How to Make Mentaiko?

Mentaiko: Spiced Salted Cod Roe

Sushi is undoubtedly a world-famous Japanese dish these days, and fish is a favorite food of many Japanese. One reason for this is that Japan is surrounded by sea, so seafood is abundantly available. Also, we don’t like to waste anything – we try to eat every part of the fish. This leads to another unique aspect of the Japanese diet: we love to eat fish eggs. Readers might be familiar with caviar, but have you heard of ikura (salmon eggs), kazunoko (Pacific herring eggs), karasumi (flathead mullet eggs), tobiko (flying fish eggs) or tarako (Alaska Pollock eggs)? They are all popular, and are eaten every day in homes and restaurants throughout Japan. But of all these, karashi mentaiko or mentaiko for short, is the favorite. Mentaiko is a spicy version of tarako – the eggs are the same. According to Teikoku Databank, a corporate credit research company, 15,335 tons of tarako and 36,014 tons of mentaiko were produced in 2010. That’s a total of 51,349 tons. If divided by Japan’s population of about 120 million, each person consumed about 430g, which works out  to 12 roe sacs per person.

  Mentaiko is a popular ingredient in onigiri (rice balls). You can find mentaiko onigiri at convenience stores around the country. It is also a very popular ingredient at sushi restaurants in Japan. So, how is this national dish made? We visited a newly-built museum in Aichi Prefecture to find out.   Many companies make mentaiko, but Kanefuku Co., Ltd. has the largest share of the market. The company has built a museum called Mentai Park in Tokoname, Aichi Prefecture, which is open to the public all year round except during the New Year holidays. This is the company’s second such facility. The first Mentai Park is in Oharai, Ibaraki Prefecture. “We get about a million visitors every year at Oharai. We expect double that amount – two million – at Tokoname,” said Junichi Enokida, Kanefuku’s managing director.

The museum, which opened at the end of last year, was busy even on a weekday. From an airy vestibule, you enter the museum through a cave-like gate. Inside, a dark room lit by a dim blue light makes you feel like you are deep in the ocean. Here, you will learn where mentaiko comes from. Sukesodara, or Alaska Pollock, is a type of cod fish. There are other species of cod, but only sukesodara’s roe can be called mentaiko. Sukesodara live in the northern part of the Pacific Ocean. However, their habitat is shifting northward due to global warming. Fish roe has several stages of development. The top one in this photo is firm, so it is good for grilling. The bottom one is soft, so it is good for mixing with things like pasta. The best one to use for mentaiko is the second from the top.

<How to Make Mentaiko>

About 95% of sukesodara roe is imported, mainly from the US. The roe sacs arrive at the factory frozen. To retain freshness, they are defrosted slowly over the course of about 20 hours by having air blown over them at different temperatures.

1. After the defrosting process, the roe sacs are cleaned. Fish scales and bones are removed by hand.
2. After cleaning, they are soaked for one day in water containing salt and pepper, becoming salted cod roe sacs.
3. Salted cod roe sacs are sorted by size. Blood vessels and peritoneums are removed
4. After sorting, they are soaked again, this time with a variety of different flavors: red peppers and other seasonings such as sake (Japanese rice wine), mirin (sweet sake used for cooking), etc. They are marinated for between 48 and 72 hours. Enokida said that other makers add other spices or herbs, such as yuzu (a small citrus fruit) or garlic, but that his company tries to make flavors everyone can enjoy, rather than anything out-of-the-ordinary.
5. After the seasonings have soaked into the roe sacs and the flavors have matured, the sacs are measured by weight, selected for use in different kinds of products, and packaged. Some are sold as is, while others are used as ingredients in a different dishes.

Visitors can learn about the whole process by observing it from a glass-walled corridor. Afterwards, they have the opportunity to sample some freshly-made mentaiko.