Sushi Ingredients | Sushiblog

Current status of salmon farming in Japan

A photo of salmon block — Salmon boasts a vibrant orange color, a good amount of fat, and a melt-in-your-mouth texture.

Salmon is the most popular item at conveyor-belt sushi restaurants in Japan, and demand continues to grow both domestically and globally. In response, Japan’s salmon farming industry has been rapidly expanding. Domestic production is projected to reach approximately 33,000–34,000 tons in 2026, up about 10% from the previous year and marking a new record. This growth is driven by both traditional sea-based aquaculture and the rapid development of land-based farming using Recirculating Aquaculture Systems (RAS).

In coastal regions such as Aomori and Hokkaido, sea-based farming remains a core production method. In the cold, fast-moving waters of the Tsugaru Strait, salmon develop firm flesh and rich fat content—qualities highly valued for sushi and sashimi. Companies such as Okamura Foods are leading this sector by introducing advanced Nordic technologies and large-scale farming systems. Working closely with local fishing communities, they produce branded fish such as “Aomori Salmon,” while expanding operations to include land-based hatcheries and remote-controlled feeding systems.

At the same time, Japan is seeing significant investment in land-based aquaculture. Pure Salmon Japan is developing one of the world’s largest RAS facilities in Tsu, Mie Prefecture, with a planned annual capacity of 10,000 tons. Other major players include FUJI ATLANTIC SALMON in Shizuoka, Atland (a joint venture between Mitsubishi Corporation and Umios) in Toyama, and FRD Japan in Saitama. These operations aim to produce high-quality salmon with fully controlled water conditions, reducing disease risk and enabling year-round production.

A defining characteristic of Japan’s salmon farming industry is its diversity of species and local brands. Farmed salmon in Japan includes a range of types, each with unique traits. Below is a detailed overview of major salmon species and brands:

Species	Brand / Regional Name	Location	Farming Method	Estimated Annual Production (tons)
Atlantic salmon	FUJI ATLANTIC SALMON	Shizuoka	Land-based (RAS)	4,700〜5,300
Atlantic salmon	Atland	Toyama	Land-based (RAS)	2,500
Atlantic salmon	Pure Salmon Japan	Mie	Land-based (RAS)	10,000
Coho salmon	Kaikyo Salmon	Tohoku–Hokkaido	Sea-based	Not publicly disclosed
Coho salmon	Miyagi Salmon	Miyagi Prefecture	Sea-based	Not publicly disclosed
Coho salmon	Date no Gin	Hokkaido Pacific coast	Sea-based	Not publicly disclosed
Coho salmon	Kinka Gin	Miyagi Ishinomaki area	Sea-based	Not publicly disclosed
Coho salmon	Gin no Suke	Regional	Sea-based	Not publicly disclosed
Rainbow trout / Trout salmon	Sakura Gin	Various farms	Sea-based / Land-based	Not publicly disclosed
Rainbow trout / Trout salmon	Kiwami Sake	Various local cooperatives	Sea-based / Land-based	Not publicly disclosed
Rainbow trout / Trout salmon	Yamanashi / Nagano	Regional	Land-based	Not publicly disclosed
Chinook (King) salmon	Various premium farms	Regional	Sea-based / Land-based	Not publicly disclosed
Donaldson trout	Various farms	Regional	Land-based / Hybrid	Not publicly disclosed
Hybrid crosses	Various farms	Regional	Land-based / Sea-based	Not publicly disclosed

Despite this growth, Japan still relies heavily on imports, with around 80% of its salmon sourced from Northern Europe and South America. However, global factors are reshaping the market. The Ukraine–Russia conflict has increased air freight costs and extended delivery times from Norway, while geopolitical tensions involving the Middle East, including Iran and the United States, have driven up oil and electricity prices. These factors not only raise import costs—already up roughly 60% over the past five years—but also impact domestic production, particularly energy-intensive land-based systems.

Each farming method presents its own advantages and challenges. Sea-based farming allows for large-scale production and natural growth conditions but is vulnerable to environmental risks such as red tides and disease. Land-based RAS systems offer precise control over water quality and eliminate marine pollution, yet require substantial capital investment and high energy consumption. Hybrid systems, in which fish are raised on land before being transferred to the sea, provide a balance between efficiency and quality but add operational complexity.

Looking ahead, Japan’s ability to establish itself as a major salmon-producing nation will depend on how effectively it integrates these approaches. Expanding branded domestic production, improving energy efficiency, and leveraging technological innovation will be essential. At the same time, imported salmon is likely to remain important for premium markets, while domestic farmed salmon increasingly supports local demand.

In this evolving landscape, Japan’s salmon industry is shifting from import dependence toward a more diversified and resilient production model—one that combines regional identity, species diversity, and advanced aquaculture technology.

What is the difference between Real and Imitation wasabi?

A photo of Imitaion wasabi — This is imitation wasabi served with uramaki.

When most people think of wasabi, they picture a bright green paste with a strong, nose-tingling heat. In reality, what is served in most sushi restaurants around the world—including in the U.S., Europe, Asia, and China—is usually imitation wasabi.

This is not because restaurants want to mislead customers, but because real wasabi is incredibly difficult to grow and very expensive. The Wasabia japonica plant needs pure spring water, cool temperatures, and several years of careful cultivation, which makes large-scale production nearly impossible. As a result, genuine wasabi is rare even in Japan, and much harder to find abroad.

A photo of Imitation wasabi — Imitation wasabi is a food product primarily made from horseradish. It contains added coloring, flavoring, and thickening agents that give it the appearance and taste of real wasabi.

