In terms of taste, crabs lose their original taste after they die. There is also a histidine substance in crab, which is easy to decompose and can produce histamine and histidine-like substances under the action of decarboxylase. After the death of crab, the midgut gland will soon fall apart, and histidine and digestive enzymes in it will decompose crab meat. So the taste of dead crabs is very strange, and the taste is greatly reduced.
The crab itself is non-toxic, but after the crab dies and its shell is broken, the protein in the crab will breed bacteria, and the infected bacteria will multiply in large numbers, and the bacteria may produce toxins. Dead crabs may be poisonous.
Crabs are easy to carry heavy metals. After the death of a crab, the midgut gland will quickly fall apart, and the digestive enzymes scattered inside will decompose the crab meat. Intestinal glands are relatively easy to enrich heavy metals, and heavy metals will also come out to produce pollution after decay.
If crabs die for a short time, they can still be eaten in cold storage. Remember, refrigeration is not freezing. Sea crabs are better than river crabs, because the living environment of river crabs is worse and there are more bacteria.