Dead crabs contain toxins. According to traditional Chinese medicine, crabs have a salty and cold nature. Individuals who frequently experience cold hands and feet (especially women), those with a cold constitution, or those who are physically weak should avoid excessive consumption. Alternatively, adding more pungent spices like ginger, scallions, and garlic during cooking can help neutralize the crab's cooling properties with their warming attributes.Alternatively, drink a cup of brown sugar ginger tea after eating crab to warm the stomach, eliminate fishiness, and dispel cold. Additionally, folk wisdom advises against eating cold-natured fruits like persimmons before or after crab consumption—this prevents excessive intake of cold foods that could cause bodily coldness and discomfort.
Crabs are highly resilient scavengers with strong immunity. Though they consume bacteria- and virus-laden food, their immune systems suppress these pathogens. However, once a crab dies—or even when it's near death—bacteria and viruses proliferate rapidly, producing harmful biological toxins.Because crabs feed on decaying matter like animal carcasses, their digestive tracts often harbor pathogenic bacteria and toxic substances. Upon death, these pathogens multiply rapidly.Additionally, crabs contain significant amounts of histidine. This amino acid breaks down easily, producing histamine and histamine-like substances through decarboxylase action. This process accelerates after death. The longer a crab remains dead, the more histamine accumulates internally. When histamine levels reach a certain threshold, poisoning occurs.Therefore, if you see crabs that appear half-dead or lethargic, it's best not to eat them.
Consuming such crabs can cause severe food poisoning, leading to dehydration, electrolyte imbalance, convulsions, and even shock, coma, or sepsis. Common symptoms include nausea, vomiting, abdominal pain, and diarrhea.
Some might ask: If you boil the crab, isn't it still dead? Aren't you still eating a dead crab?Why can't we eat naturally dead crabs?
There's a difference here. When crabs die naturally, toxins in their bodies multiply. These toxins also break down the crab meat. However, when you cook crabs yourself, they've already expelled toxins from their bodies and undergone high-temperature cooking. This effectively prevents bacterial spread and better kills bacteria.
Moreover, boiling them for about 20 minutes after the water comes to a boil is necessary to kill pathogens within the crab meat. While crab is incredibly delicious, if it died due to improper storage, it's best to toss it straight into the trash. This is for your own health and the health of your family.
While crabs offer rich nutritional value and come with specific preparation guidelines, consuming dead crabs is absolutely prohibited. After reading this guide, you should now understand more about crab safety. If you're a crab enthusiast, memorizing these precautions is essential to avoid compromising your health.
How to select crabs: Those that bubble when out of water are alive.
After capture, crabs often struggle, increasing lactic acid in their bodies. This causes bacteria to multiply rapidly after death and spread into the crab meat.Bacteria break down amino acids in the crab, producing harmful histamines that cause allergic food poisoning. Another substance, histamine-like compounds, can induce vomiting, abdominal pain, and diarrhea. Therefore, careful selection is crucial.
Always purchase live crabs, as dead crabs contain toxins harmful to human health. When a crab dies, histidine in its body breaks down into toxic histamine. The amount of toxins produced increases steadily with the duration of death. Therefore, selecting live crabs is essential.
When selecting, gently press the shell near the crab's eyes with your finger. If the eyes move immediately, it indicates strong vitality. You can also place your finger between the claws; if the claws are powerful, it signifies the crab is vigorous. Additionally, if a crab spits out bubbles when removed from water, it is alive and safe to purchase.
Distinguishing male from female crabs is straightforward: flip the crab over. A triangular underside indicates a male, while a rounded underside signifies a female.
Experts, however, can tell by examining the legs alone. Female crabs have grayish-black tufts of hair on their claws, absent elsewhere. Males possess fine, brush-like hairs arranged on all eight legs.