Hairy crabs are soaked in antibiotics to prevent disease, and chestnuts fried in sugar are added with paraffin...

Are these claims circulating on the Internet reliable?

◎ Reporter Chen Xi

Corn whiskers, sorghum hanging. In October, when the harvest is abundant, autumn delicacies such as hairy crabs and chestnuts appear on the tables of each household. At the same time, many rumors about food have also begun to emerge - hairy crabs are soaked in antibiotics to prevent diseases, the meat of freshly slaughtered pigs, cattle and sheep is the most delicious, sugar-fried chestnuts are added with paraffin, and eating water spinach will cramp... These unreliable statements are widely circulated online.

Today, the reporter of Science and Technology Daily will take stock of the rumors in October one by one to help you clear the fog and find the truth.

Hairy crabs soaked in antibiotics to prevent disease?

Truth: Antibiotics are not good for crab growth

Every year when hairy crabs are on the market, rumors related to them will "reappear". Among the many "old rumors", the rumor that "hairy crabs are soaked in antibiotics to prevent diseases" worries consumers the most, for fear that eating "antibiotic hairy crabs" will affect their health.

However, this rumor seems to Zhang Shulin, a professor at the School of Fisheries of Tianjin Agricultural University, to have no scientific basis.

"The hairy crab that the people say is the Chinese mitten crab, and the hairy crab disease needs to be prevented and combined. If antibiotics are sprinkled in water to prevent disease, it is a bit like giving a shot to the harmful bacteria in the water, which may make the harmful bacteria immune to the antibiotic and thus develop resistance. Zhang Shulin further said that once the harmful bacteria have drug resistance, when the bacteria make the hairy crab sick, and then feed the hairy crab with antibiotics, the efficacy will be greatly reduced, which greatly increases the difficulty of follow-up treatment. At the same time, broad-spectrum antibiotics can not only kill harmful bacteria, but also kill beneficial bacteria, destroy the ecological balance of the water environment, but are not conducive to the normal growth of hairy crabs.

"At present, the state is very strict in the management of the use of aquaculture inputs, and the Ministry of Agriculture and Rural Affairs has issued the "Notice on Strengthening the Supervision of Aquaculture Inputs" to accelerate the establishment of a white list system." Zhang stressed that if hairy crabs get sick, they can be treated with drugs from the white list and mixed with bait, but the use of non-white list inputs is strictly prohibited. Once the local agriculture and rural (fishery) departments discover illegal use, they will investigate and deal with it in accordance with the law, and those suspected of committing crimes will be transferred to the judicial department for criminal responsibility.

So, how can you help hairy crabs prevent various diseases?

Zhang Shulin introduced that before breeding hairy crabs, it is necessary to choose excellent disease-resistant varieties through modern biotechnology. At the same time, it is necessary to purify the water quality by planting aquatic weeds and using indigenous microecological agents, improve the ecological environment of the pond, and block the transmission of pathogens.

Is the meat of freshly slaughtered pigs, cows and sheep the tastier?

Truth: Contains a lot of lactic acid that affects the taste

Autumn fat is pasted, and all kinds of meat are indispensable. In many people's perception, the meat of freshly slaughtered pigs, cows, and sheep is the most tender and delicious.

In this regard, Wang Hao, a professor at the School of Food Science and Engineering of Tianjin University of Science and Technology, said in an interview with a reporter from Science and Technology Daily that after pigs, cattle and sheep are slaughtered, their normal metabolism and blood oxygen supply will stop, and the glycogen stored in the muscles will be degraded into a large amount of lactic acid, which will coagulate myosin, cause muscle contraction, and make meat stiff.

The meat of cattle will become stiff 2.5 hours after slaughter, and the meat of sheep and pigs will become stiff 1 hour after slaughter. Meats in the stiff phase are not suitable for processing because they are hard, lose a lot of juice, and are not easily cooked.

Therefore, after pigs, cows, and sheep are slaughtered, it is best to deacidify their meat first. Pork needs to be detoxified in an environment of minus 5 degrees Celsius for 24 to 36 hours. Beef and mutton need to be left in an environment of 2 degrees Celsius for 1 to 2 days to remove acid. In addition, these meats produce an enzyme during the acid removal process.

