Fatty tuna | Sushiblog－Sushiuniversity

The migrating route of Inshore Pacific bluefin tuna and fishing place!

An illustration of Kuro maguro main prodution area — This is the migration route of Kuro maguro (bluefin tuna).

Tuna caught in the coastal regions of the Japan Sea is notable as the best bluefin tuna in January. Iki, a small island in Kyushu area is one of the famous ports for tuna.

In February and March, the tuna auction market becomes slack due to rough weather. Just a few tunas from Nachikatsuura where is also the famous port for tuna are on the market.

In March and April, tunas become thin because their eggs need many nutrients.

In May, large tuna is seldom seen in the Tsukiji Fish Market. Even if there is, its body is really thin. “Kinkaimono” which means a shore-fish is generally considered as high-class tuna, but in this season, imported tuna is useful instead.

It is said that Pacific Bluefin tunas spawn around Japanese waters between Taiwan and Okinawa in April and May. And then, they go up to fertile, north sea along the eastern coast of Japan.

In June, “Chubo” which is young and small tuna is taken hugely off the coast of the Sea of Japan. The school of Chubo begin moving northward in this season.

In July and August, tunas can be seen occasionally but their bodies are still thin. Instead, Boston Tuna which is caught in the Atlantic Ocean and nicknamed “Jumbo” is on the market. Its fresh is softer than “Kinkaimono” and it doesn’t have medium-fatty part which “Kinkaimono” has.

In September, Boston Tunas are at their best with plenty of fat on them. The best season of Boston Tuna is limited and ends in October. But fortunately, Japanese tunas come into season.

The school of tunas split up into two groups, the one takes Pacific Ocean route and another takes the Japan Sea route and both of them move northward along the Japanese Islands. Some of them reach the Tsugaru Strait where and the season of Tuna begins from September to next January. Oma town and Toi town is famous nationwide for its catch of tuna from the Tsugaru Strait. The flavor of tuna in September is still weak but it becomes stronger in October. In November, feed of tunas such as Pacific saury or Japanese common squid with plenty of fat increase and flavor of tuna also gets stronger. In December, the peak season comes around.

A catch of tuna falls off in January and it enters the final season. The temperature of sea water gets cold and feed of tuna, squids decrease and the fishing season in this area ends.

Related contents: TYPES OF TUNA

[sc_apply url=”https://sushiuniversity.jp/apply/”]

We hope this information will be helpful.

Revision date: August 20, 2018

Share this article

Tuna is allowed to rest before it is used.

Once a bluefin tuna is caught, it arrives in Tsukiji fish market within a day or two. However, that fish is not used as a sushi topping that day. No mater how good the tuna is, it starts out very stiff and is not in a state where it should be eaten. The meat is hard and the white muscle lines are left in your mouth. The odor and acidic taste of the red meat is strong and the unique sweetness of the fish is nowhere to be found. After it has rested the muscles soften, bringing out the fat.

Then, when the sushi chef gets the tuna, he first separates the red, lean meat and the fatty toro portion, rewraps them separately and, seals them in plastic and puts them on ice. Next is waiting for the “young” meat, not yet suitable for eating, to mature. The number of days the fish will be rested depends on the size of the fish and the temperature. The smaller the cut and the warmer the temperature, the shorter the rest time. Generally the time is from 3-14 days.

This “young” fish not ready for consumption is a fresh, deep color but as it matures the color darkens, the fat is brought out and becomes a fleshy color. Proper care must be taken because if it’s rested for too long, the color changes too quickly.

Related contents: TYPES OF TUNA

[sc_apply url=”https://sushiuniversity.jp/apply/”]

We hope this information will be helpful.

Revision date: August 13, 2018

Share this article

What is Uwami and Shitami?

Large fish that are caught are always kept and transported on their side with their heads facing left from the port to the market and to the restaurant where they are served. The part of the fish facing down when in this position is called “Shitami” or the “bottom body” and the part facing up is called “Uwami” or the top body. The Uwami costs more than Shitami. This is because the Shitami takes on the weight of the Uwami, reducing the freshness and possibly causing cracks in the body (cracking occurs on the edges of the muscles).

This mostly applies to Pacific bluefin tuna (tuna that is consumed without any freezing after being caught). At any rate, since this fish costs hundreds of dollars per kilogram, a full-grown fish may be worth more than a luxury sports car. Therefore, from the time they make their catch, the fishermen work quickly, which affects all aspects of the quality. Most of all, this work affects the price. A Pacific bluefin is never placed directly on the deck of the ship. If a fish weighing 100 kg or more is set directly on the hard deck, its own weight would cause injury to its surface. Naturally, any damage or injury to the fish reduces the price. Instead, each fish is laid on a soft, spongy mat to protect its skin surface. Next, the blood is drained, the spinal cord nerves are destroyed and the fish is submerged in ice water. It might be easier to understand if you imagine handling a luxury vehicle, like a Ferrari, rather than a tuna fish.

