Why do crabs and shrimp turn red shells when cooked

Why do crabs and shrimp turn red when cooked?

Why do shrimp and crab turn red when cooked? It's about chemistry. It turns out that there is a bright red pigment in the shells of this cooked shrimp and crab.

If the red shell of a crab is immersed in a chemical called acetone, the pigment will dye the acetone a beautiful orange red, and the shell will fade and lighten. Later, someone isolated this pigment from lobster eggs and called it astaxanthin. Astaxanthin-containing animals are not only shrimp and crabs, but many crustaceans also use astaxanthin to dress themselves.

Some small shells mainly contain fenocyanins, and some crabs contain pterenthin. These pigments, including astaxanthin, have a similar structure to carotene, and they are abundantly and widely distributed in nature. The chemical name is ketone carotenoids, and they are the main components of the pigments contained in animals such as "shrimp soldiers and crabs".

The body color of living crustaceans varies depending on the species and the environment, but no matter what the body color of the living "shrimp soldier crab" is, as long as it is soaked or heated with formaldehyde, it will also turn red. This is because the pigment protein in the organism is denatured when it is heated, and the pigment that was originally bound to the protein "escapes" out, revealing the red color. In addition, after death, shrimp and crabs, due to the denaturation of proteins in the body, the pigment escapes, and the shell will also turn red.

Contains astaxanthin in the body.

The pigment area of the exoskeleton of shrimp and crab contains a protoastaxanthin, which is originally orange-red, but can be combined with different kinds of proteins to change to other colors such as red, orange, yellow, green, blue and violet. When the protein is destroyed, denatured, or separated from the original astaxanthin, the color changes to the original orange-red, so the shell of the shrimp and crab will turn red when cooked.

Under normal conditions, the shells of live crabs and shrimp are turquoise. But when the crabs and shrimp are in the pot. Most of the pigments are decomposed when exposed to high temperatures, only astaxanthin is not afraid of heat, and will not decompose when exposed to high temperatures, but will show a bright red color.

So, the boiled crab and shrimp turn red.

Astaxanthin has been widely recognized for its antioxidant, coloring, and immune-enhancing properties. The United States and other countries have been allowed to be used as food additives in production, as natural food additives, has broad development prospects.

Natural astaxanthin is a highly oxidizing carotenoid, which has the effects of antioxidant, anti-aging, anti-tumor, and prevention of cardiovascular and cerebrovascular diseases, and has been used in health food, high-end cosmetics, pharmaceuticals and other fields internationally. Astaxanthin itself is not stable, easy to oxidize, easy to decompose when seen in light, and its activity is mostly retained in the form of astaxanthin gel on the market.

1. The shrimp and crab turn red when cooked because the shrimp and crab contain astaxanthin.

2. The exoskeleton of shrimp and crab contains astaxanthin, which is a kind of carotenoid, after the pigment is combined with protein, it will turn into red, yellow, orange, green, blue-violet and other colors due to different proteins, when the protein is destroyed or denatured or the protein is separated from the pigment, the color will change back to the original orange-red, and the shell of the shrimp and crab will become red after cooking.