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Maguro: an iconic food that is now international

January 30, 2017

Nothing is more evocative of Japanese cuisine than tuna sushi. The bite-sized patties of white rice topped with perfectly rectangular slices of gleaming-red raw fish are so instantly recognizable that they even have their own dedicated emoji.

Known generically in Japanese as maguro, tuna is prized at sushi counters around the world. This majestic, fast-swimming, pelagic fish has played an important role in Japanese food culture since ancient times, especially among the common people. But it is only since the development of preservation techniques in the past half century, that it has become such an iconic part of the cuisine.

These days, maguro is considered an essential component of any sushi meal, whether in Japan or around the world. In fact it could be argued that without tuna sushi itself might never have achieved its global popularity.

Sashimi or sushi, it has to be raw

There are actually eight different species of true tuna, including albacore and yellowfins. All are eaten in Japan, but it is the three kinds of bluefin that are treasured most highly. Known either as kuromaguro (“black tuna”) or honmaguro (“true tuna”), they are considered the kings of the ocean.

Although some of the fish are processed for canning or used in cooking, the vast proportion of the bluefin tuna consumed in Japan is eaten raw, either as sashimi or sushi. Thanks to its striking color and rich flavor, maguro is considered a key ingredient in platters of mixed sashimi, usually served alongside white-meat fish such as red sea bream (tai), flounder (hirame) or squid (ika).

Sometimes, maguro sashimi is served as a donburi, on top of a large bowl of fresh-cooked rice, either alone or alongside other ingredients such as salmon roe (ikura). Invariably, it is eaten with a small dab of grated wasabi root and a dip of soy sauce.

But it is at sushi restaurants that maguro has really come to be considered as the king of seafood. Many offer three very different cuts of the fish, which are often served consecutively or even side by side, as a way to compare the differences in taste, texture and appearance.

The most common of the cuts is simply called maguro or akami (literally “red flesh”). This is the dark-red lean meat taken from the back and sides of the tuna fish. Because it is relatively abundant, it is also the most affordable cut of tuna. Sometimes this akami is briefly marinated in a mixture of shoyu, mirin and sake to imbue it with greater umami and depth of flavor -- a preparation called zuke.

The fattier cuts from the belly of the fish are known as toro. These are divided into two levels -- chu-toro (medium-fat) and o-toro -- although there will be considerable variation in the color and distribution of fat within those categories.

O-toro is the marbled flesh found on the section of the belly closest to the head. Often it is so full of fat it can appear more white than red, and it literally melts in the mouth. Chu-toro is the light pink meat taken from the belly and parts of the upper back. Characteristically it is composed of strips of leaner meat interspersed with fine layers of fat. Although o-toro is the more expensive cut due to its rarity value, many sushi connoisseurs tend to prefer the texture and less oily quality of chu-toro.

Lesser grades of akami are often chopped up with negi (scallions), and served under the name negi-toro. A similar but superior preparation comes from the meat that is left on the bone or around the sinews after the rest of the meat has been carved away. Known as naka-ochi, this is scraped away and served in minced form, usually inside nori-maki rolls.

The black gold of the sea

For visitors to Tokyo’s iconic fish wholesale market at Tsukiji, one of the most defining images is that of bluefin tunas carefully arrayed for auction looking much like lines of torpedoes.

While some tuna are brought to Tsukiji with their dark skin still glistening and fresh, most of them arrive flash-frozen to minus-60 degrees Celsius. This not only preserves the fish over the time it takes to get them to market, the ultra-low temperature also ensures that the meat keeps its color and does not lose its juices when it is thawed out, keeping it fresh for consumption as sashimi.

Fully mature Pacific bluefin can weigh almost 500 kg (half a metric ton), with a length of up to three meters. The all-time record set for a single maguro is 155.4 million yen (equivalent to 703,000 yen per kg.) in 2013, although it was only about half the size of the largest recorded specimens. Bluefin tuna caught off the coast of Japan are generally considered the very highest quality. These spectacular fish are landed at ports such as Oma, on the northernmost tip of Aomori Prefecture.

Inside the wholesale market, there are merchants who specialize solely in maguro. Visitors can sometimes watch as the workers carve up the giant fish using maguro-bocho, special knives with blades of up to 150 cm - twice as long as traditional samurai swords and requiring two people to handle them.

Once the fish have been broken down, the individual cuts are set aside in blocks of around 1 kg. But the best rarely makes it onto the retail market. Instead it is kept aside for trusted regular customers, including Tokyo’s high-end kaiseki restaurants and the premium sushi counters that are thickly concentrated in the nearby Ginza district.

Fish farming for the future

Most of the global catch of Pacific bluefin tuna is consumed in Japan, just one indication of how popular it is in this country. But in recent years the taste for sushi has spread; demand is increasing elsewhere in the world.

Meanwhile there has been a precipitous drop in tuna populations, and anxiety about overfishing is spreading. Atlantic bluefin and Southern bluefin are especially endangered, with Bigeye and Pacific bluefin considered vulnerable, and although quotas have been imposed for some species, stocks appear to be at risk of collapse.

In response, much research has been done on setting up commercial fish farms for bluefin tuna. Initial efforts focused on catching tuna fry and raising them to maturity. But now one Japanese venture led by Kindai University has successfully developed techniques for raising maguro from farmed fish rather than from young tuna caught in the wild.

This “100 percent farm-raised” bluefin has been available for the last few years at a select number of restaurants. Although there are still many concerns, it is hoped this initiative will help alleviate pressure on stocks of bluefin in the wild.

Text: Robbie Swinnerton

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