Japanese Bonito Flakes (Katsuobushi):
Strong Umami, Rich Benefits

Japanese Bonito Flakes, Katsuobushi

If you search for Japanese foods or fish in the internet, you might stumble with Japanese dancing fish flakes, or something abour fish flakes wiggling.

If what you saw is like the thing on the image above, then its name is actually "katsuobushi" or bonito flakes.

So before we go to the main article about bonito flakes, here is a trivia:
Why do bonito flakes move?

Bonito flakes are so thin light that some amount of warm steam makes them waver and curl, as if they are wiggling and dancing.

When they come in contact with steams of hot foods, the layers of muscle fibres in the bonito flakes (it has fibres because it's originally a fish meat) rehydrate in different directions and at different rates due to different thicknesses.

Therefore the bonito flakes will move to the different directions, until they stop moving as they’re totally soaked.

If you put them on a hot or warm food, you can see the pinkish-brown flakes move.

In this article, we will tell you a lot of things about bonito flakes, or katsuobushi.

What is Bonito Flakes/Katsuobushi?

Bonito are a tribe of medium-sized, ray-finned predatory fish in the family Scombridae--same family with the mackerel, tuna, Spanish mackerel tribes, and the butterfly kingfish.

Bonito flakes is smoked, dried, fermented, shaved bonito fish.

In Japan, it is called "katsuobushi". But, katsuobushi is actually made from skipjack tuna (Katsuwonus pelamis).
It widely known as bonito flakes because young bonito is used as cheaper substitute for skipjack tuna.

Whether it's made from the more expensive skipjack tuna or cheaper bonito, the term "katsuobushi" is used in Japan to call this pinkish-brown savory sheets of ingredients as shown by the image below.

Katsuobushi then translated as bonito flakes in English. So you can use the term to call either of them too!

bonito flakes

Bonito flakes and kombu kelp are the main ingredients of dashi (Japanese broth/soup stock).

Bonito flakes has a distinct umami taste which comes from its high inosinic acid content.

There are two types of bonito flakes, "arabushi" and "karebushi". Which we will explain them in other section of this article.

In this article, we will tell you a lot of things about bonito flakes, or katsuobushi.

To not bring confusion between the Japanese and English term (athough they have same meaning), from now on we will use the English term, bonito flakes.

The Umami in Bonito Flakes

bonito flakes umami

Bonito flakes is very popular around the world. Bonito flakes has smoky, savory, and slightly fishy flavor.

It can bring the rich yet clear flavor through the synergy between "umami" and aroma.

"Umami", source of savory flavor, is considered as one of the 5 fundamental tastes along with sweet, sour, salty and bitter.

Umami is derived from the Japanese word umai (means delicious) and is characterized as savory, brothy, and meaty.

Ikeda first described the principle of umami in 1909 (a translation of this work was published in 2002 (source).

Ikeda investigated konbu, a dried seaweed, used together with flaked bonito (Japanese katsuobushi, dried fermented skipjack) to make dashi, the flavorful broth that is used in many Japanese recipes.

It was observed that next to kombu and dashi there were many foods such as asparagus, tomatoes, cheese, and meat that had a common taste different from the known basic tastes.
Ikeda isolated this flavor in the broth by extracting crystals of glutamic acid, which had a distinctive character that was named umami.

What makes "umami" taste is glutamic acid and inosinic acid. With bonito flakes is particularly high in inosinic acid, it can bring depth and complexity in umami flavor.

Aroma is also an essential part of the savory flavor of bonito flakes. The long and intense process of "smoke and dry", and the mold applied to the fermentation process brings out this special aroma.

Dried bonito dashi is a complex mixture composed of umami (inosine 5′-monophosphate (IMP), L-amino acids), sour (lactic acid) and bitter (histidine, creatinine, anserine, carnosine) substances as well as over 400 odorants that add to its taste and aroma.

bonito flakes umami

Bonito flakes is different from other dried and smoked foods because no salt and other seasonings is added.
It gives us a new taste experience.

Salt plays an big role in flavor of a dish. Unfortunately, excessive salt consumption can trigger lifestyle diseases.

