What is hybrid artificial fish?

A photo of Kue-tama
The appearance of Kue-tama

What is hybrid fish?

Both Yamame (Landlocked Sakuramasu) and Japanese Iwana (Char) are members of the salmon family. Iwana and Yamame both inhabit the upper reaches of rivers, although Iwana prefers slightly cooler water. In rivers where each species lives alone, both fish occupy the upper reaches of the river, but in rivers where both species live, they do not mix, with Iwana occupying the uppermost reaches and Yamame occupying the lower reaches after a certain point in the upper reaches.

In nature, different species sometimes interbreed and produce hybrid fish. For example, hybrids between Yamame and Iwana are common in nature. The characteristic spots of the Iwana look like those of the Saba (Mackerel), a marine fish, and hence the name Kawasaba. They also rarely become smoltified (silvering) and become the descending sea type, but they do not reach sexual maturity.

Incidentally, the Kawasaba is thought to have been created by the uncontrolled release of Yamame into an area originally inhabited by Iwana, resulting in the mating of two species whose habitats do not originally overlap. The “hybrids” created by thoughtless releases may be a symbol of the destruction of genetic diversity.

 

What is hybrid artificial fish?

In the aquaculture industry, high growth and survival rates, good flesh quality, and disease resistance are important requirements for a superior species, and artificial crossbreeding has long been used as a method to create such breeds.

In 1964, Kinki University in Japan succeeded in breeding the first hybrid artificial fish, a female Red seabream (Madai) with a male Blackhead seabream (Kurodai). Since then, he has produced many hybrid combinations. The name “Ma-kurodai” is a combination of “Madai” and “Kurodai. In addition, he has created nearly 20 new fish species, including Madai x Hedai (Ma-hedai), Madai x Chidai (Ma-chidai), Ishidai x Ishigakidai (Kin-dai), and Buri x Hiramasa (Buri-hira).

 

Typical hybrid artificial fish will be mentioned briefly.

What is Buri-hira?

Buri hira is a crossbreed between a female Japanese amberjack (Buri) and a male Goldstriped amberjack (Hiramasa). Buri, which is in season in winter, is characterized by its high fat content and strong flavor, but its meat is tender and its dark red meat (chiai) tends to discolor during the summer. Hiramasa, on the other hand, is firm, has less dark red meat (chiai), and is less prone to discoloration, but has less fat and a lighter flavor, and is only available in summer.

Buri-hira is a very tasty fish that combines the “good points” of these two fish species and combines the “umami” of Buri with the ” chewiness and beauty” of Hiramasa. Because it is completely farm-raised, it can be served all year round, and major conveyor-belt sushi chains have already begun serving Buri-hira. Buri-hira can be caught in the wild very rarely, but they are so few that they are not generally available on the market.

 

What is Kue-tama?

It is a hybrid species, having as its father a Giant grouper (Tamakai), one of the world’s largest members of the grouper family that can grow to 270 cm in length and 400 kg in weight, and as its mother a Longtooth grouper (Kue), which is a rare and high-end fish with an outstanding taste and popularity.

The hybrid is characterized by the fact that it inherits the growth rate of Tamakai and grows to shipping size in about two years, whereas it normally takes four to five years for farmed Kue to grow to shipping size.

This makes it possible to significantly reduce production costs, and it also has properties that make it resistant to disease and easy to grow. Major conveyor-belt sushi chains have already begun offering Kue-tama.

 

What is Be-ster?

Be-ster is a hybrid of Beluga and Sterlet, known for producing the finest caviar among sturgeon. Developed by Russia several decades ago for aquaculture, the Be-ster was created amid a worldwide ban on capturing wild sturgeon as an endangered species.

 

What is Kin-dai?

Kin-dai is a hybrid of a female Barred knifejaw (Ishidai) and a male Spotted knifejaw (Ishigakidai) and was first successfully produced by Kinki University in 1969, and patented and trademarked in 1975.

Ishigakidai, on the other hand, takes more than six years to mature and produces fewer eggs, but grows quickly to commercial size. Kin-dai combines the best features of both, with a good texture and excellent taste. Its name is the same as the abbreviation for Kinki University.

Ishidai is called “Kuchiguro (kuchi means mouth and guro means black)” because its body turns silvery white and the area around its mouth turns black. Ishigakidai, on the other hand, is called “Kuchisiro (shiro means white)” because they have a black body and the area around their mouth turns white. Kin-dai’s entire body turns black, and the tip of its mouth also turns black.

 

What is Ma-chidai?

Kinki University has also produced a hybrid Ma-chidai, a cross between Red seabream (Madai), which grows well, and Crimson seabream Chidai, which has a less faded red coloration, and has traits that give it a red coloration like natural fish and faster growth than Chidai.

Finally, a second generation has already been produced from the sexes of the hybrid fish. If the hybrid fish are released into natural waters, contamination will occur through genetic infiltration. We should not leave a bad legacy for future generations.

What is Torokinme?

A photo of Fusenkinme.

Fusenkinme (Red bream) is occasionally caught along with Splendid alfonsino (Kinmedai). Until recently, they were considered to be the same species. Kinmedai has elongated slit-like posterior nostrils, while Fusenkinme has oval-shaped posterior nostrils. Kinmedai can grow over 50 cm long, whereas Fusenkinme stops at 40 cm.

Fusenkinme is fattier than Kinmedai and is called Aburakinme or Torokinme by fishermen, in areas that distinguish between Fusenkinme and Kinmedai, there is a difference in market price, but it is rarely distributed and is consumed locally.

Torokinme does not refer to the belly part of Kinmedai but to Fusenkinme, a rare species of Kinmedai. Incidentally, three Kinmedai, Nanyokinme, and Fusenkinme species are distributed in Japan.

Related contents:
Kinmedai

Nanyokinme

What is the thought behind Toro?

What is Torokarei?

A photo of Torokarei fillet
The appearance of Torokarei fillet

Consumers are inevitably confused by the word Toro. It isn’t easy to separate the word from a mere marketing term. Therefore, the market contains fish names with Toro as a prefix.

Torokarei (karei means flounder) is a trade name for a fish named after the toro of tuna, which has a rich, tender texture, and is an arrowtooth halibut (Aburakarei).

Aburakarei is distributed north of Choshi, the northern Sea of Japan, the Sea of Okhotsk, and the western Bering Sea. Aburakarei is a typical eating fish among flounder species, and unfortunately, it is considered the most tasteless and has low commercial value. Black halibut (Karasugare), a relatively tasty and inexpensive fish, has become expensive, so perhaps it is Aburakarei’s turn.

So a name that would sell was needed, so it became Torokarei.

In recent years, Aburakarei has been imported from the U.S. and other countries in large quantities of fillets processed for frying. It is inexpensive and its distribution is stable. Aburakarei is characterized by its meat containing so much fat that it melts when heated. Even when heated, the flesh remains tender, and it is often used overseas for frying as fish and chips. The most common type of engawa at conveyor-belt sushi restaurants is either Aburagarei or Karasugarei.

Related contents:
What is the thought behind Toro?

What is Kudoa septempunctata?

A photo of Kudoa septempunctataKudoa septempunctata is a species of parasite (mucous sporozoite) of the genus Kudoa that parasitizes Bastard Hailbit (Hirame). It is approximately 10 µm in size and has a “hemispherical” shape when parasitized on fish.

Most cases of food poisoning due to cudweed are associated with fresh flatfish for raw consumption (e.g., flatfish sashimi). The infection rate and amount of infection are particularly high in farmed flatfish, which accounts for 60% of the food ingredients that cause kudoa food poisoning.

It is characterized by transient vomiting and diarrhea within a few hours after eating, with symptoms ending in a mild illness. Kudua has been shown to lose its virulence by freezing at -20°C for 4 hours or more, or by heating to a core temperature of 75°C for 5 minutes or more.

Therefore, food poisoning can be prevented by freezing it once and then eating or cooking it.

Related contents:

Studies on Seasonal Changes in Occurrence of Food-Borne Disease Associated with Kudoa septempunctata


We hope this information will be helpful.

Revision date: April 13, 2024


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Standing sushi bar in Tokyo that foreigners should definitely try!

a photo of Isami zushi
Isami zushi, which has a long history, is as inexpensive and delicious as Conveyor belt sushi, and has the atmosphere of a traditional sushi bar.

A quick cup of coffee and off to work I go. In this case, of course, you are standing rather than sitting on a chair. But when it comes to eating, sitting on a chair is the universal practice, isn’t it? In Japan, however, many restaurants allow customers to eat standing up, such as standing buckwheat noodles.

