Never consume dead crabs, as they can cause poisoning or even death. After capture, crabs often struggle, increasing lactic acid levels in their bodies. This leads to rapid bacterial proliferation after death, spreading into the crab meat. Bacteria break down amino acids, producing histamine—a harmful substance that causes allergic food poisoning.Additionally, substances like histamine may form, causing vomiting, abdominal pain, and diarrhea. Therefore, careful selection is essential.
Crabs typically feed on decaying matter, such as animal carcasses. Pathogenic bacteria, parasites, and toxic substances often reside in their gills and digestive tracts.Despite this, consuming live crabs (with gills and internal organs removed) generally does not cause poisoning. This is because live crab muscle tissue typically lacks pathogenic bacteria and toxic substances. However, as a crab remains out of water, its vitality gradually diminishes over time. Bacteria both inside and outside the body begin to multiply extensively, penetrating deep into the muscle tissue where decomposition begins. Once the crab dies, bacterial growth accelerates dramatically, resulting in the carcass becoming heavily contaminated with bacteria and toxins.
This toxin is histamine. As a high-protein food, crab contains the amino acid histidine. Under the action of histidine decarboxylase, histidine undergoes decarboxylation to form histamine. When histamine accumulates to a certain level, consuming the crab poses a risk of poisoning.
Generally, adults ingesting over 100 milligrams of histamine can experience allergic reactions such as facial flushing, skin allergies, and conjunctival hyperemia, accompanied by headaches, dizziness, rapid pulse, palpitations, thirst, throat burning, and lip swelling.Some may also experience numbness in the mouth, tongue, and limbs, along with generalized weakness and restlessness. More severe cases may involve asthma, breathing difficulties, dizziness, and fainting.
Some might ask: After boiling crabs, aren't they still dead? Aren't we still eating dead crabs?Why can't we eat naturally dead crabs?
There's a difference here. When crabs die naturally, toxins in their bodies multiply, and these toxins 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 ensures all pathogens in the crab meat are eliminated, leaving the crab deliciously fresh.
However, if a crab dies due to improper storage, it should be discarded immediately. This is crucial for your health and the health of your family.
How to select fresh crabs?
As crabs spend more time out of water, they gradually lose vitality, their texture deteriorates, and toxic substances may even develop. Therefore, ensuring the crab's freshness is paramount.
To determine freshness: Touch the crab's eyes—vigorous reaction indicates vitality. Flip the crab belly-up; if it flips back on its own, it's sufficiently healthy. Place your finger between its claws—strong pinchers signify robustness. Observe for foam: a crab expelling bubbles out of water is alive.
How to select hairy crabs? Careful selection involves five key observations.
First, examine the shell. Crabs with a dark green, glossy carapace typically have thick, plump meat; those with a yellowish shell are often leaner.
Second, inspect the belly button. A protruding belly button usually indicates a crab rich in roe and fat; a sunken one often signifies insufficient body fat.
Third, examine the claws. Those with dense, bushy hairs on the claws are robust and mature; claws lacking hairs indicate a soft, underdeveloped body.