Why do shrimp change color when cooked?

The question that many people wonder is why shrimp changes 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 site 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 gray-blue shell. This shell contains a protein called astaxanthin. Fish also have this substance in their scales, but crustaceans like shrimp and crabs have a particularly high amount of it.

Astaxanthin is a carotenoid, a group of substances also found in carrots. They absorb blue light and appear red, orange, or yellow. But when present 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. Shrimp meat does not have this orange-yellow color. We see the orange-yellow meat simply because it is absorbed from the color of the shell.

This phenomenon is not only true for 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 shrimp shells 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's skin turns slightly orange if they eat too many carrots. However, unlike flamingos, humans will not turn orange or yellow if they eat a lot of shrimp, according to The Daily Meal .

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