On June 15, reporters from the Huashang Daily and inspectors came to a large agricultural product wholesale market in the west of Xi'an. In the aquatic product area, the inspectors selected three merchants with the most customers to take samples. Each purchased a portion of crayfish and brought them back to the laboratory for testing.

A reporter from the Huashang Daily interviewed several citizens who came to buy crayfish at the aquatic product market. They all believed that crayfish are safe and can be eaten with confidence.

■Testing location: Xi'an Guolian Quality Inspection

■Testing objects: three crayfish purchased from the aquatic product market, sample one, sample two, and sample three

■Testing tools: sterile distilled water, sterilized centrifuge tubes, iodine solution, 33% zinc sulfate, absolute ethanol, slides, ultrasonic cleaning machine, crayfish sample numbering, microscope, etc.;

■Tester: Huai Ruijuan, Director of the Microbiology Department of Xi'an Guolian Quality Inspection Food Division

■Testing steps:

1. Place crayfish in a vessel filled with sterile distilled water .

2. Place the utensils in the ultrasonic cleaning machine for 2 hours.

3. Pour the liquid cleaned by the ultrasonic cleaner for 2 hours into a sterile centrifuge tube, and centrifuge for 3 times for 5 minutes in a centrifuge at a speed of 2815 per minute. The impurities in the water become precipitated for easy observation.

4. Pour off the supernatant of the separated liquids from the three samples, pour 33% zinc sulfate into the precipitated material, mix in a spiral mixer, and mix the mixed liquid Centrifuge for one minute and take out for observation.

5. In order to make the detection results more accurate, we use a microscope to observe.

■Test results:

The reporter observed that at the beginning, the inspectors put the lobsters into sterile distilled water and observed that the water was relatively clean. After the crayfish were cleaned in an ultrasonic cleaning machine for 2 hours, the water in the vessel became obviously turbid. Water No. 3 was the dirtiest, water No. 1 was cleaner, and water No. 2 turned yellow.

The three samples were observed with the naked eye and it was found that there were live insects in sample No. 1, while no parasites were found in sample No. 2 and No. 3.

It was observed under a microscope that no parasite eggs or cysts were detected in sample No. 2, while parasite eggs were detected in item No. 3.

This also means that parasites were detected in two of the three samples.

Huai Ruijuan said that some crayfish contain parasitic metacercariae. Once people eat such crayfish, they are likely to be infected with parasites and suffer from paragonimiasis.

It is difficult to kill parasites when cooking crayfish at home

When a reporter from Huashang Daily interviewed on the street, many citizens said that when cooking crayfish at home, they simply blanch them. After watering, stir-fry with chili peppers. Some people even deliberately shorten the cooking time in order to make the crayfish taste better, thinking that the meat will become unpalatable after being cooked for a long time.

Huai Ruijuan reminds citizens that these are not advisable. "It is difficult to remove parasites from crayfish. Ordinary cooking and frying may not kill the parasites. In addition to cleaning the crayfish before eating, the tendons on the back of the crayfish must also be removed. When cooking, the parasites must be removed. Cook them thoroughly, and it is best not to eat the heads of crayfish.”

Experts remind: Cook crayfish at high temperatures and cook them thoroughly

Huai Ruijuan reminded the public that dead lobsters are not safe. It is inedible. Because lobster is a high-protein organism and contains a lot of bacteria in its body. Once the lobster dies, the bacteria will decompose immediately. People who eat it will be easily poisoned and have diarrhea.

After buying live lobsters, it is best to keep them in clean water for 24-36 hours to allow them to spit out the sediment and other impurities in their bodies.

When processing lobster, the dirt in the gills must be removed, because a lot of bacteria are absorbed in the gill hairs. It is best to scrub the shrimp shell with a brush. The roots of the lobster's thin claws are most likely to harbor dirt and must be cut off.

When cooking crayfish, you must cook them thoroughly at high temperatures to ensure that the bacteria and parasites in the lobster are killed. How to ensure it is cooked through? Huai Ruijuan said: "Don't eat crayfish after stir-frying, because stir-frying does not make the crayfish completely cooked, and live parasitic metacercariae may still exist in the crayfish. Generally speaking, when cooking, Before frying, steam the crayfish for ten minutes in a steamer or use a pressure cooker for 10 minutes. The temperature reaches 100°C and continues for 10 minutes to kill the parasitic metacercariae in the crayfish."