Basic Knowledge | Sushiblog－Sushiuniversity

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

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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

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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

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What’s the difference between mariage and pairing?

In the past, the word ‘mariage’ was often used when matching sushi and sake. Of course, that word is still used, but ‘pairing’ is more common now. It doesn’t matter which you use, both have the meaning of ‘matching’ or ‘combining’. The only real difference is that pairing is closer to just matching things, while mariage has the implication of combining things to create something new.

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Revision date: August 7, 2019

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It’s not just only farmed fish which has been accumulated toxic substances.

Natural fish are part of the food chain and have concentrations of harmful substances. Since 2000 the amount of mercury found in fish has become an issue. The American Natural Resources Defense Council has said tuna is a fish that should be avoided if pregnant or planning to get pregnant. A more recent problem is the large amounts of micro plastics found in fish meat. This shocking phenomenon will likely be reported by research organizations at some point in time. If it does reach that extreme, then it will be better to avoid the danger of eating fish.

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Revision date: April 22, 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

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Reevaluating the serious risk to health posed by farmed salmon!

Before continuing, please read the exclusive articles in major media and research papers.

The red tide (algal bloom) frequently occurs off the coast of Chile and it is resulting a large amount of salmon deaths. In 2015 27 million salmon died in a mass event, of which 25,000 tons were powdered and then fed to the healthy salmon (according to the UK’s Guardian reports).

Chilean fish farmers are using large quantities of antibiotics to control fish diseases. They use 500-700 times more antibiotics than Norway does. 80% of antibiotics imported into Chile are intended for the fish farming industry. Faced with the risk of bacteria resistant to antibiotics emerging, as highlighted by the World Health Organization (WHO), the Chilean National Fish Service is calling for a reduction in the use of antibiotics. (Extract from Le Monde diplomatique Japanese edition）

The bright color of salmon is something that you would never see a long time ago, but is now commonplace. It is likely due to the Canthaxanthin pigment mixed into their feed. Salmon is in fact a white fish. The salmon that is caught in Japan is called “Shirozake” or white salmon and its flesh is not a pink before it goes out to sea. Once it is out at sea, it swims around consuming small plankton and crustaceans such as shrimp and krill. Its body then takes on a pink color due to the intake of natural coloring of Astaxanthin. This Astaxanthin has antioxidant effects and it is noted for playing a part in relieving fatigue and preventing aging. However, the synthetic pigmentation that creates the salmon pink does not provide the same health benefits.

The US Food and Drug Administration (FDA) gave approval for genetically modified salmon on November 19th, 2015. This genetically modified salmon is called “AquAdvantage salmon.” It grows faster than regular salmon and its body length is almost double. There are groups opposing the sale of this salmon, including US citizen group Center for Food Safety, the Japanese Seikatsu Club, and the European parliament. There are still many unknowns regarding the safety of this type of fish for human consumption, and a number of issues are still being debated. The discussion has been featured in “Nature” magazine.

Endosulfan is a type of organochlorine compound, like Dichloro Diphenyl Trichloroethane, Dicofol, Heptachlor, Chlordane, Mirex, Pentachlorophenol, and is known to be extremely toxic, but the EU approved Endosulfan for use as feed in Norway’s salmon farming industry in 2013.

Researchers analyzed the risk-benefit ratio based on levels of contaminants like dioxins, PCBs and chlorinated pesticides versus omega-3 fatty acid levels. While farmed salmon is higher in omega-3s, it is also significantly higher in these toxins (about 10 times) which can produce birth defects, lower IQ, and cause cancer. They determined the following based on origin of the salmon: “consumers should not eat farmed fish from Scotland, Norway and eastern Canada more than three times a year; farmed fish from Maine, western Canada and Washington state no more than three to six times a year; and farmed fish from Chile no more than about six times a year. Wild chum salmon can be consumed safely as often as once a week, pink salmon, Sockeye and Coho about twice a month and Chinook just under once a month.” (Extract from The Journal of Nutrition)

There is a saying, where there’s smoke, there’s fire. It is unlikely that big media outlet and research organizations would join forces to circulate incorrect information. Furthermore, this is not a problem that only affects certain countries like Chile or Norway. It should be considered as a problem for the entire farmed salmon industry.

On the other side of the debate, there are articles such as the following. Norway’s NIFES (National Institute of Nutrition and Seafood Research) sampled 13,180 farmed fish (of which 90% were salmon) and monitored them for medicines, substances that are prohibited by law, and other pollutants, publishing their report on August 17th 2015. In their latest report, it concluded that Norwegian farmed fish were safe and that illegal and undesirable substances were not observed to exceed standards. Further, it seems that they have confirmed decrease in most of the pollutants analyzed in the investigation.

But the fact is that, according to these articles, while the chemicals did not exceed standard values, they were certainly found to be present in farmed salmon. The other extreme would be to say that eating natural un-farmed salmon will not expose you to the potential risks from these types of chemicals.

However, that’s not really practical. The global production of farmed salmon is 2.5 million tons a year, approximately three times the 800,000 tons of naturally fished salmon. No matter what way you slice it, the option of farmed salmon isn’t going away anytime soon.

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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 (Lutjanidae). Over 100 different species of snapper inhabit tropical coastal waters. Red snapper is mainly fished in the Gulf of Mexico.

They are called American red snapper or Northern red snapper in supermarkets. The scientific name is Lutjanus campechanus.

