Oboro and Denbu look the same, and the ingredients are also pretty much the same. In other words, there are no clear differences between them, but what it is called differs depending on the restaurant’s policy and the locality. There are various theories for this, but there is no clear line distinguishing oboro and denbu.
Denbu (田麩) is mainly boiled white fish that is then loosened and made into fibers, then seasoned with sugar, mirin, salt, etc., then roasted until the moisture is gone. Some are colored with red food coloring (called sakura denbu) while others are left as the brown color similar to tsukudani. The appearance is as if only the fibers of the original ingredients remain. This is why it was written with the kanji “田夫” (the literal meaning of kanji: rice patty+husband). The word “田夫” means “someone from the countryside” or “rough-cut” and refers to the way the fish is turned into a coarse form by pulling the meat apart. It is also used as a coloring for chirashizushi, futomaki (large sushi rolls), bento boxes, etc.
On the other hand, Oboro (朧) is made by using a grinding bowl to break down the meat of shiba shrimp or white fish, then seasoning with sugar, mirin and salt before removing the moisture over low heat. Oboro is used for bara-chirashi, futomaki (large sushi rolls), etc., and is also sometimes used between the topping and shari (vinegared rice) in nigiri sushi. This gentle sweetness and the shrimp aroma are essential for Edo-style sushi. Making oboro is laborious work, so there are fewer and fewer Edo-style sushi restaurants that make their own oboro.
In most cases, Fugu (blowfish) poison is found in non-meat parts of the fish such as the liver, ovaries, stomach, intestine, skin and eyes. There are Fugu that do not contain poison in these parts, but most of the Fugu in the waters near Japan are poisonous. A mistake in preparations that allows the meat to touch the poison of the liver or ovaries results in immediate death. Therefore, the general rule is to only eat Fugu at restaurants with an expert licensed in Fugu preparation. Cases of poisoning by Fugu are nearly always a result of an amateur trying to prepare the fish.
The toxin in Fugu is a chemical substance called tetrodotoxin and even heat from boiling or frying can’t detoxicate it. Even Torafugu (Japanese pufferfish) that we find so delicious (we eat the meat, skin and testes) has poison in the liver, ovaries and intestines. The toxicity is said to be at least 1,000 times that of potassium cyanide. They say 10 people would die from the organs of a single Torafugu. In the case of Fugu poisoning, the first poisoning symptoms occur between 20 minutes and three hours after eating the Fugu. It starts with numbness in the lips, the tip of the tongue and fingertips. This is followed by headache, stomachache and severe vomiting. The victim will stagger when trying to walk. Soon they will experience sensory paralysis, speech disturbance and difficulty breathing, accompanied by a decrease in blood pressure. After that, the entire body becomes paralyzed and the victim can no longer move even a finger. Finally, they will fade out of consciousness and eventually both breathing and heartbeat cease, resulting in death. If the consumer doesn’t notice they are experiencing poisoning symptoms, they will surely die.
The strength of the toxin of the fugu also varies depending on the season. Even on an individual basis, some fish have toxins while others don’t. It’s not possible to determine this based on appearance, so it’s better to never eat the organs and eyes, which have a high probability of containing poison.
Fugu has already been successfully farmed and is on the market. No toxins have been found in this farmed Fugu. If farmed Fugu has no toxins, it’s only natural to question what factors generate toxins in wild Fugu and apparently it‘s a cumulative effect of toxins from the food chain. Fugu’s main sources of nutrition are starfish and shellfish. Starfish and shellfish accumulate poison in the body by eating zooplankton with vibrio attached to them. This vibrio creates poisons. Then, Fugu accumulates toxins in the body by eating starfish and shellfish that have toxins accumulated in their bodies. Therefore, farmed Fugu are raised on man-made feed that doesn’t contain Fugu toxins, and since they don’t ingest Fugu toxins and there is no bioconcentration, so the Fugu does not contain poison.
During the Edo period, samurai would change their names at Genpuku (coming-of-age ceremony and career stages. Fish that are called by names as they grow older/larger are called “shusseuo (出世魚)”, are considered lucky and are used in cooking to celebrate milestones in life.
Shusseuo doesn’t just change in name, they also change in taste. The bigger the body, the more fat. However, young fish also have their own delicious, refreshing taste unique to their age. For example, using the young fish for deep-frying and fatty fish as sashimi is an interesting way to put it.
