Black Spots on Shrimp – Normal Or Spoiled?

If you’re a fan of seafood, you know it’s important to ensure that your shellfish are safe to eat. But even though there are plenty of ways to tell if shrimp has been contaminated, it can be tough to know if black spots on a shrimp or other shellfish are safe to eat.

What Are Black Spots On Shrimp?

Although shrimp are delicious, they do have some downsides. One of the downsides to shrimp is that they sometimes develop black spots on their shells. Various things, including poor water quality and improper handling procedures during processing, can cause these black spots.

Black spots on shrimp are not harmful, and you can safely eat black-spotted shrimp. But they make your shrimp look less attractive and may cause you to lose customers if they see them while eating at your restaurant!

Two Reasons Your Shrimp Has Black Spots

Black Spot Disease

A few different things can cause black spots on shrimp. One possibility is that the spots are naturally occurring melanized areas on the shrimp’s shell. Melanosis, also known as “black spot disease,” is a condition that affects crustaceans such as shrimp, lobsters, and crabs. It is characterized by the presence of black on the shell or flesh of shrimp.

Shrimp can sometimes have shell discoloration in the form of a black spot or melanosis. This is not caused by bacteria but an enzymatic reaction caused by naturally occurring amino acids and sunlight. If shrimp has black spots, it can still be of good quality and safe to eat.

Various factors, including physical damage, infection, or certain chemicals, can trigger melanosis. In shrimp, melanosis is often associated with the accumulation of a chemical called dopaquinone, which is produced by certain bacteria. Dopaquinone can be found in the environment and absorbed by the shrimp, leading to the development of melanosis.

Physical Damage

It is also possible that the black spots are the result of bruising or physical damage. If the shrimp have been handled roughly or subjected to rough conditions, they may develop black spots as a result of trauma. In this case, the spots should heal on their own over time.

Can You Eat Shrimp with Black Spots?

In general, black spotted shrimp are safe to eat as long as they’re fresh and handled properly. If the black spots are melanized areas of the shrimp’s exoskeleton, they are not harmful and do not affect the quality or safety of the shrimp.

However, if the black spots result from an infection or infestation by a pathogen or parasite, it is important to take care when handling and preparing the shrimp. If the shrimp are visibly ill or show other spoilage, it is best to avoid eating them to prevent the risk of foodborne illness. More on this later.

Look at shrimp that show obvious signs of melanosis but aren’t unsafe to eat.

Takeaway: it’s tough to reach any conclusions about the eating quality of shrimp simply because it’s sporting melanosis.

7 Ways to Check Shrimp For Freshness

Shrimp with black spots may have one of two things. Here’s how to distinguish between them:

1. Defrost shrimp

Thaw your shrimp in cold water. In this manner, you can distinguish between ice crystals and black dots on shrimp. You must defrost your shrimp for 20 minutes at room temperature before cooking them to check if they are safe to consume.

2. Remove the shell.

A quick and easy technique to tell if shrimp are safe to eat is to remove their shells. They are safe to consume if you can easily remove the shell from them. If it’s difficult or impossible, then your shrimp most likely include certain toxins that must be avoided. Fresh shrimp should have a mild smell.

3. Smell

Whether or not shrimp is safe to eat can be determined by how it smells. Take a quick sniff to assess the shrimp’s quality. This is because bacteria, freshness, and age affect how shrimp smell. If the shrimp smells rancid, it most likely tastes the same way.

4. Look

Fresh shrimp should have a moist, firm texture. If the shrimp looks slimy or discolored, it may be spoiled. The surface of the shrimp may appear cloudy or milky, and the flesh may have a gray or yellow tinge. The shrimp may also have a sticky or tacky texture.

5. Expiration date

Check the expiration date on the package of shrimp before purchasing or consuming it. If the shrimp is past its expiration date, it is likely spoiled.

Uses of Black Spotted Shrimp For Cooking

Shrimp frozen for too long can still be used for cooking, and the same goes for WSSV-infected shrimp. That’s right. You can even eat shrimp that has this disease, as the virus isn’t harmful to humans. The same goes for freezer-burned shrimp.

Freezer-burned shrimp are still great for cooking because they have the same taste and appearance as fresh shrimp. Nevertheless, the shrimp will become tough and rubbery if it is not thawed properly. One way to thaw the shrimp is to put them in a bowl of cold water.

One of the most noticeable changes in shrimp that have been freezer burned is that they can become drier due to a lack of moisture. This makes it tougher to chew than usual, but there are a few things you can try to help out, like adding some herbs, salt, and lemon.

You should avoid cooking them to eat on their own, as the changes present may be unpleasant. However, you can use them in other dishes, such as pasta, salads, and more. This will mask these issues and make them completely edible again.

So, use your shrimp with white spots for:

  • Pasta
  • Appetizers
  • Dips
  • Stir-fries
  •  Salads

How to Prevent Black Spots on Shrimp

According to LSU Louisiana Sea Grant researchers, you can prevent black spots in old shrimps using a compound derived from kiwifruit. They’re also developing more products and procedures for the Louisiana seafood industry using this compound.

Picture courtesy of Nick Hadad from LSU.

Here are other ways of preventing black spots from appearing on healthy shrimp:

Several factors, including disease, injury, or bacterial infections can cause black spots on shrimp. To prevent black spots from appearing on healthy shrimp, it is important to follow good management practices, including:

Maintaining proper water quality: Keep the water temperature, pH, and salinity within the appropriate range for the species of shrimp being raised. Perform regular water changes to remove excess waste and toxins.

Providing a balanced diet: Feed the shrimp a high-quality, nutritionally balanced diet to support their overall health.

Implementing proper sanitation practices: Keep the shrimp tanks and equipment clean to prevent the buildup of harmful bacteria.

Monitoring for signs of illness: Keep an eye out for any signs of illness or injury in the shrimp and take appropriate action if necessary.

Related Questions

Is the black stuff in shrimp poop?

Sometimes when you buy shrimp, you will notice a thin, black line along its back. Although removing that line is called deveining, it is not a vein or a blood vessel. It is the shrimp’s intestinal tract, and its dark color means it is filled with unappetizing grit.

What happens if shrimp turns black in the fridge?

If shrimp turns dull in the fridge, it is likely that they have begun to spoil and are no longer edible. You should store shrimp in the refrigerator at a temperature of 40°F or below to prevent the growth of harmful bacteria. If you’ve stored shrimp in the fridge for an extended period or has been left at room temperature for too long, it can begin to spoil and turn black.

If the shrimp has turned black and has a strong, unpleasant odor, it is best to discard it. Consuming spoiled shrimp can cause food poisoning and other health issues. To prevent shrimp from spoiling, it is important to store it properly and use it within a few days of purchasing it. If you are not planning to use the shrimp within a few days, it is a good idea to freeze it to extend its shelf life.

Read more on how to tell if shrimp has gone bad here.

What are black spots on shrimp meat?

 Black spots on shrimp meat are typically melanized areas that occur when the shrimp is damaged or injured. They can also result from the shrimp being infected with a bacterial or fungal infection. The black spots often indicate decomposition or spoilage and may be accompanied by an unpleasant odor. 

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