“Aseptic eggs” ≠ sterile! Do you still dare to “eat them raw”?

Audit expert: Wang Guoyi

Postdoctoral fellow in Nutrition and Food Safety, China Agricultural University

When you think of eggs, what do you think of? Fried eggs, boiled eggs, tea eggs...

Eggs are one of the most common foods in our daily lives. They are not only highly nutritious, but also taste great. When money is tight at the end of the month, eggs can temporarily replace meat and provide a high-quality source of protein.

In recent years, with the popularity of Japanese cuisine in China, a type of egg has attracted a lot of attention, and that is the "sterilized egg".

In the promotional slogans of merchants, sterilized eggs are said to contain no salmonella, have no eggy smell, can be eaten raw, and are even more nutritious. Is this really the case?

Source | pixabay

Revealed! Are sterile eggs really sterile?

Before explaining the origin of sterile eggs, let us first understand where the bacteria in eggs come from?

There are many kinds of bacteria in eggs. The most common pathogen is Salmonella, which is a common foodborne pathogen. This bacteria may be found in the meat and milk we eat daily.

There are generally two ways for Salmonella to enter eggs: one is maternal infection, that is, entering the body from the hen's diet and infecting the yolk and egg white; the other is entering the eggs from feces and dirt. Because eggs are not completely sealed, they have a porous structure, and external bacteria can enter the eggs through contact.

Source | pixabay

The so-called sterile eggs generally refer to eggs that have been sterilized by pasteurization or ozone sterilization, and then specially packaged and transported. During the production process of sterile eggs, the number of microorganisms in chicken feed, chicks, water sources and breeding environment will be strictly controlled, and random inspections will be carried out many times during the period to avoid eggs being infected with Salmonella to the greatest extent.

Are sterile eggs really sterile? The answer is no. Although eggs can be sterilized by pasteurization and ozone sterilization, the current egg production environment cannot implement a strict sterile environment. Therefore, it can be said that the bacteria content in sterile eggs is very small, but it cannot be guaranteed to be completely sterile.

Are sterilized eggs better than regular eggs?

The popularity of sterilized eggs in the consumer market is inseparable from the vigorous promotion of merchants. In recent years, people have paid more and more attention to green and healthy diet, and are more likely to pay for sterilized eggs.

Some of you may say that even if sterilized eggs are not completely sterile, their taste and color are better than ordinary eggs.

In fact, the “no egg smell” advertised in many sterilized eggs actually has little to do with the sterilized eggs, but is mainly related to the feed formulation and chicken breed.

If more rapeseed oil, choline chloride, fish meal, etc. are added to chicken feed, the eggs laid by chickens that eat these feeds will have a stronger fishy smell.

Source | pixabay

As for the color of the egg yolk, it is also related to the feed of the chicken. If more lutein, beta-carotene and other coloring ingredients are added to the feed, the yolk color of the eggs laid by the chickens that eat this feed will be darker.

Finally, let’s talk about the nutritional value. Whether it is sterile eggs or ordinary eggs, they are rich in high-quality protein, amino acids, vitamins and other substances. This has nothing to do with whether the eggs are sterile.

How to eat eggs more healthily?

Consumers are chasing after sterilized eggs simply to pursue a healthier diet. So which is healthier, eating raw sterilized eggs or eating cooked ordinary eggs?

Although sterile eggs contain less bacteria, they are not completely free of bacteria. For people with poor digestion, the elderly, children and pregnant women, eating raw eggs can easily cause bacterial infection and cause abdominal pain and diarrhea. Although ordinary eggs contain more salmonella, this bacteria has a characteristic that it is afraid of heat but not cold.

Salmonella is resistant to low temperatures and can survive in the refrigerator for 3 or 4 months. However, Salmonella is not heat-resistant and will die when the temperature inside the egg reaches about 71°C. Therefore, ordinary eggs should be fully heated and cooked before eating, so that food safety can be guaranteed.

Source | pixabay

In addition, about 91% of the protein in cooked eggs can be absorbed by the human body, but because raw eggs contain protease inhibitors, the amount of protein absorbed by the human body is reduced to about 55%. Raw eggs also contain anti-biotin protein, which will inhibit the body's absorption of biotin.

In general, raw sterilized eggs are not as good as cooked eggs in terms of nutrient absorption. So does sterilized eggs have no advantages?

Sterilized eggs produced by regular manufacturers contain even fewer microorganisms. If you have the need and preference to eat raw eggs, it is recommended to buy sterilized eggs. In addition, sterilized eggs generally come with traceability codes, so consumers can buy and eat them with confidence.

Another thing to note is that sterilized eggs are generally marked with a "best before date". If they have exceeded this date, it is recommended to heat them before eating.

Source | pixabay

Whether it is sterile eggs or ordinary eggs, learning how to choose eggs is also an important knowledge. How can you buy fresher eggs? Here are three tips for your reference:

First, look at the production date and choose to buy eggs produced within 7 days, as they are fresher;

The second is to listen to the sound of the egg. Shake the egg next to your ear. If you hear a shaking sound, it means the egg is stale. If not, it is a relatively fresh egg.

The third is to look at the appearance of the eggs. The cleaner and less cracked the eggshell is, the less likely it is to be contaminated by microorganisms, and the healthier the eggs are.

Food is the most important thing for people, and when eating, safety and happiness should be emphasized. Eggs that are allowed to be sold through formal channels in the market have all passed national inspection. The "National Food Safety Standard for Eggs and Egg Products" issued in 2015 has set strict standards for the sensory requirements and contaminant limits of eggs.

So, whether to buy sterilized eggs or not, we should not follow the trend blindly, just make choices based on our own preferences and needs~