However, the "umami" in bonito flakes can save us from this dilemma.
Umami not only enhances richness and roundness in flavor, but it also brings out the flavor of the ingredients.

That's why the flavor of bonito flakes can satisfy your taste-buds even with such a little salt.

Umami flavor can also make the food delicious even if it's cooked with less oil but added with bonito flakes.

This makes bonito flakes a perfect companion to meet the ultimate needs of people today; we want to enjoy foods while keeping our health.

By bringing out the flavor of ingredients and further enhancing it, "umami" can give "flavorful yet healthy" flavor.

Types of Bonito Flakes and
How Bonito Flakes is Made

Based on how the dried bonito is made (the fermentation before it was shaved), the dried bonito before it's shaved and become bonito flakes are distinguished as two different kinds:


● Arabushi

"Arabushi" refers to a piece of bonito that has not been molded. It is a cleaned, boiled, dried and smoked "Katsuo" fillet.
It features a strong scent of bonito that is not moldy and is also preferred for its relatively low cost. Its dashi has the strong and distinct "dried and smoked" lingering aroma, and the deep and slightly acidic flavor.
No mold is applied on Arabushi bonito.
About 80% of the commercial bonito flakes are made from Arabushi bonito.
Arabushi is about 19-22% in moisture content.

arabushi katsuobushi


● Karebushi

"Karebushi" is dried bonito which has mold applied on it.
It is made by shaving off the fat from the surface of "Arabushi" and repeating the "application of the mold and dry" process several times.
The mold will enhance its flavor further, therefore karebushi will create the aromatic, elegant and firm flavored dashi.
The karebushi has stronger flavor than arabushi and usually have higher price than arabushi bonito.
Chefs around the world rave it because its richness, flavor, bitterness and acidity perfectly play in harmony.
Karebushi is about 14-17% in moisture content.

karebushi katsuobushi

Bonito flakes is made by smoking and drying bonito fish.

Japan’s traditional method of making honkarebushi, the highest-quality katsuobushi, is labor-intensive, and takes about six months to complete.

Next we will intoduce you to the traditional production of bonito flakes (katsuobushi).


 How Bonito Flakes is Made


1

"Namagiri" (Slicing the Fish)

The head of bonito fish is cut, its gut and fins are removed. Then, fish is cut into 4 fillets, which is two parts from dorsal sections and two abdominal sections.
The dorsal fillet is called "obushi" and abdominal fillet is called "mebushi".

2

"Kagotate" (Arranging)

In order to make it easier to perform the simmering (shajuku) step of the freshly cut fish meat, the sliced fish meat is arranged neatly in a container so that it won't collapse even when being simmered.

3

"Shajuku" (Simmered)

After the fillets of bonito fish is placed and arranged in a metal basket called "nikago", the fillets are simmered for a few hours. The difference in temperature and time is determined by the craftsman according to the fish body and freshness of the salmon.
This critical stage is handled with extra care because this largely affects its final shape. Protein found in fillets are completely coagulated and water found in muscles is distributed in this process.

4

"Honenuki" (Deboning)

After simmering and let the fish fillet cooled down, the bones in it are manually removed using tweezers carefully without damaging the fillets.

5

"Shuzen" (Repair)

Fish paste is applied on each fillet to fill in cracks and lines from the deboning for a perfect finish. This also helps distribute water in fish to create good dried bonito.

6

"Baikan" (Smoking-Drying)

Next is drying process. Bonito fillets are smoked repeatedly with hard woods, such as oak. Depending on size of filets, smoking and the moisture removing process called "anjo" are repeated 6 to 15 times. That process is repeated for 2 weeks to a month until the water is distributed equally in fillet and its water content is reduced to about 23%.
The dried bonito made until this step is the "Arabushi".

7

"Kezuri" (Shaving)

The surface of arabushi is shaved off to remove fat.

8

"Kabitsuke" (Mold application)

After the water is removed, good mold bacteria are applied on dried bonito to bring out the flavor and to preserve it.
The mold will start to grow in several weeks, then the dried bonito fillets go through the process of "sun dry and mold application" repeatedly for few months.
Finally, "Honkarebushi" is finised. The dried bonito made until this step is the Honkarebushi.

