Significantly, this article would like to clarify that not only lobsters possess such changes but also the crabs and shrimps. They all belong to one family:crustacean family as we learned from elementary.
Exoskeletons of lobsters are made up of different pigments including red color the same with the one present in carrots called carotenoid. The very explanation why lobsters turned red when cooked is that when heat kissed the exoskeleton of the lobsters, the astaxanthin which is a carotenoid pigment responsible for their brilliant orange color reacts to the heat resulting to a more appetizing bright red-orange color. The reason why their shells appear dark and hardly seen the orange coloris because of the proteins that block the carotenoid from appearing. When the heat destroys the protein, it uncoils releasing the red pigment bringing reddish orange color to your favorite steamed whole lobster.
Beware of this. It does not mean that if they did not change color, they are not yetdone or cooked. Thus, it doesn’t have to take a lot of waiting until the color changed before removing from the fire. Overcooking might spoil the taste and juiciness of the lobster. Redness is not a reliable sign that signals your cooking is done. It shows that you have just destroyed the dark proteins in their shells exposing its most beautiful, vibrant and palatable color.