Shrimp is a popular seafood that can be cooked in a variety of ways, from grilling to sautéing. But have you ever noticed that when you wash shrimp, it foams up like soap?.
It might seem strange, but this happens because many shrimp are treated with chemicals before they get to your plate. Chemicals like sodium tripolyphosphate and sodium bisulfite are often used to keep the color and texture of cheaper shrimp, whether they are farmed or caught in the wild.
These chemicals can cause the shrimp to foam when washed, and may even affect how they cook. We’ll talk about the science behind why shrimp foams when it’s washed and what you can do to make sure your shrimp is chemical-free and tasty.
Have you ever noticed shrimp foaming excessively when rinsed under running water? The sudsy foam billowing from shrimp can be puzzling. In this article we’ll dive into the reasons behind this phenomenon and explain what causes shrimp to foam when washed.
What Causes the Foaming?
The foaming seen when shrimp is washed is caused by a protein found in shrimp blood called hemocyanin.
Hemocyanin is an oxygen-carrying protein uniquely found in the blood of shrimp and other crustaceans It turns their blood blue and helps shuttle oxygen through their bodies
When shrimp are harvested, the hemocyanin in their bloodstream gets exposed to air. The interaction between the protein, air, and water causes the hemocyanin to foam.
As the protein encounters water and air bubbles, it changes conformation. This alters its surface chemistry, greatly increasing its foaming capacity. The more air bubbles the hemocyanin interacts with, the more foaming occurs.
The Science Behind Shrimp Foam
To understand the science behind the foaming we need to take a closer look at hemocyanin itself.
Hemocyanin is composed of large subunit proteins. These proteins contain copper atoms that reversibly bind oxygen molecules. This is what gives hemocyanin its oxygen-carrying ability.
When hemocyanin encounters air at the water’s surface, the conformational change exposes more of its hydrophobic regions. These hydrophobic areas on the protein are attracted to air bubbles in the water.
As more air bubbles interact with the protein’s hydrophobic patches, the hemocyanin lowers the surface tension between the air and water. This allows for easier formation of foam bubbles.
Additionally, individual hemocyanin proteins link together, forming networks around air bubbles. This further stabilizes the foam as it is produced.
Why Doesn’t Blood Foam Inside a Live Shrimp?
If hemocyanin naturally produces foam, why doesn’t shrimp blood foam while they are alive?
Within a live shrimp, the hemocyanin only encounters oxygen, not air bubbles. The hemocyanin binds reversibly with oxygen molecules without altering its surface chemistry or foaming.
It’s only when the hemocyanin is extracted from the shrimp and meets a turbulent mixture of air and water that the foaming reaction occurs.
Tips to Reduce Shrimp Foaming
While shrimp foaming is totally natural, here are some tips to minimize it when washing shrimp at home:
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Use cold or room temperature water rather than hot water. Hot water causes more agitation and foam production.
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Rinse shrimp quickly and gently to limit interaction with air. Avoid vigorous scrubbing.
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Don’t wash shrimp in soapy water. Detergent residue can further increase foaming.
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Rinse shrimp one at a time instead of multiple at once. This cuts down on shrimp knocking together to churn up more bubbles.
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If foaming is extreme, try soaking shrimp briefly in milk or salt water. This can displace some hemocyanin protein responsible for foaming.
Is the Foam Harmful?
While shrimp foam may look strange, it is completely harmless and natural. The foam is purely the result of hemocyanin proteins interacting with air and water.
The foaming does not damage the shrimp meat or alter its safety in any way. It also does not affect the flavor. The suds are simply cosmetic and dissipate quickly after rinsing stops.
Some people prefer to remove the vein from shrimp before cooking to reduce any residual blood and foaming. But this isn’t necessary and mainly done for aesthetic purposes.
The Takeaway
Seeing shrimp bubble up into a foamy lather when washed can be peculiar and mysterious. But the science provides a fascinating explanation.
The phenomenon comes down to specialized oxygen-carrying proteins in shrimp blood encountering air bubbles and lowering surface tension. While strange, the foam is harmless and naturally occurs.
Knowing what causes the shrimps’ bubbly reaction takes the mystery out of this culinary curiosity. So next time your shrimp starts foaming excessively, you’ll completely understand why!
Why Does Shrimp Foam When Washed?
As mentioned earlier, the foaming of shrimp when washed is due to the chemical treatments that they undergo. Sodium tripolyphosphate and sodium bisulfite are often used to stop melanosis, also known as “black spot,” which happens when shrimp heads and shells turn dark after being exposed to oxygen.
When these chemicals are applied to the shrimp, they can cause a reaction when washed with water. The foaming occurs as a result of the chemicals reacting with the water and creating bubbles.
Sodium tripolyphosphate is also known to make seafood soak up water, which makes it gain weight and change its texture. This can affect how the shrimp cooks, making it steam rather than sear when sautéed.
The Food and Drug Administration says that these chemicals are safe in small amounts, but some people may be allergic to sulfites. When buying shrimp, it’s important to read the labels and ask questions to make sure it’s free of chemicals and safe to eat.
The Chemicals Used To Treat Shrimp
Shrimp is often treated with two chemicals: sodium bisulfite and sodium tripolyphosphate (STP). Melanosis is a harmless darkening of the shrimp heads and shells that happens when they are exposed to oxygen. Sodium bisulfite is used to stop it. Also, black spots on the shrimp’s shells are kept off with this to make them look better. STP, on the other hand, is used to make the shrimp look better by making it firm, smooth, and shiny. You can do this by making the shrimp soak up more water, which can make them tough and tasteless.
Both of these chemicals are considered safe by the FDA in low doses. However, they can cause foaming when the shrimp is washed due to their reaction with water. Additionally, STP can cause the shrimp to steam rather than sear when cooked, which can affect its texture.
It’s important to know that these chemicals may have been used on wild-caught shrimp before they got to shore. To be sure that your shrimp doesn’t have any chemicals on it, you should ask the fishery or distributor directly if these chemicals are used. If unsure, purchasing shelled shrimp can help avoid any chemicals applied to the shell.
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FAQ
Why do shrimp get soapy?
Should you rinse shrimp?
Do you rinse shrimp after soaking in milk?
Why do you soak shrimp before cooking?
What happens when you clean and devein shrimp?
When you clean and devein shrimp, you’re removing this shrimp poop line from the back of the shrimp, along with any sand or debris that might be trapped there. By doing this, you’ll end up with shrimp that looks and tastes cleaner.
What are the side effects of eating shrimp?
Shrimp allergy can be identified from signs and symptoms that appear after consuming shrimp or smelling it, such as itching, the appearance of red plaques on the skin, swelling in the face, especially in the eyes and mouth, and in the throat creating the feeling of a lump in the throat.
Do you clean shrimp before cooking?
Clean shrimp before cooking when making Shrimp Spaghetti, Bang Bang Shrimp, or Air Fryer Shrimp. Clean shrimp after cooking when making something like shrimp salad. Since it’s served cold, you can poach the shrimp in their shells to produce more flavor. Leave the tails on when making shrimp cocktail, grilled shrimp, or coconut shrimp.
How do you clean deveined shrimp?
Colander + Water: Transfer the peeled and deveined shrimp to a colander and gently rinse with cool water to remove any grit. Drain and pat the shrimp THOROUGHLY dry before using. Use Cleaned Shrimp: Use peeled, deveined shrimp to make your favorite recipes.