Shusseuo is not the only fish called by different names as they grow. According to the “Study of Japanese Fish Names”, there are 82 types of fish that are called by different names as they grow. Kuromaguro and kanpachi are popular examples. Kuromaguro changes from Komeji to Meji to Maguro and then to Oomaguro. Kanpachi changes from Mojako to Shiwoko to Akahana and then to Kanpachi. Even konoshiro, sawara, unagi, shake, koi, etc. are not shusseuo. Generally, it’s not those fish that are called by different names according to their growth stage that is called shusseuo. Fish that taste better as they grow, that changes little over time, and have been valued since eras when preservation and transport were not well-developed, are called shusseuo.
A good representative fish of shusseuo is the yellowtail. Its name changes as it grows and there are various forms of their names depending on the region. In the Kanto region, it changes from Wakashi (15-20cm) to Inada (30-40cm) to Warasa (60cm) and then to Buri (80cm or greater). It is said to be most delicious at 40 cm or longer and even if the body is plump, inada often has little fat.
Even if the name is the same, depending on the region, it may be referring to a different size. For example, inada is a fish up to 40 cm in Kanto but in Tohoku and Tokai, it refers to small fish of 15-20 cm. Further, although it is not related to its growth, those caught in Tohoku during summer are called “ao”. In Toyama, they are called “gan” and “gando”.
Finally, the changing names of fish demonstrate the breadth of culture. We should cherish this local diversity present in the names of our fish that capture the abundant food culture and importance of the seasons.
Caviar refers to salted sturgeon ovaries but in many European countries, caviar is also used as a generic term for fish roe. In its home of Russia, roe is generally called “ikura” and caviar specifically refers to black fish roe.
Caviar is one of the world’s three major delicacies and can command different prices depending on the type of sturgeon (egg size). It is ranked in the order: Beluga, Oscietra and Sevruga, all of which come from the Caspian Sea. Beluga from the Caspian Sea is designated as an endangered species and international trade is prohibited by the Washington Convention. Its population is very small and it does not lay eggs until 20 years into its lifespan, so the resource has yet to recover. This has brought the market price of Beluga up to around USD $400 for just 50 g.
What is the substitute for caviar?
Lumpfish roe is sold as a substitute for caviar. The size of each egg is about 2 mm in diameter and it is colored with squid ink. This gives it a taste and appearance similar to caviar. The market price is an astonishing USD $5 per 50 g.
The main ingredients of Lumpfish caviar are as follows:
Lumpfish roe
Salt
Sugar
Thickening agent
Sodium benzoate
Coloring
What is artificial caviar?
Artificial caviar is significantly cheaper than genuine caviar. It’s low in fats, lower in calories and healthier than the real thing. It is already a big hit in the U.S. The size of the eggs is a little larger than authentic caviar and the skin is thicker but most people would tell you the texture and taste is much the same. There has also been a decrease in sturgeon, and there is no sign that its price will fall in the future. The challenge is meeting the global demand through a combination of farmed caviar which has become a more stable supply in recent years, with the ever-dwindling wild caviar. The market price is reasonable at around USD $10 for 50 g.
There is a way to tell the difference between real caviar and fake caviar.
First, place the caviar on a cracker. Fake caviar (made of Lumpfish roe) has added color, and this color will bleed onto the cracker within about 30 minutes. However, the color will not transfer to the cracker from real caviar.
The main raw ingredients of artificial caviar are as follows:
Sea urchin extract
Oyster extract
Gelatin
Dextrin
D-sorbitol
Trehalose
Gelling agent
Seasoning
Coloring
Finally, seafood with a high price, unfortunately, results in substitutes, counterfeits, and artificial products. Masquerading a fake as the real thing can result in a large profit. I will tell you that it is difficult to trick a middleman who serves professional sushi chefs or restaurants. Therefore anyone in Japan who uses seafood like this, does it knowingly, which makes the crime even worse.
When you see “tai” on the menu at a conveyor belt sushi restaurant, it’s very likely that is not “madai” (Red sea bream). It’s a competitive industry where these conveyor belt restaurants have no problem using a variety of imitation or replacement fish if it means they can cut costs. In any case, the purpose for using different types of fish without even considering farmed cheap madai, is to further reduce costs.
First on the list is Nile tilapia. This fish was introduced from Egypt to rivers throughout the world as food in 1962. While it was farmed in large quantities in Japan, especially in Kagoshima, from the 1990s, production rapidly declined with the stagnant prices of farmed madai. However, they are extremely fertile and proliferate naturally, and started living in the thermal regions and the rivers where warm wastewater flow throughout Japan.
The commonly used names for this is “izumidai” or “chikadai”. While izumidai (Nile tilapia) is a freshwater fish, it was likely named after “tai” (sea bream) because of the similarities in appearance. In Taiwan, it is considered to be so similar in appearance and taste, that it is called “Taiwanese sea bream”. It is a popular fish for consumption on a global scale with high production and distribution volume.
