【Reading】じゅくせいずし

【English Name】Narezushi

Jukusei-zushi refers to a technique—or the sushi made by that technique—in which the seafood used as a topping is rested for a certain period so that proteins break down into amino acids, drawing out umami.

The concept of "aging" in sushi has a long history, with its roots tracing back to narezushi (fermented sushi). Narezushi is a fermented food in which fish is pickled with salt and cooked rice, achieving long-term preservation and increased umami through the action of lactic acid, and it is the prototype of nigiri-zushi. It is said to have originated in a region spanning from Southeast Asia to southern China, and is thought to have been brought to Japan along with the introduction of rice cultivation in the Yayoi period.

Modern jukusei-zushi, while drawing on the knowledge of such traditional fermentation techniques as its background, mainly uses the method of resting the topping for several days to several weeks while managing temperature and humidity. As the proteins in the fish flesh change into amino acids, a profound flavor different from freshly cured fish is produced.

It should be noted that traditional narezushi is still handed down today as a local cuisine in various regions, with funazushi of Shiga Prefecture, hatahata-zushi of Akita Prefecture, and kabura-zushi of Ishikawa Prefecture cited as representative examples. They are divided into two types: the "narezushi type," fermented with cooked rice alone, and the "izushi type," in which koji is added to impart sweetness.