What Is Katsuobushi? Types, Uses and Dashi Making

Living in Ho Chi Minh City and trying to cook Japanese food, have you ever wondered, "What exactly is katsuobushi?" or "How do I use it?" Katsuobushi (dried bonito flakes) is one of the most fundamental ingredients behind the umami of Japanese cuisine. This article covers katsuobushi basics, types, how to make dashi, everyday cooking uses, and where to buy it in HCMC, organized into seven parts.

What Is Katsuobushi: The Hardest Food in the World

Katsuobushi is a traditional Japanese food made by processing and drying skipjack tuna (katsuo). Known as "bonito flakes" in English, it is an indispensable ingredient for dashi and seasoning in Japanese cooking. Its history dates back to the Muromachi period, supporting Japanese cuisine for more than 500 years.

The finished katsuobushi has a moisture content below 15%, earning it the title of "the hardest food in the world." This extreme concentration of umami is the source of the delicate flavors that define Japanese cuisine.

!A block of katsuobushi and a shaving tool

Production Process: From Skipjack Tuna to Karebushi

Traditional katsuobushi production takes several months to over half a year. The main steps are as follows.

1. Fresh cutting (namagiri): Fresh skipjack tuna is filleted, then separated into back loin (obushi) and belly loin (mebushi)
2. Simmering (shajuku): Boiled in water at 80 to 90 degrees Celsius for 1 to 2 hours. Proteins coagulate and the flesh firms up
3. Deboning and shaping: Bones are carefully removed and the shape is refined
4. Smoke-drying (baikan): Smoked with wood fire over several days to reduce moisture. The product at this stage is called "arabushi" (rough-dried fillet)
5. Mold-curing and sun-drying: Mold (Aspergillus glaucus) is applied to the surface of the arabushi, then sun-dried, repeated 3 to 4 times. The mold draws moisture from within and increases umami compounds. The product after this stage is called "karebushi" (finished fillet)

Arabushi has a smoky, robust aroma, while karebushi, through the action of mold, has off-flavors removed, resulting in an elegant, clear flavor.

Types: Hanakatsuo (Thin Shavings) vs Kezuribushi (Thick Shavings)

Katsuobushi comes in various shaving styles and types, each suited to different purposes.

Hanakatsuo (thin shavings) are katsuobushi shaved into thin, wide flakes. Their wispy shape resembles flower petals, hence the name. At roughly 0.03 mm thick, they flutter and dance when placed on hot food. They are a staple for making dashi and as a topping for chilled tofu or okonomiyaki.

Kezuribushi (thick shavings) are somewhat thicker and primarily used for simmering over extended periods to extract dashi. The extra thickness yields a richer, more robust broth, making them ideal for soba dipping sauce and simmered-dish dashi.

Additionally, finely ground katsuobushi powder (katsuobushi-ko) can be used directly as a furikake or seasoning, offering great convenience.

The Science of Umami: Inosinic Acid Powers Japanese Cuisine

The key umami compound in katsuobushi is inosinic acid (IMP), a nucleotide-based umami substance. IMP is produced when ATP (adenosine triphosphate) in the fish flesh breaks down during processing and aging.

The critical concept here is "umami synergy." When inosinic acid is combined with glutamic acid (an amino-acid-based umami compound found in kombu), the perceived umami multiplies roughly 7 to 8 times compared to either alone. This scientific principle is why "combined kombu and katsuobushi dashi" is the foundation of Japanese cooking.

!Katsuobushi flakes dancing on hot tofu

Cooking Uses: Dashi, Toppings, and Onigiri

Katsuobushi is not just a dashi ingredient; it is remarkably versatile in everyday cooking.

Making Dashi (Ichiban Dashi)

Ichiban dashi (first dashi) is a clear broth that showcases the full flavor of katsuobushi.

1. Bring 1 liter of water to a boil in a pot
2. Turn off the heat and add 30 g of hanakatsuo
3. Do not stir; wait 1 to 2 minutes
4. Line a strainer with a paper towel and pour the dashi through gently
5. Do not squeeze the flakes: squeezing extracts off-flavors

!Making dashi from katsuobushi in a pot

As a Topping

Hanakatsuo adds flavor and umami simply by placing it on top of a dish. Classic uses include:

• Chilled tofu (hiyayakko): Place a handful on tofu and drizzle with soy sauce for a complete dish
• Okonomiyaki and takoyaki: Katsuobushi flakes dancing on the hot surface are visually appealing and appetite-inducing
• Blanched greens (ohitashi): Toss boiled vegetables with katsuobushi and soy sauce for a simple side dish

As an Onigiri Filling

Katsuobushi mixed with a small amount of soy sauce, called "okaka," is one of the most popular onigiri fillings in Japan. The recipe is simple: mix 2 tablespoons of katsuobushi with 1 teaspoon of soy sauce. It is perfect for bento lunches and holds up well even in HCMC's hot climate.

!Katsuobushi onigiri

Where to Buy Katsuobushi in HCMC

In HCMC, Japanese supermarkets and online shops are the main options for finding katsuobushi. However, selection and freshness can vary from store to store.

On Farmi, you can order katsuobushi products imported directly from Japan through the app. Delivery covers all of HCMC, saving you the effort of carrying heavy grocery bags.

• Katsuobushi pack (Product ID: 6397) on the Farmi app
• Dashi pack (Product ID: 10084) on the Farmi app

Purchase through the Farmi app. Download the app and search for "katsuobushi" to explore products.

Conclusion: Katsuobushi Is the Origin of Japanese Umami

Katsuobushi is a traditional Japanese food with over 500 years of history, and it is the foundation of umami in Japanese cuisine. Whether making quick dashi with hanakatsuo, using it as a topping, or filling onigiri, it is an extraordinarily versatile ingredient.

The umami synergy between inosinic acid and kombu's glutamic acid in combined dashi is the culinary wisdom that Japanese cuisine shares with the world. In HCMC, you can easily source quality katsuobushi through Farmi. Start with ichiban dashi and take your home-cooked Japanese meals to the next level.