Recently, it was reported that a family of three in Shenyang was poisoned after eating scrambled eggs. The reason for poisoning was that the eggs were spoiled, while the eggs were spoiled because they had been washed before preservation. Since the report did not explain how doctors determined that the cause of poisoning was rotten eggs rather than other food, it was impossible to evaluate whether this attribution was reasonable.
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However, even if the three members of the family are really poisoned by eggs, the problem is not "cleaning".
The EU really opposes cleaning eggs
Although the surface of the egg shell is full of pores, at the same time, there is a layer of gelatinous film to "close" those pores. The eggs of pheasants and other birds can hatch after being placed in the wild for a long time, thanks to this membrane.
This film is really easy to be washed away. After the eggshell loses its film, external bacteria can easily invade, leading to the loss of water in the egg white and the decline of egg quality. Therefore, the EU opposes cleaning eggs. With very few exceptions, Class A eggs in the EU are not allowed to be washed.
American eggs must be washed before they can be sold
However, eggs are a kind of food easy to be infected with bacteria. The larger the activity space of the chicken, the more likely the eggs are to be contaminated with dirt. For example, Salmonella is a major risk factor affecting egg safety. If the hen is infected with salmonella, the inside or shell of the egg it laid may also be contaminated. In addition, if there is salmonella in the chicken coop, it may also contaminate the egg surface. In a word, eggs may carry salmonella on the surface from birth.
Salmonella has very strong viability. Even if the membrane on the eggshell remains intact, they can still penetrate the eggshell into the inside of the egg. Destroyed the membrane, just reducing the difficulty of their penetration. Therefore, the United States, Japan, Australia and other countries require cleaning eggs to directly remove Salmonella and other microorganisms from eggshells. Under the standard cleaning process specified by the U.S. Department of Agriculture, the number of bacteria on the surface of eggs can be reduced by 100000 times, which is equivalent to the bus sterilization effect of milk. Although cleaning opens the passage for bacteria to enter the egg, it is more conducive to food safety to first kill the bacteria on the eggshell, especially Salmonella. Since then, although other bacteria may enter the environment, the risk is not as high as Salmonella. Especially when eggs are placed in the refrigerator, even if bacteria enter, the proliferation of bacteria will be greatly inhibited under low temperature. From the safety point of view, the safety has been improved after cleaning and storing in the refrigerator.
Which is safer, wash or not?
The "no washing" in the EU and the "must washing" in the US, Japan and Australia are all based on the safety of eggs. Although the requirements are diametrically opposite, each has theoretical support and can justify itself. As for "which kind of regulation is more reasonable", there has been no clear debate. In 2011, a study published in the Journal of Food Protection showed that the outer membrane of eggshell was not significantly damaged under reasonable cleaning methods. This at least shows that the theoretical basis of washing and not washing may be taken into account.
Therefore, no matter whether eggs are the culprit of poisoning of three people in a family, "cleaning" should not be the root cause. Even if the eggs are really polluted, the problem lies in the storage environment, temperature and duration of the eggs, rather than the "cleaning" operation itself.
So how to store eggs?
Eggs on the American market are all washed and are required to be stored at a refrigerated temperature (4 ℃). Generally, the recommended storage time is not more than two weeks. After more than two weeks, it does not deteriorate in the usual sense (that is, bacteria invade and cannot be eaten), but mainly changes in the physical state, such as scattered yellow, egg white thinning, etc. However, as long as the refrigerator is clean, this change in physical state will not affect safety. The eggs in Europe are not cleaned. If the eggs themselves are not contaminated by bacteria, they can be kept at room temperature for 4 weeks. If put in the refrigerator, the storage time will be longer. Because there are no laws and regulations in China, we can't judge whether the eggs we bought have been washed. However, if you put it in the refrigerator and keep it clean, you can keep it for two or three weeks.
[This article is a contribution from Tencent's Mizhen platform, which is forbidden to be reproduced without authorization. More original science popularization of food health is pushed through mobile phone "Squirrel Cloud"]