However, even though has “sea bream” in the name, it is not actually related to the sea bream at all.
As an aside, at least 90% of the tilapia found in the U.S. is imported. Most of those imports come from China. It’s often said that they are raised on a large volume of antibiotics and pesticides, and they are kept fresh using high amounts of chemicals. It’s best to avoid eating it if possible. The tagline they give it is “Sushi grade tilapia is a high quality, firm fish with a mild, clean taste perfect for sashimi and sushi applications” You’ll be hard-pressed to even find kaiten sushi restaurants using this in Japan. In addition, it would never be used at restaurants that describe themselves as Edomae Sushi.
Engawa has both a unique, crunchy texture and delightful fat distribution and is said to be the most delicious part of hirame.
But what exactly is engawa?
Engawa is the generally used name for the meat muscle that moves the soft ray of the dorsal and ventral fins of flatfish (such as Hirame and Makogarei). Most people in Japan think of the hirame version when they hear the word ‘engawa’.
To go into a more advanced level of detail, there are three types of muscles that move the dorsal and ventral fins in fish: the erector spinae, the depressor and the scalene muscles. These muscles are well-developed in fish that move their dorsal and ventral fins often, like flatfish and flounder. Actually, not all three of these types are always consumed. If we look at the way hirame and makogarei are cut for preparation, the slanted muscle is taken to be used for engawa while the erector spinae and depressor are left, affixed to the fin ray, etc. In other words, to be exact, engawa is the slanted muscle of the dorsal and ventral fins.
The unique, crunchy texture comes from the high content of collagen, which is a scleroprotein. “Kakushi boucho” is used to make the crunch pleasant and is one of the skills a sushi chef must perfect. The delicious flavor is related to the high amount of fat compared to body meat. There is also a sense of elegant sweetness. Only four pieces of engawa can be taken from a single flatfish, so it makes sense that foodies love it.
The name “engawa” comes from its resemblance to the unique veranda structure of Japanese-style homes. This veranda is called “engawa” in Japanese.
Incidentally, substitutions have become common at kaiten sushi (conveyor belt sushi) restaurants, and the topping is especially popular among women lately. So the question is, how is it possible to eat this valuable topping that is only rarely available at expensive sushi restaurants, so cheaply at kaiten sushi? Actually, Greenland halibut engawa and Kamchatka flounder engawa are used as substitutes to hirame engawa. The proof of this is in a menu that lists only “engawa” and not “hirame engawa”.
While high-quality tuna toro used to be unattainable for normal people, it’s now become a much more affordable item. This is thanks to fish fattening practices of the southern bluefin tuna, which is equivalent in quality to the Pacific bluefin tuna. The fattening method of catching young southern bluefin tuna in roll nets or something similar, and then keeping them in fish preserves until they grow big enough was developed in the 1990s in Australia.
There have been changes in the Pacific bluefin tuna as well. In the late 1990s, the southern bluefin tuna fish fattening method started to be used in the seas throughout the world, and this led to the fattening of the Pacific bluefin tuna, which became all the rage. Most of these are exported to Japan, and account for about half of the consumption of southern bluefin tuna and Pacific bluefin tuna in Japan.
As a bonus, tuna that has been fattened in this way has such a high volume of fat that it is said to be “all toro”, and it’s taken the Japan high-grade toro market by storm. Also, both southern bluefin tuna and Pacific bluefin tuna are served at kaiten-zushi (conveyor belt sushi) restaurants.
The fattening of Pacific bluefin tuna started on the east coast of Canada in the mid-seventies. In the summer, large volumes of Pacific bluefin tuna are caught in the fixed shore nets on the Atlantic seaboard, and since they have already spawned, they have slimmed down and aren’t worth much commercially. These fish are fed and fattened, and a new route to Japan has been developed, giving the fish new commercial value.
Both fish fattening and fish farming mean to hold fish in fish preserves, but the purpose differs between the two. The purpose of fish fattening is an adjustment for fishing while the purpose of fish farming is to grow fish to a certain size. Therefore, in fish fattening, they are not fed food to promote growth, but they are in fish farming. However, even in fish fattening, if the period of time they are held for shipping adjustment stretches out too long, they are fed in order to prevent a decrease in meat quality and cannibalism. This can blur the line between fish fattening and fish farming quite a bit.
The Pacific bluefin tuna fish fattening started in Canada is similarly vague. In that case, the purpose was fattening, so it may be fair to call it fish farming. However, shipping adjustment was also one of the major objectives. What about the fish fattening of southern bluefin tuna and Pacific bluefin tuna in Australia and the Mediterranean Sea? These are in place clearly for the purpose of growing small fish, so we can call them fish farming.