Why do these restaurants exist?

Certainly, a businessman who does not want to waste time will not allocate elegant time for a meal. In a sense, a businessman who wastes his time on such a wasteful activity may be a dropout. That said, how about eating a meal while standing up? According to Japanese eating etiquette, it is against manners to eat while standing. In many countries, it would be called ill-mannered.

And it is impossible to eat sushi, which has a strong image as a representative of high-class Japanese cuisine, standing up is not allowed. Nigiri sushi, however, was originally a yatai food (street food) for the impatient Edo people and could be called the fast food of the time. That and the fact that the customers were allowed to eat standing up and the seller sat down to make sushi, which is impossible today, but it was the norm back then.

Here, we would like to introduce Standing sushi bars in Tokyo that we would like foreigners to visit by imagining what yatai (street food) sushi was like about 200 years ago.

Standing sushi bars have been popping up in Tokyo since around 2021. It is impossible to rapidly increase the number of customers in a high-end sushi bar where the bill is several hundred dollars. Even if they opened a second sushi bar and entrusted the management to their apprentice, they would need to charge a certain amount of money to make it viable.

Therefore, the number of “standing sushi bars” should have increased to encourage people to come to the restaurant more casually. To be honest, while the business model was still in the exploratory stage, standing sushi bar Akira was selected as a Michelin Bib Gourmand in 2022. standing sushi bar is now in the limelight.

There are currently about 50 standing sushi bars in Tokyo, and among them, I would like to introduce Isami zushi, which has a long history, is as inexpensive and delicious as Conveyor belt sushi, and has the atmosphere of a traditional sushi bar.

Turn left from the east exit of Oimachi Station, turn left at the first corner, and enter the Higashikoji street that you will see immediately. Isami zushi will be on your left.

This area is a maze of narrow alleys and side streets with 60 to 70 bars and eateries that are reminiscent of the Showa period. Although not yet well known to foreigners, it is sure to attract attention as a town where one can feel the lifestyle of the people who live there.

Isami zushi has been in business for 67 years. The current owner, Masaaki Fujioka, is the third generation and has been running the restaurant for 25 years. The restaurant has an L-shaped counter and can accommodate seven people. At best, seven Japanese women can just barely fit inside. And if I may be rude, it feels even smaller than it is because of the lack of organization and placement of things.

The price per piece of nigiri sushi is 30 yen (Geso), 40 yen (Tamagoyaki), 60 yen (Ika), 80 yen (Tobiko), 100 yen (Aji, Aoyagi, Ebi, Saba, Akami, Hotate, Iwashi). , 120 yen (Tako, Kanpachi, Kohada, Hamachi), 140 yen (Torigai, Anago, Toro, Shako), 160 yen (Makimono), and up to 200 yen (Uni, Ikura).

You can order from two pieces. There are always about 20 different kinds of neta (toppings) available. Popular toppings are sometimes sold out, so it is best to get there early. Sushi rice is not too sweet and is suitable for eating sushi with a drink. Of course, sashimi is also available, so you can drink sake as well. The rice is a blend of Koshihikari and Sasanishiki, which gives the rice a delicious flavor and a flaky texture when you put it in your mouth.

How to Order

A sushi chef does not speak foreign languages. There is no English menu, so you must choose from a wooden tag with the name of the toppings written on it, or from a whiteboard with today’s recommendation. Or you can point to the fish in the glass case. Gari is not available at the counter like at conveyor-belt sushi restaurants, so please ask the sushi chef for “Gari-Kudasai” (Kudasai is a Japanese word meaning “please” in English). And regulars order three different sushi toppings at once. In any case, the hurdle may be quite high for foreigners. Even if your sushi order does not go as expected, it is inexpensive, there are no rip-offs, and it will be a memorable experience.

Why is it dramatically cheaper?

First, the restaurant is operated by a single sushi chef, which reduces labor costs. Second, he selects fish from the Toyosu and Ota markets, and fish arrives directly from Odawara, Nagasaki, and other areas. And because he strives to sell out the sushi topping every day. Also, he has reduced the size of his shari and sushi topping compared to previous years. These efforts are nearing their limits, so there may be a price increase soon.

How do I make a reservation?

Reservations are not available, so you will have to line up before the restaurant opens. The restaurant will be full as soon as it opens. Even if you say you will wait, you do not know what time it will be. Please be patient.

Payment Method

Credit cards are not accepted. Cash only. No table charges.

Actual Eating Report

We tried it and here is our report.

Well, we ate standing up, so we thought we could only hold out for about 30 minutes, but we didn’t mind quite a bit. Before our visit, we wanted to eat about 20 pieces as a goal. Japanese people consider someone’s feelings or wishes. In other words, if you are reporting on a sushi restaurant, you should write an article that will please the owner. I will say that this report does not have that element at all.

As soon as you enter the restaurant, a geta (sushi wooden tray) is placed in front of you and you are like, “Now what shall we nigiri? We think every sushi restaurant was like this 30 years ago. First, we ordered a beer. What a surprise, a can of beer was served. In Japanese restaurants, canned beer is rarely served. This is because cans can be drunk at home, and since the price is known, customers do not have a good feeling about it.

To start the conversation, we ask about the history of the restaurant. Then we confirm that it is okay to take pictures and will explore the most important sushi chef’s personality.

a photo of Black scraper (Umazurahagi), and Marbled rockfish (Kasago)
Black scraper (Umazurahagi) has a blurry appearance and does not look tasty, but once peeled, it reveals a clear white flesh similar to that of pufferfish.

Today’s shiromi was Hokke, Black scraper (Umazurahagi), and Marbled rockfish (Kasago). All of these sushi toppings are quite rare as shiromi. They are not served at high-end restaurants by mistake. Isami zushi uses natural fish from domestic fisheries for almost all of its topping. Because they do not use any farm-raised fish, the selection of toppings changes daily, but diners can enjoy rare local fish from all over Japan.

We ordered Umazurahagi and Kasago. The customer next to us also ordered Umazurahagi without a moment’s delay, but it was hard to miss the fact that he started making his order from ours. He does not make the nigiri sushi for the sake of efficiency. And of course, the fish is kept cold in a glass case with the skin on. This prevents oxidation of the ingredients as much as possible. And since the skin is the most delicious part of the fish, this is why we want to keep it on the meat until the very last minute. These are the basics of a sushi chef.

The liver is served on top of the Umazurahagi nigiri. Liver goes bad fast. It is meant to be alive and super fresh until a few hours ago. Its taste is often compared to that of foie gras, but it is not. Natural fish liver has a decidedly better aftertaste than foie gras. It makes you want to eat another piece. Kasago used to be a popular fish in the past, but now it is popular as a high-end fish. Sushi rice enhances the sweetness of the meat and gives it a different flavor from that of Red seabream (Tai) or Bastard halibut (Hirame).

A photo of Southern Bluefin tuna (Minami maguro)
Some sushi connoisseurs even prefer Southern Bluefin tuna (Minami maguro), as the lean meat lacks the slight acidity and faint aroma of blood that can be found in Pacific Bluefin tuna.

Next is the main dish, tuna. He insists on fresh, not frozen, tuna. He uses Mebachi and Minami-Maguro to keep the price reasonable. Today’s tuna was Minami-maguro. April to May is the time when the fat is removed from the meat of Kuro-maguro caught in coastal waters. Minami-maguro is next in rank to Kuro-maguro, but that is not true. Minami-Maguro is not widely distributed, so its richness is not well known. It also changes color quickly, which is its weak point.

Next is Geso, a specialty item at 30 yen per piece, Geso is squid’s leg. In fact, geso is not suitable for nigirizushi. The squid’s body is wrapped in a thin skin, and it is especially difficult to remove it from Geso. It is best for Tsumami when boiled or grilled. Fresh Geso, properly salted, has no fishy smell at all. The taste of the squid itself is concentrated. Try it with a dash of Nikiri shoyu.

Next is Aozakana (Blue-backed fish). These are caught in the morning and sent from the producing area. Today he has Horse mackerel (Aji) and Japanese sardine (Iwashi). The Aji is a top-quality fish from Amakusa, Kumamoto Prefecture, a famous fish producing area. The meat is thick and sweet when chewed. The ginger is used as a condiment to give it a refreshing taste. The Iwashi is in its peak of fatty season, and its light flavor was so delicate that one could hardly believe it was Iwashi.

Gizzard shad (Kohada) has larger pieces of sushi topping and smaller pieces of sushi rice. It is coated with a brush of Nikiri shoyu, so there is no need to dip it in soy sauce. The color is glossy and the fat is wonderful when eaten. And it is the type served at long-established sushi restaurants with the sourness of vinegar.

