Crabs can not be eaten when they are dead, the meat of the dead crabs will change and will damage human health. The reason is analyzed as follows:

Crab in the water is mainly to dead fish, dead shrimp and other dead animal carcasses for food, thus in the crab body will be specific large number of bacteria, live crabs can through their own metabolism will be excluded from the body, but the dead crab bacteria will be gathered in the body of the crab, and at the same time will produce toxins, people eating dead crabs will be poisoned.

Second, how long after the crab is dead can not eat?

Despite the fact that the crab is just dead, it contains proteins and fats, etc. will become the nutrients of the bacteria, resulting in a large number of bacterial growth, and at the same time decomposition of proteins into cadaverine and histamine, cadaverine and histamine have toxicity, eaten will lead to toxicity and histamine can lead to allergies, limb numbness, skin allergies, general weakness, and even asthma, respiratory difficulties in allergic phenomena.

If you find crabs dead, you will not be poisoned if you cook them immediately. But for the sake of health, it is best not to eat dead crabs.

Three, eat the dead crab will be?

1, poisoning

Crab is carrion, often eat some dead animal carcasses, because the crab body contains some bacteria, pathogenic bacteria and other substances, so when it is dying or dead, bacteria will quickly decompose the protein of the crab, resulting in a rapid rise in the content of cadaverine and histamine, which is a poisonous substance, so human consumption will lead to poisoning or allergies.

2, diarrhea

After the death of the crab, the bacteria in the body quickly invade the inside of hairy crabs, hairy crabs are rich in protein and fat, rich in nutrients, the invasion of the bacteria quickly grow, consumption is easy to diarrhea, vomiting, abdominal pain and so on.

Four, how to see the dead and alive crabs?

1, pick up the bundled hairy crabs with a hand touch the eyes to see if the blinking, blinking means live.

2, take half a basin of water, put the tied crab into the water, see if the crab's mouth spit bubbles, spit bubbles means live. (Remember, do not put the bundled crab into the water for a long time, because the water does not have enough oxygen, the crab will soon suffocate and die)

3, touch the crab claw, straighten the smallest claw, see whether it is quickly and naturally curved, if it is naturally curved, it means that the crab is fresh and alive.

4, untie the bundled crab, see if the crab crawling, can crawl that the crab is very lively.

Fifth, how to choose crabs?

1, look at the crab shell

Where the back of the shell is black-green, with light, are thick and strong meat; while the back of the shell is yellow, the meat is thin.

2, look at the navel

Where the navel protrudes, are fat cream full of fat; and navel concave, the fat body is not enough.

3, look at the chelipeds

Where the chelipeds on the fluffy tufts, are fat feet old and healthy; and chelipeds without fluffy, the body is soft without fat.

4, look at the vitality

River crabs will be placed on their backs, abdomen to the sky, all can quickly turn over and crawl, it is old and healthy; and can not turn over and crawl, the vitality is poor, can not buy.

5, see male and female

Lunar September around, female crab gonads mature, meat; lunar October after, male crab gonads mature, meat.

Dead crabs can't be purchased and consumed no matter how cheap they are. In addition, the crab body contains more histidine, the longer the crab is dead, the more histamine accumulated in the body. Histamine is a toxic substance, when it accumulates in the body to a certain extent, it will cause poisoning.