Kyoto is known for its temples, gardens, and beauty, so it figures that I'm here to visit a factory. I take a cab from the train station to a nondescript commercial street and enter Denkichi Matsuno's tiny, neat shop, which veils the entrance to his rambling shoyu kojo, or soy sauce factory.
The factory is dark and moist. Everything, it seems, is made of wood: beams, planks, buckets, rakes, scoops, and baskets, have all been worn smooth by decades of hard labor. This wood has personality.
So does the mixture of soy and wheat, which is going to be tossed, aged, cooled, warmed, salted, and stored. It will ferment and bubble and turn mahogany, the same color as the wood that stores it. Behind the green rawness of the mash, I smell the promise of good soy sauce and I get hungry, instantly.
In Japan, shoyu (soy sauce) is ubiquitous, irresistible, and the heart and soul of the nation's food—one never tires of it. Soy combines all the urgency of salt (one of its major ingredients) with the complexity of Parmesan (like the cheese, it is fermented and aged) and the convenience of a liquid condiment.
My own near-addiction to shoyu is what compelled me to visit Japan. East Asian food was my first culinary love, and it remains my favorite. Now, in middle age, I felt that I had gone long enough without understanding shoyu's complex roots.
In Japan, when two people from different regions are newly married, the type of soy used in the household becomes an issue, one that is resolved by a combination of who does the cooking and who holds the power. A Japanese person would switch soy preferences no sooner than most Americans would change their brand of mayonnaise. And as much as we use mayo, it's nothing compared to how often shoyu appears in Japanese food. Shoyu is served at breakfast, for dipping toasted nori or broiled salmon; at lunch with meat, fish, or chicken; and at dinner with noodles, tempura, or sushi. It's part of snacks as well as large meals, where it often appears in every dish, including dessert.
The origins of shoyu are not clear, though it likely began as an extract of fish preserved in salt (a similar sauce, garum, was used in ancient Rome, and nam pla remains a staple in Southeast Asia). Shoyu, like tofu and miso, is believed to have come to Japan from China. There are mentions of it in the Taiho-Ritsuryo, an eighth-century A.D. law code, but it was only in the 17th century that the process used today was fully developed.
Denkichi Matsuno's factory is made up of a series of large, high-ceilinged wooden rooms, some open to the elements, some closed. The shoyu-making process begins with the steaming of several hundred pounds of soybeans and roasting an equal weight of wheat (Matsuno's roaster is gas-fired)—the most common proportion used to produce koikuchi shoyu, the standard blend. The hot ingredients are scooped onto a wooden board, spread out, and sprinkled with aspergillus oryzae, the special fungus that causes fermentation. The mixture is then shoveled and tossed, shoveled and tossed.
When well mixed, the mash (no one calls it that, but this is so much like making beer that it seems natural) is scooped into a metal cart with wire partitions, which in turn is put in a closed room. Here it will sit for two days, during which time it becomes koji. The mixture must ferment, but not too much, or it turns into a sticky, smelly paste unsuitable for making shoyu.
Treated correctly, the koji dries out and gains a chestnut-like aroma; at this point it is combined with salt water in 600-gallon vats. The mixture in the vats is called moromi; it must be stirred daily in summer, when it ferments, bubbles, and sends out ripples in mysterious patterns, but only occasionally in winter, when it remains practically dormant.
I taste. At six months, the moromi is delicious but one-dimensional, young and simple, like new wine in a barrel. At 18 months—the time it takes to produce top-quality shoyu—the moromi is darker in color, and even more delicious. You want to eat it with a spoon, and I do. Moromi can be used as a condiment or ingredient in cooking; to the uninitiated, like me, it looks like loose miso, and tastes like it, too.
When it's ready, the moromi is pressed, and the resulting liquid is heated (which not only preserves the flavor but also intensifies it) and bottled. Matsuno makes several kinds of soy sauce, including one that requires a two-year process, in which shoyu, replacing the salt water, is once more mixed with fresh koji and then re-fermented to make saishikomi. This blend has powerful umami, the complex, brothy "fifth taste" associated with the essential Japanese stock called dashi (most often made from kelp or dried bonito), Parmesan cheese, MSG, and a host of other foods.
The walls and ceilings, as well as the exteriors of some of the vats, are mottled and dark with fungus, the result of nearly two centuries of bacterial action: a sight hideous or beautiful, depending on your perspective. (You can tell that representatives of the USDA have not yet gotten around to sanitizing the soy sauce-making process, or this would all be gleaming stainless steel, like a cottage-cheese factory.)
Matsuno loves this fungus; his livelihood depends on taming, shaping, and using it to produce the liquid that has been his family's stock-in-trade since 1805. He represents the sixth generation to run the business, and though he has undoubtedly been the most enterprising of his line (his shoyu is sold at Takashimaya on Manhattan's Fifth Avenue at five times the price of commercial soy sauces available in the United States), he may be the last. Over tea, he told me that his daughter shows little interest in following in his footsteps.
Matsuno makes 26,000 gallons of shoyu a year. A couple of days earlier, I spent some time in the Kikkoman factory in Noda, which produces more than 90,000 gallons a day. Of the approximately 1,600 companies making soy sauce in Japan, Kikkoman is the largest, turning out at least a dozen different varieties—ranging from a traditionally made shoyu to relatively light (and even "lite" or low-sodium) soy sauces.