A technic to freeze tuna is quite amazing!

Once tuna caught in the open sea is processed by draining its blood on the ship, it is flash-frozen at ultra-low temperatures (-60℃). Ultra-low temperatures stops the enzymatic hydrolosis of protein, oxidation of fat and cultivation of microorganisms so it can be stored over a long period of time. The process can prevent discoloration for over two years and maintain a freshness worthy of being served as sashimi. Therefore, skillful sushi restaurants mature the thawed tuna in the refrigerator for about one week to attain the perfect balance of umami and change in color.


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Revision date: February 4, 2020

Are Hamachi and Buri the same thing?

In the United States and other countries, “buri : right image” is called yellowtail, but this word refers to fish like “buri” and “hiramasa” and actually can be applied to a large number of fish. Actually, it isn’t far off since a layman can’t tell the difference between a “buri” and “hiramasa” just by the pretty yellow lin on the side of the fish’s body.

In Japan, “buri” is the most well-known fish that goes by different names depending on its stage in life (shusse fish). Actually “buri” has many different names even depending on the region you are in. For example, in the Kanto region, it may be called wakashi (0 to 30 cm) -> Inada (30 to 60 cm) -> Warasa (60 to 80 cm) -> Bri (80 cm or more), and from Kansai on further west, it is called, tsubasu (0-30 cm), Hamachi (30- 60 cm), mejiro (60 to 80 cm) or burri (80 cm or more).

This is where the term “hamachi” came from. West of Kansai, full-grown buri, at about 30 to 60 cm is called Hamachi. In other words, Hamachi is a young buri.

Of course, it’s not that simple. You can get hamachi sashimi at grocery stores all over Japan, all year long. Hamachi is not only used from Kansai on westward, it is also used at grocery stores throughout Japan. This may lead you to believe that hamachi is a different fish and not the same as buri, but you would be mistaken.

Behind the curtain, buri cultivation is thriving in Japan (and throughout the world). More than 80% of the buri on the market is said to be farmed. Because it is not apparent by appearance whether the buri was raised in the wild or by aquaculture, the wild-raised fish is called buri by market affiliates in order to make it easier to understand. That means farmed products have come to be called hamachi.

Also, in the Setouchi region, people preferred to eat the young hamachi rather than the adult buri. Kagawa Prefecture became the first in the world to successfully cultivate hamachi in 1928, and that is what led ‘hamachi’ to become synonymous with ‘farmed fish’. Of course, that would be one reason that people call farmed buri, hamachi.

As an aside, three cousins (closely related species) of buri are often used as sushi toppings in sushi restaurants. In the Fish Name Dictionary, the translations of these cousins are Goldstriped amberjack (Hiramasa : right image), Greater Amberjack (Kanpachi), and Japanese amberjack (Buri). Sushi University also adopts these terms.

But if you dive deeper into the fish name dictionary,
Hiramasa is known as amberjack or yellowtail. Kampachi is known as amberjack or yellowtail. Buri is known as… you guessed it: amberjack or yellowtail.

When lumping them all together, they are called yellowtail, as is common in the U.S.

I’m sure you’re interested in the price, and while the price of the seasonal winter buri varies, it is generally around $10-20 per kilogram. Since there is very little distribution of hiramasa, the price is said to be about double that of buri. The price of kampachi : right image is somewhere between that of buri and hiramasa. These prices refer to the wild-caught fish.

Finally, if you eat and compare buri, kampachi and hiramasa in sashimi form, most people can’t tell the difference in fat distribution. When made into sushi, the sweetness of the fat and the flavor of the fish emerge splendidly, and the taste of each fish becomes distinct and obvious. Even the still-developing inada, with very low fat content, is used as a sushi topping and its refreshing taste is unforgettable. This showcases both the depth and greatness of Edo Style sushi.


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Revision date: January 6, 2020

Why do they say that the quality and price of tuna is determined by the processing after the fish is caught?

Why is only tuna brought into certain ports high-priced, even though all of the tuna is caught in the seas near Japan? This is because the level of stress caused to the fish when it is caught has a huge impact on the quality, including taste, color and texture. In other words, the same fish may be delicious or taste unpleasant depending on how the fisher handles the fish directly after catching it. Naturally, everyone ends up wanting the fish from the ports with fisherman who are skilled in this practice*. Furthermore, it is individuals who process the fish. The quality changes drastically depending on who caught it.