Shellfish available today are Ark shell (Akagai) and Common scallop (Hotate). Shellfish is a material in which it is easy to tell whether the quality is good or bad. If something tastes like chewing gum that has lost its flavor, it is not good. For Akagai, the key is whether or not the aroma of the sea pervades your mouth. Of course, the shells were removed after receiving the order. This way, the aroma of the sea does not escape. At first glance, the small-sized Hotate did not seem to have much sweetness, but I was impressed by its modest and elegant sweetness.

If we dare to make a bad comment after eating here, both the sushi topping and the sushi rice are 30% smaller than they were a few years ago. But that’s no surprise. They haven’t raised their prices even though prices have skyrocketed so high. In these days of conveyor-belt sushi, the toppings are as flimsy as paper.

Today we ate 18 pieces of nigiri sushi and 1 piece of Makimono in less than 1 hour. It is not painful at all to stay standing. Sushi is served on time, so you don’t have to wait around for it. And all this for only US$30. I think you can experience nigiri sushi to the fullest.

Basic Information

Address: 5-3-13 Higashioi, Shinagawa-ku, Tokyo

TEL: +81-3-3474-8089

: 1 minute walk from East Exit of JR Oimachi Station

Business hours: 18:00-23:00 (closes when all toppings are gone)

Closed: Saturdays, Sundays, and national holidays

https://www.instagram.com/isamizushi_oi/

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We hope this information will be helpful.

Revision date: March 19, 2024


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What is Kewpie mayonnaise?

An image of Kewpie mayonnaise
Since its launch in 1925, this mayonnaise has been the most popular mayonnaise in Japan!

Find out why Mayonnaise has become a citizen on the dinner table

Japan is not a large country. Even so, fresh produce from the sea and mountains is abundant. Even without a large-scale distribution system in place, we Japanese have been able to obtain fresh ingredients in fresh conditions easily.

This is thought to have given rise to a raw food culture in which vegetables, eggs, fish, and even internal organs such as horse meat, beef, and liver are eaten raw. Since fresh ingredients are readily available, it is only natural that there is no need to make unnecessary modifications to them. For this reason, Japanese cuisine has become dominated by methods that do not require much modification of the ingredients. In Italy, the ingredients are fresh, and in China and France, cooking techniques have developed to compensate for the lack of freshness of ingredients. This is just my personal opinion.

And speaking of Japan’s unique food culture, we must not forget its rice culture. Japanese rice is japonica rice, which is light and delicate in flavor. Inevitably, the rice is not eaten by itself but is accompanied by a strong-flavored side dish.

This is likely what led to the development of flavorful seasonings in Japan. The traditional Japanese soy sauce and miso, not to mention ketchup and Worcestershire sauce, which are two of the most popular sauces in Western cuisine, along with mayonnaise, are seasonings with a very distinct flavor. Likewise, mayonnaise is a strong-flavored seasoning, so it is assumed that side dishes made with it went well with rice.

In general, the Japanese palate is said to be well suited to amino acids and the peptide umami before it becomes an amino acid, and this amino acid is found mainly in fermented foods. Japan’s mild and humid climate is ideal for the production of fermented seasonings, and it is no wonder that miso (fermented soybean paste), soy sauce, and salted fish, which are fermented foods, have developed.

Interestingly, mayonnaise also begins to mature about a week after it is made, and the protein contained in the egg yolk in mayonnaise is broken down into amino acids and peptides, resulting in the umami that the Japanese like. Mayonnaise is usually not pasteurized because it separates when heated. This phenomenon occurs because the mayonnaise is still alive after being packed in the container.

Compared to the Western type of mayonnaise, which uses whole eggs, the yolk type of mayonnaise is more common in Japan. The yolk has a higher umami of amino acids and peptides than the egg white, and this may be the reason why Japanese mayonnaise has adapted well to Japanese tastes. The combination of this taste backbone and the umami of Japanese-style mayonnaise has helped mayonnaise to firmly establish itself in Japanese food culture.

 

What kind of food is mayonnaise?

I said mayonnaise is a food, but many people may think of it as a condiment. Mayonnaise, as you know, is made from vinegar, oil, and eggs. In Europe, where it originated, it was made from lemon juice, wine vinegar, olive oil, and eggs. However, in modern Europe, mayonnaise seems to be made at home, unlike in the United States or Japan.

Mayonnaise has some notable characteristics. First, the oil in mayonnaise has the effect of masking the bitterness of the food. Furthermore, the oiliness of mayonnaise is reduced by emulsification, making it very easy to eat. The bitterness of vegetables is sometimes unacceptable, but mayonnaise envelops it. Meat marinated in mayonnaise becomes tender. It has the effect of softening the hardened tissues of meat. Mayonnaise quickly removes the odor of raw fish. The sour vinegar flavor overcomes the unpleasant smell of raw fish, and when it is eliminated, it has so many positive aspects that there is no end to it.

Japanese mayonnaise is restricted by JAS standards for consumer safety. Incidentally, JAS is based on the standards of the U.S. FDA. According to the standard, mayonnaise contains 65% or more edible vegetable oil, vinegar and citrus juice, egg yolk and egg white, salt, sugar, spices, chemical seasonings, acidifiers, and citric acid. In Japan, mayonnaise may not contain any preservatives, emulsion stabilizers, food coloring, or soy protein. Yellow mayonnaise is just made with lots of eggs. This is why the JAS standard does not allow the use of food coloring that misleads people into thinking that there are lots of eggs in the product.

 

Why doesn’t commercial mayonnaise go bad?

Japanese standards for mayonnaise prohibit the use of any preservatives or food coloring. It is natural to ask the question, then, why mayonnaise does not spoil when it is made from egg yolks.

Simply put, think of pickles pickled in vinegar. Depending on the method of production, they can be stored for a year or more. The reason for this is that the acetic acid in vinegar has powerful bactericidal properties.

According to mayonnaise standards, at least 65% of the edible vegetable oil does not go rancid. The sterilizing power depends on how much acetic acid and salt are present in the remaining 35% of the ingredients.

Homemade mayonnaise made at home or in a restaurant is used up quickly, so there is no need to think about shelf life, just make it to your own taste. However, this is not the case with store-bought mayonnaise. And since mayonnaise is not heat sterilized, its composition is very important to prevent it from spoiling in its raw state. Of course, it is also important to manufacture it hygienically in a factory. The combination is determined by considering factors such as the fact that it must not separate during transportation and that it must have a taste preferred by the consumer.

According to actual bacterial test data, Escherichia coli is killed in 6 hours in mayonnaise. Staphylococcus and salmonella, which cause food poisoning, are killed in 24 hours. Even the yeast Hansenula anomala, which is relatively acid-resistant, dies in about 8 days.

As a general guideline, raw food is considered hygienic if it contains less than 100,000 live bacteria per gram. Frozen food that is heated and eaten meets the criteria of the Food Sanitation Law with a count of 3 million live bacteria or less per gram. Normally, it is considered that even if there are 100,000 bacteria per gram of food, the food will not spoil, but if the bacteria count exceeds that level, the food will gradually start to spoil or go rancid. In other words, most bacteria die in mayonnaise. Therefore, it is safe to assume that commercial mayonnaise is first of all free of bacteria.

 

Why is vinegar good for your health?

The answer is simple. It is because vinegar lubricates the citric acid cycle. In 1953, Dr. Hans Krebs of England won the Nobel Prize in Physiology or Medicine for his research on the pathway of tissue respiration in the human body. This is called the citric acid cycle, which is the only mechanism that produces the energy necessary for life, and without this cycle, organisms cannot live!

The problem here is that during strenuous exercise or illness, large amounts of glucose are burned, creating an abnormally high amount of pyruvate, which is further converted into lactic acid. That lactic acid makes body fluids and blood acidic, causing so-called Acidosis. In addition, lactic acid combines with proteins in body tissues to form lactic acid protein, which causes stiff shoulders and muscle pain, as well as increased deposition of cholesterol, leading to arteriosclerosis and hypertension.

At this time, it is explained that when vinegar is eaten with salads, the organic acids contained in vinegar, such as acetic acid, malic acid, and citric acid, can smoothly advance the citric acid cycle and bring lactic acid back into the cycle. In other words, vinegar has been elucidated to act as a lubricant for the Citric acid cycle.