The Kindai University Aquaculture Research Institute has succeeded in a complete farming process of taking eggs from spawning Pacific bluefin tuna, incubating them and raising adult fish. Research for a complete farming process began around 1970, so it has taken 30 years for success. These fully farmed tuna are also raised in fish preserves and fed small fish like sardines as well as artificial feed for fattening, resulting in all-toro tuna. However, even though the Kindai University tuna have been featured by the media, you never see them in the supermarket. Why is that? Even though the university has succeeded in a mass-production method, the absolute quantity is extremely low even though raising the fish takes a lot of time and effort, so the price is extremely high.
Whether they are fattened, farmed, or fished in the wild, consumers always welcome delicious, high-quality toro at a reasonable price.
In Japan, they say, “Japanese cooking means taking away and Western cooking means adding.” This concept is well-known among Japanese chefs, but it may be difficult for western chefs to understand. This is verified in the way the white Japanese sea bass, the representative fish of summer, is prepared. This is all connected to clearly explaining the irrefutable differences between sushi and western fish cuisine, which also involves differences in cultivated history and culture.
In the case of Sushi, a representative of Japanese cuisine, the decisive point is to prepare the fish in a way that removes the fishy odor characteristic of Japanese sea bass. At the same time, the finished piece should be a simple dish that can be enjoyed with only a minimal amount of nikiri soy sauce and wasabi, so as not to override the natural refreshing flavor and umami of the fish. It should let the customer imagine sea bass swimming in the summer sea. And yet, the deep flavor required for the dish is successfully brought out using only a balanced combination of vinegar rice, the topping, wasabi and soy sauce. The method is really just to take out the excessive elements of the dish.
Meanwhile, the method for making sea bass dishes in French cuisine, representative of western cooking, includes seasoning the fish with salt and pepper and saute in butter, then adding rich, creamy sauce as well as other things like herbs, caviar, black truffles, etc., creating a dish that allows enjoyment of multilayered flavor. This sort of dish beautifully makes up for the flavors that the light, white fish lacks and portrays a flavor with depth through the finished plate over the individual flavor of the sea bass. In this cuisine, it can be said that the cooking method is more important than the raw ingredients. It can be thought of as cuisine that adds many ingredients.
Comparing the two, it’s clear that the approaches are completely opposite. Another difference is how the flavors are treated. Flavors that are experienced by “fragrance” can be defined as “fragrant flavor”.
If this fragrant flavor were not important in sushi, then there would be no debate on whether to use wild or farmed fish. For example, sea bream is available both in the wild and as farmed fish. There is not much difference in amino acid composition and umami content between the two. So how is it that farmed sea bream and wild sea bream end up tasting so different? The reason is undoubtedly the fragrance. The subtle fragrance components in the fat of the sea bream determine the essential flavor of the fish. You can’t expect to get this flavor from a farmed fish. Doesn’t that mean that the pleasure of eating sushi comes from the awareness of this fragrance?
On the other hand, in Western fish cuisine, the culture is to combine many different fragrances, as if concocting a perfume, probably because people want complex flavor. In addition, in French and similar cuisines, care to serve dishes at a temperature that is warm, but not hot, in order to bring out the natural flavor of the ingredients. While cooking the dishes, the temperature is strictly controlled so that the components of the ingredients don’t change from the heat, in order to maintain the taste and fragrance. This method does not neglect fragrance by any means.
In either method, the one essential element is this “fragrance”. The only true difference is how that is expressed.
In order to maintain the quality of tuna, when it is caught in the sea, the ikejime technique is used first, then rapid freezing is used as a matter of course. This means that the quality of the thawing technique is also important. Poor thawing conditions mean that the drip outflow volume will be too high, shrinking the meat and worsening the texture. Here I will explain a thawing method that doesn’t cause drip, uneven thawing, or loss of color.
What exactly is drip anyway?
I’m sure you’ve seen it before in any type of thawing frozen meat, but there is a red liquid that comes out of the tuna when thawing. This is called ‘drip’. This liquid includes the tuna’s umami, and when the fish loses a lot, it naturally detracts from the flavor.
First of all, we will explain the worst thawing methods. Never thaw naturally at room temperature or in the microwave. These are common methods at home, but they are out of the question.
Next we will explain the general method of thawing.
Mix 30 g of salt with 1000 cc of warm water at 40℃ to create a saltwater mixture.
Place the frozen block of tuna in this 40℃ saltwater, submerge for one to two minutes and then drain the water.
Wash any remaining salt off the surface of the block of fish with fresh water and remove moisture from the surface with paper towels.
Wrap the fish in clean paper towels, wrap with plastic over that and leave it in the refrigerator for about a day to thaw naturally.
