Ikura is a Russian word meaning fish roe. Most of the salmon roe used in Japan comes from Chum salmon. Roe harvested in either September to October are separated gently and then marinated in a mixture of soy sauce, Japanese sake, dashi etc., to be transformed into a sushi ingredient.
Shinanoyuki-masu (信濃雪鱒) is a cold-water fish classified in the genus Coregonus, which is related to salmon, and was not originally from Japan.
In 1975, eggs were introduced to Nagano Prefecture from former Czechoslovakia, and after 10 years of testing and research at the Nagano Prefectural Fisheries Experiment Station, the prefecture succeeded in establishing the world’s first aquaculture technology.
In 1983, full-scale production began on a private-sector basis, and the fish was named Shinanoyuki-masu (shinano means ‘Nagano prefecture’, yuki means ‘snow’, and masu means ‘trout’), an appropriate nickname for its silvery-white appearance reminiscent of snow.
The neighboring Saku Aquaculture and Fisheries Cooperative Association also sell sturgeon roe under the name Golden caviar after separating the muscle-like roe into pieces and marinating them in salt. However, this is not a Golden caviar, but rather a Yellow caviar.
Generally, River trout, Char, Yamame, and Amago, which grow only in rivers and lakes, do not take red pigments, so their eggs themselves remain yellow. Yellow is also associated with roes but can also come from an albino fish. Rainbow trout is almost always orange, but can also be yellow using a feed that does not contain astaxanthin.
Immature salmon eggs still wrapped in ovarian membrane and salted are called sujiko. Ikura is salmon roe in which each mature egg is separated from the ovarian membrane before laying the eggs and then salted or marinated in soy sauce. The ikura of Chum salmon going upstream in the Kushiro River and Tokachi River in Hokkaido From October to December are considered to be premium ikura.
For cheap ikura, roe broken up inside the ovarian membrane in a fish that is approaching spawning time called “barako” is used. When the ovarian membrane of barako is torn, the eggs will fall out and scatter, so while they don’t take much work to prepare for serving, they also don’t taste particularly good. Even cats turn up their noses at barako, so they are also called “neko-matagi”, which literally means “the cat walks over it” and is used to refer to unpalatable fish. However, each egg is large and they look very appealing, so they are used at higher-end conveyor belt sushi. Unlike the 100-yen (US $1) restaurants, these higher-end restaurants don’t use disguised fish or substitute fish. This is because their basic business strategy is to differentiate themselves by attracting customers with authentic toppings. Generally they market the high quality of their toppings, but the ikura is actually this cheap “neko-matagi”.
Beneath this strategy of attracting customers with authentic toppings is this “Deceptive business strategy”. Salmon also swims upstream in the rivers of Tohoku and Hokuriku. However, the taste of ikura tastes inferior to that in Hokkaido. This ikura is also served at the higher end restaurants. That’s because although it doesn’t taste as good, it’s orthodox ikura. In case of orthodox ikura, the roe is used within one hour of the catch. But, if time passes and the freshness drops, the eggs will dry out and the surfaces will dimple, wrinkling. This is the type of ikura that is cheaper and often served at the cheap conveyor belt sushi restaurants.
The most commonly used roe in conveyor belt sushi restaurants is ikura from cheap Alaskan or Russian Chum salmon. An even cheaper type is masuko. Besides the masu roe, raw materials included soy sauce, salt, fermented seasoning, amino acids, reduced sugar syrup, enzymes, fish sauce, and fish and shellfish extract. For homemade versions, only soy sauce, mirin (sweet cooking sake) and sake are used.
In Japan, salmon roe that has been separated from the ovarian membrane and then salted is called ikura. At sushi restaurants, this is also marinated in broth that includes soy sauce, mirin and sake. This is called ikura marinated in soy sauce, or simply ikura. Worldwide, caviar is considered to be of more value than ikura. Therefore, in an attempt to improve the impression of soy sauce-marinated ikura, it is sometimes called ‘salmon caviar’. This is behavior especially seen among manufacturers selling soy sauce-marinated ikura.
Not to belabor the point, but the following is dependent on the following. In Japanese salmon is referred to as “鮭” (sake/salmon) or “鱒” (masu/trout). The characters look different, but they are part of the same family and there aren’t clear biological categories to separate them into. Incidentally, in English the type that makes their way into the sea are called “salmon,” and those that remain in freshwater their entire lives are known as, “trout.” They are all considered to be part of the salmon family. Now, foreigners who know about Japan may imagine Japanese sake (the alcoholic beverage) when they hear the word “sake” so we spell sake/salmon as “shake”, which is close to the sound pronounced by Japanese people.
First of all, shake is mainly Chum salmon, caught in the seas near Japan. Masu caught in the seas near Japan are mostly Pink salmon (Humpback salmon) and Sakura masu. Masu caught in rivers and lakes are generally Char or Rainbow trout.
Now we finally get to the topic of this article, shake roe that has been removed from the ovarian membrane then salted or marinated in soy sauce is called ikura while masu roe is called masuko and they are clearly distinguished. This is because masuko can be bought at just 20-40% of the cost of ikura. However, the difference is really that each egg is smaller than that of ikura and in general people can’t taste a difference.
