DRIED BONITO FLAKES

Dried Bonito Flakes, are a commonly used ingredient in Japanese cuisine, but their ubiquity should not detract from their remarkable nature. To those uninitiated with Japanese cuisine, they may appear quite unusual in appearance, but even more special is the way in which they are produced; a painstaking process that takes months and has been honed for centuries.
A remarkable ingredientThe katsuo, or ocean bonito, is a popular fish in Japan, which has been eaten since the Jomon period (c. 10,000-3,000 BC). It is generally caught during early summer in the northern seas off Hokkaido and during autumn in the warmer waters further south. Its red, meaty flesh is eaten fresh, particularly as tataki, when the outer part of the fillet is briefly grilled over a flame leaving the centre raw, and is also often cooked in a teriyaki sauce.The fish is best known, however, for being made into katsuobushi, which are shaved from a bonito fillet that has not just been dried but also smoked and mould cured over a long period of time to create something that in shape, colour and hardness very much resembles a piece of wood. Having been eaten fresh for millennia, the first record of dried bonito being consumed dates from around the eighth century. It was not until the Muromachi period (1336-1573) that records speak of something vaguely resembling katsuobushi as we know it today; not simply dried, but also hardened. During the Edo period (1603-1867), meanwhile, the techniques of smoking fish and meat products to remove the moisture from them and mould curing became more widespread and bonito-processing centres able to carry out these tasks sprang up along the Pacific coast of Japan. Today, the katsuo fishing industry is centered on Makurazaki in southeast Kyushu and Tosa on the south of the island of Shikoku, both in the warm waters at the south of the country.
A painstaking processThe process of making katsuobushi is a painstaking and fascinating one, and begins soon after the fish have been landed. After being filleted, the flesh of the fish is boiled for between twenty and thirty minutes to set the proteins and the bones removed using special tweezers, a process known as hone nuki. The fish is then wood-smoked for several hours a day for up to two weeks until the moisture content is reduced to around a quarter of what it was at the outset. Next, the fillets are dried in the sun for two or three days, in preparation for the curing process. The fish is placed in a chamber impregnated with a mould called Aspergillus glaucus, a close relation of the kojikin mould, Aspergillus oryzae, which is used in the making of miso, sake, mirin and other Japanese beverages and condiments. In many cases, the same chamber may have been used for many years, which not only means that it is unnecessary to add additional mould, but also that the mould present will be unique to that chamber and give the resulting katsuo a distinctive character. After the mould has had two weeks or so to develop on the fish the fillets are removed from the chamber and placed in the sun to kill off the surface mould. They are then returned to the chamber and the moulding and sunning process is repeated for up to six weeks until the fish has completely hardened. The blocks of bonito are traditionally shaved using a device called a katsuobushi bako, which is identical to a carpenter’s wood plane but collects the shavings in a box underneath. The flavour and aroma of katsuobushi are at their best immediately after shaving and the process should therefore be carried out as close to the time of cooking and eating as possible. So much so that it is said that in some top quality restaurants the chef does not shave the katsuobushi until the customer has arrived at the restaurant. The majority of homes and restaurants in Japan nowadays, however, do not shave their own katsuobushi, even though it used to be quite common in many families until around the 1970s. Instead, the majority of katsuobushi used nowadays are pre-shaved and sealed in airtight bags to preserve flavour and aroma.
Many flakes, with many uses As discussed earlier in this chapter, the importance of katsuobushi lies in the fact that it imparts the umami taste. The long, slow fermentation process causes the proteins in the fish to break down releasing, amongst other substances, the nucleotide inosinate, which is one of the three main umami-imparting ingredients. Its role in ichiban dashi is particularly important, with the 5’-inosinate being combined with the glutamate of the konbu to create a powerful umami hit. dashi is also sometimes made just with katsuobushi, when it is ideal in suimono clear soups and forms the basis for tempura dipping sauce. The intensely savoury flakes have a number of other uses besides dashi , however, and are particularly effective in very simple and lightly seasoned dishes such as o-hitashi (boiled and seasoned green vegetables), hiyayakko (a block of chilled tofu) and yudofu (tofu hotpot), with the combination of katsuobushi and soy sauce creating a delicious, synergistic umami hit. The flakes are also often used as a garnish for savoury foods such as o-konomiyaki (savoury pancakes) and takoyaki (chopped octopus in batter), which are both often topped with a thick, dark Worcester-style sauce and mayonnaise before being sprinkled liberally with katsuobushi, which appear to dance and writhe around on the hot food.