Rumor has it that vendors inject water into lake crabs to increase their weight; an experiment shows they die 8 minutes after injection

When the autumn wind rises, crab legs get itchy, and it is almost time once again for the fine season of eating lake crabs. But not long ago, rumors spread online that unscrupulous vendors were injecting water into lake crabs to make them heavier and sell them for more money. People began to worry: can these tasty and nutritious lake crabs still safely climb onto our dinner tables? To solve this mystery, yesterday the Hangzhou Food Safety Supervision Association entrusted the third-party testing agency Zhejiang Gongzheng Inspection Center to conduct an experiment on water-injected crabs. A reporter followed the entire process and kept a detailed record.

Experimental materials: 4 fresh, live lake crabs. Among them, male crab No. 1 weighed 125.74 grams, male crab No. 2 weighed 123.10 grams, female crab No. 1 weighed 87.60 grams, and female crab No. 2 weighed 82.06 grams.

Experiment 1: Injecting clear water

Experimental method: Use a syringe to inject water (clear water) into female crab No. 1 from the back, 2 injections in total, 5 milliliters each;

Inject water into female crab No. 2 from the abdomen, also 2 injections in total, 5 milliliters each.

Experimental observation: During injection, water continuously flowed out from the injection holes or from the lake crab's mouthparts;

After injection, both crabs gained only about 4 grams;

Two minutes after injection, the vitality of both crabs was noticeably weakened;

Eight minutes after injection, female crab No. 2, which had been injected through the abdomen, died, while female crab No. 1, which had been injected through the back, still had a slight reaction in its eyes.

Expert explanation: A person in charge from the Hangzhou Market Supervision Administration told the reporter that crabs, like humans, have an electrolyte aqueous solution in their bodies, and injecting clear water destroys its normal concentration. This is like a person receiving an IV drip, which must inject an isotonic solution (referring to a solution with an osmotic concentration equivalent to that of blood plasma, such as 0.9% NaCl solution and 5% glucose solution. A solution lower than the osmotic concentration of blood plasma is called a hypotonic solution, and cells in a hypotonic solution can swell and even rupture. A solution higher than the osmotic concentration of blood plasma is called a hypertonic solution, and cells in a hypertonic solution can dehydrate and shrink). If clear water were injected, how could there be no problem? The fact that lake crabs die quickly after being injected with water follows the same principle.

Experiment 2: Injecting normal saline

Reporter's question: If that is the case, then if lake crabs are injected with an isotonic solution, will they not die?

Continuing the experiment: Take experimental normal saline (0.9% NaCl solution) and inject it into male crab No. 1 from the back, 2 injections in total, 5 milliliters each;

Inject it into male crab No. 2 from the abdomen, also 2 injections in total, 5 milliliters each.

Experimental process: During injection, there was no obvious overflow of water, which may be because male crabs have a relatively larger body capacity;

After injection, both crabs gained about 8 grams; two minutes after injection, there was no obvious change in the condition of the two crabs;

Eight minutes after injection, male crab No. 2, which had been injected through the abdomen, had poor vitality, and male crab No. 1 also showed weakened vitality;

Ten minutes after injection, both crabs had basically lost their vitality.

Expert explanation: When injected with normal saline, lake crabs will likewise lose their vitality and will also die before long. Because 0.9% NaCl solution is an isotonic solution intended for the human body, as for what an isotonic solution usable for lake crabs should be like, probably only professional researchers know. If ordinary small vendors wanted to use such an isotonic solution to make lake crabs heavier and sell them for a few more coins, the loss would outweigh the gain.

Experimental result: Whether lake crabs are injected with clear water or normal saline, they will lose their vitality or even die within a short time. Clearly, using these two methods to make dirty money seems unreliable. Then, could there be other methods? The relevant departments will continue to pay attention and follow up with inspections.