Imitation wasabi, made from horseradish, mustard, and green coloring, became the practical solution. It is affordable, easy to store, and widely available, which has allowed sushi culture to spread and become popular worldwide. Without this substitute, sushi culture might not have grown as quickly outside Japan.

Even in Japan, most wasabi served at conveyor-belt sushi chains or sold in supermarkets is not 100% hon-wasabi (hon means real). There are powdered forms that must be mixed with water, and smooth pastes packaged in tubes. Their compositions vary: some include a small amount of domestically grown wasabi rhizome, others add mustard powder for extra sharpness, and many rely primarily on horseradish. In other words, “imitation wasabi” in Japan exists on a spectrum—from blends with real wasabi to products made almost entirely from substitutes.

By contrast, at high-end sushi restaurants and traditional ryotei in Japan, chefs freshly grate real wasabi rhizomes on sharkskin graters and serve it directly with sushi. These chefs deliberately choose authentic wasabi because it brings out the natural character of the fish and rice. Its fleeting heat, subtle sweetness, and refreshing aroma work in harmony with the sushi rather than overpowering it. In other words, real wasabi is not just a condiment—it is an essential element that allows the true flavor of the ingredients to shine.

In recent years, a few farms in the United States—in places like Oregon, North Carolina, and California—as well as in Europe, China, and other parts of Asia have begun cultivating real wasabi. However, the same challenges remain: it cannot be mass-produced, so supply is very limited.

So while most people around the world—and even many in Japan—have only encountered imitation wasabi, it exists for very practical reasons. And when diners finally taste freshly grated real wasabi, they often discover a surprisingly delicate, even slightly sweet flavor unlike anything they expected.

For travelers visiting Japan, tasting real wasabi at a sushi restaurant or ryotei is a unique culinary experience. It is an opportunity to appreciate the subtlety and harmony of authentic Japanese cuisine—something that cannot be fully replicated elsewhere.

What is the difference between Sabazushi and Battera?

Both sabazushi and battera are types of oshizushi made with mackerel. Oshizushi is made by layering vinegared rice with vinegared mackerel and shiro-ita konbu, then pressing the mixture into a wooden mold. Mackerel has been abundant in Japan since ancient times, which led to the development of this dish as a practical preserved food.

There are clear differences between Sabazushi and Battera, so let us explain them.

A photo of sabazushi — The appearance of sabazushi

Sabazushi is said to have originated in the Edo period. Mackerel is salted and transported from its place of origin in Wakasa to Kyoto, where it arrives after 2 to 3 days, by which time the seasoning is just right. This salted mackerel is used to make Sabazushi. Even today, with the development of refrigeration technology, it remains popular with many people and is also a local dish of Kyoto. There are also long-established sushi restaurants that have been in business for generations. Additionally, Sabazushi can be found in other regions such as Hyogo, Hiroshima, and Wakayama, which have adopted the dish from Kyoto.

Sabazushi is prepared using a unique method. First, the air is removed from the vinegared rice to extend its shelf life. Then, the vinegar-marinated mackerel is formed into sticks with a cloth or bamboo mat. Finally, shiroita konbu or rausu konbu is placed on top to prevent the mackerel from drying out. Only half of the mackerel is used so that the thickness of the flesh is evident. The cross-section is rounded, which is why it is also called bozushi (bo means “stick”).

A photo of battera — The appearance of battera

Next, Battera is a type of Oshizushi made by placing thinly sliced mackerel marinated in vinegar and shiroita konbu simmered in sweet vinegar on top of vinegared rice. It is typically shaped using a square mold. The mackerel is cut with a knife to minimize waste, resulting in an almost uniform thickness.

Battera is said to have been invented in 1894 by Tsunekichi Naka, the founder of Sushi Tsune, a sushi restaurant in Osaka. At the time, Sushi Tsune was selling Oshizushi made with Konishiro (Gizzard Shad), which was commonly caught in Osaka Bay. Due to its popularity, the traditional method using a cloth became insufficient for production, so a wooden, boat-shaped mold was used instead.

Customers reportedly referred to the mold as “bateira,” a Portuguese word meaning “boat,” which evolved into “battella.” Over time, this name further transformed into “Battera.” As the price of Konishiro (Gizzard Shad) rose, mackerel was adopted as an alternative, and due to its ease of shaping, square molds became the standard.

In summary,

Sabazushi: Use a bamboo mat to shape the fish into a round form, using thick slices of mackerel left whole. The cross-section has a rounded shape.

Battera: Shaped into a square using a wooden mold, thinly sliced mackerel is arranged evenly. The cross-section is square.

Sabazushi is a traditional regional sushi centered around Kyoto, while Battera is a type of sushi that became popular among the general public in Osaka.

What is the difference between Chirashizushi and Barachirashizushi?

A photo of chirasihizushi — This is what most people think of when they hear the word chirashizushi.

Recently, I came across an image on social media of Barachirashizushi made by an American sushi chef. I was surprised to see that Barachirashizushi, a dish traditionally made only by a few sushi restaurants that uphold the Edomae-style, had been created by a sushi chef outside Japan. However, it was labeled as Chirashizushi, which I found disappointing, so I will explain the difference.

The term “chirashizushi” (or “chirashi sushi”) originates from the act of scattering various ingredients over or within vinegared rice and is sometimes referred to simply as “chirashi.” Generally, “Gomokuzushi” refers to vinegared rice mixed with ingredients, while “chirashizushi” refers to vinegared rice topped with arranged ingredients. However, these terms are not strictly distinguished. The names may vary depending on the region (e.g., Kanto or Kansai) and generation.

