【Reading】かいばしら

【English Name】Kaibashira (Shellfish Adductor Muscle)

Kaibashira (adductor muscle/scallop) is the muscle that closes the shell of a bivalve—the "adductor muscle" (heikakukin)—made into food. It is also called "nikuchu" or simply "chu."

The representative sushi neta is the scallop (hotategai), but pen shell (taira-gi), small adductors of trough shell (the kobashira of aoyagi), and Japanese baking scallop (itayagai) are also widely used. In the market, "kaibashira" sometimes refers to pen shell, and one must note that the meaning differs by region and context.

The adductor muscle is composed of striated muscle and smooth muscle, and because it is rich in betaine and succinic acid, it has a distinctive sweetness and umami. In addition to being high in protein and low in fat, it is said to also contain taurine, zinc, iron, and so on.

In sushi, raw nigiri is the standard, and it can also be enjoyed as sashimi, vinegared dishes, fry, butter-sautéed, tempura, and more. Because pen-shell adductor muscle tends to harden when heated, raw consumption tends to be preferred. Dried adductor muscle is also known as an ingredient in Chinese cuisine, and the pale-brown type called "shiraboshi" is considered high quality.

The adductor muscle of the scallop is said to increase its glycogen and grow sweeter mainly from May to July, making this period the best time to eat it.