How are Bonito Flakes Made?

November 13, 2023

Bonito flakes - known as katsuobushi in Japanese - are a strange food upon first sight. They are known to move or dance when used as a topping on foods such as okonomiyaki and takoyaki. It can be an odd sight upon first viewing if moving food makes you squeamish. However, it is nothing to be alarmed about. The bonito flakes move due to their thin and light structure upon the hot food and are not alive.

Bonito flakes are made from dried bonito fish that is grated into flakes. It's one of the main ingredients in dashi - a staple ingredient used in almost all authentic Japanese dishes.


Fresh bonito is cut into 3 pieces (right side, left side, and the spine). From 1 fish, 4 pieces of "Fushi" will be made (Fushi is the dried bonito piece)


2. KAGODATE (placing in a basket)

The bonito will be placed into a basket called "Nikago" which means 'boiling basket'. They will be placed into the boiling basket in an organised fashion, the bonito will be placed in such a way as to boil the fish in the best way. It can't be placed randomly or the fish won't boil correctly.


The bonito will be boiled at 75-98 degrees centigrade for 1.5hrs to 2.5hrs.
The chosen boiling times can vary depending on the fish itself, freshness, size and quality are all taken into account when a professional decides each bonito fishes unique boiling time, it can take many years of experience to master this. It also depends on the brand of bonito flakes. Each company has a set amount of time that they boil the fish.


Once boiling is done, the small bones are removed by hand with tweezers.


Once small bones and fish skin is removed, bonitos will be smoked. Cherry blossom and oak are often used as the kindling to smoke bonito. This is repeated between 10 to 15 times.  


The tar and fat is then shaved off from the surface of the smoked bonito.


7. Drying

The Bonito is then baked under the sun for 2 to 3 days, after which some mold is applied on the bonito. This is repeated a few times. After this whole process is completed, 5kg of bonito only becomes around 800-900g of bonito flakes. This whole process takes between 5 months and 2 years. 


8. Shaving

Dried bonito is shaved with special shaver, which way you shave affect flakes, if its shaven incorrectly, it can become powder. 

The classic bonito you can currently purchase in shops are flakes that are dried bonito shaved with this special shaver.


How to make dashi with bonito flakes

Boil 1 litre of water, turn off the fire then put 30g of bonito flakes in to the boiled water. Leave 1-2 min till bonito flakes sink. Filter it and its done! 

Also, in Japan, some other fish are used to make dashi soup. 

Iriko dashi - dashi that is taken from sardine. Often used for miso soup.
Ago dashi - taken from flying fish. Flying fish have got less fat than other fish so it has got less fishy smell in dashi. Used as ramen soup and udon soup. 

Buy Bonito flakes here

Also in Masterclass

Chef Focus: Dan Ashmore, ASKR
Chef Focus: Dan Ashmore, ASKR

February 27, 2024 0 Comments

Dan Ashmore has been on our radar for some time as Dean Banks Group Executive Chef, overseeing all of Dean's venues. He's now ready to open a place of his own at Chef Patron at ASKR, and he sat down with us to tell us all about it...

View full article →

Chef Focus: James Nicklin, Winteringham Fields
Chef Focus: James Nicklin, Winteringham Fields

February 26, 2024 0 Comments

We sat down with James Nicklin, the new Head Chef at the iconic Winteringham Fields, to find out about his culinary journey and to talk all things Japan!

View full article →

Exploring Koji: A Journey into Culinary Alchemy
Exploring Koji: A Journey into Culinary Alchemy

February 23, 2024 0 Comments

Embark on a journey into the heart of Japanese culinary tradition as we delve into the subtle art of koji. For centuries, this unique mold, born from the fermentation of rice or soybeans, has been quietly transforming simple ingredients into culinary treasures.

View full article →