First, let’s explore the origin of chirashizushi. The term “barazushi” appears here, but it is different from barachirashizushi.

Barazushi, a type of sushi from Okayama, is said to date back to the early Edo period. At that time, the feudal lord of Okayama Domain, Ikeda Mitsumasa (1609–1682), promoted frugality and simplicity. He issued the “One Soup, One Side Dish Edict,” which restricted side dishes to one item other than soup.

They finely chopped ingredients such as simmered shiitake mushrooms, kanpyo (dried gourd strips), and carrots and secretly mixed them into the rice. According to one story, sushi ingredients were placed at the bottom of a box and covered with seasoned rice to disguise them as a simple meal. The box was then flipped over just before serving.

As “Barazushi” spread throughout Japan, a style of scattering the ingredients on top of the vinegared rice rather than mixing them in was developed, and this became known as “Chirashizushi.”

Now, let’s look at the difference between chirashizushi and barachirashizushi, focusing on the names used in sushi restaurants in Tokyo.

a photo of Chirashizushi — The appearance of Chirashizushi

In Tokyo sushi, specifically Edomae sushi, Chirasushizushi refers to a dish where sushi toppings used for Nigiri sushi are arranged on top of vinegared rice (also known as Namachirashi, Fukiyosechirashi, or Edomaechirashi). However, in regions outside the Tokyo area, Chirashizushi generally refers to a dish where seasoned ingredients are mixed into vinegared rice and decorated with shredded omelette and seaweed (also known as Gomokuzushi or Barazsuhi). This is just my personal opinion, but I think that even in Tokyo, the latter is called chirashizushi.

Dishes made with plain white rice rather than vinegared rice are generally called seafood bowls. Sushi restaurants do not serve bowls of plain white rice (they cannot), but some restaurants call dishes made with vinegared rice seafood bowls. In my personal opinion, most seafood bowls served outside of sushi restaurants are made with plain white rice.

A photo of Barachirashizushi — The appearance of Barachirashizushi

Additionally, a dish with randomly arranged sushi toppings on vinegared rice is called “barachirashizushi.” Some traditional sushi restaurants in Tokyo offer two types: chirashizushi, which is primarily served in-store, and barachirashizushi, which excludes toppings that are not suitable for takeout and can be taken home.

Incidentally, chirashizushi made with sushi ingredients is not typically prepared in Kanto-style households. More precisely, it may include decorative toppings such as ikura (salmon roe), tobiko (flying fish roe), and steamed shrimp; however, the standard ingredients are dried shiitake mushrooms, lotus root, carrots, snow peas, and shredded omelet.

The role of green onions in sushi

A photo of Ao-negi — Other names for ao-negi include ha-negi, sho-negi, and bannō-negi.

We think foreigners may be unable to tell the difference between Japanese green onions just by looking at them. There are two main types, but even though they are the same onion, they have different names, which can be confusing. In the Kanto region and northern Japan, shiro-negi (Japanese leeks) are commonly eaten, while in western Japan, ao-negi (green onions) are the mainstream variety. Green onions used as a condiment in udon and soba noodles are also Japanese leeks in the east and green onions in the west.

A photo of Naga-negi — Other names for Naga-negi include Shiro-nrgi and Nebuka-negi.

Onions with more white parts are called “Nebuka-negi (根深ネギ),” while those with more green parts are called “Ha-negi (葉ネギ).” In Eastern Japan, the term “negi” simply refers to Nebuka-negi (also called Naga-negi or Shiro-negi), which is grown by mounding soil around the plant as it grows to protect it from direct sunlight, resulting in a strong flavor and thick stems. Other types are distinguished by specific names such as “Wakegi,” “Asatsuki,” “Bannō-negi (also called sho-negi),” and “Kujo-negi.” In western Japan, the thin Ha-negi grown in the sun is called “Ao-negi,” and Nebuka-negi is sometimes referred to as “Shiro-negi” or “Nebuka.”

In summary, the word negi in Japanese cuisine is a broad term that can refer to several varieties: Ao-negi (青ネギ), common in western Japan; Naga-negi (長ネギ), more popular in eastern Japan; and their subtypes such as Bannō-negi (万能ネギ), an improved cultivar of Ao-negi, and Kujo-negi (九条ネギ), a Kyoto specialty. These variations can be confusing to foreigners, but they reflect how regional food culture has shaped the way green onions are used in Japanese cooking.

Onions Commonly Used in Sushi Restaurants

In Japanese sushi restaurants, several types of onions play important supporting roles in flavor and presentation. The most common are Bannō-negi (万能ネギ), a versatile fine green onion; Ao-negi (青ネギ), the standard leaf onion; Naga-negi (長ネギ), a long Welsh onion often used as Shiraga-negi; and Me-negi (芽ネギ), the tender young sprout onion. Each type has its own distinct characteristics and culinary uses.

Bannō-negi, often translated as “fine green onion,” is actually an improved cultivar of the broader Ao-negi group. Compared to standard Aoba-negi, it is thinner, softer, and milder, making it especially suitable as a garnish for sushi or sashimi.

By contrast, Naga-negi has a thick white stalk. In sushi, it is often shredded into fine strips called Shiraga-negi (白髪ネギ), which are placed on top of fatty fish to balance richness with a refreshing sharpness. By the way, Shiraga (meaning “white hair”)-negi refers to the white part of Naga-negi, sliced thinly like white hair.