The vinegar in mayonnaise does more than just accentuate the delicious taste; it also helps to clear away fatigue. The Citric acid cycle explains why the blood and body fluids of healthy people are slightly alkaline and become acidic when tired or ill. It also depends on the diet. Eating only acidic foods, i.e., meat and seafood, will cause the blood and body fluids to become more acidic, and cholesterol will be deposited in the blood vessels more easily. The diet must be well-balanced. This is where vinegar comes into play. Vinegar is burned efficiently in the body and is incorporated into the metabolic mechanism to act as an alkaline food. Other effects include increasing appetite and aiding digestion, and it is also very effective in cleaning the body and activating the body’s internal energy.

Where does mayonnaise’s good taste come from?

Mayonnaise is an oil-rich food. Oil stimulates the brain to release hormones that make us want to eat again. However, oil does not remain in its original state, but is scattered throughout the food, creating a richness. Humans respond to this richness with a sense of deliciousness. In other words, mayonnaise is a synergy between the richness created by the oil mixed and dispersed in the egg and the richness of the egg yolk itself.

What makes mayonnaise different from other seasonings is that it contains the egg itself, rather than food extracts or essences. We believe that mayonnaise itself may be regarded as an independent food or dish, beyond the framework of a mere sauce.

Isn’t too much mayonnaise bad for you?

One of the main components of mayonnaise is egg, a food high in cholesterol. However, since mayonnaise is a food high in cholesterol, it is too early to assume that it is bad for you.

The main functions of cholesterol include “making cell membranes,” “making bile acids,” and “being a raw material for sex hormones and adrenal corticosteroids. The production of cell membranes is the basic building block of the human body, without which the human body would not exist. Bile acids are necessary for digestion, and without normal amounts of bile acids in the body, digestion would be out of balance. The same is true for hormones. Without a certain amount of cholesterol in the body, the human body cannot function normally.

The term “cholesterol” refers to both HDL cholesterol and HDL cholesterol. HDL cholesterol is necessary for the body, and most of the cholesterol contained in egg yolks is HDL cholesterol. On the other hand, LDL cholesterol, which is said to cause arteriosclerosis, is not in itself bad. It is believed that oxidized LDL cholesterol, which is created when LDL cholesterol is oxidized by active oxygen, damages the vascular wall, causing inflammation and arteriosclerosis.

Cholesterol is not only ingested through diet. About 70% of the cholesterol needed by the body is synthesized in the body, and the remaining 30% is taken in by the diet. Incidentally, the amount of cholesterol synthesized by the body is 600~700mg per day. On the other hand, a 50 g egg contains about 235 mg of cholesterol. The proportion of egg in Mayonnaise is lower than it appears, and the amount of cholesterol contained in a tablespoon (15g) is only 24mg. This is not an amount to be concerned about.

The human body is well designed to maintain balance by reducing the amount of cholesterol synthesized in the body when the amount of cholesterol in the diet is too high. In addition, cholesterol is transported from the liver to each tissue, and conversely, cholesterol is collected from each tissue to the liver, thereby keeping the amount of cholesterol in the blood at a constant level. The problem is not the intake of cholesterol itself, but the imbalance of cholesterol in the blood.

And an experiment has been conducted with surprising results. Healthy subjects and hyperlipidemic subjects were given 15 g of Kewpie mayonnaise per day for 12 weeks in addition to their conventional diet, and the lipid levels in their blood were measured. The total cholesterol concentration in the blood of the healthy subjects was slightly decreased. The hyperlipidemic subjects also showed a decreasing trend. It would seem that a constant intake of mayonnaise would increase the amount of cholesterol, but in the experiment, there was no trend toward an increase. In addition, there was no change in body weight after 12 weeks of mayonnaise consumption, a result that defies the conventional wisdom about mayonnaise. Similar experiments have been conducted elsewhere with the same results.

New Possibilities for Eggs

The amount of choline needed per day is said to be around 450 mg. 1 egg weighing 60~70 g contains 1000 mg of choline. 1 tablespoon of 15 g of mayonnaise contains about 110 mg of choline, which is 1/4 of the daily requirement. One-quarter of the daily requirement of choline can be obtained from a 15 g spoonful of mayonnaise. Incidentally, 200 cc of milk contains 28 mg, and a tablespoon of butter contains 20.4 mg, so eggs are by far the most efficient way to eat.

Mayonnaise contains a lot of salt

Mayonnaise is a sour and salty food, and while one may worry about too much salt if one eats too much, it is much less salty than one would generally imagine. The saltiness is due to the seasonings and spices. It contains less salt than other seasonings. Mayonnaise has 0.3 g of salt per tablespoon, the lowest amount of salt among the major seasonings, compared to 0.6 g of ketchup, 3 mg of soy sauce, and 2 mg of miso. Despite its low salt content, the full-bodied mayonnaise can add a lot of flavors to ingredients even in small amounts, and may be considered a good choice for dieting.

Does eating mayonnaise make me fat?

Usually, a tablespoon of mayonnaise has 100 kcal. One hot dog has about 289 kcal, so three tablespoons would be the same calories. It is certainly a high-calorie food. It is a very oily food, but the vinegar makes it surprisingly refreshing, which is one of the reasons why we tend to eat a lot of it. We should not eat too much of this food just because it tastes good but try to eat about 1 tablespoon per meal. It is not harmful to your body even if you continue to eat it every day, but only if you know how much to eat. It is not recommended to eat so much that you can’t see the salad. Instead of worrying about gaining weight, one should try to eat a well-balanced diet by eating green and yellow vegetables together.

Pairing mayonnaise with other foods

The range of uses for mayonnaise is unlimited. Please listen to this article without preconceived notions that mayonnaise would not be suitable for such foods. First of all, in the case of Japanese food, it is difficult to find foods that mayonnaise does not go well with, such as broiled eel, tempura, yakitori, oden, chilled tofu, soba noodles, and so on. Other than that, it goes well with all kinds of food such as gyoza, ramen, shumai, spring rolls, bibimbap, kimchi, tom yang kung, beef stew, omelets, curry rice, minestrone, edamame, banana, apple, orange, apple pie, pudding, chocolate, donuts, and many others. It can soften the aroma of stinky foods, freshen oily foods with its acidity, and deepen the flavor of overly light foods with the richness of eggs.

The emergence of polyethylene multi-layered containers

When Mayonnaise was launched in Japan, it was in glass bottles. In the 1960s, plastic was developed, polyethylene containers appeared, and bottling containers were quickly converted to polyethylene containers. Glass bottles were used because oxygen permeation would oxidize the mayonnaise oil and form peroxides, which would gradually ruin the flavor. However, the ability to squeeze out without using a spoon seems to have been significant, and it seems to have been replaced.

The difference in preservation effect on mayonnaise between polyethylene containers and glass bottles was that polyethylene alone had the disadvantage of poor preservation compared to bottling due to its oxygen permeability.

In the 1970s, technological advances made it possible to improve the oxygen permeability of polyethylene. A three-layer technology was developed, with polyethylene on both sides and an oxygen-impermeable plastic-like eval resin in between.

The three-layer polyethylene-eval resin-polyethylene container is used today for most food containers. This has greatly improved the shelf life of mayonnaise and has made bottled and polyethylene multi-layer containers nearly identical in terms of quality.

Bottled mayonnaise is more prone to oxidation after opening because of the large area exposed to air when the lid is opened. Polyethylene multi-layer containers have become the mainstream in Japan because of their advantages such as easy squeezability, no risk of breakage, lightweight, and low container cost.

 

Here is a summary of the characteristics of Kewpie mayonnaise.

The main ingredients of Kewpie mayonnaise are also oil, eggs, and vinegar. Of course, each of these ingredients should be carefully selected and good ones used, but the strange thing about mayonnaise is that it does not taste perfectly delicious on its own.

What became clear in Kewpie’s laboratory is that what is important is the compatibility of vinegar and oil, and vinegar is a major key, especially in terms of umami. Surprisingly, vinegar and oil go together better when they are both strong. If one of the habits is weak, the other will win out and instantly become unbalanced.

Let’s look at the history of the oil used in Kewpie mayonnaise. In the postwar period when mayonnaise became popular, cottonseed oil from cotton seeds was mainly used. Since this oil has a strong habit, it was combined with malt vinegar, apple cider vinegar, and other vinegar with strong characteristics. However, with the development of synthetic fibers in the 1960s, cotton cultivation decreased and cottonseed became scarce. This made it difficult to secure cottonseed oil, and other oils with weaker characteristics were used instead. Kewpie has changed the vinegar to match the oil.

These days, Kewpie uses a blend of vinegar made from sake lees and grains. The ingredients of oil that are good for the body are generally considered to be oleic acid, linoleic acid, and α-linolenic acid in the ratio of 60:32:8. Rapeseed oil, for example, is close to this ratio, and Kewpie uses salad oil that is also close to this ratio.

