Beijing Carrefour supermarket pretends to be cod with oily fish. The oily fish contains a large amount of wax esters that are difficult to digest and causes diarrhea (or stool pulls out a lot of oil). The "cod" is a common and unfamiliar fish food. Push to the peak of the peak and valley. In the market, there are many kinds of fish called "cod", the price ranges from a few yuan a catty to a hundred yuan a catty. It''s no surprise that things that happen to be good or bad are sometimes happening. Reports of using oil fish to impersonate cod and causing adverse events were reported in 2007. The report of the Food Safety Centre of the Hong Kong Special Administrative Region said that as of the end of January 2007, they had received 700 reports and inquiries about the matter.

　　From the perspective of the standard classification of fishes, "cod" belonging to the genus Codidae is considered to be real cod. There are three types, namely Atlantic cod (Gadus morhua) and Greenland cod (Gadus) ogac) and Pacific cod (Gadus macrocephalus).

　　 Atlantic cod production is the largest, but we Chinese do not eat much. This fish lives in the northern Atlantic Ocean and is a cold-water fish that can grow up to nearly two meters long and weigh a hundred or two hundred pounds. At present, the annual catch of Atlantic cod is around 800,000 tons, and its price is not high. In 2011, the price of processed boneless fish was about 4-6 US dollars per kilogram. There is no Atlantic cod in my country''s waters, but China is the largest supplier of Atlantic cod in the European market. The reason is that large cod fishing countries such as Russia will ship their catches to Chinese ports one after another, and our reprocessed cod products can be sold to the world thanks to my country''s lower human resource costs.

　　 Pacific cod (pictured), regardless of its size or fame, is smaller, but its shape is very similar to Atlantic cod, and its taste is similar. my country''s Yellow Sea and Bohai Sea are one of the Pacific cod producers, and the annual catch is also high, but coastal residents are not interested in it, and the market price in Yantai is about 15 yuan per catty. And more Pacific cod is used to make frozen fish fillets to meet the needs of domestic and foreign markets.

　　Greenland cod has few appearances on the market due to its low production.

　　These three kinds of real cod are big-headed, big-mouthed and fat belly, with obvious lateral lines on the side of the body, the most conspicuous thing is that they have a beard on their chin. However, these characteristics are actually not helpful for consumers to buy cod, because most of the cod are sold in supermarkets, with no head, no mouth, no belly, no sidelines, and no beards.

　　The largest consumption of "cod" is not the above three, but the yellow thread pollock (Theragra chalcogramma (pictured), it is also called Alaska cod (Alaska Pollock) or Ming Taiyu. It is used by KFC''s cod products or McDonald''s Ayu. "Ming Tai Yu" is the most common and classic name for Korean food. Some good quality "crab foot sticks" are also made with it, but many cheap crab foot sticks (crab sticks) in China are made with starch and flavor, which has nothing to do with it.

　　The yellow line pollock has no beard and is thin, but its name covers the above three true cods, and it is currently the second largest commercial fishing fish in the world. According to a survey by the Food and Agriculture Organization of the United Nations, 2.7 million tons of yellow thread pollock were caught globally in 2008. Most of them are made into pieces of meat, minced meat and ground meat (re-pressed). Not surprisingly, the price of yellow thread pollock is cheaper.

　　Another type of cheap cod is more than a dozen commercial fish belonging to the codidae hake family. Although the output is not as much as yellow pollock, it also contributes a lot of frozen fish meat and Minced fish. Sometimes the meat is kindly called hake or white cod by the merchants, and in English it is called Hake or Whiting.

　　 At this point, the "cod" with a real name and high price has not yet appeared. It is codfish, and the pseudonyms are black cod and blue cod. In fact, cod is not a cod. In the standard classification, it is not a codfish, but a scorpionfish. Its standard name is Anoplopoma fimbria, pictured). Codfish are mainly produced in the northern Pacific Ocean, and most are processed on the shores of Alaska. But its main consumer is not the United States, but Japan. In Japanese cuisine, codfish is a standing item, used for making sushi or grilling. In 2011, the price of frozen codfish slices offshore in Alaska was about US$18 per kilogram, or about 50 yuan per kilogram, which is considered a very expensive aquatic product. Although my country is not a traditional consumer of cod, imports have also been rapidly increasing in recent years. Among them, my country imported 1,000 tons of cod in 2011.

　　 Except for cod (naked capfish), "cod", which is not cod better than cod, is Icelandic cod, or flat cod. It is actually a very large flounder, and the standard name is Hippoglossus stenolepis, pictured), also called Pacific halibut, pictured. Its body is 2.5 meters long, and the slices are flat on the side, so it is named "flat cod". However, its origin is in the Pacific Ocean, and it has almost nothing to do with Iceland, but why is it called "Icelandic cod"? That is because it is often used to replace a very delicious fish that has been produced in the Icelandic region (Atlantic Ocean) but has very little production- —Yellow flounder (Hippoglossus) hippoglossus). The price of the small scale halibut is about 15 US dollars per kilogram, which is regarded as high-end goods.

　　The above two "counterfeit" cod have greatly improved the grade of cod. The other kind of counterfeit cod, oily fish, hurts the image of the cod and can be called the perpetrator. Oil fish is named because it contains a lot of oil (including wax), the standard name is "snake mackerel", including Lepidocybium flavobrunneum (pictured above) and spiny-spotted mackerel (Ruvettus pretiosus, below) two kinds. They are deep-water fish that live in tropical and temperate oceans, and can both impersonate cod and white tuna.

　　According to the literature, these fish contain wax esters about 20% of their body weight. These wax esters come from snake mackerel foods, which are all kinds of small fish. Because these two types of fish do not decompose the wax esters naturally present in their food, the wax esters accumulate in the body, including fish skin and fish meat.

　　 Wax esters are not absorbed by the intestine in the human body and are discharged through the anus. Some consumers have diarrhea of varying degrees, such as the rapid discharge of a small amount of yellow or orange oil; or severe diarrhea with nausea, vomiting, and headache. The complication is that not everyone who eats these fish will be affected. Sensitivity to wax esters seems to vary from person to person, and some people seem to be completely unaffected by these fish and will not experience any discomfort after eating.

　　 Affected people will usually have symptoms within 30 minutes to 36 hours after eating fish, mainly oil drainage and diarrhea, and heal within 24 to 48 hours.

　　 Wax esters will not decompose through cooking or freezing process. Use cooking methods that remove most of the body fat (e.g. grilling) And discarding the boiled liquid soup, although in theory can reduce the wax ester content and reduce the risk, but there will still be problems with oil drainage and diarrhea.

　　 The current price of oil fish on the international market is about US$5 per kilogram, which is quite or slightly higher than that of real cod (US$4~6), but much lower than "codfish" (US$18) or " "Icelandic cod" ($15). Moreover, the taste and nutrition of oil fish is also good, and even the sale is not inferior to cod. Therefore, my country, including Taiwan, and most Southeast Asian countries do not restrict the trade and consumption of this fish. It is allowed to be eaten in Canada, the United Kingdom, Singapore, Sweden, Denmark and China’s Hong Kong, but it must be packaged; the packaging label must list its trade name and scientific name in detail, and it should not be confused with other fish; it should also be prompted to eat on the packaging The risks and consequences, and give recommendations (usually recommended that the first consumption should not exceed 6 ounces, which is about three or two). Only Japan and Italy consider it necessary to ban the import and sale of oil fish.