Shrimp and crab exoskeleton pigment area contains a proto-prawn erythrin, belongs to the carotenoid pigment, the pigment was originally orange-red, but can be combined with different kinds of proteins, and will become red, orange, yellow, green, blue and purple and other colors. When the protein destruction, denaturation or separation of the original shrimp red pigment, the color is changed to the original orange-red, so shrimp and crab cooked, the shell will become red. In the crab, shrimp shell below the cortex, there are many pigment cells, can show different colors, and with the environment of light and dark, these pigment cells can also stretch or contract, when the environment is brighter, pigment cells will stretch, shrimp and crab color is more distinct, the environment is darker when the pigment cells are contracted, shrimp and crab color looks less obvious.

Under normal circumstances, the shells of live crabs and shrimp are lime green. However, when the crab, shrimp pot, most of the pigments encountered high temperatures are decomposed, only astaxanthin is not afraid of heat, encountered high temperatures will not be decomposed, but instead of showing bright red, so the cooked crab, shrimp will become red.

It's because of the shrimp. Crabs originally contained a substance called astaxanthin. It makes the whole thing look green. When boiling. Because of the oxidizing effect of astaxanthin.. So it turns red!

Carotenoids, to reduce astaxanthin is the most important, it is the composition of shrimp and salmon and other red main substances Original astaxanthin exists in the shell of shrimp, because of the protein binding, so blue-purple, once the heat denaturation of proteins, it will immediately return to the original red but Ban Ao Xanthan and protein binding, still showing yellow. Orange. Or red, this is some shrimp or crab in the living body, its shell itself is the reason for the red color

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