【Reading】じゅくせい

【English Name】Aging

Jukusei (aging) refers to a technique of changing flavor and texture by letting ingredients rest for a certain period. In the world of sushi, it is known as a preparation technique that utilizes the phenomenon in which the proteins of seafood are broken down into peptides and amino acids by the action of enzymes, increasing umami.

In Edomae sushi it has long been called "nekase," and a method developed of resting white-flesh fish, tuna, and the like for several days after kobujime (kelp-curing) or applying salt. In recent years, "jukusei-zushi," in which neta are aged while temperature and humidity are strictly managed, has been attracting attention.

The principle of aging is common to meats as well, with the key points being the increase of amino acids accompanying protein breakdown and the improvement of umami through the action of enzymes and microorganisms. In the case of meat, a representative method is to rest it for about 14 to 35 days in an environment of 0–4°C and about 80% humidity. If the temperature is too high it spoils, and if too low it freezes and aging does not progress, so delicate temperature management is indispensable.

In the aging of fish, freshness management becomes even more important, and the precision of preparation such as blood draining and shinkeijime (nerve destruction) greatly affects the finished result. In fields of fermentation and distillation such as cheese and brandy, aging is also an important process that determines quality, making it a concept deeply rooted in food culture as a whole.