Crayfish has once again caused controversy. Net-transmitted crayfish was introduced to China by the biochemical troops of the Japanese invaders to dispose of corpses. At the same time, it is said that harmful heavy metals such as lead, cadmium and chromium have accumulated in its body. What is the truth? The reporter interviewed food safety experts, popular science experts, hospitals, cooking associations and other people yesterday to answer questions for the public.

1 crayfish is a worm?

It is rumored that crayfish is not shrimp, but an insect, and foreigners don't eat it.

The thin camel, a popular science expert who asked for evidence from the shell network, introduced yesterday that crayfish is a kind of freshwater crayfish and belongs to the crustacean crayfish subfamily. It has its own scientific name, Procambarus clarkii. Crayfish's hometown is not in China or Japan, but in North America. Its main habitat is along the Gulf of Mexico, especially near the mouth of the Mississippi River.

The characteristics of this kind of shrimp are fast growth and strong adaptability, and they can survive in clean and polluted environment. Crayfish can eat a lot and have a good appetite. It belongs to omnivorous animals and can eat aquatic plants, algae, aquatic insects, animal carcasses and so on.

The reporter inquired yesterday that the FAO has statistics that the annual global trade volume of crayfish is as high as 300,000 tons. Thin camel, a popular science expert, said that in America, the hometown of crayfish, it started more than 200 years ago.

I ate a lot of crayfish, and there are many markets specializing in crayfish. European countries also eat crayfish, but Japanese people really don't like crayfish because they think crayfish meat is firewood.

Used to help the Japanese dispose of the bodies?

It is said that during World War II, the biochemical troops of the Japanese army stationed in China genetically modified crayfish (the predecessor of crayfish) and transported it to the Japanese army station to feed on the remains that were not completely cremated.

confirm

Thin camel, a popular science expert in shell network, said that crayfish is the scientific name of crayfish, not its predecessor. The time when Japan introduced crayfish from the United States was about 1927, mainly as feed for bullfrogs. Besides,

Crayfish was indeed brought to China by the Japanese, probably 1929. It was also used as feed and food, and the earliest landing place was near Nanjing. But at this time, War of Resistance against Japanese Aggression has not yet broken out, and Nanjing and its surrounding areas have not been occupied by the Japanese.

Area, no disposal of the body.

In addition, during the War of Resistance against Japanese Aggression period, the concept of gene had not been formed, let alone transgenic.

The thin camel said, "crayfish have strong viability, but they don't have the ability to deal with pollution."

3 most of the crayfish in the restaurant come from the river ditch?

It is rumored that the cost of crayfish breeding is high, and the retail price is generally 2.50 yuan/kg, which is unprofitable. All the crayfish in the market are collected by idle farmers in the local river ditch. Usually, the more polluted the river is, the cleaner the water is, and the faster they die.

confirm

Bian Jiang, assistant to the president of China Cuisine Association, said that crayfish grow in paddy fields and rural ditches, but these alone cannot meet the market demand. In addition, crayfish have strong adaptability and strong reproductive ability, and are bred.

This is not high. At present, the crayfish served in restaurants are mostly farmed. For example, Ma Xiao, the most famous crayfish in Guijie, Beijing, mainly comes from Jiangsu, and has established a specialty store with Xuyi, Jiangsu.

Frontier said that he had been to a special crayfish breeding base in Xuyi, Jiangsu Province, and had high requirements on the cleanliness of water. Crayfish can grow in clean water, which is similar to the life characteristics of crucian carp, soft-shelled turtle and loach, and can survive in clean water and sludge environment.

4 all kinds of heavy metals in the body exceed the standard?

It is said that crayfish has a strong adaptability to toxic water, and the accumulation of heavy metals such as lead, mercury, manganese, chromium and arsenic in the body can reach several hundred times of the normal value.

Yi Zhu, an associate professor at the College of Food Science and Nutritional Engineering of China Agricultural University, said last night that even if there are heavy metals in the water environment, they are generally concentrated in the head from the perspective of biological enrichment, but they will not accumulate too much heavy metals, so it is recommended not to eat shrimp heads. Generally, as long as it is legally farmed crayfish, the problem is not big.

Thin camel, a popular science expert in shell network, said that crayfish can transfer heavy metals into the shell and toxins out of the body by constantly molting, so the heavy metals in its body may not exceed the standard. "Judging from the current monitoring data in i query, no heavy metals in crayfish have been found to exceed the standard."

It is reported that Shanghai, Suzhou, Anhui and other places have investigated the content of heavy metals in crayfish, and no problems have been found.

5 is related to rhabdomyolysis?

It is rumored that crayfish with paragonimiasis are carried for life, which is easy to cause rhabdomyolysis?

Verification Yesterday, the Beijing Municipal Health Supervision Department said that crayfish and crabs are intermediate hosts of paragonimiasis, and processing methods such as roasting, frying, salting and drunkenness cannot kill all the paragonimiasis cysts (larvae) that may be carried in crayfish. City CDC said that as long as you don't eat raw or half-eaten crayfish and crabs, you can prevent paragonimiasis.

According to experts, the cooking temperature should be kept above 100℃ for no less than 10 minutes to ensure the killing of paragonimiasis. In addition, the head of crayfish is prone to lurk bacteria and parasites, and it is generally not eaten.

20 10 a case of rhabdomyolysis occurred in Nanjing, and the Ministry of Health once said that it was related to crayfish. But the specific reasons are still controversial.

Science expert thin camel told reporters that eating crayfish may lead to rhabdomyolysis, but the probability is low, and eating other aquatic products may also have this symptom.