The water content of honkarebushi is as little as about 15%.

When two pieces of honkarebushi are hit together, they make beautiful dry and resonating sound.

When you cut through the honkarebushi, it will reveal the beautiful ruby like inside color.

Health Effects of Bonito Flakes

Many researches had been conducted regarding the health effects of bonito flakes, especially dried bonito broth or katsuo dashi, which is a broth made from bonito flakes.

Here we will tell you some of health benefits of bonito flakes!

※ Anti-aging Effect

dried bonito flakes katsuo dashi health effect

Katsuo Dashi (Dried Bonito Broth) which is made from bonito flakes, the distinct umami flavor of katsuobushi comes from its “inosinic acid” content. The high energy produced by the inosinic acid activates body cells. This will lead to anti-aging effect.
With katsuo dashi, you can enjoy the umami flavor and helps you stay young.

Bonito flakes is also really rich in amino acids that the human body cannot produce which are fundamental to keep your body healthy, and crucial for how in the production of strong teeth and bones. It also has low fat content.

※ Fatigue Relief Effect

bonito flakes health effects

Some research showed that katsuo dashi made by bonito flakes may improve the mood states, may reduce mental fatigue, and may increase performance on a simple calculation task (source).

※ Lowering Blood Pressure

bonito health effect

The daily ingestion of bonito broth might lower systolic blood pressure, reduce levels of a urinary oxidative stress marker, and improve emotional states.

The results of a research indicate that the systolic blood pressure significantly lowered during the ingestion of dried-bonito broth compared to water ingestion (p = 0.037) (source).

※ Improving Emotional States and Mental Condition

katsuobushi health effect

Bonito flakes might improve mental condition by increasing blood flow; that is, by enhancing peripheral circulation.
It also might reduce levels of a urinary oxidative stress marker, and improve emotional states.

When dried-bonito broth was ingested, the urinary 8-OHdG (oxidative stress marker) content significantly decreased during the ingestion period, while no significant changes were observed when water was ingested.

Changes in the emotional states also shown to get better during the ingestion period of bonito flakes (source).

※ Antiobesity and Anti-Inflammatory Effects

bonito flakes health effects

A research showed that extract of bonito might have antiobesity and anti-inflammatory effects.

Evidence from epidemiological surveys clearly indicates a relationship between obesity and multiple chronic diseases, including cancer cardiovascular disorders, and neurological and behavioural disorders. Bonito extracts ameliorated the scores of mental fatigue and sleep disruption. All this accumulating evidence may support the antiobesity and anti-inflammatory effects of extract of bonito (source).

How to Use Bonito Flakes

You already know that bonito flakes have so much health effects, especially when you make it to broth, or katsuo dashi.

Bonito flakes can be eaten as it is, or used in various dishes as an add-on, topping, and ingredient.

You can find bonito flakes as add-on and topping in takoyaki, okonomiyaki, monjayaki, etc.

But one main use of bonito flakes used in Japanese dishes is to make dashi (Japanese broth/soup stock).

Bonito Flakes for Dashi (Japanase-style Broth)


Dashi, the traditional Japanese stock, is an indispensable part in Japanese cuisine because of its flavor enhancing action and hence sometimes referred to as ‘the heart of Japanese cuisine’.

It is is a basic Japanese stock or broth which can be made from various ingredients.

Dashi is used to add flavor to not only soup but also to Japanese salad and simmered dishes in Japan.
Dashi is a common ingredient of many Japanese recipes, such as boiled dishes, noodles, and soups.

The three most popular ingredients used in making dashi are shiitake mushrooms, kombu kelp, and katsuobushi or dried bonito flakes.
These each contain a large quantity of umami substances: shiitake containing guanylic acid, katsuobushi inosinic acid, and kombu glutamic acid.

In this article about bonito flakes, we will tell you the recipe of Japanese main bonito-flakes-dish, that is bonito broth or katsuo dashi.

Here is the recipe to make bonito broth (katsuo dashi), a Japanese-style broth made by bonito flakes.