Another variation is Me-negi, which are delicate and visually appealing. They provide a crisp texture and a subtle, grassy fragrance that complements lighter sushi toppings.

Together, these different forms of onions demonstrate how sushi chefs carefully choose the right variety to balance flavor, texture, and presentation.

Types of whales used as sushi toppings

A photo of minke whalesashimi — Sashimi is a standard menu item at whale specialty restaurants.

It has been six years since Japan withdrew from the International Whaling Commission (IWC) and resumed commercial whaling. Many consumers had hoped that whale meat would become cheaper and appear on dinner tables. This is because whale meat is a nutritious and versatile ingredient that can be used in a variety of dishes. However, the amount of whale meat available in circulation has decreased compared to the era of research whaling. What exactly were the Japanese government and the whaling industry trying to protect?

On the other hand, the three countries strongly pushing for a “whale hunting ban” in Japan are the United States, Australia, and New Zealand. Why is Japan not allowed to engage in commercial whaling when Iceland and Norway are permitted to do so? Such inconsistencies also exist.

In fact, very few Japanese people actually want to eat whale meat. According to a survey by Greenpeace, 95% of Japanese people do not particularly want to eat whale meat. It is said that the average annual consumption of whale meat per person in Japan is now 40 grams. It was quite a challenge to find images of whale sushi in our saved files.

In other words, whales may now be used as political and economic tools, transcending issues such as human food and the environment.
To put it bluntly, it may be the fault of a few members of parliament elected from constituencies with many whaling-related interests and hundreds of bureaucrats who do not want to lose their budgets.

This article is simply to show that whale sushi exists as part of Japanese food culture. Although rare today, whale occasionally appears as sushi neta (topping). So, what kinds of whale are actually used for sushi? Let’s take a closer look.

1. Minke Whale (Balaenoptera acutorostrata　Lacépède, 1804)

A photo of Minke whale　nigiri sushi — The appearance of Minke whale nigiri sushi

Minke whales in the northern hemisphere are about 8 meters long. Seen from above, their heads are pointed at the tip. There is a white patch on the upper center of the pectoral fins. The dorsal fin, about 30 cm high, is located toward the rear of the body and is often clearly sickle-shaped. The back is black, the sides are gray with a blurred pattern, and the lower jaw and abdomen are white.

It generally feeds on krill, small squid, and fish. It filters its food through bristle-like baleen plates, made of keratin. The Japanese name for the minke whale is higekujira, which means bearded whale.

Description: A relatively small baleen whale, measuring about 7–10 meters in length.
Use: The most commonly caught species in Japan’s commercial whaling, widely utilized for sushi toppings, sashimi, and bacon-style preparations.
Flavor: The red meat is tender with little odor, making it one of the more approachable types of whale meat.

2. Bryde’s Whale (Balaenoptera edeni Anderson, 1879)

A photo of Bryde’s Whale nigiri sushi — The appearance of Bryde’s Whale nigiri sushi

Bryde’s Whale is a close relative of the Sei whale. It was named “Nitarikujira” (meaning “similar whale”) because it resembles the Sei whale. It grows to a maximum length of about 15 meters and is slightly smaller than the Sei whale.

Description: A medium-sized baleen whale, usually 12–15 meters long, larger than the minke whale.
Use: Its red meat is served as sushi or sashimi, while fatty cuts and tail meat are often cooked.
Flavor: The red meat has a richer taste with a pronounced umami and iron-like character.

3. Sei Whale (Balaenoptera borealis Lesson, 1828)

Sei whales are baleen whales belonging to the family Balaenopteridae. They migrate across the open ocean in schools of sardines, feeding on them, which is how they got their name.

Two subspecies are recognized: the northern hemisphere subspecies (B. b. borealis) and the southern hemisphere subspecies (B. b. schlegelii). They are distributed in the southern Indian Ocean, the North Atlantic and South Atlantic, and the North Pacific and South Pacific.

Its body is slender and spindle-shaped, with a sickle-shaped dorsal fin. The dorsal color is dark blue, the ventral color is light blue, and there are blurred patterns in between. The head is V-shaped, enabling it to swim at high speeds. The maximum body length is approximately 18 meters.

Description: A baleen whale that grows 12–18 meters long. In the past, it was more frequently caught, but today only limited numbers are harvested.
Use: The lean red meat is used for sushi or sashimi, while fattier portions are processed into bacon or fried dishes.
Flavor: The meat is tender and relatively mild, with a clean, elegant taste.

4. Sperm Whale (Physeter macrocephalus Linnaeus, 1758)

Sperm whales are distributed worldwide from the Arctic to the Antarctic, with the largest populations found in deep ocean waters. Male sperm whales grow to a length of 15 to 20 meters and weigh between 40 and 60 tons. Their body color is blackish gray, but it becomes whiter with age. In particular, the head tends to become whiter. The dorsal fin is mountain-shaped, with several ridges extending from the rear toward the tail fin. The surface of the body, except for the head, is rough and uneven.

Description: A toothed whale and one of the largest whale species, reaching 15–20 meters or more in length.
Use: Rarely used as sushi. Instead, its distinctive fatty tissue is made into “toothed whale bacon” or other processed foods.
Flavor: The fat has a unique aroma and a very rich, heavy taste.

5. Baird’s beaked whale (Berardius bairdii Stejneger, 1883)

Baird’s beaked whale is a toothed whale traditionally consumed in areas such as the Boso Peninsula in Chiba Prefecture. It weighs 8 to 10 tons and measures around 10 meters in length.

