Cooking lobster always feels a little magical: You drop a blue shellfish into a pot of boiling water, and a few minutes later, you take out a bright red shellfish.
Even scientists have long been at a loss to explain the chemistry underpinning this alchemy. One team of chemists from the University of Manchester in England believed they had an explanation way back in 2002, but later work indicated that their hypothesis only explained a third of the color change.
Now that same team of chemists thinks they've solved the other two-thirds of the mystery.
Their new research affirms their earlier idea that a chemical called astaxantin is involved in the color change; it has a red hue and is found in the shells of raw lobsters as well as cooked ones. But in raw lobsters, the redness of the astaxantin is obscured by the dark blue color of another chemical, crustacyanin, that is also present in the shell.
But when you cook a lobster, the blue crustacyanin molecules become denatured, or lose certain biological structures. This allows the red astaxantin, which is not denatured by the boiling water, to shine through. In this way, the changing color of a lobster shell is distantly related to the changing color of tree leaves in autumn. Leaves always contain the pigments that make them red, orange and yellow, but for most of the year, those pigments are masked by the bright green color of chlorophyll. Only in autumn, when the temperature cools and the sun's light starts to dim does the level of chlorophyll wane enough to make these warm-hued pigments visible.
This new research takes a little of the magic out of the color-changing lobster shell, but nothing will ever dim the splendor of the taste of a claw dipped in melted butter.