Although oil accounts for the largest proportion of ingredients, vinegar can be said to be the key to flavor. Taste preferences are said to change over time; for example, Kewpie mayonnaise was sourer in the past. The percentage of vinegar is said to be less now than in the past. In the past, there were few homes with air conditioning, and people sweated a lot. Therefore, mayonnaise with a lot of vinegar and a strong flavor was preferred. On the other hand, today, air conditioning is available everywhere, and people do not sweat as much, so the amount of vinegar is less than in the past.

Compared to mayonnaise made overseas, Japanese mayonnaise generally contains almost double the amount of vinegar. This is because mayonnaise is a unique egg yolk type of mayonnaise in Japan, and cannot be heat sterilized like other foods because it decomposes when heated. In addition, mayonnaise with high yolk content is prone to spoilage, and to prevent this, a lot of vinegar, a natural preservative, was used. This ultimately made Kewpie mayonnaise tastier.

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Revision date: March 15, 2024


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What is sushi or sashimi grade fish?

sushi or sashimi grade fish photo
Do you know when this fish was caught?

Fish is not only cooked and eaten as grilled or boiled fish but also eaten raw as sushi or sashimi. Naturally, the way to eat fish depends on individual tastes. But in fact, the way we eat fish depends on the time frame after we catch it.

Fish that is still alive or freshly dead is ideal for sashimi. In this case, you should enjoy the elasticity of the flesh, or texture, rather than the umami of the fish. Only the freshest fish is suitable for sashimi. The fish will go rigor mortis within a few hours at the earliest, and within a few days at the latest. The period leading up to rigor mortis is the time when the umami component increases, making it ideal for sushi.

On the other hand, the flesh becomes softer, so it is the sushi chef’s job to find the right balance between the umami and the chewiness of the fish. Of course, for those who prefer fish with more umami, it can also be served as sashimi. The rigor mortis of the fish is eventually dissipated and it gradually begins to decompose, so it is consumed as sashimi or sushi until a certain point in time.

The chef’s job is to determine when the fish cannot be used as sashimi or sushi. After that, the fish will be consumed as grilled or boiled fish. Eventually, the color, taste, and aroma of the fish will change dramatically, and it will reach the so-called putrefied state, making it inedible. The chef’s job is to determine when the fish cannot be used as sashimi or sushi. After that, the fish will be consumed as grilled or boiled fish. Then the color, taste, and aroma change dramatically, and the fish reaches the so-called putrefied state and becomes inedible.

A variety of conditions exist before rigor mortis sets in. Ideally, the fish should be properly processed and cooled as soon as possible after it is caught. Without this, rigor mortis will set in immediately, shortening the time until the rigor mortis is dissipated and speeding up the decomposition process. In other words, it will affect the length of time the fish can be enjoyed.

It is difficult to judge whether fish can only be used for grilled or boiled fish. It is not a simple matter of how many hours after the fish has died. Even if the fish is in sushi or sashimi grade, you can imagine that some are in good condition, and others can only be used almost exclusively for grilling or boiling.

Look around the world and you will see fish being sold around fishing ports as soon as they return from fishing. The fish is truly freshly caught and could not be fresher. Usually, the fish is cooked by dinner at the latest, so the loss of freshness is not a concern at all. People call fish in this state very fresh. To be more precise, it takes a few hours from the time the fisherman catches the fish to the time it is on the market, or at most 12 hours before it is served for dinner. This is what we call sushi or sashimi grade. However, because the fish is not caught in large quantities, it is not distributed to supermarkets in urban areas. This is limited to fishing with small boats.

Large vessels use large nets and other equipment to catch large numbers of fish. When the nets are raised on deck, many of the fish are live. They are quickly sorted, cooled with ice or other means, and placed in refrigerated or frozen storage. Some of the larger fish are stored after Ikejime, etc. Once fishermen go out to fish, they are not allowed to return for at least three days and as long as several months.

Although refrigeration and freezing technology have advanced considerably, freshness is not the same when the fish is caught as it is when it returns to the fishing port. And by the time the fish reaches the supermarket, which is a long way from the fishing port, it is arguably even less fresh. It has already been almost 24 hours since the fishermen caught the fish. It will then spend several days in the supermarket enduring temperature changes and drying out. One wonders if this can be called sushi or sashimi-grade fish.

So far, we think you can understand that this is a typical situation in countries other than Japan.

The situation in Japan is a bit different.

Regardless of the size of the boat, the fish are not allowed to get out of control, Ikejime and other processing is done. And cooling is always done. That is what even the average fisherman does as a matter of course. In other words, it is recognized that keeping fish fresh means delaying the time until rigor mortis.

On top of that, a distribution system has been established to deliver the caught fish to markets and restaurants while keeping them alive. Not only are the fish kept alive, but the know-how to reduce stress during fishing and transportation is shared among fishermen. For example, fish are transported by truck to the consumption area in a state of suspended animation to prevent them from getting out of control. In other cases, fish are not shipped immediately from the fishing port, but are allowed to calm down in a fish tank. By trying to keep the fish as close as possible to the state in which they were swimming in the sea, the fish can recover their original amount of adenosine triphosphate. This is because adenosine triphosphate is the source of umami, which eventually converts to inosinic acid.

In other words, a system is in place to distribute fresher and tastier fish. As a matter of course, it is safe to say that the fish is delivered from the fishing port to the place of consumption and then displayed in supermarkets within 12 hours.

The minimum requirement is that the fish must be usable for sashimi. The words sushi or sashimi grade do not exist in the market. Who caught the fish? What time and minute it was caught? How was it processed? Whether the fish was caught by fishing or by netting, and other details are required. These things change the price of the fish in the market.

In summary, there is no legal definition of sushi or sashimi-grade fish. When seafood is labeled as sashimi grade, it means that the seller, such as a supermarket, has determined that the fish is suitable for sushi or sashimi, based on its evaluation of criteria such as bacteria levels, temperature, parasites, appearance, odor, taste, display method, and time since catch. It is very vague and does not state that they are responsible for any problems that may occur, such as food poisoning. In the extreme, it is merely a marketing term for sales promotion purposes. Above all, they say nothing about actual quality or taste.

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Revision date: March 1, 2024


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What does texture have to do with the taste of sushi?!

Texture is a tactile sensation that is felt when food is physically stimulated in the mouth. Tactile sensations are felt by pressure receptors in the skin, tongue, and periodontal ligament of the mouth that are deformed.

The role of the pressure receptors in the mouth is to obtain information to determine if food can be digested and nourished. Digestion is made possible by physically destroying the food, making it smaller, and breaking it down with enzymes. Only when the molecules are small enough can they be absorbed by the small intestine and other organs. Chewing in the mouth is the first step in this process. In the process of chewing, the food becomes smaller and smaller, and the texture changes rapidly.

The Japanese are the ethnic group with the most textural language. According to a survey on the number of terms related to texture, Japanese has about 500 words related to texture. In contrast, Chinese has about 150 words, French about 250, and German and English about 100. The Japanese have created a wide variety of foods with different textures by distinguishing and enjoying the differences among these many words used to describe textures.

Texture and taste are not directly related, since they are sensed by different receptors and are carried as information to the brain by different nerves, but the release of taste substances from hard foods is slower, and thus taste is perceived more slowly. On the other hand, the opposite is true for soft food, which tastes more quickly.

Nigiri sushi is made with an emphasis on texture. The act of aging sushi topping is waiting for the texture to soften in terms of physical changes. The purpose of this is for the sushi topping to adhere to the sushi rice. In conjunction, it is waiting for the production of inosinic acid, an umami substance. Shrimp, squid, and other ingredients not only become softer but also change to a gooey state. In this way, there is an aspect that makes it easier to perceive the taste.

Several techniques are used to mix the sushi ingredients and sushi rice in the mouth. We make sure that one or the other does not move first from the mouth to the back of the throat. If the sushi rice remains in the mouth, it is equivalent to eating sashimi, and the synergistic effect of umami cannot be expected. The way to do this would be to slit the sushi topping as much as necessary. The sushi rice and the sushi topping become as if they are one food. Of course, this also serves to improve the texture by cutting off white streaks and small bones.

Even the same portion of the same sushi item can have different textures depending on the sensitivity of the sushi chef. In other words, the taste changes. It is as if one were to choose a 500-word term for the texture, and then cast a spell on the sushi item. It is fun to guess what the sushi chef wanted to express.

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Revision date: February 26, 2024


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What is development fish?

The Fisheries Research Center of the Fisheries Research Agency (FRA) is engaged in a project to find new fish from the world’s oceans that suit the Japanese palate.

