- 15 Mar 2002
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Katsuobushi (鰹節), also known as bonito flakes, is dried and smoked bonito (Katsuwonus pelamis), a fish belonging to the mackerel and tuna family, and is a cornerstone of Japanese cuisine. It forms a key ingredient in dashi, the traditional Japanese soup stock. To prepare it, the hard, wood-like blocks of katsuobushi are shaved into thin flakes using a specialised tool called a katsuobushi bako. These flakes, often cooked briefly with pieces of kombu (sea kelp) in water, release their rich umami flavour to create dashi. Katsuobushi flakes (削り節 kezuribushi) are also used directly to season dishes, acting as a natural flavour enhancer. The savoury umami taste primarily comes from inosinic acid (inosine monophosphate), a compound naturally present in fish and other sources.
The production of katsuobushi, developed around 1675 in Kishu (southeast of Osaka), is a meticulous process: The fish is first filleted and lightly boiled for around 20 minutes. After an hour, the bones are removed, and the fillets are smoked for up to two weeks, six hours a day, reducing their water content from roughly 70% to 25%. At this stage, the fish is known as arabushi (荒節). It is then sun-dried for two to three days, becoming hadakabushi. Finally, the fish undergoes fermentation with a mould, typically Aspergillus repens or Aspergillus ruber, until it reaches its complex, wood-like final form. Every two weeks or so, the blocks are briefly placed in the sun to kill the surface layer of mould, gradually producing the distinctive texture and flavour that characterises true katsuobushi.
This process, which combines boiling, smoking, sun-drying, and fermentation, has been refined over centuries. Katsuobushi remains essential not only for dashi but also as a versatile seasoning that embodies the depth and complexity of traditional Japanese cuisine.
The production of katsuobushi, developed around 1675 in Kishu (southeast of Osaka), is a meticulous process: The fish is first filleted and lightly boiled for around 20 minutes. After an hour, the bones are removed, and the fillets are smoked for up to two weeks, six hours a day, reducing their water content from roughly 70% to 25%. At this stage, the fish is known as arabushi (荒節). It is then sun-dried for two to three days, becoming hadakabushi. Finally, the fish undergoes fermentation with a mould, typically Aspergillus repens or Aspergillus ruber, until it reaches its complex, wood-like final form. Every two weeks or so, the blocks are briefly placed in the sun to kill the surface layer of mould, gradually producing the distinctive texture and flavour that characterises true katsuobushi.
This process, which combines boiling, smoking, sun-drying, and fermentation, has been refined over centuries. Katsuobushi remains essential not only for dashi but also as a versatile seasoning that embodies the depth and complexity of traditional Japanese cuisine.