Collector urchin nigiri

Collector urchin (Shirahige uni)

【Nigiri sushi: Gyoran】
The collector sea urchin (Shirahige uni) has a thin shell, and its roe is delicate and easily falls apart, so it is generally served as gunkan-maki. The roe is pale yellow and, compared with varieties such as Ezo-bafun uni, has a milder sweetness, with an elegant ocean aroma and a clean aftertaste.

Wild stocks have declined significantly, and catch volumes are now extremely limited. As a result, even in its main fishing areas, such as Okinawa and the Amami Islands, opportunities to taste shirahige uni are rare. In Tokyo, it is even more difficult to find, making it an exceptionally rare sushi topping.

However, at the popular sushi restaurant “Sushi Watanabe” in Arakicho, Tokyo, shirahige uni is occasionally offered as a special menu item for a limited period during summer, making it a seasonal delicacy appreciated by knowledgeable sushi enthusiasts.

【Umami components of Shirahige uni】
A study conducted by researchers at National Taiwan Ocean University, which analyzed the gonads of Taiwanese Shirahige uni (Tripneustes gratilla), reported that glycine was the most abundant free amino acid, with alanine and glutamic acid also identified as major components. Glycine and alanine are known to contribute to sweetness and are considered important components contributing to the mild sweetness of Shirahige sea urchins.

On the other hand, amino acids such as valine are believed to contribute to the bitterness of sea urchins, while methionine is thought to influence their distinctive flavor and aftertaste. The levels of these free amino acids are also known to vary depending on factors such as the season and the condition of the gonads.

Because Shirahige uni is rich in sweet-tasting amino acids, particularly glycine, its flavor tends to be characterized by a mild sweetness. As a result, they have a relatively delicate flavor and a clean, refreshing aftertaste.

【Related contents】
Global sea urchin resources

What is uni sushi?

Why is it that sea urchin sushi can taste bitter?

List of Nimono, Gyoran and Others