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Ark of Taste

Ark of Taste is a project to select rare and traditional unique ingredients and traditional processed products according to global guidelines and to protect and pass on small producers, their production and consumption, and the diversity of food in the region.

Slow Food Ark Of Taste  registered ingredients in Mt. Fuji area

(Bonito Preserved in Salt)

Izu Peninsula

Traditional  TOKOROTEN 

(Fermented Dried Bonito)

(liquid seasoning made from bonito)


・Bonito Preserved in Salt(SHIO-KATSUO) *Tago,Nishi-Izu Town


-The origin of bonito soup-

To make shio-katsuo, frozen bonito is defrosted, cleaned, and salted inside and out with a large quantity of salt over two weeks. It is then dipped in salt-dip that has been used for the previous preserving, before being rinsed with clean water. The bellies of the fish are opened with bamboo skewers, and two fish are tied together and hung in pairs. The fish then dry in a shady area for about three weeks.

Shio-katsu can be eaten sliced thinly and marinated in vinegar or lemon, and pairs well with sake. Another traditional dish using this product is ochazuke, which consists of a bowl of rice and a bit of the fish topped with hot water or tea, creating a soup dish with a strong umami flavor. Shio-katsuo flakes can also be used as a seasoning or topping for udon noodles, pasta or salad.  

People began producing shio-katsuo regularly during the Edo period (1603 – 1868) in the district of Nishi-izu. It is not only thought of as a food but also as a sacred food offering to God. Dried bonito was also used as a currency in paying taxes. Shio-katsuo was also part of the New Year’s celebration, where it would display in front of houses or in shrines in the hopes of a good fishing season and protection at sea and luck and prosperity for individual families. The product was also part of a traditional feast shared among fishermen at the end of the season; sharing this dish meant the same crew would work together at the next season. While shio-katsuo is still part of New Year’s festivities, the custom of the shared meal related to the fishing crew has been lost.   

Today, just a handful of producers still make shio-katsuo, processing about 800 bonitos per year. The product is mainly consumed locally, both for special occasions and as an everyday food. The use of the fish in the traditional New Year’s celebration, though, is declining, and with most producers in their 60s with no young people to continue the tradition, shio-katsuo is on the brink of being lost for good.
Bonito Preserved in Salt is a preserved food made by immersing in high-concentration salt.

Even the internal organs and bones removed in the process of making are fully utilized.

* The manufacturing method is completely different between Katsuo-bushi(Fermented Dried Bonito), which has been manufactured since the Edo period, and  Shio-katsuo(Bonito  Preserved in Salt)which has been manufactured since 1300 years ago.


Slow Food Mt. Fuji Youtube channel
(Click the photo to see the video)

​Making "Shio-katsuo"


​The food culture of BONITO passed down in the Tago district of Nishi-izu Town


・Izu Peninsula Traditional TOKOROTEN


Tokoroten is a traditional Japanese dish of noodles made of gelatin derived from marine algae. It likely developed during the Heian Period (794-1185) but did not become widespread among the general population until the Edo Period (1603-1868), when it was often eaten as a cooling dish on hot summer days. Tokoroten is made by boiling various species of red algae, known in Japanese as tengusa, so that they release the polysaccharides that support their cell walls. The resulting gelatinous liquid is the basis for agar, the clear jelly that is used in laboratory sciences as a growth medium for microorganisms (the seaweeds that make agar are known collectively as agarophytes). Agar also has numerous culinary applications as a thickener and a vegetarian substitute for gelatin. Known in Japanese as kanten, agar may have been accidentally discovered in Japan in the 17th century when a seaweed soup was left outside during the winter and froze, resulting in a dry substance that was reconstituted through boiling to create a jelly with a pleasant texture.