In 1971, the former Marine Fisheries Resource Development Center was established as a public organization to research new fishing grounds and fish and shellfish, and to study business feasibility, and was given the mission to find fish and shellfish that had not been distributed in Japan before.

The seafood distributed domestically by the Center was called “development fish”.

The term “development fish” does not refer to the creation of new types of seafood through breeding or other means, but rather to efforts to make new use of fish and shellfish that have not been distributed domestically. A similar term is “substitute fish,” which is used in place of fish and shellfish that have been conventionally consumed, but developed fish are not intended to be substitutes.

For example, “Gindara (Black cod)” is a fish that was investigated in collaboration with the United States.

This fish is not a codfish, but a member of the Gindara family. At first, it was distributed mainly as surimi because it was black and unattractive, but later it was also consumed as fillets and boiled fish.

The “Karasugarei (Greenland halibut)” is found in the Arctic Ocean, the Bering Sea, and the Sea of Okhotsk. It is often used as Engawa in conveyor-belt sushi.

There is another fish called “Gasutoro“. This fish, named after the leader of the Cuban Revolution, is used in fried white fish. The meat of the “Gasutoro” is white and unctuous, and it is caught along with tuna in longline fisheries.

Since its establishment, the FRA has developed a total of 46 species of fish and shellfish, including Sunfish, Kingklip, and Jumbo flying squid, to provide new food sources. The “development fish” has also enriched our diet.

Unfortunately, the development of “development fish” ended about 20 years ago.

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Revision date: February 9, 2024


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Do you know the dangers of eating raw tuna?!

Cutting Tuna
Sushi chefs make sushi toppings from tuna.

We would like to examine this challenging title that appears regularly in the media.

This story has not recently come to a boil; in fact, it is already widely known. However, the reason it is a recurring topic is due to the fact that the assumptions between the writer and the reader do not match. The reason for this is that the writer tends to exaggerate a bit in order to get people to read the article. The readers, on the other hand, are overwhelmingly uninformed and are led to feel uneasy about what they hear. Here’s what we guess.

So, in order to explain this issue properly, we will squash any ambiguities.

There are three major risks.

The first is food poisoning due to bacterial growth. The second is food poisoning by parasites. The third is the medium- to long-term effects on the human body of mercury, dioxin, microplastics, and other substances that accumulate in tunas.

a photo of Food poisoning prevention
The best way to prevent food poisoning is to keep hands clean.

We can say that food poisoning caused by bacterial growth is a very rare and serious matter that can affect the survival of a business, if only in sushi restaurants. Here are some data to support this. According to data from the Tokyo Metropolitan Government, the percentage of food poisoning cases occurring at sushi restaurants is less than 0.8% of the total number of food poisoning cases. The data shows that food poisoning rarely occurs at sushi restaurants.

 

The reasons for this are largely related to soy sauce, salt, and vinegar. First, soy sauce has bacteriostatic properties, and by marinating tunas and other fish in soy sauce, the growth of bacteria is inhibited. Second, salt has a bactericidal effect, killing bacteria on the surface of the fish. Besides, it uses osmosis to expel the rotting components of fish meat, etc. And vinegar also has a sterilizing effect. Since the ㏗ is 2~4, the bacteria are almost killed when they come in contact with vinegar. Sushi chefs put vinegar on their hands or wipe their knives with a cloth dipped in vinegar to sterilize them. Shari is made with vinegar and salt, so it is also sterilized. In other words, more steps are taken to prevent the growth of bacteria than in any other dish.

 

Next, we will examine food poisoning caused by parasites; Anisakis accounts for 50% of all cases of food poisoning. It can be said that raw seafood always contains parasites, but removing these parasites is the foundation of a sushi restaurant, and Anisakis, which can be visually identified, cannot be overlooked. On July 2, 2021, a method to kill Anisakis with a high current was also announced and will soon be put to practical use.

 

Also, it totally depends on where you eat. Do you buy it at the supermarket or fish market and eat it at home or a sushi restaurant? Even at the same sushi restaurant, there is a difference. Is it a conveyor-belt sushi restaurant with a chain or an individual restaurant run by a master and his apprentice? In our opinion, however, food poisoning caused by Anisakis has not occurred in private restaurants.

 

We will examine the medium- and long-term effects of toxic chemicals. First, let’s look at the effects of mercury. For example, the level of effect is naturally different for those who consume tuna every day and those who eat tuna once a week. Although the Japanese eat a lot more tuna than other countries, the effects of mercury accumulated in tuna have not yet been widely discussed. The effects of mercury on the mother’s body are well known, and the following warning is given by the doctor in charge.

 

In Japan, if you eat more than 160 grams of tuna per week, you need to be careful. Pregnant women do not bother to eat 160 grams of tuna in the first place. In addition, although Kuromaguro (Bluefin tuna), Mebachi (Bigeye tuna), and Minamimaguro (Southern Bluefin tuna) have safe amounts, Kihada (Yellowfin tuna), Binnaga (Albacore), and Mejimaguro (Young bluefin tuna) do not require any restrictions on the amount eaten. Also, there is no need to worry about canned tuna. This is also a well-known story.

 

And, this may come as a shock to tuna lovers, but it is the toro part of the belly that tends to accumulate the most dioxin, which is considered the best part of the fish. The toro is mostly fat, and dioxin taken in from feed and seawater accumulates there. In nature, the toro portion of tuna is normally about 20% of the tuna meat. However, in fattened tunas, 70~80% of the body is toro. The meat of fattened tuna is a habitat for dioxin. According to some research data, the amount of dioxin accumulated in fattened Kuromaguro was about 2 to 3 times higher than that in wild tuna, and in fattened Minamimaguro, it was about 2 to 10 times higher.

The final section examines microplastics’ medium- and long-term effects on the human body.

In the North Pacific Ocean gyre, famous for the Pacific Garbage Belt, plastic fragments have been found in the digestive tracts of 10%-35% of the fish examined. Many researchers have noted that microplastics are vectors that bridge harmful pollutants to fish and marine life. U.S. health officials estimate that less than 0.3% of microplastics taken into the human body reach the body’s lymphatic and circulatory systems from the gut. And only a very small fraction of these microplastics affect the body’s organs. Still, the effects of microplastics taken into the body on human health are not fully understood.

 

In 2014, the Ministry of the Environment’s survey on the actual state of marine debris reported that the amount of microplastics in the waters surrounding Japan was 16 times more than in the North Pacific Ocean and 27 times more than in the world’s oceans. And yet, around 2020, major media outlets are only now beginning to report on the issue. Unfortunately, this is one of the topical issues that Japan is still turning a blind eye to. In fact, this is a more serious problem in the world, and we imagine it will be sensationalized soon. We should put some restrictions on countries and companies dumping plastics into the oceans. Japan must be proactive in this regard in order to achieve the SDGs.

In conclusion, we think this title comes from the media’s self-righteousness.

We are not a researcher and cannot say that it is absolutely safe. It is a medium- to long-term issue that should not be neglected with careful monitoring. But in general, Tuna is an expensive food, so it should be economically difficult to consume it in large quantities. Instead, the media should focus on rice, wheat, corn, and other foods that are consumed daily. For your information.

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Revision date: September 8, 2023


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What is traditional Ikejime?

a photo of Ikejime Madai
In order to fully drain the blood from the red seabream, the spinal cord at the base of the tail is also cut off.

Articles related to Sushi are now filled with jargon such as Shinkeijime, Chinuki, Noujime, Ikekoshi, and Korijime. That much confirms the fact that opportunities to eat fish are increasing all over the world. And it has also become a common occurrence to find articles written by people who have heard Ikejime in bits and pieces. According to what we have heard, Ikejime processing is one of the reasons why red seabream from Akashi, which is said to be the best in Japan, is so tasty, and the technology has been around since the Edo period (1603-1868).

The Ikejime procedure consists of four parts or some of them, and the point of Ikejime is to kill the fish in a relaxed state.

The first step is a brain-dead the fish by stabbing it in the head with a sharp object. This process is called Noujime (Nou means brain and jime means kill).

After the fish is out of the water and before it gets out of control, it is stabbed in the head with a hook called a Tegaki (手鉤). If the brain is not destroyed by one blow, the fish will struggle. When this happens, a large amount of ATP, which is the source of umami, is consumed. As a point of caution, the right side of the head is stabbed so that the puncture wound is not on the upper side, as the fish will be handled later in the distribution process with the belly facing forward and the head facing to the left.

Next, use a knife to quickly kill the live fish.

