Recently, the information about the price reduction of crayfish has been on the hot search on the Internet many times. Many crayfish lovers shouted "happy" in the comment area, "I eat crayfish twice a day"...... However, some netizens expressed concern because they had heard: "Crayfish grow in stinky ditches, like sewage, heavy metals exceed the standard, and cannot be eaten".
So, are crayfish really that dirty?
The picture is taken from the Internet
Crayfish love sewage
Usually heavy metals exceed the standard?
Many people have heard of the saying that crayfish live in sewage, excessive heavy metals, and are harmful to health.
In reality, the rumors are not true.
First of all, in terms of growing environment, crayfish are not suitable for living in sewage. At present, crayfish are standardized artificial breeding, and the scale of breeding is continuously expanded through the intensive cultivation of shrimp seedlings. In the process of breeding, it is necessary to properly fertilize and clean up the water body, and ensure the transparency and cleanliness of the water quality in the breeding area, and ensure that the water quality is clean.
Experiments have also shown that crayfish not only have no preference for high concentrations of ammonia nitrogen-type sewage, but also actively avoid when the concentration reaches a certain value, and if they can't avoid it, they will have abnormal behavior and even death. Therefore, this is enough to show that crayfish also prefer clean water, and sewage is not conducive to the survival and reproduction of crayfish.
Secondly, on the issue of heavy metal content in crayfish.
Some researchers tested the heavy metal content of different parts of crayfish, and the results showed that there were significant differences in the content of heavy metal elements in different parts of crayfish, and the content of heavy metal elements in abdominal muscles was significantly lower than that of shrimp heads, and the general trend was that shrimp heads > shells> feet > abdominal muscles.
This is because the liver, kidney, pancreas and other detoxification and excretory organs of crayfish are in the head, and these organs can produce a large amount of metallothionein to bind heavy metal elements, so heavy metal elements are more likely to be concentrated in the head of crayfish;
So, if you are really worried about the problem of heavy metals, if you love crayfish, you can stop talking about crayfish heads.
It should be pointed out that the heavy metal content of crayfish is closely related to the living environment, and if the aquaculture is standardized and the quality of the water source is maintained, the safety of crayfish meat can be ensured. The heavy metal content of the edible parts (abdominal muscles) of regular crayfish on the market is within the safe limit, so it can be eaten with confidence.
How nutritious are crayfish?
Crayfish is native to North America and has now become an important freshwater aquaculture shrimp in the middle and lower reaches of the Yangtze River in mainland China, and eating crayfish has become a dietary preference for more and more people. As long as the crayfish is purchased through formal channels, there is no need to worry about heavy metal residues, and the nutrition of crayfish is also good, so let's take a look.
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1 ordinary crayfish, the edible part is about 9 grams, 100 grams, equivalent to eating more than a dozen crayfish, think about it is also very enjoyable, so these dozen crayfish, what are the nutrients? Let's talk about it in detail (all take 100 grams of crayfish meat as an example).
1
High in protein and low in fat
Crayfish contains 19% protein, which is still a high-quality protein that is easy to digest and absorb, and the fat content is only 1.1%, and the calories of 100 grams of crayfish are only 90 kcal, which is lower than eating 1 large apple.
Such a high-protein, low-fat and low-calorie delicacy is very suitable for those who need to lose weight.
2
Rich in zinc
At 2.79 mg/100 g, 100 grams of crayfish can meet 22% and 37% of the average man's and women's daily zinc needs, respectively.
Zinc deficiency can make people picky eaters, and in severe cases, it can also lead to pica, affect brain function, affect wound healing, susceptibility to respiratory infections, induce ADHD, affect male fertility, hair loss, rough skin and epithelial keratosis.
3
Rich in selenium
The selenium content is as high as 39.36 mg/100 g, which is twice that of Chinese prawns and nearly 5 times that of pork loin that we commonly eat. Eating 100 grams of crayfish can meet 66% of the general population's daily selenium needs.
