[Minnan Net]
Now that freshwater crabs are fully mature, it is a good time for people to eat crabs. Some merchants will sell crabs labeled "wild", although the price of such crabs is much more expensive than ordinary crabs, but many people still flock to it. In fact, not only crabs, people in life often favor wild things, and has been circulating such a saying: wild is greener, safer, breeding whether taste or nutrition is not as good as wild. But is the wild really that good?
Specific analysis of specific problems Is not meaningful compared to wild and farming alone
"It doesn't make sense to simply compare the wild and farmed crabs which are safer and greener." On November 17, Cheng Yongxu, a professor at the School of Fisheries and Life Sciences of Shanghai Ocean University, said in an interview with Science and Technology Daily.
Cheng Yongxu said that to talk about this issue, we must first figure out the meaning of wild. Wild usually refers to animals and plants that live in the wild in their natural environment and are not domesticated and cultivated by humans. For animals, the meaning of wild can also be derived as animals that are artificially released into the natural environment and escape to the natural environment.
At present, wild crabs may mainly be crabs that escape to rivers and lakes (or are released into rivers and lakes) in culture. In the usual sense, such wild crabs are greener and safer than farmed crabs (such as those farmed in the same rivers and lakes and ponds of the same water source) and taste delicious. However, if the wild environment is polluted, such as the presence of heavy metals, dioxins, etc., it may affect the safety of wild crabs through the food chain and other means. Conversely, if the cultured environment is very well managed, there is no pollution, and the feed is safe and healthy, so that the farmed crabs are also safe and green.
Taking site circulating aquaculture as an example, this can also be said to be the most modern aquaculture, due to the modernization of the whole process of water environment control, there are supporting biochemical filters with high processing efficiency, as well as the direct use of pure oxygen automatic oxygenation, while the feed is strictly controlled, so the safety of this type of product is higher.
However, if the fish pond high density culture is used. Due to the difference in product varieties, geographical differences, differences in the use of water sources, and differences in the concept of farmers, the safety of their products will be uneven.
Therefore, Cheng Yongxu believes that crabs cannot be judged simply by wild or farmed crabs as green and safe. Speaking of wild, it is necessary to understand the source of its seeds and the degree of environmental pollution; when talking about breeding, we must understand what kind of breeding methods, feeding environment and feed control are, so that there is comparativeness to speak of.
There are safety hazards The risk of wild aquatic parasites is higher than that of aquaculture
"Consumers must be reminded that the consumption of wild aquatic products should be said to have certain safety risks." Cheng Yongxu said. Due to the uncertainty of timing and space in the pollution of the wild environment, in Europe, people usually prefer to eat farmed aquatic products, such as salmon, one of the main reasons is the farmed salmon, the environment, feed is controllable, traceable, and the safety is guaranteed.
Then there is the parasite, the study found that lung flukes can indeed parasitize freshwater shrimp and crabs, but freshwater shrimp crabs are only the second intermediate host of lung flukes, if people eat these infected freshwater shrimp crabs raw, lung fluke larvae have the opportunity to invade the human gastrointestinal tract, follow the abdominal cavity through the diaphragm and develop into adults, damaging the lungs, abdominal organs.
At present, the farmed crabs and crayfish are freshwater shrimp and crabs, why is there no safety hazard of lung flukes? Cheng Yongxu explained that this is because the first host of this parasite is the short ditch, also known as the river curl, which mostly lives in the mountain streams in the hilly areas of the mountains or in the long flowing water environment with pebbles, rocks and sand bottoms. At present, it is difficult for crabs and crayfish to have such a breeding environment, and without the living conditions of the first host, the second host of this parasite will not appear.
However, it should not be overlooked that there are some wild shrimp and crabs living in mountain streams, and shrimp are currently found to be able to infect lung flukes with Changbai Mountain lobsters (also called grass lobsters, water butterflies), which mainly live in mountain streams in the northeast or in rivers and lakes near mountains; crabs are mainly Huaxi crabs. "These shrimps and crabs are potentially safe if they are eaten raw or not steamed at high temperatures." Cheng Yongxu stressed.
In response to the misunderstanding that "wild fish are safer than farmed fish", Wang Guitang, a researcher at the Institute of Hydrobiology of the Chinese Academy of Sciences, once wrote that if you look at it from the perspective of preventing parasitic diseases, it will be more scientific on the contrary. In other words, it is actually safer to eat farmed fish than wild fish. Salmon trout, for example, are safer to farm in both seawater and freshwater than wild ones. Artificially intensively farmed salmon (whether freshwater or seawater), even if eaten raw (although not recommended), has a low chance of contracting parasites; but if you prefer to eat sashimi such as wild Atlantic salmon and tuna, be very careful about infecting xenoderma. The same is true of Mycodylistheasis, which has a much higher infection rate in wild carps in China than in intensively farmed fish.
Is the advantage and disadvantage of wild taste although good enrichment of toxins may be more
Some people may think that even if it is difficult to say which is better in terms of safety, but in terms of taste, wild is always better.
"At present, in our country, it is undeniable that most wild aquatic products taste better than farming." Cheng Yongxu said that this is mainly the aquatic products we breed, the aquaculture water environment is usually worse than the wild environment, the density of breeding is high, the quality of the feed fed is poor, if in the breeding process, pay attention to the aquaculture water environment, moderately reduce the breeding density and aquaculture output, and improve the quality of aquatic products feed, the taste and quality of farmed aquatic products should not be much different from the wild taste.
"In this regard, the river crab research group of Shanghai Ocean University has built a 'high-quality river crab ecological breeding technology system based on fully combined feed and nutrient regulation' in view of the current river crab breeding, such as the use of low-quality feed and irregular release, and the quality of the farmed river crab and the quality of high-quality lake crab is comparable, and the safety is more reliable and traceable." Cheng Yongxu said.
An industry insider also said that many people value wild aquatic products, one of the important reasons is that the breeding variety generally has a short growth cycle and the taste is not as good as wild. But as everyone knows, for crabs, too long a growth cycle will bring another problem, that is, the amount of natural enrichment of toxins is more.
"The total amount of aquatic products in China is so large, most of the problems with aquatic products are still wild, and now the aquaculture aquatic products are better." On the contrary, I often find that fish caught in the river always smell of kerosene, and I am now more at ease with farming. Zheng Pengfei, editor of Aquatic Frontier Magazine, said.