Place the fish with its head facing left, open the gill cover, and cut a spinal cord below the lateral line that is visible on the fish’s body. Since bones have hard parts, move the cutting edge slightly to the left and right if it is difficult to cut. If you don’t cut it completely, you have not killed the fish, and the blood will not drain well. To drain the blood sufficiently, the spinal cord at the base of the tail is also cut off. Place the fish’s head to the right and cut the front part of the tail so that the spinal cord is visible. At this point, the knife should be placed at a right angle to the spinal cord so that the cut surface is not at an angle.

The next step is to remove the nerves and delay rigor mortis. This process is called Shinkeijime (Shinkei means nerve).

Shinkeijime is a technique to delay rigor mortis in fish. A wire is inserted into a small hole in the upper part of the spinal cord. When the wire hits the nerve, the fish will act violently, so hold it down. The nerve hole tapers from the head side to the tail, so when stabbing in from the tail side, make sure to insert the wire securely first, so that the wire does not pierce through the nerve hole and pierce the body. Once you have securely inserted the wire, repeatedly pull out and insert the wire to completely destroy the nerve in the hole. When the nerve is destroyed, the body color quickly changes to white. The destroyed nerve appears as a white, sludgy fluid.

Any wire can be used for this purpose as long as it is straight, but a piano wire that does not bend easily can be used many times. The diameter of the nerve hole differs depending on the fish. Use a thick wire for Tai and Suzuki, which have large nerve holes, and a thin wire for Aji and Anago, which have small nerve holes. Several types between 0.8mm and 1.5mm should be enough. As you get used to it, you will be able to stick the wire in without visually seeing the nerve hole. If you remove a few scales from the upper part in front of the tail, insert the wire along the spinal cord, probe the nerve hole, pierce it, and destroy it, you can remove the nerve without making any cuts on the fish’s body. The same applies to the head side. The nerve hole is probed and pierced from the head side, but the key is to keep the head and body straight so that the nerve hole is not misaligned by the spinal cord severed behind the gills. In any case, it takes experience and familiarity to pierce the nerve hole without seeing it.

The final step is to perfectly remove the blood from the fish’s body. In Japanese, it is called Chinuki (Chi means blood and nuki means remove).

The blood is removed by cutting the spinal cord and immersing the fish’s body in seawater. At this time, running water is more reliable to remove blood. In the case of stored water, leave it for a while and then replace it with other stored water. If the water does not turn red with blood, the fish has already been drained. Blood has a tendency to clot, so it is important to wash off any blood that has clotted on the gills or other parts of the body. The body temperature of the fish is raised by the Ikejime process and by human hands. Since the fish were originally in the sea, which has a lower temperature range than that of the ground, the higher temperature increases the speed of deterioration, so the fish is soaked in ice water to lower the temperature of the fish’s body. If the fish is soaked too long, its body surface will turn white, so remove it from the water when it cools down.

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Revision date: August 18, 2023


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Authentic sushi toppings only eaten in Tokyo!

a photo of making nigiri sushi
A sushi chef adds wasabi to sushi topping.

Sushi continues to spread throughout the world. Nowadays, not only sushi rolls but also Nigiri sushi can be eaten all over the world. But if you have the opportunity to come to Tokyo, we want you to go home with sushi toppings that you can only eat in Tokyo. Not seafood exported from your country, but sushi made from natural seafood caught in the seas around Japan.

First of all, what kind of sushi do you think of when you hear the word “Nigiri sushi”? Most people think of sushi with Hamachi or Salmon on top of vinegared rice.

This is correct if you only look at the appearance. However, from the essence of Nigiri sushi, it is clearly wrong. In order to make your understanding perfect, we dare to confuse you, but we would like to understand the term “Edomae sushi” as well.

What is Edomae sushi?

Nigiri sushi and Nigiri are words you may have heard before. However, “Edomae sushi” is a word you may not be familiar with, so it is important to understand exactly what it is.

It is quite simple.

Edomae sushi consists of Nigiri sushi and Nori maki. Nigiri sushi originated in Edo (now Tokyo) about 200 years ago, while Nori maki is said to have originated 50 years earlier. And Edomae sushi has remained almost in its original form to the present day. We will skip the explanation of Nori maki here, so you can just assume that “Edomae sushi” and “Nigiri sushi” refer to the same thing.

Now let’s dig deeper into the story of Nigiri sushi. You have probably seen Nigiri sushi and Nori maki before. If you do not like fish and nori, you have probably eaten them.

However, many people, including the Japanese, misunderstand Nigiri sushi.

They think that Nigiri sushi is sushi with sashimi such as salmon on top of vinegared rice. Many cookbooks and other books say this as well, so it is no wonder they understand it incorrectly.

To correct here, nigiri sushi consists of prepared fillets on a bed of vinegared rice. Preparation means sprinkling salt on the seafood, soaking it in vinegar or soy sauce, boiling it, simmering it, etc. This preparation is called Edomae shigoto (Edo-style preparation) in Edomae sushi restaurants. To confirm, sashimi is unheated seafood or other ingredients cut into small pieces.

Why do they dare to prepare super-fresh seafood?

The reason is said to be that in the Edo period, there was no such thing as a refrigerator, and people had to devise ways to keep seafood from spoiling even a little. Then it seems that it is not necessary now. However, this preparation process helps to make seafood more delicious (to give an example, inosinic acid is produced, which, combined with the glutamic acid and other substances that seafood originally contains, produces a synergistic effect of umami). This is why they still use prepared seafood today.

On the other hand, salmon nigiri sushi found overseas uses sashimi. Even in Japan, in regions where fresh seafood is available, sashimi is used. This is because the priority is not the synergy of umami, but rather the texture and security of freshness. And there is no way to know that this is clearly different from Edomae sushi (Nigiri sushi) on the main road.

If you make nigiri sushi with sashimi, you don’t have to be a sushi chef to do it. In fact, to put it bluntly, anyone can do it. There is an experience to make Nigiri sushi for tourists, but you understood that this is only to make Nigiri sushi in appearance, right? And to learn Edomae shigoto (Edo-style preparation), the sushi chefs need a long period of training.

Let’s get to the point here.

Here are 8 sushi toppings you should try in Tokyo. We divided it into 4 so that you can see the opportunity to eat.

The first is the typical sushi toppings at Edomae sushi. It is a sushi topping that can be eaten regardless of the season (of course, there is a season), but it shows the characteristics of the sushi restaurant. The boiled Kuruma ebi, with its beautiful red color, aroma of the sea, and complex umami, is a must-try. Next is not eel but Anago (Japanese conger). The soft- simmered anago instantly falls apart in your mouth, spreading the ummai of the fish, and the restaurant’s unique sauce, called Nitsume, is not to be missed.

Second, sushi toppings are only available at certain times of the year. The season is short, so even if you want to eat it, you will have to wait until the next year when the season is over. For example, don’t you think you can eat Bluefin tuna all the time? The season for fresh bluefin is from around September to early January. This is the time when all parts of the fish are at their best. Shinko, the juvenile kohada, can cost as much as $2,000 per kilogram at the beginning of the season, and sushi chefs are forced to pay a premium for this fish because sushi lovers compete to be the first to eat it. The taste is not as good as kohada, but the aroma may be a cut above.

Chum salmon is not eaten raw in Japan. This is because of problems such as anisakis. Even so, you should definitely try Keiji (young Chum salmon) nigiri, which has a completely different quality of fat. It is very rare and costs more than US$1000 per fish. Then there is Hoshigarei, the king of flounder. The moderate fat and fresh aroma will fascinate you. Next, the Red sea urchin is caught in Kyushu and other parts of Japan. Sea urchin has a rather complex flavor. However, red sea urchin has a refreshing aftertaste. It is a mysterious sushi material.

The fourth is the sushi items that you should eat without grumbling. You should be happy to eat these items in season. Ezobafununi, caught in Hokkaido during the summer, is exceptional. Many people say they can’t eat sea urchin, but if you eat this, you’ll become a sea urchin lover. And then there is Akagai (Ark shell). Many shellfish enjoy the delicate balance of sweetness and bitterness, but Ark shell is a great ingredient to enjoy the scent of the sea.

If you want to eat Hamachi or Salmon, which you often eat as Nigiri sushi, you have to go to a conveyor belt sushi restaurant. Buri, which is farmed, is called Hamachi. Salmon is also mostly farmed, with Norway and Chile being the world’s leading producers. There is no point in going all the way to Tokyo to eat them.

