Farmers share secrets to identify shrimp injected with impurities

Graduated from Nha Trang University of Fisheries in 2009, Mr. Duong Dinh Nam has 7 years of experience in shrimp farming and working as a "shrimp driver" in Ca Mau. Dan Viet would like to share Mr. Nam's article on the secret to help housewives choose truly clean shrimp for their family meals.

Characteristics of "identifying" shrimp injected with impurities

In order to earn more profit, many sellers have injected impurities into shrimp with the purpose of increasing the weight of the shrimp. The simple impurities they often use today are:

- Algar (grass jelly): This type is quite commonly used and easy to recognize.

- Shrimp meat: they grind small shrimp meat and inject it into large shrimp because large shrimp are many times more expensive than small shrimp. Whether this is considered an impurity or not is unclear because it is all shrimp meat.

- Purified water (clean water): This method is only used when selling fresh shrimp on the spot because after 18-24 hours, when shrimp is frozen, the shrimp absorbs about 5-10% of its weight in water. Therefore, when newly caught, in order to make a profit, many sellers inject water into the shrimp. Pumping purified water is basically difficult to detect and does not affect the health of consumers, but from an economic perspective, it will cause damage to the buyer.

With the naked eye, we can easily recognize shrimp that has been injected with impurities. Specifically:

- Shrimp body injected with impurities is abnormally fat and round.

- The shrimp head swells up.

Shrimp injected with impurities. (Illustration photo. Source: Internet)

- Tense joints are difficult to stretch.

- The flared tail cannot be folded.

- The spikes at the tail are raised and not folded down like normal.

Distinguishing between wild tiger shrimp and industrially farmed tiger shrimp

For the same size, farmed shrimp are always lighter than wild shrimp (or to put it simply, wild shrimp are firmer than farmed shrimp). Farmed shrimp are usually only 80% as heavy as wild shrimp. For example, 10 farmed shrimp will weigh the same as 8 wild shrimp of the same size.

Naturally farmed shrimp have a dark, firm color.

In terms of color, natural shrimp are often dark in color and have more beaks. Industrially farmed shrimp are lighter in color, ivory white and have less beaks.

The shell of natural shrimp is hard and rough, while the shell of farmed shrimp is softer.

After processing, the shell of natural tiger prawns is very red, the meat is firm, fragrant and sweet. Industrially farmed prawns are red mixed with white, the meat is slightly loose and powdery.

Another special thing that housewives need to note is that the hepatopancreas, located on the head of natural shrimp, will be green, red or black because they eat algae, plankton... but industrially farmed shrimp are only black because they eat industrial food.

Beware of mixed whiteleg shrimp and freshwater shrimp (shrimp).

Mixing goods often occurs between whiteleg shrimp and freshwater shrimp (also known as silver shrimp or shrimp). Why do they mix goods? Because they are 70% similar. And for the same size, whiteleg shrimp is 50% cheaper than freshwater shrimp. And whiteleg shrimp is easy to buy in quantity, while freshwater shrimp is much more difficult.

Shrimp is also known as freshwater shrimp or silver shrimp.

It is not too difficult to distinguish these two types of shrimp. White-leg shrimp have white legs, flat body, smooth white shell, short and white antennae. Land shrimp have red legs, round body, redder shell, rough and dotted, long red antennae.

According to Dan Viet