Sep 14, 2012

Why Crustaceans Turn Red

Crabs, lobsters, crayfish, shrimp, and some other crustaceans turn red/orange when cooked from their typical blue-green to grayish color.

The exoskeletons of such creatures are made up of several pigments, one of which is a carotenoid called astaxanthin, which provides it’s reddish coloring (astaxanthin is the same carotene that gives salmon its color). At normal temperatures and when alive the astaxanthin pigments are hidden because they are covered with other protein chains that give their shells the bluish-gray or brownish-green color we see.

Exposure to heat destroys this protein coating, while the carotenoid pigment, astaxanthin still remains stable. So when you cook a crab or lobster or other crustaceans,  the heat breaks down all the pigments except for astaxanthin, causing the bright red color we see in cooked lobsters, crabs, and crayfish or the reddish-orange color of cooked shrimp.

Only the albino crab and lobster do not turn red when cooked because they have no pigmentation, so they remain the same white color even when cooked.

A one pound lobster is about seven to eight years old, and a eight pounder may be 20 to 50 years old. Lobsters are capable of living over 100 years.