Katsuo Dashi

The katsuo dashi is a dashi made with katsuobushi.
It is characterized by its refined taste and rich aroma, and it's an all-purpose dashi that brings out the taste of any ingredients.

This dashi doesn't need much time to soak in the water like other ingredients, so you would be able to make it quickly when you want to eat miso soup.

The flavor of katsuo dashi will be improved by combining it with the vegetable-based kombu dashi.

Ingedients for4 servings
Cooking Time20 minutes
Katsuo Dashi

 Ingredients

・Water
1 litre
・Katsuobushi
30 grams

 How to Make


1
Put water in a pot and turn on the heat, then turn off the heat when it's boiling.
2
Put katsuobushi in the boiled water and wait 1 to 2 minutes.
3
Drain the katsuobushi with cloth, kitchen paper, or strainer.
Then, your katsuo dashi is completed!

When making dashi, kombu kelp which is high in glutamic acid, is often added to bonito dashi to everage the umami synergy effect.

Applying this principle, using bonito flakes which is rich with nosinic acid along with cheese, mushroom or tomato, or other foods which have high glutamic acid, also leverages the "Umami".

Such matching and paring of ingredients can also be applied when preparing non-Japanese cuisines.

For other kinds of dashi, please check this article.

what is dashi

What is Dashi? ~ Everything You Need to Know About Japanese Soup Stock ~
Soup stock is an extract of certain foodstuffs, such as fish, meats, vegetables, and seaweed, and it is often used to add flavor to cooked dishes.
In Japan, soup stocks are commonly made from certain fish, seaweed, and mushroom.
These soup stocks are called “dashi.”
Dashi is not only used to make miso, but it can be used in a lof of various dishes.
In this article, we will tell you a lot of stuffs about dashi from what exactly dashi is, dashi recipes, to its health benefits.

Read the article of "What is Dashi? ~ Everything You Need to Know About Japanese Soup Stock ~" here.



Bonito Flakes for Other Uses


Aside from bonito dashi, you can use bonito flakes for various dishes.

Bonito flakes is mainly used as add-on and toppings to other dishes.

To know more, take a look at the bonito flakes' recipe section below!

Bonito Flakes Recipes

So, here in this section, we will tell you about how to use bonito flakes aside from eating them as it is and make them into bonito broth/katsuo dashi

Here are the recipes!

Cold Tofu with Umeboshi

A tofu dish for your diet; refreshing side dish for summer!

You don't have to use fire to make this recipe. It’s just a cut-and-put!

If you don't want to eat carbohydrates and meats, try this tofu recipe.

Ingredients for2 servings
Cooking time10 minutes
Cold Tofu with Umeboshi

 Ingredients

・Tofu (kinugoshi tofu
or silken tofu)
1 block
・Plum paste
40g
Umeboshi
2 pieces
・Grated radish
Appropriate amount

 For Condiment

・Radish sprouts
1 piece
・Myoga ginger
(Japanese ginger)
1 piece

 For Sauce

・Ponzu sauce
20cc
Strong Flavored Shoyu
10cc

 For Finishing Touches

・Bonito flakes
Appropriate amount
・Shredded nori
(dried seaweed)
Appropriate amount

 How to Make

1
Cut the tofu in half and serve on a plate.
2
Cut only the leaves of the radish sprouts into two halves.
Cut the myoga ginger into half vertically, slice it, and mix with radish sprouts.
3
Put the ingredients for condiment, grated radish, and plum paste on the tofu.
4
Mix the ingredients for sauce and pour onto tofu.
5
Finish it by putting umeboshi, bonito flakes, and shredded nori on the tofu!

