It all starts with blood, water and fire. In the end, an ancient process that originated more than 1,500 years ago turns the small tuna species bonito into a rock-hard delicacy. Katsuobushi, known to us as bonito flakes, is the basic seasoning of Japanese cuisine and adds depth of flavor to broths, sauces and soups. Yasuhisa Seriwaza represents the fifth generation of Kanesa Bonito Manufactory. He is not only a producer using old traditional methods, but also a networker. He seeks publicity, goes to fairs and organizes events to tell about the old traditions and production methods. Serizawa is president of Slow Food Mount Fuji and aims to preserve traditional tastes.
Archaic force in a family business
On this Monday in September, we witness how the process from fish to flake begins. It has been going on in this place for 138 years and five generations. Yasuhisa Serizawa’s factory is inconspicuously located in a bend on the way down to Tago Bay in the west of the Izu peninsula with its bizarre rock formations. Two tons of tuna are delivered in the late afternoon. The fish are frozen and poured into three large basins to thaw. Outside, the sultriness of the day has subsided and the temperature is perfect for the fish to be ready for processing the next morning.
Cocktail fans and sunset photographers drive carelessly past the manufactory toward the beach. There is a bar there that only opens for the sunset spectacle. Countless photographers get into position and wait for the moment when the ball of the sun slides into the natural and round recess of the rocks for a brief moment like a precious stone. Admittedly, this expectation is not fulfilled today. The natural spectacle – as old as the earth itself – is therefore not quite so kitschy today. The course of events in Yasuhisa Serizawa’s manufacture, on the other hand, is real and of archaic force.
Namagiri – The battle begins
The next morning, work begins for Yasuhisa Seriwaza and a good 15 employees. Among them are his parents. Next to the basins, a kind of guillotine is brought into position. The head of the small tuna species bonito, weighing about five kilos, is cut off in the rattling machine. Then begins a process based on the division of labor, in which everyone knows their place and their task. Steam is rising, water is splashing out of the hoses. The work surface is constantly cleaned with a gush of fresh water. There is never any idling. The headless fish are cut in half with a knife and the innards removed. A job that requires strength and skill.
The Japanese attach great importance to the complete utilization of an animal. The heart of the tuna sits very close to the head. A worker kneels in front of a vat of fish heads and carefully detaches the tuna heart. It is considered a delicacy in Japan. The hearts are later picked up by a restaurant owner. At a small round table, two women squat on stools. With their small knives, they sort the offal. The stomach contents are removed. Almost everything else is collected for further processing for a fish paste that is later rubbed into the fillets.
Shakuju is a matter for the boss
The division of labor is as conscientious and calm as each half of the fish seems to have its place in the production process. There is little talking. The foreman, who has just detached the tuna hearts from the headboard, is now setting up a new workstation. Steam rises.
The immersion tanks for the boiling process have long since been brought up to operating temperature. And this temperature is 90 degrees. Rather than fish, it now smells of blood. The billowing steam gives this place the atmosphere of an eerily beautiful movie set.
Serizawa guides the basket, called a nikgao, containing the tuna halves into a custom-made dip tank. This is the most sensitive part of the production. This is because the careful simmering of the fish determines its shape and is the basis for the desired intensity of flavor. Shakuju is absolutely a matter for the chef. Serizawa has its own clock for each dip. The water must never boil, it must only simmer and the whole process must not exceed two hours.
The long tradition of tuna processing
In Nishi-Izu, people have been living off tuna for 1,500 years. It started with the preservation by sun drying. Later, salting was added to the sun. In the Edo period, about 360 years ago, the production of katsuobushi developed. Sun-drying and salting is preceded by simmering the fish fillets in 90-degree water.
The next workstation is set up. The water is let in and a newly formed team begins the laborious process of deburring the fish halves. They are now split into two pieces, approaching their eventual shape. Despite great caution, pieces break off again and again during the deburring process. This blemish is leveled by the paste of fish guts. Each piece of fillet is rubbed and brought into shape. Syuzen (repair) is the name of this step.
After boning, the fish comes into contact with the smoker for the first time. The fillets are placed on wooden stretchers and stacked over a wood fire. 130 to 150 degrees has this first heat. It is a traditional smoking method. Only a handful of katsuobushi producers throughout Japan still smoke with these old ovens. This requires two people to watch the fire for about eight hours.
What makes katsuobushi like honkarebushi
Then begins a process that is repeated ten times at Serizawa. The fillets go into the smokehouse for a day and then rest for a day. The internal residual moisture of the fillet permeates to the outside. The fish is put back into the smoking chamber. The residual moisture escapes to the outside and is dried again. At the end, the fish has a residual moisture of around 23 percent and can call itself Arabushi. But a lot of time and work will pass before the perfect bonito flake, honkarebushi, is achieved.
Using the means of fermentation
Unlike the major factory producers in the country, Serizawa still brings fermentation into play at this point. This involves spraying the outer smoke crust of the fillets with Aspergillus Ripens and storing them in cedar barrels. This watering can fungus can stand up to high dryness. If the fish ferments too long, the mold culture does a great job and the fillets become soft like blue cheese, Serizawa explains.
To control the koji fungus, the fillets are placed in the sun. The entire courtyard of the manufactory is then covered with tatami mats. The fillets now look like whole fish again and form a beautiful pattern on the mat. After sunbathing, the mushroom has been given a damper, the fillets are wiped off and placed in the cedar barrel for another 20 days. This procedure is repeated six times. If the fish looks rather bluish at the beginning of this procedure, it turns beige-brown at the end. The desired effect is a further reduction of the water content with simultaneous extraction of umami.
Feather-light flavor booster
Six months after the bonito tuna is delivered to Yasuhisa Seriwaza’s Kanesa Bonito Manufactory, the fish has reached a water content of 17 percent. With the help of a plane, the fish is planed from tail to head. In order to know where the top and bottom are after six months of intensive treatment, part of the skin is left on the end of the tail. Freshly planed, the Honkarebushi has its most intense flavor. A real gourmet product. In stores and for everyday use in making daily miso soup, Japanese buy the sliced variety.
Bonito in bast dress
Shio-katsuo, salted and sun-dried used to be even a means of payment to the administration. The custom of hanging it on the front door on New Year’s Day has survived to this day. After the New Year, the fish is cut up by the father and eaten with the family. Today, Serizawa is still the only producer in all of Japan that does this according to the old methods. The oldest way of preserving tuna is dying out. To preserve the taste of Shio-Katsuo and with it the tradition is another mission of Yasuhisa Serizawa.