Uni (Sea Urchin) Sushi

Uni / Sea Urchin

Fish Roe

Share Post LINE

Phylum Echinodermata, Class Echinoidea

Sea urchins are widely distributed from shallow waters to the deep sea and from the tropics to the polar regions, with about 950 species inhabiting oceans around the world. They are roughly 3 to 10 centimeters in diameter and are often found clinging to rocks, and they can move by swinging their spines widely from the base.

Sea urchin is the general term for creatures belonging to the phylum Echinodermata, class Echinoidea, which, like starfish and sea cucumbers, have a structure in which five identical parts are arranged radially from the center of the body. They feed mainly on algae and inhabit oceans all over the world. The sea urchins that can be eaten in Japan belong to the families Strongylocentrotidae, Echinometridae, and Toxopneustidae. Six species are well known: the Ezo bafun sea urchin and the bafun sea urchin, the Kita murasaki sea urchin and the murasaki (purple) sea urchin, all common in northern areas such as Hokkaido, Tohoku, and Russia; the aka (red) sea urchin, common in western Japan; and the shirahige sea urchin, common in Okinawa. In addition, species such as the Chilean sea urchin and the American purple sea urchin are imported from countries including Chile, Peru, the United States, and Canada, but they tend to have a slightly blander flavor than the six species above. The edible part of the sea urchin is the gonads. The testes are considered richer and more delicious than the ovaries, and high-end sushi restaurants often use the testes. As with other sushi toppings, freshness is crucial, so ideally they are eaten immediately after the shell is cracked open. However, since the condition cannot be known until the shell is opened, "box uni" arranged on a tray after being soaked in alum solution as a preservative is often used. Because alum-treated sea urchin tends to develop astringency and bitterness, additive-free sea urchin preserved in salt water or sea urchin still in the shell is generally said to let you enjoy its true flavor. The peak season varies by region because the fishing periods differ, so it is not always consistent, but early summer before spawning is the general rule. Sea urchin sushi is usually served as gunkan-maki (battleship roll), but some sushi chefs believe that the aroma of the nori seaweed masks the flavor of the sea urchin, so it is sometimes served as nigiri or as a gunkan-maki wrapped with a thinly peeled sheet of cucumber.

The two great red-and-white sea urchins: Ezo bafun uni and Kita murasaki uni

Sea urchin sushi is a well-known luxury sushi topping, but its price ranges greatly from about 500 yen to over 100,000 yen per box, depending on the species and brand of sea urchin. The Ezo bafun sea urchin and the Kita murasaki sea urchin in particular are known as Japan's two great red-and-white sea urchins, top class in both flavor and price. The red Ezo bafun sea urchin has strong sweetness and a rich aroma, with vividly orange flesh. The white Kita murasaki sea urchin is characterized by moderate sweetness, an elegant flavor, and pale-colored flesh.

One of Japan's Three Great Delicacies

The Japanese kanji for sea urchin can be written as a character meaning "sea liver" because the orange gonads look like liver, or as a character meaning "sea chestnut" because the shell resembles a chestnut burr, but another kanji is also used for processed sea urchin. The difference is that the first two characters refer to fresh sea urchin, while the third refers to processed sea urchin.
Salted and effectively turned into a fermented sea urchin paste, processed sea urchin is known as one of Japan's three great delicacies, alongside karasumi (salted, dried mullet roe) and konowata (salted fermented sea cucumber intestines). The "Echizen uni" of Fukui Prefecture is one famous example of salted sea urchin.