Types of whale meat

Saezuri (さえずり)

A photo of saezuri — The appearance of Saezuri

Saezuri is very fatty, and the taste and texture differ between the root and tip of the tongue. It has a deep umami flavor and is used in simmered dishes and oden. It is one of the most popular delicacies of whale meat.

Onomi (尾の身)

A photo of Onomi — The appearaance of Onomi

The back section from the dorsal fin to the tail, with fat marbled like snowflakes (shimofuri). Considered the most delicious part of whale meat, it is also known as whale Otoro.

Unesu (畝須)

A photo of Unesu — The appearance of Unesu

The white, accordion-shaped part running vertically from the lower jaw to the navel is called Une, and the red inner part is called Sunoko. These two parts together form Unesu. It has a soft, gelatinous texture and is one of the most popular whale meat cuts, cherished for generations.

Bacon (ベーコン)

A photo of Whale bacon nigiri sushi — The appearance of Whale bacon nigiri

Bacon is a processed food made by salting and smoking the part called Unesu.

For reference.

Sudachi vs. Kabosu: How Sushi Chefs Use Citrus to Enhance Flavor

A photo of sudachi vskabosu — The appearance of sudachi and kabosu

Sudachi is small in size with an intense aroma and a sharp, refreshing acidity. In contrast, kabosu contains more juice and offers a milder sourness, giving it a soft flavor that enhances other ingredients without overpowering them. Sudachi is about the size of a golf ball, while kabosu is about the size of a tennis ball.

【Nutritional value of kabosu】
Vitamin C
Citric acid
Potassium
Pinene
Limonene

【Nutritional value of sudachi】
Sudachitin
Vitamin C
Citric acid
Potassium
Beta-carotene
Vitamin E
Calcium
Dietary fiber
Polyphenols

At sushi restaurants, these characteristics are carefully utilized. Sudachi is often paired with delicate toppings such as white fish or shellfish, where just a drop can add a refreshing fragrance and highlight the clean flavors of the fish. It is particularly valued when the sushi chef wants the citrus aroma to leave a memorable impression or to give a lighter, fresher finish to the sushi.

Conversely, using sudachi repeatedly in an omakase course can mask the flavors of the sushi toppings.

Kabosu, on the other hand, is chosen when the balance of flavors is more important than fragrance alone. Its gentle acidity and abundant juice make it suitable for richer or fattier fish, grilled items, or simmered dishes, where it softens heaviness and provides an elegant aftertaste.

A photo of Kikabosu — The appearance of Kikabosu

Aged kabosu (Kikabosu), with its mellow and rounded aroma, is sometimes used to enhance the sophistication of high-end sushi. For example, a light drizzle of kabosu over sushi made with the mild-flavored pen shell (Tairagi) elevates the shellfish to a higher level. Sudachi or young kabosu, however, are too pungent and would merely serve as a simple accent.

In short, sushi chefs distinguish between the two by using sudachi when they want to highlight aroma and freshness, and kabosu when they wish to bring harmony and subtlety to the flavor.

【Related contents】

Condiments for sushi

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 is Moshio?

a photo of moshio — Natural salt with a pleasant taste

The “Mo” of “Moshio (藻塩)” means “seaweed (海藻)” and “shio” means “salt (塩).” The only ingredient in Moshio is Hondawara, a type of seawater and seaweed. It is also called Mojio.

The way it is made is extremely primitive. First, Hondawara (Gulfweed), etc. is soaked in seawater then wrung out and dried multiple times over 2 to 3 days. This creates a brown-colored seawater infused with the umami and color of Hondawara. In the end, Hondawara is dried and grilled, then the charcoal ash is mixed with the seawater infused with the umami and color. This is left for a day, where the ash naturally sinks to the bottom, completing the dark-brown seawater. Moshio is made by boiling down this seawater. This is said to be the origin of salt-making far longer ago than the manufacturing method of using salt farms.

A former chef from a Michelin-starred sushi restaurant uses a blend of red vinegar and moshio to make sushi rice. While searching for the perfect rice to complement various toppings, he serendipitously discovered Moshio. After much trial and error, he perfected a versatile sushi rice recipe with Moshio, claiming that it enhances both red- and white-fleshed fish.

It is characteristic in that there is no sharp spiciness and it has a very mellow flavor, so it brings out the taste of the elements of seafood, etc. The color is a light beige and the salt can be called a concentration of umami made from nothing but seawater and seaweed. Perhaps switching to Moshio is a good idea.

Sushi restaurants that use moshio (seaweed salt)

・Sushi Fukumoto
・Sushi Dai
・Yoshino sushi honten
・Sushi Iwamoto
・Sushi Haka
・Sushi Ichi
・Sushi Inukai

What is Geso?

Geso is not the name of a fish or shellfish.

Geso refers to the 10 arms/tentacles of a squid.

A photo of Geta — The appearance of Geta (wooden clogs)

The reason squid arms came to be called “Geso” is that the shoes that are removed before entering the indoors in Japan are referred to as “Gesoku”. The name comes from a time when restaurants used to hold onto their customers geta (wooden clogs) and the cloak would tie them with a string in 10-pair units.

Geso can be lightly boiled or grilled. For large squid, a butcher knife is inserted at the tip of the arm to peel off the skin membrane, and then the tips of the arms are cut off so the sizes match. When Nitsume or other sauce is applied and it is made into Nigiri, it has an excellent springy texture and scent of the sea. It is also used as Tsumami when drinking alcohol. In my personal opinion, the Geso child of Sumiika is nice and soft and worlds above any others.