Incidentally, the idea behind keeping the “Left side up (or prioritized), right side down,” is a fixed Japanese etiquette, passed down through China from the Asuka period. Perhaps the reason fish are also served for eating and photographed with the head on the left side is due to this influence as well. However, this is only a fixed practice within Japan.

At sushi restaurants, one of the many things the chef teaches their apprentice is to, “Start using purchase fish from ‘Shitami’.” Once a sushi topping is prepared, it may be served for several. It’s hard to imagine that the Shitami would start to go bad during these several days, but it is attention to these small details that make a master sushi chef.

Related contents: TYPES OF TUNA

[sc_apply url=”https://sushiuniversity.jp/apply/”]

We hope this information will be helpful.

Revision date: June 13, 2023

Share this article

What is the difference between the taste of marbled and lined fatty tuna?

It is often said that when you eat Otoro, it melts in your mouth like a snowflake. With its smooth texture and rich flavor, it is enormously popular. Otoro is located on the belly side near the head and can be divided into two types.

A photo of otoro shimofuri — The appearance of Otoro shimofuri

Marbled tuna (Shimofuri) is the part in which it looks like the fat has fallen like a frost and melts like snow on your tongue then leaving only the umami taste. By cutting thinly and widely at an angle to the saku, a delicate flavor and aroma are produced.

A photo of Otoro jabara — The appearance of Otoro Jabara

The lined fatty tuna (Jabara) is the part that has white fat lines running through it. When you first take a bite, surge of aroma and umami flavor fills your mouth. After that, the potent fatty umami fills your mouth. Cut the Jabara into thick, slightly shorter pieces and make nigiri sushi.

The way the fat melts in your mouth differs between Jabara and Shimofuri, so which you like better depends on preference.

A photo of otoro aburi — The appearance of Otoro aburi

Some people find the fat in Otoro to be too rich. By searing it, the excess fat is removed and the moisture is evaporated, so the umami components are concentrated, and adding a savory aroma enhances the flavor.

Related contents: TYPES OF TUNA

[sc_apply url=”https://sushiuniversity.jp/apply/”]

We hope this information will be helpful.

Revision date: October 5, 2024

Share this article

Can’t-miss Tokyo sushi toppings (Meji Maguro)

Meji Maguro (AKA: Meji) caught in fixed net fishing is one type of sushi topping that you really should try. Meji is the larval fish of Pacific bluefin tuna, made and served at expensive restaurants, but not usually available as Edo-style sushi. Its fat is lighter and it doesn’t have the impact that fatty tuna has. Efforts are put into seasoning to avoid this. Using a pinch of ginger, Japanese basil or onion between the topping and rice, along with the wasabi, really brings out the fresh flavor of the young fish as well as the sweetness of this fatty part.

Related contents: TYPES OF TUNA

[sc_apply url=”https://sushiuniversity.jp/apply/”]

We hope this information will be helpful.

Revision date: March 26, 2018

Share this article

Why is sushi with tuna topping so expensive?

A purchase of raw tuna costs at least JPY 30,000 per kilogram. Furthermore, good tuna is judged not only by taste, but appearance is also highly regarded.

The surface is gradually oxidized by letting it sleep (mature) and the sushi chef makes sure that parts are cut of as they change color, when the timing is perfect for both the taste and appearance. In other words, skin is taken from the freshly purchased tuna, the meat of the fish darkened by blood (the blackened area that can’t be used as sushi toppings) is removed, the parts that have changed color are shaved off and then only the remaining, best parts used as toppings are left.

This is why the price is high.

Related contents: TYPES OF TUNA

[sc_apply url=”https://sushiuniversity.jp/apply/”]

We hope this information will be helpful.

Revision date: February 5, 2018

Share this article

Tuna was not a premium fish during the Edo period!

During the Edo period, tuna was not highly valued as a sushi topping and it was referred to as “Gezakana” meaning that it was inferior to normal fish. The reason was the big size of the tuna. At this time there was no ice, so tuna had to be salted. It was cut into blocks, salt was spread all over and in it, and that was it. At Uogashi (the market prior to Tsukiji) it was treated at shops that specialized in salting fish. The dark, discolored, salty chunks of flesh really were nothing but “Gezakana*”.