"Meat that has been deacidified is better in terms of nutrition and taste." Wang Hao explained that first of all, in terms of nutrition, under the action of enzymes, the protein of sour meat is broken down into amino acids, which is easier to be absorbed by the human body. Secondly, in terms of taste, after acid removal, the muscles and connective tissues change from stiffness to relaxation, and the meat is easier to cook and taste.

In addition, the growth and reproduction of most microorganisms in acid-draining meat has been inhibited, and the number of harmful bacteria such as Clostridium botulinum and Staphylococcus aureus has been greatly reduced. At the same time, a layer of dry film will be formed on the surface of the sour meat, which can prevent the invasion of external microorganisms, thereby improving the storage resistance of the meat.

Sugar-fried chestnuts with paraffin?

Truth: The state strictly prohibits such additions

As the saying goes: "July star fruit and August hawthorn, October chestnut laugh haha." "Every year when it is the season to eat chestnuts, the topic of "sugar-fried chestnuts with paraffin" will be turned out and re-searched for a few days.

In this regard, Wang Hao said that paraffin is not allowed to be added in the process of frying chestnuts.

As a mineral oil, paraffin is a mixture of crude oil obtained by fractional distillation. Paraffin wax is further divided into industrial grade and food grade. According to the requirements of the National Food Safety Standard for the Use of Food Additives (GB 2760-2014), food-grade paraffin wax can only be used as a processing aid. "According to national regulations, food-grade paraffin wax can only be used in the food production process when it has to be used. Paraffin wax is used as a release agent and is used in the range of confectionery and baked goods. And it is not necessary to use it when frying chestnuts, so it is not allowed to be added during the process of frying chestnuts. Wang Hao explained.

When making sugar-fried chestnuts, adding paraffin wax will make the chestnuts brighter in color, thus attracting consumers to buy them. Therefore, in the past, some merchants illegally added paraffin wax in the frying of chestnuts, and even industrial-grade paraffin. This paraffin wax contains many impurities, including strong carcinogens - polycyclic aromatic hydrocarbons, which are easy to cause damage to human cranial nerves and liver organs. Nowadays, under the supervision of the relevant state departments, such illegal additions are rare.

"It is not appropriate to add paraffin wax during the frying of chestnuts. Consumers don't have to be too nervous, though. Paraffin wax will only be wrapped around the chestnut skin, and we all peel the chestnuts when we eat them. If it is not consumed in large quantities, the paraffin wax ingested by the human body is very small. Wang Hao suggested that consumers should not pursue "appearance" too much when buying sugar-fried chestnuts, and at the same time do not buy chestnuts that are too smooth to the touch.

Do you get cramps when you eat water spinach?

Truth: There is no scientific basis for this claim

Water spinach is a common vegetable with very high nutritional value. But last month, water spinach was named "cramp dish" by some people on the Internet, and some netizens said that "eating water spinach will cause cramps", and many people are convinced of this.

In this regard, Wang Hao said that there is no scientific evidence that water spinach is related to cramps.

Cramps are a colloquial term for muscle spasms. In general, cramps in the human body are caused by sudden, uncontrollable contractions of muscles and are usually related to factors such as excessive exercise and electrolyte imbalance in the body.

There are many reasons that cause cramps, but the reason why eating water spinach is rumored to cause cramps is mainly due to the high oxalic acid content in water spinach. When oxalic acid is combined with calcium, calcium oxalate is formed, which affects calcium absorption. A high concentration of calcium oxalate decreases the amount of calcium ions in the blood. When the level of calcium ions in the blood is too low, it is easy to cause muscle excitement to increase, and muscle spasms will occur when slightly stimulated.

"For the average person, when the amount of calcium ions in the blood is too low, the calcium in the bones will be replenished, so there is basically no situation where the amount of calcium ions is too low." Wang Hao explained.

Not only water spinach, but also many vegetables have a relatively high oxalic acid content, such as spinach, celery, kale, etc.

"When cooking vegetables with high oxalic acid such as water spinach, it is best to blanch first, which can remove more than 95% of oxalic acid. At the same time, we should achieve a balanced diet in our daily life, and when eating vegetables rich in oxalic acid, we can combine them with foods high in calcium. Wang Hao suggested.