And there is another species of fish called the Red Snapper. The Australasian snapper or silver seabream (Japanese name is Goushu-madai) is a species of porgie found in the coastal waters of Australia, Philippines, Indonesia, Taiwan, and New Zealand. It is a close relative of the Japanese Tai and similar in shape, but the body color of this species is golden pink, with a lighter reddish tinge than Tai, and the blue spots are lighter in color and somewhat larger. It has softer flesh and less flavor than the Tai, but has a light, delicious taste. Its scientific name is Chrysophrys auratus.

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” family (Sparidae).

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”. Splendid alfonsino is a type of deep-sea fish.

In American supermarkets, Porgy (Stenotomus chrysops) is sold, which has a beautiful cherry color and looks like Tai itself. However, the taste is different from that of Tai, being softer and lighter in flesh. Around New York and New Jersey, it is called Porgy, and in Massachusetts, it is called Scup. It is native to the Atlantic Ocean.

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 madai. There is no “zatsumi” (overpowering bitterness) and it has a slight sweetness to it. This is the taste of tai, known as the king of the white fish. Just for your own reference.

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What is Kakushiaji?

Kakushiaji refers to a technique where a single seasoning (For example, sugar, vinegar, soy sauce, salt, etc.) is added to a dish. The Kakushiaji contrasts with the finished dish’s flavor, and is added in an amount too small to notice when served. This produces a clear improvement in flavor.

Examples include adding a little salt to heighten sweetness, or adding a little vinegar to a simmered dish. Sometimes these combination of flavors can be quite surprising, like adding a touch of chocolate to a curry.

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Revision date: November 7, 2018

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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

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What is the difference between “鮨,” “鮓” and “寿司” (all ready “Sushi”).

As far as I know, there are three ways “sushi” is written on sushi restaurant curtains in Japanese kanji characters: 鮨, 鮓 and 寿司.

Do you know the difference? Most Japanese people don’t know the answer to this question.

Broadly, in the Kanto area 鮨 is generally used while 鮓 is more common in Kansai. 寿司 is used commonly everywhere in Japan.

However, of the three, only 鮨 and 鮓 are seen in ancient Chinese literature. 鮨 was seen as a dictionary entry as early as the 5th to 3rd centuries B.C., and it’s origin is described as combining “fish” and “shiokara” (briny flavor) resulting in the term 鮨.

On the other hand, in A.D. 1st to 2nd century dictionaries, “鮓” appeared, and is explained to depict “a storage container for fish.” Toward the end of the second century 鮓 was used for the term “narezushi”.

But around the third century, the briny meaning of 鮨 and the term “narezushi*” written as 鮓 started to be used interchangeably. That is how the words were imported to Japan.

In Japan, the character “鮓” was often used in literature from the end of the Heian era to the end of the Edo era. Eventually the use of “鮨” was revived during the Meiji era (for unknown reasons). It was a natural transition that Kanto came to use “鮨” and Kansai came to use “鮓”.

Incidentally, the kanji “寿司” was created from the phonetics. Its use for celebratory occasions became commonplace throughout Japan.

*”Narezushi” is the primitive version of Japanese sushi. It means covering seafood with salt and then soaking in rice for a few years as a form of lactic acid fermentation, which brings out the acidity.

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Revision date: April 29, 2020

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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.

Where should soy sauce be applied to the sushi?

The most delicious way to eat sushi at restaurants where the sushi chef applies Nikiri (soy sauce perfectly evaporated with sake) for you is just the way it was prepared. However, at restaurants where sauce is not applied for you, the sushi is eaten by dipping it in soy sauce. The soy sauce used for dipping is provided for you at the counter or table. Many restaurants use the same evaporation formula for the dipping soy sauce.

Soy sauce for dipping is put into a small dish for use, but don’t put in too much. It depends on the depth of the small dish, but the diameter of the circle of soy sauce after being poured should be approximately 25mm.

When dipping sushi into the soy sauce, turning it upside down (although it will be somewhat tilted) and dipping the topping seems to be the most common method. If you keep the topping on the bottom when you put the sushi in your mouth, the flavors of the soy sauce and the fish are in complete harmony and the delicious taste spreads through your mouth. There is also an opinion that turning the sushi upside down for dipping is unacceptable practice. There are also some with the opinion that whether to eat with your hands or chopsticks depends on the situation.

Make sure not to get any soy sauce on the Shari (vinegar rice). You don’t want to add unnecessary saltiness to the Shari, which has already been seasoned. It would be a terrible waste to cancel out the exquisite balance of the topping, wasabi and Shari with the saltiness of soy sauce.

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.

Why is freshly-caught fish allowed to age?

The most delicious time to eat fish differs depending on if it is served as sashimi, as sushi, or boiled. Fresh does not necessarily mean delicious. For example, Japanese Amberjack should be used in sashimi 3-5 days after being caught, in sushi a week after being caught and it can be used in a stew or boiled once it turns black around the edges. This is because the inosine acid, which is responsible for the umami taste, increases after rigor mortis ends and understanding the timing of the peak in flavor is up to the skill of the sushi chef.

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Revision date: March 12, 2018

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Category: Basic Knowledge

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

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

What are fish seasons?

What’s the difference between mariage and pairing?

It’s not just only farmed fish which has been accumulated toxic substances.

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

Reevaluating the serious risk to health posed by farmed salmon!

Before continuing, please read the exclusive articles in major media and research papers.

Related contents:

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

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

What is Kakushiaji?

What is Umami?

What is the difference between “鮨,” “鮓” and “寿司” (all ready “Sushi”).

Do you know the difference? Most Japanese people don’t know the answer to this question.

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

Where should soy sauce be applied to the sushi?

What is Uwami and Shitami?

Why is freshly-caught fish allowed to age?