Why do crustaceans turn red when cooked?

[Global] Today, let us find out why crabs, lobsters, crayfish, shrimp, and some other crustaceans turn red/orange when cooked.

Typically, the exoskeleton of most crustaceans has a blue-green to grayish color and sometimes they appear a brown or olive green, with just a hint of red; with a few exceptions like the blue and yellow lobsters and crabs.

Crustaceans have exoskeletons, and while the animal is in the sea, the exoskeleton primarily has a blue-green to grayish color. The exoskeletons contain a carotenoid called astaxanthin.

Carotenes are pigments, and astaxanthin is the same carotene that gives salmon its color. When crustaceans are uncooked, the astaxanthin pigments are hidden because they are covered with protein chains; these protein chains give the shells their bluish-gray color. Heat destroys the protein coating, and when the animals are cooked, the astaxanthin molecules are released, thus changing the color of the crustaceans.


In general, animals do not synthesize carotenoids de novo, and so those found in animals are either directly accumulated from food or partly modified through metabolic reactions.  Only plants and protists (bacteria, algae, fungi) are capable of synthesizing carotenoids. Therefore astaxanthin must be available in either their native habitat or manufactured diet to meet metabolic nutritional requirements.

Why Do Crustaceans Turn Reddish-Orange When Cooked

In the natural aquatic environment, astaxanthin is biosynthesized in the food chain within microalgae or phytoplankton at the primary production level. The microalgae are consumed by zooplankton, insects or crustaceans which accumulate astaxanthin, and in turn are ingested by fish which then accrue astaxanthin.

Benefits of this essential carotenoid include roles as an antioxidant and provitamin A activity, as well as enhancing immune response, reproduction, growth, maturation, photoprotection, and defense against hypoxic conditions.


Exclusively reported by Algae World News

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