delicious that the locals wanted to find a way to produce it in large quantities. It was then that they successfully adapted the kinzanji miso production method to create soy sauce, which is a more liquid form of tamari with a similar flavor.
Founded in 1841, Tsunenori Kano’s Kadocho is one of the oldest operating soybean factories in Yuasa. The soy sauce they produce is as close to the original as you can get in Japan today.
Few soy sauces are still made in the traditional way using wooden barrels and long spatulas — Photo: GETTY IMAGES/BBC
As we left the fermentation room, Kano showed me around the factory and explained how the soy-making process had been adapted from the production of miso kinzanji.
Pointing to old wooden tools and iron machines, he said that only two types of beans (boiled soybeans and roasted wheat) are used to make soy sauce – they are crushed to better extract their flavor and umami (while in the case of kinzanji, miso , they are left intact).
The beans are then mixed with koji kin (green spores of the fungus Aspergillus oryzae) 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 that promote fermentation.
This mixture is then placed in wooden barrels with plenty of fresh water and salt (which replaces the water-rich vegetables used for cilantro miso) and fermented for at least a year and a half to achieve the same smooth taste. miso complex.
A strong-looking man, Kano says most of his work is done by hand, including regularly stirring the dough from his 34 large barrels with long wooden spatulas and squeezing the soy sauce out of the mixture when it’s ready. Finally, Kano slowly heats the soy sauce in an iron pot for half a day to stop the fermentation, using pine wood for the fire.
— Photo: TOM SHILLER/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 grader. A self-proclaimed shoyu sommelier (there are only three in Japan), Kuroshima is the author of a comprehensive guide to soy sauce: Shoyu Hon (The Book of Shoyu, 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, often using artificial means to speed up fermentation,” she explains.
“Wooden barrels help create a greater variety of flavors thanks to the micro-organisms that live in them. They also better reflect the manufacturer’s technique and greater dedication to the process.”
Kadocho soy sauce, with the characteristic taste of soy sauce produced in Yuas, has a rich taste and rich taste, but at the same time it has a pleasant aroma and velvety like aged cognac. Its flavor partly reflects the use of a higher proportion of protein-rich soy versus wheat compared to the industry standard.
Most manufacturers, even traditional ones, use a 50:50 soy to wheat ratio, which results in a less rich and lighter soy sauce.
Kubota Soy Sauce Factory – another former Yuasa manufacturer – produces two types of soy sauce. One, to my surprise, is made from 80% soy and only 20% wheat. The other, according to family head Fumiyo Kubota, is a “light” soy sauce made up of 70% soy and 30% wheat.
When I visited her, she was busy making koji—a mixture of koji-kin, soy, and wheat—for a new batch of soy sauce, which she left to ferment for a year and a half to two years.
Encounter with competition
The number of shoyu producers in Yuasa has declined sharply over the last century. According to Kuroshima, the main factor is competition from mass producers, “who mostly compete on price since the quality of their soy sauce is standardized.”
Traditionally brewed soy sauce is about two to three times more expensive than mass-produced soy sauce.
“Competition is so intense that in recent years it has been crowding out not only traditional manufacturers, but even mass producers,” she says.
Traditional soy sauces have a wider flavor range – Photo: GETTY IMAGES/BBC
But some manufacturers are challenging this trend. One of them is Toshio Shinko, who is working to restore Yuasa’s position as a leader in shoyu production. 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 conveniently located on a hill on the outskirts of the city. He claims to strive to “make the best shoyu in the world” by combining the finest ingredients with ancient techniques such as wooden barrels, as well as new production methods.
And their base soy sauce, called Kuyo Murasaki, includes a special ingredient: some rare tamari, a by-product of kinzanji’s family-owned miso.
Shinko has also created a line of specialty products, including organic and halal soy sauce, to keep the condiment on the table for years to come.
The official recognition of Yuasa as the birthplace of soy sauce has revived the community, promising more variations and uses for soy sauce.
And to celebrate this exciting future, before I left Yuasa Soy Sauce, I went to the factory canteen and had a cone of their soy sauce ice cream – delicious.
Soy sauce is used in many Asian dishes – Photo: GETTY IMAGES/BBC