Why Do Lobsters Turn Red When Cooked?


Picture a lobster in your head. What colour is it?


Red, right? Well, it may surprise you to hear that lobsters are actually usually a greenish-brown colour in the wild (see below). It's really not as aesthetically pleasing as the red lobsters we imagine. The truth is that lobsters remain this colour until they're cooked.

This crazy colour change isn't just a chef's special, to make it look more vibrant on your plate, but is the result of a chemical reaction to heat!


A living lobster has a protein in its shell, called crustacyanin, which is wrapped around a pigment called astaxanthin. This pigment absorbs blue light, so it appears to be an orangey-red colour. The crustacyanin wraps so tightly that it flattens the pigments, changing the way it absorbs light. The resulting crustacyanin-astaxanthin complex appears blue-green in colour.


This soon changes when the lobster is cooked. Crustacyanin doesn't cope well with heat, so when put in a pot of boiling water, the bonds break, unwinding the complex. Now it's not being flattened by crustacyanin, astaxathin's orginal light-absorbing properties are restored and appears red.


Did you know: Flamingoes get their colour from astaxanthin. They feast on shrimp, which also contain this pigment. The pigment is released during digestion, giving the feathers a pink hue.

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