*Gezakana －Relatively low-cost sushi ingredients, such as gizzard shad and horse mackerel. Bluefin tuna used to be also called gezakana in the Edo period, for losing its freshness easily.

Related contents: TYPES OF TUNA

[sc_apply url=”https://sushiuniversity.jp/apply/”]

We hope this information will be helpful.

Revision date: December 30, 2017

Share this article

You know toro tuna and akami, but have you heard of the more rare parts of the tuna?

A single bite of the same bluefin tuna differs greatly depending on the part of the fish it came from.

The body of the fish is broadly categorized into the dorsal (back) and the ventral (belly) sides, which taste completely different. Of course the meat near the head tastes completely different from the meat near the tail. If you dig even deeper, there are parts that aren’t as well-known as the Otoro (fatty), Chutoro (medium fatty) and Akami (lean) tuna meats. We’d like to explain those now.

“Hachinomi (ハチの身) or Tsunotoro Nouten” is the meat from the crown of the head. It is fatty and rich and also called “Head Toro”. Only about 1kg of this precious meat can be taken from even a very large fish, and it is only shared with regular, loyal customers.

“Kamatoro (カマトロ)” is taken from behind the jaw. It is known as “shimofuri (霜降り)” or marbled meat. There are no veins in this part so the meat is soft and the marbling is more detailed than Otoro, so it is sticky and melts in your mouth. The balance of fat and sweetness in this part is unparalleled. It can be said that otoro (such as shimofuri and jabara) of tuna is the representative part of toro tuna. This is an image of the shimofuri on the right, and the jabara (蛇腹) on the left.

“Chiai (血合い)” is the part with the most veins, so it is a dark red color. It has a strong odor of blood and has multiple times the acidity of the lean meat, so it is not used as a sushi topping.

“Chiai Gishi (血合いぎし)” －Located right next to chiai, this is the meat you can taste the umami of the rich red meat and the sweetness of toro fat at the same time.

“Wakaremi (分かれ身)” is a precious part with very little meat found next to the dorsal fin. The part especially close to the dorsal fin is popular and called “Setoro (背トロ)”. Setoro has both the umami of akami and the umami of fat. The fat isn’t overbearing so you can eat a ton. However, this part is hard to get, even in high-quality tuna and is not available except to regular customers in almost all sushi restaurants.

A sushi chef, Hiroyuki Sato, serves a tossaki hand roll as the first sushi piece of the course. “Tossaki (突先)” is an exclusive cut of tuna that goes well with sushi rice using red vinegar, which is less sour but has more umami and flavor compared with white vinegar. Because tossaki is the base of the tuna’s head and it moves a lot, there are a lot of muscular striations. Therefore it needs to be prepared using the back of a knife carefully as if peeling it off (Hagashi). It is said that tossaki is a high-tuna-flavor cut. A couple of Sato’s apprentices also offer a hand roll to open up the meal in the same way.

The meat of tuna gets leaner and muscular striations are fewer towards the inner center of the body. “Tenpa (天端)”, surrounding the spine, is deeper in color and tastes stronger. It features the tender texture coming from the finest meat quality. This is also called Tenmi (天身).

A photo of Hohoniku maguro — The appearance of Hohoniku maguro nigiri

“Hohoniku (ホホ肉)” is cheek meat. The cheek meat of tuna is a rare part of the fish, with only a few hundred grams being taken from a 100kg fish. It is crescent-shaped, with one on either side. It can be taken from not only bluefin tuna, but also bigeye tuna, etc., but if you want to eat it as sashimi or nigiri sushi, you need to be careful about its freshness. Once frozen, it can only be used in dishes where the smell is masked by cooking with garlic, pepper, olive oil, etc.

Its cheek meat is juicy, stringy, and low in fat. When making nigiri sushi, it is often Aburi to soften the stringiness. Aburi enhances the flavor of this part of the fish. And there are almost no sushi restaurants that buy tuna heads or whole fish. Therefore, the only places that can offer this part of the fish are conveyor belt sushi restaurants and izakaya.

“Hireshita (ヒレ下)”－Located right above the first pectoral fin. Characterized with the tender meat which is relatively low in fat content but rich with umami flavor. This truly is the valuable part of whether there will be even enough for 10 pieces of sushi from an over 200 kg tuna.

If you are fortunate enough to get an opportunity to taste these, you can take it as proof that you have been accepted as a regular and loyal customer. It is difficult to distinguish these parts by appearance alone, so make sure you try them at a sushi restaurant you can trust. Just for your reference.

Related contents: TYPES OF TUNA

[sc_apply url=”https://sushiuniversity.jp/apply/”]

We hope this information will be helpful.

Revision date: September 16, 2024

Share this article