This is one of the sushi terms that even most of the general public in Japan knows well.

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Revision date: July 2, 2024

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Do you know why canned crab is wrapped in paper inside the can?

Crab protein has a high sulfur content. This sulfur can bind with the iron in the can, resulting in ferric sulfide that causes black spots in the meat. Black discoloration of the crab meat significantly mars the appearance and reduces the product value. In order to prevent this, parchment paper with superior water resistance and oil resistance is used to keep the crab meat from coming in contact with the can.

Meanwhile, the trace amounts of magnesium, ammonium and phosphoric acid contained in crab and fish meat sometimes bind to create magnesium ammonium phosphate glassy crystals. This chemical phenomenon is called struvite.

These crystals have no taste or odor and dissolve easily in the stomach so they are not considered to be an issue under the Food Sanitation Act. However, large crystals may hurt the oral cavity so efforts are made to improve production methods to prevent generation of crystals and keep any crystals that do form as small as possible. However, parchment paper does not reduce the struvite phenomenon.

In summary, do you now understand the truth of why crab meat is wrapped in white paper? Of course, nowadays the surfaces of cans are processed in a way that the iron doesn’t start to dissolve, so perhaps the correct theory is that the parchment continues to be used to give a sense of luxury.

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Revision date: August 1 2022

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What is Odori?

Both conveyor belt sushi and premium sushi have versions of sushi made with raw sweet shrimp or botan shrimp. However, in Edomae Sushi, boiled shrimp is always used. The use of raw shrimp in sushi started in the Kansai region. Moreover, in the Kansai region, there are many restaurants that make sushi with live Kurumaebi known as “Odori or Kassha”. However, this way of eating may be declining nationwide. It is probably because there is increased texture when boiled, so it tastes better.

Going back to Odori, “Odori” means “dance” in Japanese and it is said that this name came from the fact that shrimp twitches on the sushi rice and looks like it is dancing. If you look up the roots, it seems that this method of serving started at a sushi restaurant in Kyoto City in the early Showa period. It spread throughout the Kansai region, but although Odori may look easy to make, the method is actually quite elaborate.

Let’s introduce the common recipe here. First wash the live Kurumaebi with fresh water and start by bending the head with your hand while detaching it from the body, then peel off the shell. Next, peel the skin off the abdomen and cut the abdomen open vertically. Fresh shrimp is difficult to peel, so it is important to do it very carefully. Next remove the veins from the back and sprinkle on just a bit of mirin and vinegar, then lightly rinse off with ice water. After that, parboil just the tail in boiling, salted water to make it look attractive.

Then make the sushi with the open side facing up. The direction is important because it is easier to tell that the shrimp is dancing when it is arranged this way. To finish, sprinkle lemon juice over the shrimp meat. This stimulates movement of the body.

Now let’s discuss how a customer eats Odori. It goes without saying that since the shrimp is still alive, the moment you dip the topping in the soy sauce, the shrimp twitches in its death throes, convulsing violently. Apparently the customers are greatly pleased to see this. We don’t recommend the faint of heart to order this dish.

Incidentally, eating only the shrimp in this way is called “Odorigui”. In China there is a dish in which living shrimp is soaked in Shaoxing rice wine or fermented alcohol, made drunk, and then eaten once it has settled down. These sorts of methods may be considered cruel in some western countries.

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Revision date: June 6, 2022

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The answer to the question, “Can I eat sushi leftovers the next day?”

Nigiri sushi is generally made with raw seafood. It can be said that the seafood starts to go bad as soon as it is put on warm rice. Of course, at the stage of preparation, there are procedures being taken to reduce the causative micro-organisms of food poisoning. Out of all food that is commonly eaten raw, sushi is considered to have the least micro-organisms that cause food poisoning.

For example, Vibrio parahaemolyticus, a typically known bacteria that causes food poisoning, attaches to seafood, and if the conditions, such as temperature, are just right, it proliferates at double the speed of other food poisoning bacteria. When you are eating at a sushi restaurant, bacteria growth is being suppressed. However, if you take sushi home to eat it, depending on conditions bacteria could proliferate.

This is why as a basic rule, you cannot take sushi home from a sushi restaurant.

So then, what is the difference between sushi sold at the grocery store and prepared at sushi restaurants?

There are obvious differences between sushi made by sushi chefs and take-out sushi, as explained below.

Take-out sushi is lined up at the store, selected by the customer, then eaten at home, which takes time. Therefore, a higher amount of salt seasoning is used compared to Nigiri sushi restaurants, in order to delay the degradation in quality. Sushi made by sushi chefs at restaurants has a salt content of about 1% in the sushi rice, while that of take-out sushi has about a 2% content.

Next, with a pH of around 4.5%, it is difficult for bacteria such as Salmonella, Staphylococcus aureus, E. coli bacterium bacteria and Vibrio parahaemolyticus to proliferate, and there are experimental results that show they die out. In an experiment that measured the pH of sushi rice in take-out sushi, it was usually measured at 6%. Nigiri sushi made at a restaurant is often around 6.2%, so this acidity is put to good use in the sushi rice and could be delaying degradation.

Furthermore, although it may not be a pleasant topic of discussion, preventing spoiling and deterioration in food caused by micro-organism is done by adding preservatives to improve the shelf life. For example, classic preservatives such as benzoic acid, Sorbic acid and PH adjusters are used all over the world. There is an obligation to list these on the product label when used.

