Katsuobushi (bonito/skipjack tuna) is one of the two main ingredients to make the most prevalent dashi in Japan – awase-dashi (which I’ll be referring to as dashi from here on out – see my dashi post for why).
What is Katsuobushi?
Katsuobushi （鰹節・かつおぶし）is a piece of dried and fermented bonito. Katsuobushi is made up of two characters: katsuo, meaning ‘bonito’; and bushi, meaning ‘knob/chunk’ – so quite literally a ‘chunk of bonito’. The word katsuo comes from the bonito’s Latin name: katsuwonus pelamis.
Appearance-wise, katsuobushi is shaved into a slender boat shape with smooth, curved arcs. The surface is a dusty beige-tan or brown colour (some may look like pieces of bark), while the inside is a beautiful garnet red similar to the colour of prosciutto. The insides also have a gem-like sheen; this is because after undergoing the fermentation process, katsuobushi becomes extremely hard.
History of Katsuobushi
Being an archipelago, seafood has always been a large part of the Japanese diet. For centuries the bonito fish was the most prized fish in Japan, first due to its abundance in the nearby oceans, and later because it became an essential ingredient in dashi. Fatty tuna （大とろ・大とろ ootoro）has replaced bonito in modern times as a most prize-worthy fish, but this does not diminish the importance of the bonito in the Japanese diet.
Katsuobushi was invented during the Edo period (1603-1868). Its predecessor, arabushi （荒節・あらぶし ’smoked bonito’) was first made in 1674. A common story of how arabushi came to be was that a Kishu fisherman named Jintaro became stranded when his ship capsized during a storm. He experimented with smoking his bonito over a wood fire and discovered that the smoke greatly improved the umami flavour. Later on, around 1770, the Japanese discovered that fermentation of arabushi further increased the umami flavour. Many stories point to this discovery via serendipity – a general story would describe how one day someone found mould on their arabushi and decided to try it instead of throwing it away. Post-fermentation, the arabushi is now called katsuobushi.
Making of Katsuobushi & Different Types of Katsuobushi
Even though dashi only takes around half an hour to make, the process of making true katsuobushi takes months. It is a labour of love and perfected to an art form in small parts of Japan.
The process starts with fresh bonito (かつお katsuo). The bonito is cut into large fillets, simmered in water for a few hours, and then deboned. The fillets are then coated with a fish paste, which helps fill in the gaps by the bones. They are then smoked for one month, after which they are now called arabushi （荒節・あらぶし）. Most of the so-called ‘katsuobushi’ on the supermarket shelves nowadays are actually arabushi. It is more economical for producers and consumers. An interesting note: ara （荒）means ‘rough or crude’; hence one could take the name arabushi to mean ‘an unrefined katsuobushi‘.
The next step in this process is to shave off the surface fat of the arabushi, sun-dry them, and then adjust their shape so they look like long, slender ‘canoes’. After they are shapes, the product is called hadakabushi （裸節・はだかぶし）, with hadaka meaning ‘naked’.
The final step is to coat the hadakabushi with a special mould and then leave them to ferment. After fermentation, we now get the illustrious katsuobushi. The end product is also called honkarebushi （本枯節・ほんかれぶし ‘true dried fillet’, which is the highest grade of katsuobushi） or shiagebushi （仕上げ節・しあげぶし ’finishing touches fillet’）. Note: 仕上げ means ‘end’ or ‘finishing touches’.
(It is interesting to see how in each stage of the process, the bonito is given a unique name. From what I’ve seen so far, this is fairly common in Japanese. For example, there are many words for ‘rice’. Uncooked rice is called kome （米・こめ）, while cooked rice is called gohan （ご飯・ごはん）).
Other types of dried bonito include:
- Wakabushi（若節・わかぶし）：semi-dried katsuobushi
- Satsuma Honkarebushi（薩摩 本枯節・さつま ほんかれぶし）：a type of honkarebushi made in Makurazaki (the largest producer of honkarebushi).
- Kezuribushi（削り節・けずりぶし）：bonito flakes/shavings. If you buy a whole katsuobushi, you can make your own kezuribushi by using a special wooden box grater called a kezuriki （けずりき）
- Okaka（おかか）：bonito flakes/shavings. It’s another name for kezuribushi.
Yet more words to describe the bonito: hatsukatsuo （初鰹・はつかつお）and modorikatsuo （戻り鰹・もどりかつお）. Hatsu means ‘first/new’, and modori means ‘returning’; therefore the former is the first bonito of the season, and the latter is the returning bonito.
The first bonito of the season (hatsukatsuo) is the bonito that are travelling north from Kyushu (the Southern most main island of Japan). These bonito have less fat since they are travelling in search of food. When the bonito reach the areas between Sanriku and Hokkaido (the Northernmost main island of Japan), they change direction and begin travelling south. They are now returning, and hence called modorikatsuo. Modorikatsuo have a higher fat content due to a greater intake of food.
During the Edo period, bonito became the most prized fish (and possibly food item), most likely due to the discovery of smoking and fermentation, which lead to the creation of katsuobushi. Hatsuokatsuo was very expensive; for it being regarded as a common fish nowadays, back then commoners would not be able to afford to eat it. There is a Japanese phrase that illustrates how expensive this was, and how well regarded you were if you were able to eat it:
女房 を 質屋 に 入れて も 食いたい 初鰹
にょうぼう を しちや に いれて も くいたい はつかつお
Nyoubou wo shichiya ni irete mo kuitai hatsukatsuo
Hatsukatsuo is worth eating, even if you have to pawn your wife to do so.
(Lit: If you want to eat hatsukatsuo, put your wife in the pawnshop)
Fujita, C 2002, Dried Bonito, The Tokyo Foundation, March 30, viewed April 1 2017, <http://www.tokyofoundation.org/en/topics/japanese-traditional-foods/vol.-15-dried-bonito>.
Inoue, A 2014, Makurazaki Boasts a Proud Tradition of Producing the Finest Katsuobushi, Shun Gate, December, viewed 2 April 2017, <http://shun-gate.com/en/roots/roots_13.html>.
Itoh, M 2013, Katsuo: Japan’s ubiquitous tuna, The Japan Times, April 26, viewed 2 April 2017, <http://www.japantimes.co.jp/life/2013/04/26/food/katsuo-japans-ubiquitous-tuna/#.WOh8dRJ96b8>.
Lombardi, L 2015, Katsuobushi: the dried fermented fish rock that’s in almost every Japanese dish you’ve eaten, Tofugu, April 3, viewed April 1 2017, <https://www.tofugu.com/japan/katsuobushi/>.
ナツメ社 2004, 英語つくる和食、ナツメ社、日本。