*This is a method of cutting off the medulla oblongata and aorta of a fish, essentially keeping the body alive while killing the fish. There is also a method of inserting a thin wire, like a piano wire, into the backbone. This technique paralyzes the nerves while at the same time suppressing the putrefied substance that comes from the spinal cord. Using the ikejime method extends the time until rigor mortis starts, and makes it easier to maintain freshness, while at the same time preventing raw fish odor and damage to the body by inserting a butcher knife into the base of the tail to drain the blood and keep oxidized blood from running throughout the body.


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Revision date: December 17, 2019

What is the real reason for the emphasis on freshness in seafood?

The human tongue tends to sense food that is slightly acidic as delicious, and tends to sense it as not delicious when there is alkaline. When fish is alive, the alkaline levels are low, but after dying and beginning to stiffen, the glycogen in the muscle meat turns into lactic acid and becomes acidic. However, as more time passes, the rigor morris releases and the body softens. This is when it tastes the best. After that the proteins break down increasing the amount of alkalines such as ammonia. Also, since the proteins dissolve when they become alkaline, the body breaks down as the alkaline increases. This is the reason that fish tastes worse as it loses its freshness.


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Revision date: October 1, 2019

What’s the difference between Japanese mustard and Western style mustard?

Japanese mustard refers to oriental (yellow) mustard and is a condiment with a strong spiciness. It is used for cooking Japanese and Chinese food. Western style mustard refers to white mustard, which has a more subtle flavor and fragrance and is not as spicy. It is used for sandwiches and sausages. Whole grain mustard is made by mixing white mustard with black mustard seeds and used for things like flavoring vinegar. Sushi chefs use Japanese mustard to offset the greasiness of fatty fish such as bonito and tuna.


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Revision date: September 16, 2019

What are fish seasons?

Fish seasons are categorized as the ‘catch season’ and the ‘flavor season’. The ‘catch season’ is the time when lots of fish can be caught and are cheap. Take Japanese Spanish mackerel (Sawara), for example, they approach the coasts during the spring to spawn and this is the peak season. This is the catch season. Once they’re about to spawn and their bodies fatten for winter, we’ve entered the tasting season. However, these seasons differ depending on the region, and may be longer or even happen twice a year.


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Revision date: September 4, 2019

Do you know why sauce made from chemical seasonings dissolved into soy sauce is used for sushi that commoners eat?

There is a sensor on the tongue that feels the degree of saltiness. This prevents us from eating too much of things that are extremely salty. Chemical seasonings confuse that sensor. The chemical seasoning palliates the degree of saltiness felt by the tongue. Even if you were to, for example, dunk your sushi into the soy sauce and chemical seasoning mixture, it won’t feel salty. If you eat sushi with the sauce, you can take in a high volume of sodium, which is a pleasure trigger for the human body, without feeling the saltiness on your tongue. In other words, it may be more accurate to say that with commoner sushi, you actually drink the sauce, not dip into it.

 


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Revision date: June 11, 2019

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Why does it taste a little bland when you had tuna at high-class sushi restaurant?

Tuna at top-end restaurants is light in flavor. Its Akami (red meat) has an indescribable acidity with a delicate harmony between the shari vinegar, the nikiri soy sauce, and wasabi. However, on the other side of the coin, it feels almost like a waste to eat it without a sense of luxury. Of course tuna with delicious akami, also has delicious fatty tuna (toro). And you’ll never get tired of it. It would be easy to polish off 10 pieces as a light snack. Contrary to popular belief, it’s not the high fat content that makes it so easy to eat. However, it is because of that popular belief that many people feel that the big chain store farmed fish with lots of fat is more delicious than luxury natural fish.

 


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Revision date: April 16, 2019

What is Red Snapper the same as “Tai” (Sea Bream)?

In the United States, Sea Bream is often called a Red Snapper. However, strictly speaking, this is not correct.

Biologically, Snapper is a generic term for all species in the snapper family. Over 100 different species of snapper inhabit tropical coastal waters. Red snapper is mainly fished in the Gulf of Mexico.

So, what is the fish that Japanese sushi restaurants call “tai”?

They say there are over 300 different species of fish with “tai” in the name, making up 10% of Japan’s fish. When we say “tai” in Japanese, we are referring to “madai” or red sea bream. Red sea-bream is categorized in the “madai” (Pagrinae) subfamily.

Incidentally, relatives of the sea bream often served at sushi restaurants include red sea bream (madai), crimson sea bream (chidai) and yellowback sea bream (kidai). While “kinmedai” (Splendid alfonsino) and “amadai” (horsehead tilefish) have the name “tai/dai” in them, they are not part of the same family as “tai” (sea bream). Splendid alfonsino is a type of deep-sea fish.

