Katauo

As evidenced by large quantities of skipjack tuna bones excavated from the Ohora shell mound along the Pacific Ocean in Iwate Prefecture's Ofunato, the Japanese have been eating the fish since the late Jomon Period (4000 BC). The word katauo, an earlier form of katsuobushi’s namesake, appears in the Kojiki, Japan's oldest historic text, dating back to 712 C.E. According to the Ryō no Shuge, the annotated version of the civil code Yōrō Code that was enacted in 757, nikatauo (boiled skipjack tuna) is listed as one option of alternate payment for taxes. This nikatauo is the progenitor product of the process of preserving fish after being dried in the shade and is said to be the origin of katsuobushi.

The Tradition Spreads Nationwide

Treasured for its high nutritional value, samurai (warriors of premodern Japan) in the Muromachi Period (c. 1338-1573) were said to have carried around katsuobushi in times of war to chew as means of staving off hunger. Invention of the modern katsuobushi recipe of smoking then drying to remove the water content is credited to Kadoya Jintaro, a fisherman in the late 17th century hailing from Inami in the Kishu region. The recipe was introduced to the Tosa Domain, where it was held as a Tosa secret for many years.However, it was spread to Kago in the Satsuma region (now the city of Makurazaki) in the early 1700s by a fisherman named Mori Yahei and to the Awa and Izu regions in the late 18th century by a katsuobushi craftsman known as Yoichi. Today, katsuobushi has grown into a staple food to all Japanese.

Making Katsuobushi

The modern process of making katsuobushi starts on the boat. The catch of skipjack tuna is flash frozen on ship and transported to the plant. At the plant, the skipjack tuna is judged for its size, quality, and marbling as it thaws before being passed through the steps of cutting, basket placement, stewing, boiling, deboning, and smoking and drying to produce a completed block called an arabushi. The arabushi then has its rough surface shaved down before having mold applied and dried in the sun repeatedly. The completed product is then called a karebushi.

Arabushi and Honkarebushi

Arabushi retains the strong aroma and robust flavor of the smoked skipjack tuna and produces a moderately acidic broth with depth when boiled. Once the surface is shaved, the arabushi is called a hadakabushi. The hadakabushi is given at least two coats of mold and dried to form karebushi. The highest grade of katsuobushi is honkarebushi, which is karebushi passed four to five times through the mold and dry process. Karebushi has a sweet and refined taste and produces a more transparent, mild soup stock than arabushi. The entire manufacturing process takes about 20 days for arabushi, two to three months for karebushi, or six months for honkarebushi.

Any Way You Shave It

Katsuobushi underpins Japanese dashi stock, the base of so many Japanese dishes, including soups, noodles, and stews. Processing into katsuobushi roughly triples the protein content of skipjack tuna. Making dashi from katsuobushi adds umami for more flavor with less salt. As such, katsuobushi is used to make a multitude of processed foods today, including seasonings, mentsuyu (noodle soup base), furikake (rice seasoning), and more. One appeal of katsuobushi is its versatility: it goes with so many dishes depending on how it's shaved.

Kezuribako (wooden grating box)

Today, most of the katsuobushi we see comes wrapped in packs of shaved flakes. Before packs became the norm, however, katsuobushi box graters were a household item. Invented in Tosa (Kochi Prefecture), the manufacturing method for these graters was prohibited to export, just as with katsuobushi itself, and didn't spread until the Meiji Period (1868 -1912). Before grating boxes, katsuobushi is said to have been shaved like a pencil using a small box and knife. Presently, there are even mechanical and electric shavers that work like a shaved ice machine.

Lucky Talismans

From the war-stricken Sengoku Period (1467 – 1478), katsuobushi doubled as lucky talismans, taking the word as a homonym for "winning warrior". Even today, it is sometimes used as an engagement gift or parting gift for wedding receptions. In this case, the homonym is written with the Kanji characters for married couple. With the perfect union of the belly (mebushi, or "female cut") and back loin cuts (obushi, or "male cut"), katsuobushi is meant to symbolize a happy couple