Cut from the block directly before consuming.
Now for the thawing method used by professionals, such as sushi chefs.
The first three steps are the same as the general thawing method above.
Place block in an air-tight plastic bag. Push out as much air as possible before sealing the bag.
Prepare ice water in a bowl or container and submerge the plastic bag in the water for one hour. Normally the bag will float, so it must be weighed down with something.
Remove the thawed tuna from the plastic bag and remove moisture with paper towels.
Wrap the fish in clean paper towels, wrap with plastic over that and leave it in the refrigerator for about a day to mature.
After thawing, the meat of the tuna may have shrunk. This is called ‘chijire’. The reason for this is, after the tuna is caught, it is frozen before rigor mortis begins, so the rigor mortis process starts once the fish is thawed. Therefore, this is proof of freshness. The meat of tuna for which ‘chijire’ has begun is tough and isn’t yet matured. However, amateurs can’t tell if ‘chijire’ is happening or not. That’s why it’s better to let the fish mature in the refrigerator for half a day to one day. Please use these explanations for your own reference.
Between the time Edomae sushi was born (1810-1830) and around 1930, the toppings used in nigiri-sushi were strictly limited to slices of seafood. There were no so-called delicacy toppings (such as salmon roe and sea urchin, etc.).
However, in 1934, a restaurant in Ginza called Kyubey started a revolution. This restaurant is still synonymous with high-end sushi, but at that time many political and business people went there as well. Then, one night… Apparently, one of the regular customers was tired of eating ordinary sushi and said to the chef, Hisaji Imada, “I want to eat some sushi that is more unusual. Ikura (Salmon roe) sounds like it would make good sushi,” as a joke. Imada, who took these words seriously, thought to himself, “But the roe would fall off if put directly on the shari (vinegar rice),” and racked his brain that night for a solution. Finally, he had an idea and said, “I know, I could just surround shari with seaweed and put salmon roe in it.” This is how the Ikura Gunkanmaki was born.
Next, when that customer came in again and Imada nervously served him his new Ikura sushi concept, it was received much better than expected. Gaining confidence from this reaction, Chef Imada put it on his regular menu. The story goes that rumors of the delicious taste spread and other sushi restaurants started to copy it. Then, the term “ikura gunkan-maki”(salmon roe battleship roll) was coined.
Nowadays, everything is used as battleship roll toppings from sea urchin to shirauo to negi-toro to mayonnaise and canned tuna-fish. It goes without saying that it all started with salmon roe.
There is only one trick to distinguishing between conveyor belt sushi restaurants (kaiten-zushi), and that is to try eating the tuna as your first dish.
Why is that, you ask?
The most commonly used ingredient at kaiten-zushi is tuna. At kaiten-zushi, the tuna is imported and frozen nearly 100% of the time. The most famous is the Southern blue-fin tun, but you’ll also find Boston bluefin tuna, Canadian tuna farmed in fish preserves, inland sea tuna from Turkey and Spain, New Zealand offshore tuna, Atlantic tuna, etc. Also, the season of each type of tuna and the timing of high-volume catch differ, which makes the prices fluctuate greatly.
Therefore, the biggest task of a kaiten-zushi chain buyer is to decide where to import tuna from. Looking for high cost-performance, they watch fluctuations in the market every single day without fail, check the flavor in detail and constantly change the locality.
In other words, the chain restaurant purchaser’s efforts are concentrated on tuna. Restaurants that serve tuna that has lost its fat, is watery or rubbery, clearly either have a purchaser with a poor eye, or poor thawing skills. Therefore, if you are disappointed with that first tuna plate, then reign in your expectations for other toppings. On the other hand, if you enjoy the tuna then you’ll have a lot of other toppings to look forward to.
One of the common ingredients of sushi rolls is imitation crab. In Japan this is called kanikama, in Europe, it’s called surimi and in the US it’s also called fake crab.
I’m sure everyone reading this has tried it before, but what is imitation crab made of?
It seems kanikama was invented in Japan. In the early 1970s, Sugiyo, a fish paste manufacturer, in a failed attempt to developed artificial jellyfish, ended up with a product that had a texture exactly like crab and shifted development to that instead.
The “kani” of “kanikama” means “crab”. “Kama” is an abbreviation of kamaboko, which is boiled fish paste, fish sausage, or fish cake. Its official name is “crab-like kamaboko”. The main ingredient is minced fish meat mashed into a paste. One of the whitefish used in Alaska pollack. But it contains no crab. Therefore, to bring out the crab flavor, crab extract, which is a combination of ingredients extracted from crab shells and meat, salt, etc., is added. In this way, the crab-like taste can be reproduced without the use of crab meat. However, those who are allergic to crab or other crustaceans cannot eat kanikama with crab extract. Also, the red color of the crab-like appearance is made with paprika dye, etc. Incidentally, there is actual crab in the kanikama sold in the US and Europe.