Selenium can protect cardiovascular and myocardial health, selenium deficiency can lead to reduced immunity, can also cause growth retardation and neurological visual impairment, severe selenium deficiency can induce Keshan disease.
4
Rich in retinol
With a retinol content of 77.6 mg/100 g, this ingredient can help relieve eye fatigue, maintain normal visual function, and protect the eyes.
However, if the cooking method is not suitable, eating crayfish will make people gain weight, so let's talk about it later.
There are 4 points to pay attention to when buying crayfish
Recently, crayfish have been listed in various places, what matters do you need to pay attention to when buying to buy good crayfish?
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1
Look at the status
Crayfish are better to buy alive. This is because the most important organ of crustaceans is a structure called the midgut gland or hepatopancreas, which secretes digestive enzymes to break down food, as well as absorb and store fat, and once the crustacean dies, it becomes a source of rapid spoilage, and digestive enzymes destroy the tubules in the glands and expand outward to the muscles, making the muscles mushy and soft, and the reproduction of microorganisms will also increase. And the high temperature in summer is more conducive to the reproduction of bacteria.
If you need to store it for a period of time after buying it home, it is best to store it at 0°C ice temperature, and the storage period should not exceed 11 days; refrigerated at 4°C, the storage time of fresh crayfish is recommended to be controlled within 8 days, and if the crayfish is refrigerated immediately after death, the storage time is within 4 days. However, considering the taste and safety, let's not be so extreme, buy crayfish and put it in the pot on the spot, and settle down for the sake of the ingredients.
Frozen lobster tails are generally processed when the crayfish are alive and can be cooked and eaten with confidence. However, it is recommended that you buy less at one time, as freezing in a household refrigerator for a long time will cause the meat to become tough and the taste to deteriorate.
2
Smell the smell
Fresh crayfish has its inherent fishy smell and aroma, and if it has a fishy smell, sour taste, and ammonia smell, it is not fresh.
3
Feeling of the hand
Fresh lobster meat that is elastic when pressed, non-sticky and tightly organized.
4
Look at the "origin"
It is best to buy farmed crayfish through formal channels, not wild crayfish.
Cooking recommendations for crayfish
Boiled crayfish will give off an aroma similar to stone fruit and popcorn, and it will taste a little sweet. Crayfish usually taste better when cooked in the shell, because the shell of the crayfish not only retains the flavor of the meat, but also contains proteins, sugars and pigment molecules, which can make the meat closer to the shell taste better.
In addition, you should also pay attention to the cooking method, as mentioned earlier, the crayfish itself is indeed high in protein and low in calories, which is very helpful in weight control. However, if you often eat spicy crayfish, fried lobster tails, braised crayfish and other heavy flavors, you may get fatter and fatter the more you eat. In contrast, steamed crayfish and garlic crayfish will be healthier.
Who should eat less or not eat?
1
People with gout
The purine content of crayfish is 174 mg/100 g, which is a high-purine food, and it is best not to eat it if you have gout or hyperuricemia. Some people like to eat crayfish with a bottle of beer, which is more likely to induce gout.
2
People with hypercholesterolemia
Crayfish has a higher cholesterol content of 121 mg/100 g, which is 2.2 times that of pork loin, and should be eaten sparingly or not at all for people with hypercholesterolemia.
3
People with allergies
Tropomyosin is one of the main allergens in shrimp, and if you are allergic to other shrimps, it is best not to eat crayfish as well. Allergies can cause symptoms such as rashes, diarrhea, asthma, shock, and even life-threatening.
4
People associated with other diseases
For example, people with asthma, kidney disease, and people taking statin hypolipidemic drugs need to follow the doctor's instructions to determine whether they can take it.
Summary:
If you eat crayfish and eat shrimp tails, then eat with confidence, if you like to eat heads, then it is better to eat less!
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Source: Popular Science China