Live shrimp appear grayish-purple or grayish-green, but after cooking, you’ll notice they turn an orange-red color. We’re probably all familiar with this appearance.

But have you ever wondered why shrimp change color after cooking? What causes it? The color of shrimp after cooking is actually due to astaxanthin. And with the arrival of autumn and winter hot pot season, every time you cook seafood hot pots like shrimp and crab, a layer of reddish substance floats in the broth. Is this normal?

How does shrimp get its orange-red color?

Shrimp primarily feed on seaweed, plankton, and feed, which contain astaxanthin. This natural carotenoid accumulates in the shrimp’s body. Astaxanthin is most abundant in the shrimp’s pigment cells, giving it its orange-red color. The orange-red color of salmon is similar to the cause.

Aren’t shrimp naturally orange-red when alive? In fact, crustaceans like shrimp and crab also produce a protein called carbazocyanin in their bodies. This protein affects astaxanthin, preventing the shrimp from displaying its color when alive.

When astaxanthin binds to protein, its three-dimensional structure is affected, causing the shrimp’s body to appear blue-purple or turquoise under light.

Changes Caused by High Temperatures When Cooking Shrimp

When shrimp, crab, and other crustaceans are exposed to high temperatures and heat, the protein in the shrimp denatures and changes its structure, separating from the astaxanthin, making it less susceptible to heat breakdown.

This is why shrimp develop the natural orange-red color of astaxanthin. This is the magical change from blue-purple to orange-red when heated.

Is it safe to produce a red substance when cooking shrimp soup?

When cooking shrimp soup, seafood soup, or shrimp and crab hotpot, a reddish layer may appear in the broth after prolonged cooking. There have been claims that this is due to the chemical astaxanthin in the shrimp, and that excessive consumption can be toxic.

The red color in the broth is caused by the release of astaxanthin. Prolonged cooking of shrimp damages the cell membranes, allowing the cell fluid and astaxanthin to leak out, resulting in the orange-red color in the broth. Properly caught or farmed shrimp should be fine after passing aquatic product inspection. However, when choosing shrimp and other seafood, it’s important to carefully consider the source and freshness of the shrimp.

To choose shrimp and crabs correctly, be discerning and avoid seafood from unknown sources. Also, observe the appearance and freshness of the shrimp. For example, check whether the head, tail, and legs are intact, whether they have a natural blue-purple or gray-green color, and whether the shell and meat feel fresh and firm.

Are there any chemicals or a strange, fishy odor? Avoid seafood that has been improperly stored or stored. Now that you know about the cooking characteristics of shrimp that cause them to change color, does this solve one of your cooking questions?