It may be spiny, spiky and not exactly appetising to look at, but for connoisseurs, the sea urchin— once called ‘sea hedgehogs’ for their formidable-looking spines—is a prized ingredient on the Japanese table.
Like the sea cucumber, the sea urchin belongs to a family of marine animals called echinoderms. They cannot survive in fresh water and live only in the oceans. There are over 700 species of sea urchin found throughout the world, from the Mediterranean and the west coast of the US, which currently exports much of the world’s sea urchins, to the rocky coasts of New Zealand and the seas off Japan, arguably its spiritual home. Of that, only a handful is consumed by humans—probably because of accessibility (some species live up to 21,000 feet deep in the sea) and taste (not all species bear the same sweet umami taste that we have come to love).
While it is now popularly known as a Japanese delicacy, historically, the sea urchin was enjoyed by fishermen and coastal communities around the world—from the ancient Greeks in Alexandria who mixed them with vinegar, sweet wine, parsley and mint, to the indigenous Aleut people on Umnak Island in Alaska. To this day, Sicilian fishermen still enjoy it with soft white bread, which is used to scoop out the prized orange centre of the urchin.
Over in Japan, the earliest records of people eating sea urchin dates back to the ninth century AD. The Japanese call it uni, which refers only to the edible part of this marine animal—specifically, its gonads, or reproductive organs, but commonly mistaken as the roe. Each spiny sea urchin bears five delicate lobes, which require dexterous skill to remove.
Admittedly, it is somewhat of an acquired taste, but gourmets are not the only ones who like it; lobsters, crabs, wolf eels and sea otters have a taste for uni, too!
The Japanese Uni
Widely considered to be the best, Japanese uni is superior in taste and texture, with a full, rounded umami sweetness that may be wanting in lesser varieties. The traditional harvesting grounds of the Japanese uni are the pristine waters off Hokkaido. The picturesque Shakotan Peninsula, two hours’ west of Sapporo, is where seafood lovers converge. Two of the most prized species of uni can be found here: bafun uni (horse dung sea urchin), with a deep orange hue and an equally rich flavour; and the murasaki uni (purple sea urchin), which is pale yellow in colour with a sweet, milder taste.
Aka uni (red sea urchin) is a variety used in many sushi-ya. Apart from Hokkaido, it is also harvested in the Kyushu region in Japan and elsewhere in the world, including off the coasts of California in North America. It has a stronger taste than bafun and murasaki, and finishes with a slightly bitter note.
Uni is graded according to freshness and texture, with Grade A being the best—fresh, sweet and firm—and Grade C, reserved for the leftover lobes or ‘vana uni’, which has been broken during processing.
What’s more, a brighter uni doesn’t always mean better quality. According to Amanda Tan, owner of online Japanese grocers Zairyo (which brings in different varieties of uni), the colour of the uni is a matter of species and not a true indication of quality.
“You get uni from Russia, for instance, that have a very bright and pretty colour, but they may not be sweet like you would expect,” she says.
Seasonality varies according to species and geographical location, although sea urchins are available in Japan almost year-round. According to Tan, who brings in uni only from Hokkaido, bafun is best in spring, while murasaki come into season from June to mid-August. October is spawning season in Hokkaido so most places there will ban harvesting.
On the Market
Uni is available on the market in myriad forms—fresh and raw (nama uni), salted (shiouni), kept in a briny solution formulated to replicate seawater (ensui uni), as a paste, blended with soy sauce and even in consommé jelly conveniently packed in a tin to pair with beer.
The Taste Test
If in doubt of freshness and quality, venture a taste. Fresh, quality uni should be umami sweet in the mouth, sans dubious pungent odours. It should certainly not be metallic, overly bitter or fishy, or smell like cat’s piss. Texture-wise, it should hold its shape and yet is creamy and smooth, not sandy. Tan describes it as “umami tofu”.
Not for Keeps
Although fresh uni keeps in the fridge for three to four days, Tan’s advice is to tuck in as soon as possible, preferably within two days upon delivery from Zairyo. (To ensure freshness, the grocers fly the uni in fresh upon order, which must be made three days in advance.) For ensui uni, consume within the day upon delivery as it doesn’t go through the same processing, she advises.
Avoid storing uni for any extended lengths of time. When removing boxed uni from the fridge, be sure to check for condensation that may occur due to the local humidity and temperatures. Use a tissue to lightly dab away any condensation.
Never. Ever. Freeze. Once frozen and thawed, fresh uni collapses into mush.
Cover: Nama, ensui and boxed uni
This was first published in Wine & Dine’s October 2016 issue – ‘Masterclass’