Does an egg with chicken manure on it really mean it's natural and original?

In today's world filled with genetically modified foods, we all hope to find traces of the natural and original in our lives. That's why "organic," "pollution-free" and "green" often appear in newspaper reports.

When we pick out eggs, our mothers warn us: remember to give them a shake and listen for any sound, and most importantly, if you see manure stuck on the egg, that's a farm egg, no mistake about it.

But for example, a Tencent report titled "Beijing APEC Menu Bursting with Beijing Flavor: Eggshells Must Be Disinfected Before Entering the Kitchen" wrote: "However, a Beijing Youth Daily reporter discovered a strange processing room: the egg washing room. It turns out that before the eggs here enter the kitchen, they must first be washed and disinfected to prevent avian flu."

This is very confusing: isn't it said that washing eggs destroys the gelatinous protective substance on the eggshell surface, and therefore actually makes the eggs harder to preserve? In fact, whether eggs should be washed at all is truly a rather controversial topic.

What exactly is on the surface of an egg?

The eggshell surface has powder from feed, feathers and manure, and often also carries pathogenic microorganisms such as E. coli, which affect and threaten human health. Currently, the internationally popular method for ensuring egg product safety is: washing and drying the egg products, disinfecting them, and applying a coating to prevent contamination.

Using the total colony count, coliform group and Salmonella as the main detection indicators, the degree of microbial contamination on the surface of fresh eggs from large and small chicken farms was measured respectively. The total colony count on the surface of fresh eggs from small chicken farms was 2.4×105 to 8.1×105 cfu per egg (fresh egg surface, same below), the coliform count was 3.4×103 to 7.4×104 per egg, and no Salmonella was detected; the total colony count on the surface of fresh eggs from large chicken farms was 2.1×105 to 7.0×105 cfu per egg, the coliform count was 1.8×103 to 1.2×104 per egg, and no Salmonella was detected.

Is there a gelatinous protective substance on the surface of an egg?

Yes, there is. A fresh egg is a living organism, and on the eggshell surface there is a layer of gelatinous substance called the eggshell membrane, which can play a protective role. Inside the egg there is also a kind of lysozyme, which can resist the invasion of bacteria and can kill the bacteria that enter the egg from outside. However, during storage, eggs are often affected by external temperature, humidity, as well as storage method and storage duration, and may spoil and become unfit to eat.

But how much protection the gelatinous substance on the eggshell surface actually provides is still unknown to us at present.

Domestic eggs and foreign eggs are handled differently

If you are in the United States, you will find that the government and other relevant organizations generally do not recommend that consumers wash eggs bought from supermarkets. The reason is not the aforementioned disadvantage to egg preservation, but rather that the eggs have already been washed. The United States Department of Agriculture requires that all eggs from farms that are sold directly to consumers for eating must undergo thorough washing to remove dirt from the eggshell surface before being packaged and marketed, so eggs bought in American supermarkets generally have a very clean exterior.

What is the correct way to handle eggs?

● If the eggs you buy come with packaging, it is best to leave the eggs in the original packaging before putting them in the refrigerator. This is because the eggshell has many tiny pores, which makes eggs prone to absorbing odors from other foods, while the packaging box can effectively block odors from entering the eggs. At the same time, if the packaging has a use-by date printed on it, it can also remind you not to eat them past their expiration.

● Before and after processing eggs or foods containing eggs in the kitchen, please wash your hands, utensils, cutting boards and other work surfaces clean with warm soapy water to avoid cross-contamination.

● Cooked eggs or foods containing eggs should be eaten as soon as possible; if there is any left over, it should be put into the refrigerator for cold storage as soon as possible. Cooked eggs or foods containing eggs should not be stored in the refrigerator for more than one week, and should be reheated before being eaten again.

In short, making sure to clean eggs thoroughly before eating can prevent bacteria from entering through the mouth, so why not take one extra step?