Why do shrimp change color when cooked?

The question that many people wonder is why shrimp change color when cooked. The simple explanation is due to the complex interaction of proteins in the shrimp shell. It is the high temperature that causes some compounds in the shell to be released and turn them orange-yellow, according to the nutrition page The Daily Meal (USA).

When cooked, the shrimp's shell will turn orange.

Raw shrimp are usually gray. Depending on the species, most shrimp have a grayish-blue shell. This shell contains a protein called astaxanthin. Fish also have this substance in their scales, but crustaceans like shrimp and crabs have it in particularly high amounts.

Astaxanthin is a carotenoid, a group of substances also found in carrots. They absorb blue light and appear red, orange, or yellow. But in shrimp shells, astaxanthin binds to a protein called crustacyanin. It is crustacyanin that affects astaxanthin's ability to absorb light.

However, when we cook shrimp, the high temperature will separate the crustacyanin protein from the astaxanthin. As a result, the orange-yellow color on the shell will appear. The shrimp meat does not have this orange-yellow color. We see the orange-yellow meat simply because it absorbs the color from the shell.

This phenomenon is not only true of shrimp but also occurs in other crustaceans, such as crabs. The discoloration of crab shells can also be explained in a similar way.

Interestingly, this phenomenon also occurs in flamingos. Flamingos have naturally white feathers. However, they eat a lot of shrimp and algae. Both of these foods are rich in carotenoids.

When ingested, the shells of the shrimp and algae are absorbed and passed into the body. As a result, the bird's feathers turn pink. This is similar to how a person who eats too many carrots will have a slightly orange skin color. However, unlike flamingos, if humans eat a lot of shrimp, their skin will not turn orange or yellow, according to The Daily Meal .

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