The universal term "umami" is one of the five basic tastes (sweet, salty, sour, bitter, and umami) discovered by Dr. Kikunae Ikeda of the former Tokyo Imperial University (now the University of Tokyo) in 1908. The three most common types of umami are glutamic acid from kelp, inosinic acid from dried bonito flakes, and guanylic acid from shiitake mushrooms. All of the umami tastes play a role in the deliciousness of food.
There are two types of dried bonito, "ara-bushi" and "kare-bushi," which are representative of umami, and each is produced in a different way. Ara-bushi is dried by roasting for about a month, and most of the dried bonito shavings on the market are made in this way. Most of the shavings on the market are of this type. Ara-bushi is characterized by its strong flavor and the aroma left over from the smoking process. On the other hand, kare-bushi is made from ara-bushi that has been dried with mold, and further aged to become "hon-kare-bushi," which takes more than half a year to produce. This mold (Aspergillus and Eurotium) absorbs and dries the water inside the dried bonito, which could not be removed by roasting, and breaks down the fat in the bonito, resulting in a highly transparent "dashi (soup stock)" with an elegant, clean, and mild aroma.
Dashi differs between the Kanto region's strong flavor and the Kansai region's light flavor. In Kanto, dashi is mostly derived from fish and is sometimes called "tsuyu" or "otsuyu." In Kansai, it is mostly kelp combined with dried sardines and dried bonito flakes, and is called "dashi" or "odashi." The dried bonito flakes used are kare-bushi in the Kanto region and ara-bushi in the Kansai region.
To make dashi, the hardness of the water differs depending on the region and water system in Japan, and there seems to be a subtle difference in taste depending on the location. Kelp dashi is more easily obtained with soft water, while hard water causes the calcium in hard water to combine with the minerals in kelp, resulting in a harsh, fishy smell and a poor umami taste. In the Kanto region, hard water tends to make kelp dashi less tasty, so the bonito dashi culture has taken root.
Another reason for the difference between Kanto and Kansai is that during the Edo period, kelp was more readily available in the Kansai region and fish with a strong flavor could be caught, so light soy sauce was used to flavor the ingredients. On the other hand, fish caught in the Kanto region tended to be lighter in flavor, and it was difficult to transport kelp from Kyoto to Edo (present-day Tokyo).
In addition to the Kanto and Kansai regions, dashi varies from region to region in Japan, such as Hokkaido, Kyushu, and Okinawa, and is influenced by local water and specialties. I would like to taste the local dashi dishes of each region.
Daiya's Bonito Sharpener
Seiryugama's Kobachi L