Can you eat the head of a crayfish? Is it yellow or poop inside?

Once upon a time, a person shuttled through the orange street lights and came to a late-night canteen - "Hey~ Boss, give me a plate of spicy crayfish!" Holding the bright red crayfish in both hands, he gently separated the shrimp head and body, took a bite of the shrimp meat, sucked a mouthful of shrimp roe, and then took another bite of the shrimp meat...ah~ The author is so hungry after writing this!

The delicious crayfish warms the stomachs of many foodies.

Warning: There are many pictures of crayfish in the whole article, so please be careful if you are hungry. | awei

Factional dispute over shrimp heads

However, before we know it, foodies have split into two groups... Some say the yellow stuff in the shrimp head is the soul of the crayfish! It's the essence! But some people sneer at it.

Shrimp head pie: The yellow stuff inside the shrimp head tastes like crab roe and is very memorable. It would be a waste not to eat it!

Shrimp body party: Shrimp balls are justice! Shrimp heads are full of dirt, so I don’t want to eat them~ Hum~

As the saying goes, "Red shrimps are prone to gossip." Naturally, there are many true and false statements about crayfish, a food that is so addictive that people can't stop eating. Here, I would like to dispel some rumors for you.

Can we talk while eating? | awei

Did China have crayfish in the past?

In fact, there are four kinds of authentic crayfish in China, namely, the Northeastern black crayfish, the Nanjing black crayfish, the Smith's crayfish and the Korean black crayfish. In addition, there are two "foreign monks", the American-originating Procambarus clarkii and the Oceania-originating Red Claw crayfish, but the Procambarus clarkii is superior and has blossomed all over China, becoming the most famous crayfish.

The delicious crayfish is actually an invasive species. This shrimp is ferocious, reproduces quickly, has a strong ability to adapt to the environment, and can also pose a threat to "indigenous people".

Japanese people don’t eat crayfish? Do foreigners not eat crayfish either?

Crayfish have been eaten in the United States for hundreds of years, and the trade of crayfish has gradually moved from rural markets to bulk transactions. Currently, the global annual trade volume exceeds 300,000 tons. Crayfish is a very common cooking ingredient in the United States, usually boiled with potatoes and corn and seasoned with Cajun powder. 98% of the crayfish used for consumption in the United States are produced in Louisiana, which selected crayfish as the state animal in 1983 and holds a "Crayfish Festival" every year.

Scenes from the Louisiana Crawfish Festival｜www.nola.com

After crayfish were introduced to Japan, they did not gain favor among Japanese consumers. After all, they are "bullfrog feed" and Japan has abundant aquatic products. In comparison, crayfish are at a disadvantage in terms of meat quality and taste.

Whether foreigners eat crayfish or not can be determined by looking at the export data. In 2011, Hubei Province alone exported more than 8,000 tons of crayfish, and the national export volume was at least tens of thousands of tons. Currently, the exported crayfish food is mainly cooked food, such as lobster tails, shrimp meat, fennel whole limb shrimp, spicy shrimp, and lobster sauce, which are mainly sold to Denmark, Sweden, Spain, Britain, France, the United States, Canada, Japan, South Korea and Southeast Asian markets. For example, 90% of the crayfish in the European market come from China.

Crayfish live in sewage and eat garbage?

Crayfish are omnivores. Their main food is organic matter at the bottom of the water. They eat water plants, algae, aquatic insects, and organic debris. Of course, they also eat small fish, shrimps, shellfish, and other living things. They even kill each other when they are hungry. Because of their omnivorous nature, they have strong vitality and can survive in polluted water. However, the crayfish in restaurants are basically farmed. For example, the crayfish in Guijie, Beijing, are basically from farms in Xuyi. In the breeding environment, animal and plant feeds should be fed according to growth needs, such as wheat bran, bean cakes, aquatic insect larvae, etc.

Crayfish can tolerate polluted water, but they don't like that kind of environment. Some scholars have conducted experiments and found that crayfish prefer fresh food and clean water sources, so living in sewage is purely forced. Moreover, crayfish have a limited tolerance for the environment. If the water quality is poor, crayfish will not only have difficulty in reproduction, but also grow poorly and molt slowly. Under breeding conditions, the density of crayfish is relatively large. If the water is very dirty, their vitality will drop significantly. When the weather is hot, the shrimp will die in large numbers, and they cannot withstand long-distance transportation, so farmers will also pay attention to water quality maintenance.

Photo｜Ansheng

Are crayfish prone to causing "rhabdomyolysis"?

There was an incident in Nanjing where many people were hospitalized due to "rhabdomyolysis". Epidemiologists analyzed the patients' dining history and highly suspected that crayfish was the culprit of this incident. However, experts conducted various tests and analyses on the collected samples, including pathogenic bacteria, heavy metals, pesticide residues, antibiotic residues, hormones, parasites, algal toxins, etc., and found no abnormalities, nor any substances that may cause rhabdomyolysis. In the end, this incident was characterized as "Haf disease". Haf disease is a type of rhabdomyolysis of unknown cause, which occurs occasionally in countries around the world. It usually occurs within 24 hours after eating aquatic products, and there is no obvious pattern other than this. In addition to eating crayfish, similar cases have occurred when eating marine fish and freshwater fish.

There is also a saying on the Internet that "shrimp washing powder" causes rhabdomyolysis. In fact, the main component of shrimp washing powder is oxalic acid, which has no mechanism to cause rhabdomyolysis. Although it is indeed highly acidic, it is water-soluble and has gone through many processing steps after washing, so it is impossible for it to have a high concentration in shrimp. Many vegetables we usually eat are also rich in oxalic acid, such as spinach.

Of course, crayfish may carry parasites, but this is not exclusive to them. Other aquatic organisms can also carry parasites, such as frogs, snails, shellfish, fish, water chestnuts, etc. The key to preventing parasitic diseases is to cook them thoroughly (the safer way is to cook them at 100 degrees for more than 10 minutes), especially do not eat raw or half-cooked crayfish.

Is the blue color of crayfish caused by heavy metal pollution?

The color of the shrimp shell is mainly formed by the carapace blue protein and astaxanthin in the shell. Depending on the content and degree of combination, it can appear in a variety of colors such as red, orange, blue, cyan, white, black, etc. For example, Australian lobsters are mainly blue. The blue crayfish that appear online are most likely genetic mutations of individual crayfish. This is not uncommon and has nothing to do with heavy metal pollution.

Finished eating｜Li Xiaokui

References

[1]ps://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=217

[2] The morphological anatomy of Procambarus clarkii as a substitute for shrimp in crustacean experiments[J]. Journal of Yangtze Normal University, 1998, 0(4)

[3] Eating freshwater crayfish poses safety risks [J]. Food Safety Guide, 2014, (1)

[4] Accumulation characteristics of three heavy metals in Procambarus clarkii[J]. Journal of Ecology, 2008, 27(9)

[5] Comprehensive Utilization of Crayfish Processing Waste[J]. Scientific Fish Farming, 2007, (6)

Author: Wakakala, Chef Zhong in the Jianghu

Editor: Heijio sister

This article comes from the Species Calendar, welcome to forward

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