To the uninitiated, all uni, or sea urchin in Japanese, look the same. In fact, there are over 950 types of sea urchin, and only a handful are worth eating. After all, those who visit top end sushi-yas in Singapore will see that it comes either neatly arranged in wooden frames or more rarely, inside the sea urchin shells itself.
Some might mistake the apricot-hued flesh as the roe, when in fact, it is the gonads of the sea creatures that are eaten. These premium delicacies often taste best at the height of their feeding season where they eat seaweed, algae, kelp and sometimes small mussels. These are then converted into energy stores in the gonads for them to spawn.
But there is an art to distinguishing the different types of sea urchin and adept Japanese chefs deploy them in different types of dishes. Here, we help you to discern some of the main types of uni and the properties that make them stand out.
Bafun uni is the most common type of culinary sea urchin and it can be found not just along the shores of Japan but in many parts of the world. It’s thus not surprising that it’s also used in the Italian culinary canon as part of pasta and risotto as well. It can be identified by its bright orange colour, a deep umami flavour that recalls the brininess of the ocean and a firm texture. In Japanese cuisine, it’s often eaten as sushi and also in a bowl of rice to add a creamy dimension.
Murasaki means purple in Japanese and this species of uni is derived from a purple coloured sea urchin that sports long spikes. The flesh itself tends to be paler than that of the bafun uni described above. While some might be more attracted to the colour of bafun uni, it is murasaki uni that is rarer and regarded as more premium thanks to its cleaner and naturally sweet flavour. It also has a light texture which would feel like it’s melting in your mouth. It is best enjoyed in its season which lasts from June to September and is typically available only at Japanese market auctions.
Aka uni may be the smallest of all sea urchin varieties but don’t let its small size fool you. It’s the most flavourful of all uni — fishy, as some might describe it. It’s found mainly in the southern islands of Kyushu where the waters are not as cold as in Japan’s northern regions. It can be identified from its bright yellowish colour with an orange tinge and is often used in sushi, chirashi don as well as pastas that call for a strong uni flavour.