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 to increase their weight. The simple impurities they often use today are:

- Algar (algae): 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. It is unclear whether this is considered an impurity or not 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, many sellers inject water into the shrimp to make a profit. 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 that shrimp 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 as usual.

Distinguishing between wild tiger prawns and industrially farmed tiger prawns

For the same size, farmed shrimp are always lighter than wild shrimp (or in other words, 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 paler, ivory white, and have less beaks.

The shell of natural shrimp is hard and rough while that 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 have a red and white color, 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 happens 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.

Freshwater 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 has white legs, flat body, smooth white shell, short and white whiskers. Land shrimp has red legs, round body, redder shell, rough and dotted, long red whiskers.

According to Dan Viet