Shrimps are pink because of the presence of a pigment called astaxanthin in their diet, especially in the algae and crustaceans they consume. Astaxanthin is responsible for the pink to red coloration of shrimps.
Shrimp turn pink due to pigments called carotenoids. These are also responsible for giving carrots their orange color and tomatoes their red color. In shrimp, astaxanthin is the main carotenoid. In its natural state, it is bound to proteins, which mask its bright color. When shrimp are heated, the proteins detach and release this astaxanthin, revealing its intense pink-orange color. These molecules also act as antioxidants, protecting the animal's cells from potential damage.
Shrimp do not produce these orange-pink pigments called carotenoids themselves. In fact, they obtain them directly from their food. When they eat algae, plankton, or other small marine organisms rich in carotenoids, such as the famous astaxanthin, they store these pigments in their bodies. Therefore, the intense pink color seen upon cooking largely depends on their diet; the more carotenoids in their menu, the more they can accumulate. Some wild shrimp can thus display a brighter color than those raised on farms, depending on the available buffet for them.
Raw shrimp contain a pigment called astaxanthin, but it is trapped in proteins, which gives them an unappealing grayish, translucent, or bluish color. During cooking, heat alters the structure of these proteins: they denature, unfold, and release the astaxanthin. Once released, this carotenoid pigment fully displays its characteristic orange-pink color that is easily associated with well-cooked shrimp. This change is irreversible, which explains why shrimp never regain their original hue after cooling.
Shrimp adapt their coloration based on their environment, particularly by adjusting the quantity and type of pigments they store. For example, shrimp living in plant- or algae-rich waters often become darker or display more pronounced colors, leaning towards greenish or brownish hues. In contrast, those living on sandy or less colorful bottoms tend to show lighter, paler, or even almost transparent shades. This phenomenon is linked to the ability of these crustaceans to accumulate or camouflage certain pigments according to their needs for discretion from predators or to facilitate hunting. Underwater lighting also plays a role by stimulating the production of pigments more or less: areas exposed to intense light generally lead to brighter coloration in shrimp compared to deeper or darker waters.
The peacock mantis shrimp has exceptional vision, with eyes capable of identifying up to 16 types of photoreceptors, compared to only 3 in humans, allowing it to perceive colors in a way that is completely different from ours.
If you see a pale or very lightly colored shrimp before cooking, it may be due to the fact that it comes from a farm with a diet low in natural carotenoids.
Not all shrimp species turn pink when cooked. Some species, such as the blue tiger shrimp, can display different coloration, shifting from blue to orange or bright red after cooking.
Some salmon also acquire their characteristic pink color due to the ingestion of astaxanthin obtained from their diet, which mainly consists of small crustaceans such as shrimp.
Astaxanthin is a carotenoid pigment responsible for the pink color of shrimp after cooking. In its raw state, it is bound to various proteins, giving shrimp a gray or translucent color. Rich in antioxidants, this pigment also helps shrimp withstand oxidative stress in their natural environment.
No, the pink color of shrimp primarily comes from carotenoid pigments and does not directly affect their taste. However, a well-colored shrimp could be an indirect indicator of a rich and varied diet, which might indirectly influence its flavor quality.
A dull or unusual color after cooking could indicate that the shrimp is not properly cooked or that it was already spoiled before cooking. It is generally advisable not to consume shrimp that does not exhibit the expected coloration after cooking.
No, most shrimp are grayish or transparent when raw due to the binding of the astaxanthin pigment with certain proteins, and they only turn pink after cooking.
This can happen because the coloration of shrimp largely depends on their diet. Wild shrimp often have a more diverse diet, rich in natural pigments, while some farmed shrimp require the artificial addition of pigments to achieve a bright color.
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