Red sea bream and red snapper look similar, but when served as sushi, their texture and flavors are entirely different. So if you come to Japan, please try and eat natural red sea bream (madai). There is no “zatsumi” (overpowering bitterness) and it has a slight sweetness to it. This is the taste of sea bream, known as king of the white fish. Just for your own reference.


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Revision date: January 29, 2019

Why do we use the counter “kan” for sushi?

When you sit at the counter and order nigiri a la carte, they will come out in pairs.* There is nothing wrong with counting these in the regular Japanese way “ikko,” “niko.”

*It is said that nigiri-zushi in the Edo period was bigger than it is today, and too big to eat in one bite. In the Meiji period, the custom emerged of splitting this one big portion into two to make more easily consumed portions, and this is why it is common to get sushi in sets of two. However, nowadays making one piece of nigiri-zushi at a time is not very efficient. We think it’s actually easier for the sushi restaurant to make them in sets of two. Of course, you can order them one by one.

But the sushi restaurant won’t count them like that. Formally, sushi is counted in this way: Ikkan (one), Nikan (two).

We have absolutely no idea where the custom of using the “kan” counter came from. It’s also not clear when use of that counter for sushi started.

Of course, there are theories. For example, there is a theory that back at a time when a single unit of money was called “kan.” The price for one piece of sushi was around 1 ‘kan’, and the counting method gained popularity. There is another theory that one sushi roll was counted with the counter for roll “巻” (also pronounced “kan”), then a different kanji was used for it later. However, these are just theories that were created after the fact and the mystery remains unsolved.

Even if you ask the owner of a sushi restaurant, they’ll probably cock their head to one side, think for a moment, and tell you that the “kan” mystery may never be solved.

Sushi rolls wrapped in seaweed rolls are counted in units of 本 (hon/bon/pon) in the wrapped state, and when cut with a knife, the units change to 切れ (kire). While these units are fairly straight-forward for Japanese language speakers and easy to understand, only the enigmatic 貫 (kan) remains a mystery.


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Revision date: January 16, 2019

Do you know that there are rankings for negitoro (minced tuna)?

The original negitoro is made from medium fatty tuna or nakaochi* chopped up finely with a knife and then mixed with chopped green onions on top. But the tuna may be switched out with filler, leading to a variety in quality of the negitoro available.

First of all, the lowest in the ranking are the offcuts of tuna that can’t be made into sashimi (mainly Yellowfin or Albacore tuna) and this is mixed with vegetable oil and minced. The type of onion used is normally green onions. You can pick this type out because it will be whitish in color. This version is normally served at conveyor belt sushi.

The medium quality uses the nakaochi of cheap Albacore tuna or Swordfish.

High quality negitoro uses the nakaochi of Pacific bluefin tuna or Southern bluefin tuna. Sometimes the green onion sprout is then rolled up inside. If you have a chance to try negitoro in Japan, we recommend you try the top quality options without a doubt. One piece will probably cost around $15 USD. But that’s the price for the real thing!

Finally, let me introduce some negitoro trivia. There is a lot of flesh on the middle bone (spine) and the surrounding area for tuna and the like. This is called “nakaochi*”. Scraping the meat from this area surrounding the spine is known as “negitoru”, which is where the word “negitoro” comes from. In other words, the name “negitoro” is not actually from the words onion (negi) and tuna belly (toro).


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Revision date: January 8, 2019

What is Umami?

Umami describes the delicious taste of savory flavor essences. For many years, people held to the belief that humans can taste only four basic flavors (sweet, sour, salty, bitter) unitil a japanese chemist named Kikunae Ikeda discovered a fifth flavor (glutamic acid) in the early 20th century.

The main umami ingredients are glutamic acid in seaweed, inosinic acid in dried bonito and meats, succinic acid in shellfish, guanylic acid in shiitake mushroom.

Many ingredients contain a wide variety of umami essences. In combination, they create a  synergistic effect which produces an even more potent savory flavor.


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Revision date: October 31, 2018

The migrating route of Inshore bluefin tuna and fishing place!

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.


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Revision date: August 20, 2018

Why can’t Pacific saury be caught?

On the Pacific Ocean side of Japan there is a three-way deadlock between sardines, mackerel and Pacific saury. There is a theory that the species take turns with increasing and decreasing populations. In recent years there has been an increase in sardines and, in turn, there has been a decline in Pacific saury.


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Revision date: July 30, 2018

What is the difference between maturing and rotting?

When fish die, stopping the supply of ATP (Adenosine Triphosphate), the source of muscle energy, the muscle fibers gradually harden. As time passes, it gently dissolves and the ATP breaks down, changing into umami components due to self-digestion. The umami created by self-digestion of ATP is “maturing” and the process after that is “rotting.”


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Revision date: July 23, 2018