It has now become a staple not only in sushi rolls, but also in sandwiches or on baguettes and even on takeout salads. It’s become even more popular than it is within Japan.
The tiny red balls around the outside of the rice on California rolls are Tobiko (飛び子). Specifically, they have salted roe of flying fish and are known for the plump, crunchy texture. This crunchy texture comes from the skin, which is relatively tough, even compared to other fish eggs. As the roe is made up of small eggs of only 1 to 2 mm, each one bursts as you bite, without leaving the outer skin in your mouth, so you can enjoy a nice texture that you won’t find with any other fish roe. Unlike the orange-colored tobiko sold in stores, natural tobiko has a pale golden color with a sense of transparency. Therefore, some processors have dubbed it “golden caviar”.
The main production areas are Indonesia and Peru, and in small quantities, Taiwan as well. The eggs from Indonesia are smaller than those from Peru. If you don’t like the skin remaining in your mouth then the Indonesian tobiko is recommended. Meanwhile, Peruvian roe has larger eggs and thus the skin is tougher, giving it an excellent firmness.
Freshly harvested flying fish roe gives you not only the satisfying popping texture like bubble wrap, but also a sense of the subtle aroma unique to fish roe. This combined with the saltiness of the sea gives you the same sort of umami found in tarako and ikura. Also, Tobiko sold at stores has even more added flavor. This is used for making hand-rolled sushi at home.
In fact, it is a registered trademark of a seafood processing company called Kanetoku, located in Hyogo prefecture, Japan. It isn’t hard to see that it’s an abbreviated version of the Japanese “Tobiuo no ko”.
Tobiko is rich in nutrients such as the minerals and vitamins potassium, phosphorus, vitamin E, vitamin C and niacin. Also, since it has a natural pigment composition called astaxanthin, which gives tobiko its bright color, it has antioxidative effects and is effective in strengthening the immune system. While Ikura has 272 kcal per 100 g, Tobiko only has 74 kcal per 100 g, adding a health factor to its charm.
What is flying fish?
Flying fish are found in the subtropical to temperate waters of the Pacific Ocean, Indian Ocean, and the Atlantic Ocean. They travel along the surface of the sea and eat zooplankton. Over 50 types of flying fish have been identified around the world. More than 30 of these have been identified in Japan, of which 4 types are used as food. Since the meat is white, low in fat, and has little odor, it is prepared in various ways such as sashimi, minced, grilled with salt, and fried. In Kyushu, flying fish is called “ago,” and it is dehydrated to be used as soup stock, called “dashi” in Japanese. Ago dashi has a refined and refreshing sweetness and a deep flavor, and it is considered to be on the higher-end of dashi stock.
The dorsal side of the flying fish is a vibrant dark blue, and the ventral side is silver The pectoral fin is considerably longer at about 30-40 cm long. It uses it pectoral fins to fly over the water’s surface to escape from its natural enemies, such as tuna Depending on the breed, it can fly an average of 200 m in one go. The larger the species, the longer distance it can fly and the longest can be up to even 600 m. Furthermore, the flying fish has no stomach and its other digestive organs are short and straight, which makes its body lighter and ideal for extended flight.
Flying fish contains a lot of a nutrient called Niacin which can help prevent hangovers. Additionally, it is rich in vitamin E, which works to prevent the oxidation of unsaturated fatty acids in the body, and as such is a good fish for preventing lifestyle-related diseases such as arteriosclerosis and myocardial infarction.
On the other hand, an orange-colored tobiko is often seen at conveyor belt sushi restaurants, etc., but this is the roe of a fish called capelin (カペリン), which is similar to shishamo smelt. A salted version of this is used for sushi rolls in the US and other places, where it is called masago. Compared to tobiko, the grains are smaller and the texture is a bit chewier. It is mainly rich in EPA (Omega-3 fatty acids) and collagen.
“Masago (真砂子)” actually means “fine sand” and therefore is used for foods that depict that image. In other words, it refers to broken-up fish roe and doesn’t indicate a specific type of fish. Dishes made using capelin roe can be called masago, but please keep in mind that dishes with broken-up tarako or kazunoko are also called masago.
What is capelin?
The shape of capelin is very similar to shishamo smelt, but the scales are very fine, barely visible to the eye. The body is a bluish silver color with an average length of 12-16 cm, but can grow up to 20 cm.
