DASHI AtoZ 10:
[Bonito Dashi] How katsuobushi Is Made?

Writer: Yumiko Ishimaru

How does fresh bonito fish become such hard katsuobushi?

After bonito fish is defrosted overnight, the head and innards are removed, the body is cleaned and then cut into 3 parts. Fish over 3kg can produce 4 fillets. (2 back side fillets and 2 belly side fillets). The back side fillets are called “Obushi” and the belly side fillets are called “Mebushi

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Left: fresh bonito, Right: dried bonito

The fillets are then arranged in a basket and simmered at 95℃ for 60 to 90 minutes. This process coagulates the protein in the fish and preserves it as well. Using years of experience and intuition, Katsuobushi manufacturers decide its simmering temperature and time depending on the size and freshness of the fish.

Once the rib bones are removed, the fillets are then dry smoked until their moisture becomes 28%. This is called “arabushi” and has a very light umami flavor.

The last stage of creating katsuobushi is to allow the fish to sun-dry using the assistance of carefully selected mold. The power of mold creates distinct umami.

If you remove the natural tar of arabushi and repeat the process of mold growth twice, it becomes “karebushi (dried fillet).” The fillets repeating this process 4-5 times are called “honkarebushi (true dried fillet)” with less than 15% moisture. If tapped together lightly, they sound almost metallic. It has a very rich and mild flavor and clear umami.

Of course, you don’t eat this large chunk of katsuobushi as it is. You need a special “kezuriki” shaver and eat its flakes.

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Kasuobushi Kezuriki (Shaver)

You cannot imagine the umami of katsuobushi from its color and looking. Please enjoy umami in katsuobushi in washoku.