Katsuobushi

Katsuobushi (Japanese: ^?) is dried, fermented, and smoked skipjack tuna (Katsuwonus pelamis). It is also known as Bonito flakes when young bonito is used as a cheaper substitute for skipjack tuna. Katsuobushi or similarly prepared fish is also known as okaka (おかか).

Shaved Katsuobushi and dried kelp - kombu - are the main ingredients of dashi, a broth that forms the basis of many soups (such as miso) and sauces (e.g., soba no tsukejiru) in Japanese cuisine.

Katsuobushi's distinct umami taste comes from its high inosinic acid content. Traditionally made katsuobushi, known as karebushi, is deliberately planted with Aspergillus glaucus fungus in order to reduce moisture. Katsuobushi has also been shown to impart a kokumi flavour.

Upon being placed on hot food, the heat waves cause the thin and light katsuobushi to move about, giving it a special aesthetic look. It is placed on pizzas to make the top of the pizza seem alive with the "dancing" katsuobushi.

The fish is beheaded, gutted and filleted. The fatty belly area does not lend well to being preserved, so it is also trimmed off. The fillets are then arranged in a basket and simmered just below boiling for an hour to an hour and a half, depending on the size of the fillets. The rib bones are removed after the fillets have been boiled.

The fillets are then smoked using oak, pasania, or castanopsis wood; this process can take up to a month. They are smoked for 5–6 hours in one session, left to rest for one day for the condensation to rise to the surface, then fired and smoked again the next day, repeating this smoking and resting cycle 12–15 times. The built up tar from the smoke is cleaned from the surface using a grinder. At this stage the fillets are called aragatsuo (荒節) and most commonly found in stores shaved and packaged for sale under the name katsuo-kezuri-bushi (鰹削り節) or hanakatsuo — they are not true katsuobushi without the last fermentation stage, but still valued as a good substitute.

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Wikipedia