It is found in a wide area from the Arctic Ocean to the frigid sea regions and also migrates to the Sea of Okhotsk on the coast of Hokkaido. The time they spawn depends on the region. The season for Canadian capelin is June to mid-July, and the season for Icelandic and Norwegian capelin is mid-February to mid-March.
They are also known as Komochi Shishamo (Shishamo with child) and are known to have a wonderful balance of fat and roe. Compared to shishamo smelt, they are leaner and have a lighter texture. Shishamo smelt is not caught in great numbers, so capelin started to be imported as a substitute for it for Japanese homes and izakaya (Japanese bar/restaurants).
Capelin rush to the coastal area in large groups to lays eggs on the sandy bottom of the beach during spawning season. The amount of eggs it lays at one time is about 5,000 to 6,000. It has spherical, adhesive demersal eggs with a diameter of around 1 mm. The eggs hatch around spring tide about 2 weeks after spawning The total length of larvae immediately after hatching is 4-5 mm, and it is thought that they leave the coastal area by utilizing waves at high tide and reach a total length of around 10 cm in the first year of life.
Capelin is a healthy fish that can be eaten in its entirety, and boasts 7 nutrients (DHA, EPA, calcium, zinc, potassium, vitamin B2, collagen). Moreover, since the sugar content is only 0.5 g per fish, about 1/3 of the amount normally contained in fish, it is perfect for those who are dieting.
If you come across wholesale Tobiko and Masago, it was likely purchased at the Toyosu Market. The reason for the ambiguous expression here is that you will rarely find nigiri sushi with tobiko or masago at sushi restaurants with counters. There may be some sushi restaurants that have tobiko or masago on their standard menu, but there are fewer than ten of those restaurants in Tokyo. In other words, in Japan, tobiko and masago are mainly used for kaiten-zushi (conveyor belt sushi) and izakaya restaurants.
Finally, we’ll let you in on a not-so-pleasant secret. Flying fish and capelin roe is actually a light yellow or beige color. However, you’ll find it in bright red, orange, yellow and lately even green or black. Of course, these are colored by either natural pigments or synthetic coloring. Furthermore, tobiko is sometimes mixed with the cheaper capelin or herring roe. Unfortunately, food fraud is common in seafood products that are consumed in high quantities.
Ending a fish’s life without stress is the key to the delicious flavor. When fish are left out in air, and die in agony it promotes rapid Adenosine triphosphate (ATP) degradation and increases in Inosinic acid. This is the worst way to kill a fish.
So what method can control the fish’s flavor or “umami”?
The delicious flavor of fish comes from the postmortem breakdown of ATP, which is the source of biological energy, and the generation of Inosinic acid, which is the component of the umami. Rigor mortis after the fish has died, progresses with the decomposition of ATP. When the oxygen supply is cut off after death, the energy required for muscles to move is no longer supplied, so the flexibility of the muscles is lost and the body starts to contract. This is postmortem rigidity. This state depends on the fish, but it is the lowest point for flavor and after that, the fish is managed at an appropriate temperature to increase the Inosinic acid.
This method has been the norm among sushi chefs who didn’t know about the mechanism that produces umami. Since long ago, the daily routine was to purchase fish that were killed first thing in the morning in the market, then increase the umami by keeping the fish in a refrigerator with a controlled temperature for 12 to 48 hours. Nowadays, the method has become a common practice among fisherman, distributors and fish handlers at the market.
Now I will explain a number of methods that maintain peak flavor.
Ikezukuri means to take a fish that’s swimming in a tank at the restaurant, and immediately making sashimi after killing it, while the meat is still super fresh. In this state, there is no Inosinic acid, but there is quite a show with movement still in the fish and this preparation method gives the best-tasting texture.
Nojime* means using a massive amount of ice to suddenly reduce the temperature, resulting in the death of the fish, either at the fishing site or at the local market. This method is used for small, cheaper mass-market fish that are caught in large amounts. Nojime starts with a reverse calculation for flavor from the day after fishing, but if the process isn’t thorough or there are any deficiencies, the fish won’t stay as fresh, so detailed care must be taken in temperature management.
Hamajime* means to cut the spinal cord at the production site, drain blood and spinal fluid, then pack in ice from the afternoon the next day and wait for the peak flavor, which will be about two days later. That’s when the seafood is shipped to make it to the consumer auction the next day. As time passes, inosinic acid is generated and the aim is to use the fish in sushi at peak flavor.
Ikejime is used so that the peak flavor will be reached during afternoon and evening business hours. The spinal cord of the live fish is cut and spinal fluid drained at the early morning market. This result is a firmness from the remaining ATP, and delicious flavor from the Inosinic acid that is generated as time passes. After some time has passed, even fish for which Ikejime is applied, can reach the same state as Hamajime if used after being refrigerated for one to two days, in order to maximize the Inosinic acid generated. Of course, sushi chefs find their own balance of firmness in meat or added flavor, and incorporate this balance for the optimum combination with their shari in each piece of sushi.