Finally, sushi chefs tend to avoid farmed fish. And the same goes for frozen fish. Some fish can only be used for Nigiri sushi if they are live. The chef cooks fish deliciously, but sushi chef is only trying to bring out the true flavor of the fish. In other words, there is no compromise in the selection of seafood. If the fish is too expensive, sushi chefs may not buy it. And sometimes they have to buy it even if it is too expensive. For your information.

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Revision date: August 12, 2023


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What is K value, a formula to evaluate the freshness of fish?

a photo of Fish market
A fish market is a marketplace used for marketing fish products. It can be dedicated to wholesale trade between fishermen and fish merchants, selling seafood to individual consumers, or both.

As fish and meat age, their components change, losing their deliciousness while at the same time producing dangerous components that can be harmful to the body. Freshness is determined by the amount of time that has passed since the fish was caught. By knowing the freshness, we can tell how fresh the food is, and at the same time, we can tell if it tastes good and is safe.

To swim, fish consume adenosine triphosphate (hereafter referred to as ATP) in their muscles to generate kinetic energy. While the fish is alive, ATP is resynthesized through respiration and the breakdown of glycogen in the body, even if the muscles are fatigued.

However, if they die and are no longer supplied with new ATP, the binding of actin and myosin, the proteins that make muscles stretch and contract, proceeds unilaterally. In combination with the acidification caused by the breakdown of ATP and the formation of lactic acid, the muscles remain contracted. This is the onset of rigor mortis. Finally, ATP is lost and rigor mortis is completed. If a fish dies while its body is exhausted from strenuous exercise, rigor begins earlier than normal. This means that ATP is consumed when fish resist violently to avoid being caught.

K value is a scientific and objective standard for judging the freshness of fish and other products.

To begin with, the postmortem flesh of fish is said to be alkaline. It becomes more acidic over time. In the process of this change, ATP is broken down into several acids as shown below, and the K value is a mathematical formula that captures some of these acids and calculates them.

ATP→Adenosine diphosphate(ADP)→Adenosine monophosphate(AMP)→inosinic acid(IMP)→hypoxanthine riboside(HxR)→Hypoxanthine(Hx)

The formula is as follows:

K value (%) = (HxR+Hx)/(ATP+ADP+AMP+IMP+HxR+Hx)×100

The rate of degradation varies among fish species, but the pathway to HxR is constant. Fish that die quickly after catching have more ATP, ADP, and AMP. Then, as time passes, IMP increases and finally HxR and Hx increase. These HxR and Hx present a tasteless or bitter taste, which causes a decrease in deliciousness. In other words, a high amount of HxR and Hx is evidence of reduced freshness.

In general, fish with a K value of up to 20% can be eaten raw, i.e., as sashimi. In the case of fish, the K value is about 5% immediately after ikejime. 20-40% is considered to be good freshness. Sushi toppings are around 40%, which is not low by any means, but it is at this value that the flavor of the ingredients is most likely to be extracted. In other words, it is a state of maturing and increased IMP. And if it is 40-60%, it is edible if cooked. In other words, it is better to eat simmered or grilled fish. If it is over 60%, it is in a state of decomposition. Naturally, it is not suitable for eating. It is also known that the rate of increase in K value is large for cod and red-fleshed fish, while the rate of increase in K value is small for white-fleshed fish such as red sea bream and flatfish.

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Revision date: July 25, 2023


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The rating of fish in the Edo period was totally different from that of today!

a photo of Rating
In the Edo period, people rated various things. It seems that there was such a rating chart.

Tuna, which is now a representative of high-class fish, was one of the lower ranks of Gezakana (ge means ‘cheap’, and zakana means ‘fish’) in the Edo period. According to an encyclopedia of the Edo period, “maguro is a very vulgar fish, and even common people who live in houses facing the main street would be ashamed to eat it. Maguro was so low-ranked fish that was said to be the food of poor people living in houses on back streets. However, due to the effects of global warming and overfishing, the number of fish called Gezakana has been decreasing. Therefore, meat is definitely cheaper than fish in supermarkets.

Next, please take a look at the ratings of fish in the Edo period as listed in Chiba University‘s study of classical cuisine.

The following fish are listed as Jyozakana (Top-grade fish)

Tai、Ankou、Amadai、Sayori、Shirauo、Suzuki、Sawara、Ishigarei、Ayu、Tara、Akagai、Kaki、Karei、Kisu、Kurumaebi

 

The following fish are listed as Chuzakana (Middle Fish)

Tako、Kochi、Hirame、Aji、Ara、Ika、Katsuo、Houbuo、Ishimochi、Ungai、Ainame、Asari、Hamaguri、Bora

 

The following fish are listed as Gezakana (Lower fish)

Buri、Kurodai、Saba、Iwashi、Fugu、Kohada、Mutsu、Okoze、Shimaaji、Maguro、Nishin、Same

 

Again, maguro is classified as Gezakana, along with today’s high-end fish such as Kurodai and Fugu, and it seems that most Jyozakana are white fish, and the oily fish, so much appreciated today, was not favored by the people of Edo. In addition, maguro was also called shibi (pronounced “shi,” which is a reference to death), and some believe that it was not popular because it was associated with death.

When large schools of maguro appeared in the seas around Edo (Tokyo) between 1340 and 1844 and were caught in large numbers, they were sold for free because they were not popular.

As a side note, a sushi restaurant made a fortune by purchasing maguro red meat at a low price, marinating it in soy sauce, and selling. This was the beginning of what is now called Zuke.

n this way, red meat was still sometimes preferred, but Toro, which tends to spoil easily, was not looked upon and was often thrown away. Even if it was eaten, it was only in Negima nabe (hot pot) and was rarely eaten raw.

It was not only in the Edo period that toro was not favored.

It was not until the development of refrigeration and freezing technology in the 1945s that otoro and chutoro became as much appreciated as they are today. It is only recently that Otoro and Chutoro have become the kings of fish. Fish grading, in fact, has a great deal to do with safety. Saba, which suddenly loses its freshness, and Iwashi, which is tender and easily loses its freshness, are both Gezakana. In other words, fish that lose their freshness easily were likely to be classified as gezakana.

Another reason was the taste of the Edo people, who preferred light fish such as Amadai, Sayori, and Suzuki to oily fish such as Saba and Buri. It is understandable that Maguro Toro, which is both fatty and perishable, is frowned upon.

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Revision date: July 24, 2023


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Here’s a Michelin sushi restaurant where photography is not allowed!

a photo of Kuromutsu nigiri sushi
Kuromutsu were disturbers a long time ago when we were fishing Splendid alfonsino (Kinmedai). And they were not really liked by Edo people who don’t really like oily taste.

In this age of social networking, there is a certain discomfort in not being able to take pictures of your food. But sushi restaurants don’t want people to write bad things about them, and most of all, other customers may feel uncomfortable about the sound of the shutter. Especially for regular customers, this behavior is not funny. On the other hand, it is human nature to want to show off on social media or record your visit to a restaurant where reservations are hard to come by. It is the policy of the restaurant, so if you cannot follow it, just don’t go there.

Therefore, we investigated Michelin sushi restaurants where photography is not allowed.

a photo of michelin-guide-tokyo-2023

Of the 30 sushi restaurants that received stars in the Michelin Guide Tokyo 2023, the following five are among those where photography is prohibited. Of these, Sawada in Ginza is the only one that has not been photographed, probably because it has been prohibited ever since it moved from Nakano to Ginza. The other four have been banned at one point or another. This means that at the remaining 25 establishments, Oyakata (Sushi master) is still allowed to take pictures, albeit reluctantly. However, the sound of the shutter is not very pleasant, so care must be taken when taking pictures.

Sushi Yoshitake

Sawada

Sushi Kanesaka

Takagaki-no-sushi

Sushi kuwano

Next up is a sushi restaurant previously awarded a star in the Schlumberger Guide Tokyo where photography is not allowed. Sushi Arai will open a new restaurant on the second floor of the same building in spring 2021, in addition to its previous location on the basement floor. Photography is not permitted at the new restaurant. Sukiyabashi Jiro will be replaced by the eldest son, and in my opinion, it will become OK (it is still NG). The reason is that the customers will be replaced by new ones.

Sukiyabashi jiro

Sushi Arai

In summary, if the restaurant offers the Omakase course, which is strongly recommended, we would like to be allowed to take pictures. The reason is that we are eating at the convenience of the restaurant, so “we are cooperating, right? Let me at least take a picture”. As one example, Sushi Saito, which has been awarded three Michelin stars for 10 consecutive years, has a section that considers photography as part of its service. On the other hand, if you eat at Okonomi, the sushi chef and the restaurant are both forced to work hard, and you are told to “Eat quickly” before taking any pictures. For your information.

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Revision date: July 22, 2023


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