【Reading】しお

【English Name】Salt

The moment a sushi chef sprinkles salt is a test of the eye for judging an ingredient's flavor. Adding just a tiny amount to delicate toppings such as white-fleshed fish or squid (ika) causes the sweetness to spread across the tongue all at once. Salt is also central to preparation work: the process called shio-jime (salt-curing) draws out excess moisture and odor from the fish while giving the flesh a supple, springy texture. With shiny-skinned fish (hikarimono) represented by gizzard shad (kohada) and mackerel (saba), a chef's skill shows vividly in the amount of salt and the length of curing.

The substance that makes up most of salt is sodium chloride. In Japan's climate, where rock salt is almost never produced, a distinctive method of boiling seawater to crystallize it was passed down through the generations. The Setouchi region and the Noto Peninsula are renowned as centers of salt production, where innovations such as the agehama, irihama, and ryuka (flowing-down) methods accumulated. The ion-exchange membrane method began spreading in earnest from the 1970s, and the nigari (bittern) produced as a byproduct of that process came to be used as a coagulant for setting tofu.

The state-run salt monopoly system came to an end in 1997, and with the full liberalization of 2002 as a turning point, distinctive sea salts emerged one after another from across the country. In the world of sushi, too, an awareness of selecting and using salt according to its origin and production method is steadily taking hold.