Finally, maintaining freshness by using Ikejime, has become common practice overseas, and the term “Ikejime” has also become standard among the fishing industry. There are many websites that go into further detail on Ikejime, which you can reference from the links below.
*At markets in Japan, the term “kill” is not used for living fish, instead the word “shimeru” meaning “close” or “tighten” is used. This expression is thought to have come from the sentiment of showing respect and appreciation for all living beings, not only humans.
Related Contents: Première poissonnerie ikejime à Paris
The fish used in sushi is generally salted or soaked in vinegar then matured for several days while the umami Inosinic acid component increases. This is called “Jukusei” (aging). Sushi made with toppings that have been aged in this way is called “Jukusei sushi”. The aging period depends on the type, individual size and origin of each fish, and some are even aged for over four weeks. However, the preparations are not only difficult and time-consuming, but the discolored parts and inedible parts must also be trimmed, so these toppings tend to be expensive. If gone too far, the Inosinic acid converts to hypoxanthine and rots. The ability to make this judgment is important. In the end, Jukusei is an evolved version of the culture of “maturing toppings” which existed in Edo-style Sushi.
How to Jukusei? (How are sushi ingredients matured?)
In order to mature seafood, after completing advance preparations (removing the head and internal organs then washing thoroughly; all blood must be removed), more than adequate considerations must be made for the fat content of the fish and management of the bodily fluids. Specifically, this includes processes like dry-aging at a low temperature, removing moisture using salt, utilizing enzymes and fermentation, wet aging by putting the item in a vacuum pack, and wrapping in aging sheets, which were developed thanks to Foodism. These processes may be used alone or in combination, whichever process is most suitable for the fish.
In the initial stage of ‘jukusei’ (maturing), the increase in inosinic acid (the umami component) improves the taste. After that, the inosinic acid starts to decrease, and once the long-term maturing stage (two weeks or more) starts, free amino acids such as glutamic acid and aspartic acid really start to affect the flavor. This has all been learned in research.
Let’s take a look at specific aging methods.
For example, for white flesh fish, a somewhat high amount of salt is sprinkled on the fish before it is stored in a refrigerator set at 3 to 4℃ with a humidity of at least 85%. The fish is not wrapped at this time. The fish is flipped over 3 to 4 times a day so that the moisture is extracted evenly. Several days later, the salt on the surface of the body and the body fluids that have seeped out is washed off with water (or thin saltwater). The fish is then wrapped in paper towels and then plastic to avoid contact with the air, and it is stored in a refrigerator at 1 to 2℃. Once the chef deems the fish is ready, it is trimmed. Excess moisture is removed and then the maturing process continues.
We would like to take this time to point out that fish like Tai (Red seabream) and Buri (Japanese amberjack) are clearly more delicious when matured. However, when farmed tai and farmed hamachi are matured, the scent of the feed they were raised on comes out, so these are better eaten fresh, as sashimi, instead of maturing.
Blue-backed fish like Aji (Horse mackerel) and Iwashi (Japanese sardine) are also not suitable for mature. Blue-backed fish lose their freshness quickly and judging the maturity is extremely difficult. Furthermore, if the fish is matured without sufficient advance preparations, bacteria breed in the remaining blood and organs. This may cause food poisoning.
These fish can be matured using the following method. The fish is put in salt-ice (water-cooled with ice and salt) as soon as it is caught. It is sent to the sushi restaurant in this state and left in the refrigerator to rest for several days. Unfortunately, what happens after this is apparently a trade secret.
The easiest method is to wrap in an aging sheet and put it in the refrigerator. After that the chef trims the fish, checking the state. An aging sheet is a cloth made from purely breeding a ‘mold’ that is harmless to the human body, and putting cultures of its recovered spores into the cloth. Originally, it is intended to be used to age meat, but it’s just started to be used for seafood too.
Finally, in a method used for ages by sushi chefs, the akami and toro (tuna) portion are taken out and the chiai* portion is removed to be matured. This is then wrapped in paper towels, put into a plastic bag in order to prevent drying out, then put into the refrigerator to rest. The temperature setting is the most important part of this process and, obviously, this is an industry secret. The chef needs to check the state of the tuna (for example whether the white lines are soft and whether the oil has risen), and any discolored portion is trimmed. After that it is refrigerated. This process is then repeated.
*“Chiai (血合い)” is the part with the most veins, so it is a dark red color. It has a strong odor of blood and has multiple times the acidity of the lean meat, so it is not used as a sushi topping.