Cooking shrimp can be easy because it cooks quickly. But there’s also a downside to the fact that shrimp cook quickly, and it’s overcooking. For that reason, it is important to know when shrimp is done. One way to know is color. Here, you’ll learn what color shrimp are when cooked.
When properly cooked, the shrimp exterior is pink. The tail is red while the flesh is white and partially opaque. The flesh can have some pink or red accents. You need a good eye for color and overall appearance to know if shrimp is done.
If the flesh is bright white and too opaque, then the shrimp may be overcooked. Meanwhile, if the flesh is too translucent, then the shrimp may be undercooked. Besides color, there are other ways to check if the shrimp is cooked. Keep reading below to find out.
Why Shrimp Changes Color
Shrimp becomes pink or reddish because of a pigment called carotenoid. Carotenoids are pigments that appear yellow, orange, or red. There are over 700 known carotenoids. The first one discovered was beta-carotene, and it was found on carrots, hence the name.
The specific kind of carotenoid that shrimp have is called astaxanthin. The astaxanthin is mostly found on the exoskeleton. So if shrimp have these carotenoids, then why are live or raw shrimp bluish-grey?
The reason is that these pigments are wrapped up and covered by protein. That protein is called crustacyanin. Crustacyanin is found in other crustaceans like crabs and lobsters. It is also a pigment that appears blue.
Hence, the name is derived from “crustaceans” and “cyan”. The crustacyanin bluish-grey color is visible instead of the pinkish or reddish color.
When cooked, the crustacyanin unravels. It then releases the astaxanthin, hence the change in color. Besides the exoskeleton, there are also carotenoids on the shrimp flesh. That is why you there are pinkish or reddish accents on cooked shrimp flesh.
Why Shrimp Flesh Turn Opaque
Another change we see on cooked shrimp is on the flesh. Raw shrimp flesh is translucent. Meanwhile, cooked shrimp flesh is white and slightly opaque. This change in appearance on shrimp flesh is similar to that on egg whites.
Raw egg white is liquid and transparent while cooked egg whites are solid, white, and opaque. The reason is protein denaturation because of heat. Proteins are folded and arranged in many complex configurations.
When heated, the energy from the heat allows the protein to rearrange and reconfigure. These physical changes are called denaturation. Ultimately, the protein denaturation on shrimp flesh makes it white and more opaque.
Other Changes on Cooked Shrimp
Another change you notice on cooked shrimp is the shape. Cooked shrimp slightly curl into a C. The shrimp curl because the muscles contract as the flesh cooks. Specifically, there is a muscle that looks like a vein that runs along the length of the shrimp on its belly. It is this “vein” that does much of the curling as shrimp cooks.
How To Keep Shrimp Straight When Cooked
You may want to keep your shrimp straight for aesthetics or presentation. Here are two ways to do it.
One way is to remove that muscular “vein” you read earlier. You need some precise knifework to do this task. Place the sharp tip of the knife under the “vein” to raise it from the abdomen. Afterwards, gently pull it out just as you would when undoing a thread from stitching.
Another way to keep the shrimp straight is to make precise shallow incisions on the abdomen. You specifically make the cuts on the hinges where the muscle curls. Be careful to not cut too deep. Otherwise, the shrimp will fall apart.
Either of these methods can make the shrimp more straight, but not perfectly straight. There may still be some slight curling. If you want perfectly straight shrimp, then you will have to skewer them. Skewer the shrimp after doing either of the straightening methods above.
Pink Raw Shrimp
There are shrimp that are naturally pink when raw. Examples are shrimp found in the Atlantic Ocean. Pink shrimp found in the Gulf of Mexico are called Gulf Pink Shrimp or simply “pink shrimp”. Many are harvested in Southern Florida.
Pink shrimp from the northern Atlantic are called Atlantic Northern Shrimp. Other names are “salad shrimp” and “coldwater shrimp”. However, fishing for these shrimp is now prohibited. Their population is getting low.
The spot prawn is another example that have a distinct red or pink color when raw. The name “prawn” is actually inappropriate. Prawns and shrimp are biologically different (More on that topic below).
These shrimp are found in the North Pacific. They are commonly harvested in the waters near Alaska. Hence, they are also called Alaskan Prawns.
Take note that, these raw pink shrimp aren’t as “pink” as they are when cooked. When raw, the pink is dull or pale. Plus the flesh is more translucent. These shrimp still turn bright pink when cooked. Their flesh also turns white and opaque.
How To Know If Shrimp Have Gone Bad
You wouldn’t want to taste shrimp that may be bad, so your next best options are to use your other senses.
The easiest way to know if shrimp have gone bad is the smell. Fresh shrimp smells a bit salty, like seawater. Spoiled shrimp simply smell awful. Even if the shrimp is just starting to go bad, you can tell a distinct off odor.
When you already smell those off odors, don’t bother cooking. You risk giving yourself food poisoning. Just throw those shrimp away.
Another way to know if shrimp have gone is by looking at them. The shells of spoiled shrimp may be detached from the body. There may also be discoloration, usually black spots on the tail or shell.
Broken shells are also a red flag because shells of spoiled shrimp break easily. If the heads are still on, the eyes of spoiled shrimp are shrunken, dried, or completely gone.
If you’re at the store or market, also check if the shells appear yellow or gritty. This color indicates that a chemical has been used to bleach the shells. An example of a bleaching chemical is sodium bisulfate. The chemical may have been used to conceal spoilage.
Lastly, you can also feel the shrimp. Spoiled shrimp are mushy and their shells break easily. Their shells also detach from the body easily. Spoiled shrimp are also slimy, which is different from just being wet.
Are prawns and shrimp different?
Prawns and shrimp belong to different classifications in the animal kingdom. Thus, they have different anatomies. But an easy way to tell is by looking at the legs. Prawns have 2 pairs of legs with claws. Shrimp have only two pairs.
Do flamingos turn pink from eating shrimp?
Flamingos are pink partially because they eat shrimp. The carotenoids from the shrimp transfer onto the feathers of flamingos. Hence, flamingos turn pink. But flamingos also get their pink color from eating algae that also have carotenoids.