Over the past 10 years or so, the masuko made from the roe of Rainbow trout farmed in France and the masu farmed in Japan have been called ‘red caviar’ by manufacturers. Of course black caviar made from the roe of sturgeon and tobiko made from the roe of flying fish are distinctive. Certainly there is no problem in calling fish roe caviar according to the Product Labeling laws, but it’s extremely clear that they are only trying to get a higher price out of it.
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:
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
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.
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.
The natural salmon roe season is the autumn. Does this mean that most of the roe eaten during the off-season is artificial Salmon roe. Not necessarily. As stated in his biography, even at the famous sushi restaurant Sukiyabashi Jiro, frozen roe is thawed as necessary.
Long ago this was an extremely expensive topping that ordinary people couldn’t afford, so artificial roe was used. There was a time when this was the case. But nowadays salmon roe is regularly imported from overseas and can be obtained cheaper, eliminating the need to use artificial roe instead.
However, we cannot overlook the commercial law for passing off artificial roe as natural roe. In Japan, the non-perishable properties of artificial salmon roe made from chemical substances (mainly sodium alginate) is utilized and used mainly in hospitals, but not sold to the general public. I’ll also tell you that it is very rare to find a sushi restaurant that serves artificial roe. Cheap roe is generally made from eggs of trout, other related species, or imported from Canada and other countries.
Unfortunately I’m not familiar with the state of things outside of Japan, but I can tell you how to tell the difference. All it takes is hot water and a moment of observation. Artificial salmon roe will show no changes in hot water, but natural roe will start to turn white on the surface. This is due to the protein reacting and changing with the heat. That said, this is not an experience you can just set up at the sushi restaurant.
As an aside…
What are the fish eggs on sushi called in Japan?
There are eight types of fish eggs served at Japanese sushi restaurants. However, not all of them are used for Nigiri sushi. Some are served as side dishes. Uni is sometimes translated as sea urchin’s roe, but it is actually the sea urchin’s genitals (testes and ovaries). Most people also don’t know that Tobiko and Tarako are not served at 99% of Edo-style restaurants. In other words, these toppings are only served at kaiten-sushi (conveyor belt) restaurants. The one type of roe topping that can probably be found at all sushi restaurants is Ikura. Even more types of fish eggs, such as Masago, Paddlefish roe and Hackleback roe are used in sushi overseas, but Japan remains more conservative. Of course, it’s only natural that fish substitutes are not well-received in the place where sushi was born.
Types of fish roe
Fish roe usually cannot be preserved as is, so it is salted or smoked to make it last longer. Today, thanks to advances in freezing technology, frozen fresh fish roe is also available, but as a raw material for processing, fish roe is often salted to reduce its water content and then frozen for preservation. Nutritional value is generally high in fat and protein and low in carbohydrates, with higher calories and cholesterol than the meat of the parent fish.
What is Tarako? －Tarako is the salted ovary of Alaska pollack. It is often colored red with food coloring. Karashi-mentaiko is Tarako marinated in a seasoning solution of salt and chili peppers, and is a well-known Hakata specialty. The name Karashi-mentaiko comes from the Korean word for Alaska pollack, Mentai.
What is Caviar? － It is Sturgeon roe.
What is Karasumi? －It is made by salting, aging, and drying the ovaries of Flathead gray mullet (Bolla). The product resembles Chinese ink karasumi, hence the name. Good ones are candy-colored, cut into thin slices, lightly roasted, and served as nibbles for drinks. Imports have been increasing recently, but the most famous domestic product is karasumi from Nomo, Nagasaki Prefecture.
What is komochi konbu? － It is Herring spawn on kelp.
Fermented beverages such as sake and wine pair well with sushi. Sake is made from rice. So it only makes sense that this would pair well with sushi – also made with rice. It is also the only alcohol that eliminates the smell of fish and shellfish.
On the other hand, when considering compatibility with wine, toppings that use strong seasonings like Nikiri, including tuna and conger eel with sweet filling, match superbly with matured red wines such as Pinot Noir.
For example, Bourgogne Chambolle Musigny, Cote de Beaune, Morey-Saint-Denis, etc.
White wines such as a lighter Chardonnay, Sauvignon Blanc and Riesling go well with white fish flavored with Citrus sudachi and yuzu or squid eaten with salt.
For example, Bourgogne Chablis.
However, neither red nor white wine goes well with herring or salmon roe. The iron specific to wine is said to contribute to the fishy smell of fish roe.
In the research of one wine manufacturer, the factor that generates the smell of fish and shellfish is the iron (ferrous ion) found in wine. Wines with relatively low levels of iron such as Sherry (Spain), Champagne (France) fermented twice in the bottle, Cava (Spain) and Franciacorta (Italy) mature without adding sulfite, which prevents oxidization. This reduces the ferrous ion in the wine and the fishy smell is virtually unnoticeable.
Either way, the research of wine and sushi pairings is still insufficient and there haven’t yet been any reports of unexpected compatibility. If anyone out there has found a wine that does pair well with herring or salmon roe, please be sure to share that information with us.