Now let’s get into the main topic.

This all being said, sometimes when you buy take-out, there are leftovers. There is no question that it is better to promptly discard them. But you may think that you can just eat it the next day, right?

You can. And it will taste the same as when you bought it.

First of all, there is something important to remember; not all toppings are equal in take-out. Unfortunately, things that require freshness like shellfish, squid, mackerel and sardines, cannot be saved. These must be consumed on the day they are bought.

Next, let’s go over how to eat your day-after sushi so that it still tastes good.

The toppings this method works for are tuna, salmon, white fish and steamed shrimp. However, the only white fish it works for are benthic fish such as flounder. As long as the meat is still transparent the next day, it’s safe. For Hamachi, which always has more than 20% body fat, which oxidizes, so avoid keeping it to the next day. Raw shrimp is out too. Steamed shrimp becomes more delicious when quickly put into sushi vinegar for storage.

The method is simple!

First, remove the Nigiri sushi topping from the rice. Next, wash that topping with running water for a few seconds and then dry well with a paper towel. Make sure you are quick in all of these steps. Finally, wrap in plastic wrap and store in the refrigerator.

Next, use a wet paper towel to wrap the sushi rice. Wrap this set in plastic and put it in the vegetable drawer if possible. If you don’t have a vegetable drawer than the normal refrigerator compartment is fine.

The next day, when you are ready to eat, heat the sushi rice in the microwave at 1000W for 10 seconds. The point is just to warm it up a little. Next, just take the topping from the refrigerator and place it on the rice. You can add some wasabi if necessary.

Incidentally, if you use this method for take-out sushi, even when consuming it on the same day, it will taste even better than just eating it right away.

The practice of sushi chefs is to put somewhat cold sushi toppings (16~19℃) or room-temperature toppings (20~23℃) on top of sushi rice that is the same temperature of the human body (37℃). We are trying to imitate this method. If you are consuming on the same day, any topping can be removed from the rice and prepared like this.

But please do not wait any longer than the next day to eat any leftovers.

Do not bend this rule. Let me warn you that the symptoms of food poisoning from shellfish and silver-backed fish are horrible. It should also go without saying that if the sushi rice has already dried out, there is no bringing it back, even with this method. Once you’ve reached that point, you just have to throw it away. Naturally, you cannot eat smelly sushi toppings.

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Revision date: April 1, 2022

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What is used as a substitute for the expensive Mongou ika?

No people in the world love squid more than the Japanese. Squid ranks third in import volume behind shrimp and tuna. Squid is brought to Japan from the oceans all over the world. There are between 400 and 500 species of wild squid on Earth. Some, like the pygmy cuttlefish, are tinier than 3 millimeters while the giant squid is over 10 meters.

There are about 100 species of squid that live in the waters surrounding Japan. Surume ika (Japanese common squid) makes up the highest volume of domestic-caught squid. It is used as a Yari ika or Surume ika topping in eastern Japan, but Surume ika isn’t used very often in western Japan. At sushi restaurants, squid like Sumi ika (Golden cuttlefish), Aori ika (Bigfin reef squid), Kensaki ika (Swordtip squid) and Mongou ika (Ocellated cuttlefish) go for high prices, but they are all caught in smaller quantities and therefore only available to high-end sushi restaurants that can procure them fresh.

There are some conveyor belt sushi restaurants that list Mongou ika (モンゴウイカ又はカミナリイカ) on the menu, but actually serve European common cuttlefish. It is produced in the waters off the coast of West Africa. Even some sushi restaurants do this. This is actually still too pricey for conveyor belt sushi though. What is generally used at conveyor belt sushi is Flying squid, which goes for only 1/10 the price of the European common cuttlefish and reaches 60 cm in length. Jumbo flying squid is also often used. The Jumbo flying squid is more than twice as long as the Flying squid and exceeds 1 meter in length. The Jumbo flying squid is mainly imported from places on the other side of the world such as Chile and Mexico. The thickness of the meat is similar to Mongou ika. However, a big drawback is that the Jumbo flying squid lacks the sweetness peculiar to squid. Therefore, it is soaked in water that has been artificially sweetened. This alters the dried out sensation to a plump, moist sensation, making the customer believe it is Mongou ika.

The squid must have a certain thickness in order to masquerade as Mongou ika. Rhomboid squid, which has a torso length of 80 cm is also disguised as Mongou ika. Rhomboid squid is found in the warm waters of the world and is even caught in relatively high volume in Japan. Large squid have a low price cost, so it’s good for the shops to make a profit. Furthermore, the sweetness is brought out more when frozen first than by serving it fresh. That means it can be used as Mongou ika without any need for the artificial sweeteners used in Flying squid and Jumbo flying squid.

The fact is that there are many substitute products for Mongou ika. But even so, it doesn’t change the fact that using ingredients disguised as others is an unacceptable practice.

Types of substitutes for the Mongou ika

European common cuttlefish: Sepia officinalis (Linnaeus, 1758)

European common cuttlefish (ヨーロッパコウイカ) is found from the Atlantic coast of France to the Mediterranean and west coast of Africa. It is often caught in the waters around Morocco. Its body length is around 30 cm. When it first arrived on the Japanese market, it was called Mongouika, hence the name.

The scientific name sepia means black pigment and officinalis means medicinal, indicating that this is a material for Chinese herbal medicine. At processing plants in Thailand and China, the fish is made into fillets for sashimi, and then vacuum-packed and sent to Japan.