Tokoroten is made by boiling dried tengusa in water until the liquid starts to thicken, at which point it is strained into a tray and allowed to cool so that it will set, forming a clear gelatin. This is then cut into long blocks and made into noodles using a tentsuki, a rectangular wooden tube with a screen at one end through which the blocks of gelatin are pushed to cut them into noodles. Tokoroten does not have much flavor; the noodles are served cold with sauces or condiments that vary by region: Black honey is popular in Kansai, fish sauce in Kochi, ponzu sauce in Kyushu, or sweet vinegar in Nagoya, for example.

Among the species of red algae most commonly used for tokoroten are Gelidium elegans (known in Japanese as makusa, and considered to be female algae) and Gelidium pacificum (known as obusa, and considered male algae). Makusa makes a soft, sticky gelatin, while obusa makes a gelatin that is thicker and firmer. Tengusa is categorized based on how it has been prepared: Akakusa is rinsed and dried tengusa; sarashi is tengusa that has been repeatedly washed and dried in the sun, giving it a very pale color (the best sarashi, which makes the highest-quality tokoroten, is called tora); kisarashi is tengusa that has not been washed; and aosarashi is tengusa that is left to sit for a while before drying. Tengusa is also classified based on how it was harvested: If picked directly from the sea floor, it is called okigusa, while washed-up tengusa gathered from the beach is known as yorigusa and is considered to be of lesser quality. Traditionally, tengusa was harvested by divers known as ama (literally “women of the sea”). Ama are best known for diving for pearls, but they also collect shellfish (such as abalone and oysters) and seaweed.

One of the areas most closely associated with tengusa harvesting is the Izu Peninsula and Izu Islands on the west coast of Honshu (about 60% of Japan’s Gelidium comes from this area), but it is also harvested in other regions of the country. Unfortunately, there are not many ama divers left—the last woman to practice this tradition in Inatori, a town on the Izu Peninsula, died a few years ago. The future of traditional tokoroten is also at risk because, instead of using dried tengusa to make the noodles at home, many people now buy agar in powder or strips; and because of the general overharvesting of Gelidium worldwide: Japan was the only supplier as recently as the early 20th century, but harvesting ramped up in other parts of the world following WWII, and peaked between the 1960s and 80s. Continuing to produce tokoroten from hand-harvested tengusa is an important way to maintain the direct link between traditional Japanese gastronomy and the sea by preserving the practices and knowledge that constitute these traditions.


・IZU TAGOBUSHI (Fermented Dried Bonito)*Tago,Nishi-Izu Town


Bonito or skipjack tuna (Katsuwonus pelamis), a medium-sized fish in the tuna family, is a fundamental to Japanese gastronomy, and is known in Japanese as katsuo.
The lean fillets of this fish are used to make a number of dried and smoked products that are collectively called katsuobushi, and which impart umami flavor to various dishes.
Thin shavings of katsuobushi are used as a condiment or as one of the base ingredients for the broth known as dashi.
One of the origins of Japanse bonito soup stock (dashi) is shio-katsuo (Bonito preserved in salt: also on Ark of Taste), which is salted but un-smoked bonito. Its history spans over 1300 years.
Katsuobushi has been made for about 350 years. It is different from shio-katsuo production method, and is produced through a lot of time and various processes.

Different types of katsuobushi are distinguished based on how they are processed: The most basic and widespread type, arabushi, is smoked and dried, while karebushi is smoked, dried, and fermented several times with Aspergillus glaucus mold, which grows on the surface of the fillets, preventing the growth of unwanted microorganisms, drawing out any remaining moisture, preventing oxidation, and sealing in the umami flavor. This fermentation technique was introduced during the Edo Period. The very finest karebushi, fermented more than 3 times, is known as honkarebushi, and is produced in just a few places in Japan.