Onigiri (Rice Ball) with Crab Sticks, Bonito Flakes, and Mayonnaise

A delicious, easy-to-make rice ball for your lunch box!
Ingredients for1 serving
Cooking Time15 minutes
onigiri

 Ingredients

・Rice
About the amount
of 1 teacup
・Crab stick*
1 piece
・Bonito flakes*
Appropriate amount
・Mayonnaise*
Appropriate amount
・Salt
Appropriate amount
・Nori seaweed
1 sheet

 How to Make

1
Put plastic wrap on a plate. Spread the rice on the wrap and put the ingredients marked with * on the rice.
You put crab stick as it is or slice it into small pieces.
2
Roll the rice until it's shaped into a ball.
3
Sprinkle salt on the whole surface of the onigiri, and wrap it with nori seaweed.
Your onigiri is ready to eat!
Tips
It'll be more hygienic if you use plastic wrap when rolling the rice.
If you don't eat it right away, put it in a dry cool place and eat as soon as possible.

Bell Pepper and Bonito Flakes

Easy-to-make, delicious recipe of bell pepper and bonito flakes.

A bell pepper recipe that can be eaten even by people who don't really like bell peppers!

Ingredients for1 servings
Cooking Time10 minutes
bell pepper and bonito flakes

 Ingredients

・Bell peppers
As much as you like
・Bonito flakes
As much as you want
・Shoyu
Appropriate amount

 How to Make

1
Cut bell peppers in half and take off the stem.
2
Cook the bell peppers in a frying pan (do not add oil).
3
When the bell peppers are well cooked, put them onto a plate, add bonito flakes and shoyu (Japanese soy sauce).
Tips
Cook the bell pepper without oil, it's better if you cook it until it's soft and mushy.

Bonito Flakes Q&A

Why do bonito flakes move?
Bonito flakes are so thin light that some amount of warm steam makes them waver and curl, as if they are wiggling and dancing.
When they come in contact with steams of hot foods, the layers of muscle fibres in the bonito flakes (it has fibres because it's originally a fish meat) rehydrate in different directions and at different rates due to different thicknesses.
Therefore the bonito flakes will move to the different directions, until they stop moving as they’re totally soaked.
If you put them on a hot or warm food, you can see the pinkish-brown flakes move.
Where to buy bonito flakes?
You can found bonito flakes in stores that sell imported foodstuffs or foreign food ingredients near you. You can also buy it via online stores, like Kawashima the Japan Store. Check it here.
Bonito flakes are often sold by its Japanese name, katsuobushi, on the packaging. So you might want to look for it in Japanese, "katsuobushi" or "鰹節" or "かつお節", or by its other name, "kezuribushi" or "削り節".
Are bonito flakes good for health?
Bonito flakes have a lot of health benefits.
It has anti-aging affect, fatigue-relief effect, antiobesity and anti-inflammatory effects, lowering blood pressure, and it can also improving emotional States and mental condition.
Check this section for details about the healh benefits of bonito flakes!
How long do bonito flakes last? Do bonito flakes expire?
Yes, bonito flakes do expire.
The expiration period depends on the product, but usually, bonito flakes last for about 6-12 months.
But, please check for the best before or expiration date on the packages.
If the taste and aroma have not become bad or spoiled, you can still eat them even if the best before date is past. But the taste might not be as fresh and delicious as before.
How should I store the bonito flakes?
Once the packages are opened, the katsuobushi will begin to oxidize and go wilted, and the color becomes dull.
It will get moist from the humidity and then goes fuzzy.
It's important to keep it dry.
In order to keep your katsuobushi fresh longer, expel extra air from the bag, reseal, and store in a cool, dry, dark location.
If the packages did not come in a resealable bag, put them to an airtight container immediately.
If you live in a humid environment, it’s best stored in the freezer.
What is hana katsuo? Is it different from katsuobushi/bonito flakes?
Hana katsuo is one type of katsuobushi/bonito flakes.
Larger, thicker shavings of bonito flakes are called kezurikatsuo (in Japanese: 削り鰹; けずりかつお). They are usually boiled with kombu to make dashi stock.
While smaller, thinner shavings are called hanakatsuo (in Japanese: 花鰹; はなかつお). They are usually used as a flavoring and as a topping for many Japanese dishes, such as okonomiyaki and takoyaki.
What do bonito flakes/katsuobushi taste like?
Bonito flakes have a smokey savory taste that is a very suitable for many Japanese dishes.
It also has a distinct umami taste which comes from its high inosinic acid content.
Many people, Japanese or not Japanese, said that bonito flakes is very delicious.

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