Flying squid: Ommastrephes bartramii (Lesueur, 1821)

Flying squid (アカイカ) is distributed in the North Pacific, South Pacific, and Atlantic Oceans. Its body length exceeds 40 cm, and it can weigh more than 4 kg. It is similar in appearance to the Surumeika, but has a darker, blackish back. It is used as a substitute for Surumeika for processing such as delicacies.

Jumbo flying squid: Dosidicus gigas (Orbigny, 1835)

Jumbo flying squid (アメリカオオアカイカ) is found only off the Pacific coast of the United States, Chile and Peru in South America. They are over 80 cm in length, weigh around 10 kg, and have as many as 100 to 200 suckers. In Peru, they are called Pota. Japanese fishing vessels used to catch flying squid mainly in the North Pacific, but their catch has drastically decreased due to the ban on drift net fishing.

Japanese vessels have switched to fishing for Jumbo flying squid, a member of the flying squid family, in the waters off Peru and other areas. Fishing for Jumbo flying squid in Peruvian waters continues from spring to fall.

Since the drifting net fishing of flying squid has been banned, it is the most promising resource as a raw material for processing. However, the larger ones store ammonia in their muscles, so de-ammonia treatment is required when processing them.

Rhomboid squid: Thysanoteuthis rhombus Troschel, 1857

Rhomboid squid (ソデイカ) is widely distributed in the warm waters of the Pacific and Atlantic Oceans. The body length is 70 cm. Its fins are diamond-shaped and the same length as its body. Because they do not form large schools and live scattered, they have been a difficult resource to exploit.

After a new fishing method was developed in the Tajima region of Hyogo Prefecture in the 1960s, the fishery began in earnest. Because of its reasonable price, it is often used in restaurants such as conveyor belt sushi restaurants. Also called Diamond squid or Diamondback squid.

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Revision date: March 24, 2023

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The general rule is to only eat oysters in months that contain the letter “R”.

In other words, avoid them from May to August.

It’s won’t hurt you to eat Magaki (Japanese oyster), which has its spawning season in the summer, but in the months with no R in the name, the glycogen concentration is low, so you can’t get the full-bodied texture that you get in winter. In addition, almost all amino acids such as glutamic acid, glycine, alanine, arginine, which are important components for delicious flavor, are known to accumulate from winter through spring, and conversely, they decrease in the summer, which is the spawning season. You cannot expect the same deliciousness from oysters in summer as you can from months that contain the letter R.

Furthermore, the oyster takes in large amounts of seawater and filters out the plankton for its food. Therefore, in warm seasons it fills up on large volumes of the toxic plankton that proliferates in the sea. Eating toxic plankton can make the oyster toxic and toxified oysters can cause food poisoning when consumed by humans. In addition, in the warmer months, the oyster loses its freshness faster after being harvested, increasing the likelihood of getting a bad one and risk food poisoning. Therefore, it’s best to not go out of your way to eat oysters in summer.

On the other hand, one certain oyster is actually in season in summer.

Iawagaki (Rock oyster) is known as the summer oyster. This type is close to the Magaki, and it lives attached to reefs at depths of 2 to 20 m, deeper than the intertidal zone and facing the open sea. A large Iwagaki has a shell length of 10 cm, a shell height of 20 cm or more and weighs more than 1 kg. However, the edible part is small compared to the size of the shell. It is an oviparous hermaphrodite. Growth is slow at a rate of around 5 cm in one year, around 7 cm in two years. It takes three to four years to reach 10 cm or more and grow big enough to harvest.

The glycogen volume in Iwagaki is high from March to July, peaking around May, and it then decreases from September to October. The main production areas are the Sea of Japan on the coasts of Akita, Yamagata, Niigata, and Tottori. Many of the Iwagaki in circulation are harvested from the wild, unlike Magaki, which is almost all farmed.

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Revision date: February 1, 2022

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There are clear differences between Sabazushi and Battera, so let us explain them.

In summary,

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Onions Commonly Used in Sushi Restaurants

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1. Minke Whale (Balaenoptera acutorostrata Lacépède, 1804)

2. Bryde’s Whale (Balaenoptera edeni Anderson, 1879)

3. Sei Whale (Balaenoptera borealis Lesson, 1828)

4. Sperm Whale (Physeter macrocephalus Linnaeus, 1758)

5. Baird’s beaked whale (Berardius bairdii Stejneger, 1883)

Types of whale meat

Sushi restaurants that use moshio (seaweed salt)

This is why as a basic rule, you cannot take sushi home from a sushi restaurant.

So then, what is the difference between sushi sold at the grocery store and prepared at sushi restaurants?

Now let’s get into the main topic.

You can. And it will taste the same as when you bought it.

Next, let’s go over how to eat your day-after sushi so that it still tastes good.

The method is simple!

Incidentally, if you use this method for take-out sushi, even when consuming it on the same day, it will taste even better than just eating it right away.

But please do not wait any longer than the next day to eat any leftovers.

Types of substitutes for the Mongou ika

European common cuttlefish: Sepia officinalis (Linnaeus, 1758)

Flying squid: Ommastrephes bartramii (Lesueur, 1821)

Jumbo flying squid: Dosidicus gigas (Orbigny, 1835)

Rhomboid squid: Thysanoteuthis rhombus Troschel, 1857

In other words, avoid them from May to August.

On the other hand, one certain oyster is actually in season in summer.

1. Minke Whale (Balaenoptera acutorostrata　Lacépède, 1804)