Tagobushi is a particular kind of honkarebushi from Tago, a village in the town of Nishiizu on the Izu peninsula in Japan’s Shizuoka Prefecture. The process for making tagobushi involves more than 30 steps and takes about 6 months: First, each fish is gutted, the head is removed, and the lean portion of the fillet is separated from the fatty belly before being simmered in water. After simmering, the bones and skin are removed, and the fillets are smoked over an open flame at a temperature of about 130°C. This firing technique, known as tebiyama, originated in Tago about three centuries ago and is the distinguishing feature of tagobushi (other kinds of katsuobushi are typically smoked at a temperature of about 80°C); it helps to seal as much flavor as possible inside the fillet and extends the product’s shelf life. Following this initial smoking, the fillets are smoked another 10 times or so to enhance flavor and remove moisture.
The smoking fires are fueled exclusively with locally harvested oak and cherry logs. Following smoking, the fillets are sprayed with mold and fermented for 20-30 days, before being scraped (so that the mold does not penetrate too far into the fillet) and dried in the sun for a day.
This process is then repeated another five times (most other honkarebushi is fermented a total of three or four times). By the end of the 6-month production process, the fillets are less than one sixth their original weight and have the appearance and texture of dried wood.
All of the byproducts that result from tagobushi production are also used: The organs and belly of the fish are salted and eaten; the wood ash from the smoking fires is used as fertilizer or to make lye (which is important in the traditional production of konnyaku); and the bones may be used as fertilizer or, along with the heads and other trimmings, to make a concentrated liquid condiment known as katsuo irori (also an Ark of Taste product).

During the Edo Period (1603-1868), the Izu peninsula was one of three leading regions for the production of dried bonito products, and Tago had an important fleet of bonito fishing boats. Until the mid-20th century, there were a few dozen shops in Nishiizu that sold dried bonito products, but today the local artisanal fishing and processing industry has declined, and Izu tagobushi is an extremely rare product, due in large part to the laborious, time-consuming manual processes involved. The remaining producers source frozen whole bonito from the nearby city of Yaizu, and sell their tagobushi almost exclusively within Japan. Production takes place year round, though demand is highest between October and January. Given its long history, strong link with the local territory, the sustainable use of byproducts and unique reliance on the tebiyama method, and its incredible flavor profile, Izu tagobushi must be protected and promoted.

・KATSUO IRORI (liquid seasoning made from bonito)  *Tago,Nishi-Izu Town


Katsuo irori is a liquid seasoning made from bonito or skipjack tuna (Katsuwonus pelamis), a medium-sized fish in the tuna family that is known in Japanese as katsuo. The lean fillets of this fish are used to make katsuobushi, a category of dried, smoked, and sometimes fermented bonito products that impart umami flavor the typical broth known as dashi, as well as to a variety of other dishes.

The product from which katsuobushi derived 4-5 centuries ago dates back at least 1,300 years and is known as shio-katsuo, or “Bonito preserved in salt” (this product is not smoked). Katsuo irori developed around the same time as shio-katsuo (both are mentioned in ancient documents as valuable products that were used to pay taxes), and is made by boiling bonito bones, heads, and trimmings (but not the organs) until a concentrated, dark, syrupy liquid is obtained. The boiling process takes about 5 days, and an initial volume of 300 liters of water yields only 4 or 5 liters of katsuo irori, which is then used as needed, dissolved in hot water to make a flavorful broth for meat, fish, or vegetables. The leftover bones and other solids are used as fertilizer.

Katsuo Irori is said to be the oldest liquid seasoning using bonito in Japan, it was the most widespread processed product used as a source of umami flavor. However, over time, fermented products and fermentation techniques, many of which originated in China, became more popular and widespread, leading to the decline of both katsuo irori and shio-katsuo. In the early days of katsuobushi being adopted as the main processed bonito product, producers continued to use bonito heads, bones, and scraps to make katsuo irori, but this practice almost completely died out during the Meiji era (1868-1912).

Today, there is just one remaining commercial producer of katsuo irori, based in Tago on the Izu Peninsula, and they make only about 50 kilograms a year. There is a similar product from Kyushu called senji, but this often contains added starch as a thickener. Katsuo irori is one of three rare bonito-based Ark of Taste products from the Izu Peninsula (the others are shio-katsuo and Izu tagobushi), and an important reflection of this region’s gastronomic culture and history.
It is in desperate need of recognition and revitalization.

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