□ Yan Zhinong
Native eggs, also known as free range eggs and Stupid Eggs, refer to eggs laid by native chickens who are raised in natural environment and eat natural food. Foreign eggs refer to eggs laid by chickens raised with modern technology. Let’s talk about people’s common misunderstandings about eggs and how to eat them more nutritionally and safely.
Are earth eggs more nutritious?
In fact, there is little difference in nutritional value between native eggs and foreign eggs, and each has its own advantages in nutritional content. Some people think that earth eggs are delicious and nutritious because of their high fat content and good taste. Taking a 100g egg as an example, the native egg contains 15.6g of fat, 11.1g of protein, 64g of water, 34mg of calcium, 4.1mg of iron and 0.193mg of vitamin A; The foreign eggs contain 11.6g of fat, 14.7g of protein, 71g of water, 55mg of calcium, 2.7mg of iron and 0.432mg of vitamin A. It is not difficult to see that there is not much difference in nutrient content between native eggs and foreign eggs.
Others think that the yolk of earth eggs is dark, so the nutrition of earth eggs is better than that of foreign eggs. Is there any scientific basis?
In fact, the color of egg yolk depends on the amount and types of carotenoids and other pigments that poultry ingest from feed. These pigments can’t be synthesized by themselves, so they need to be ingested from the outside. The main pigments in egg yolk are lutein, lutein, carotene, riboflavin, zeaxanthin, etc. The color of egg yolk is related to its pigment deposition, but not directly related to nutrition.
The darker the eggshell, the better?
The color of egg shell is mainly determined by the genes of laying hens, and also influenced by the physiological conditions of laying hens. Pigments are deposited on the outer layer of eggshell and the membrane on the shell, so the color of eggs is the comprehensive result of pigments contained in eggshell and membrane on the shell. Scientists have done experiments, feeding chickens with red preserved eggs and chickens with white preserved eggs under the same conditions, and the nutritional components of the eggs laid are basically the same. Therefore, there is no significant correlation between the nutritional value of eggs and the color of eggshells.
Do you want to wash the eggs or not?
There is a shell film on the surface of the egg, which is close to the eggshell. It is an opaque and unstructured film, and its function is to avoid the evaporation of water and the invasion of bacteria. It is understood that the United States, Australia, Japan and other countries require that eggs be cleaned to directly remove microorganisms such as Salmonella from eggshells, and then the eggs are stored in the refrigerator, so that even if bacteria enter, their proliferation at low temperature will be greatly inhibited. From a safety point of view, cleaning is better than not cleaning. Most of the eggs sold in the domestic market are unwashed, especially the eggs in bulk, which need to be cleaned before storage because of the dirt such as chicken manure. After all, the dirty surface affects the appearance and pollutes the indoor and refrigerator environment. It is recommended to brush with a soft brush, and then wipe off the surface pollutants with soft absorbent paper. Some enterprises have begun to clean and disinfect the surface of eggs, dry them after cleaning, and finally spray a protective film, which can not only reduce salmonella pollution, but also play the same protective role.
How to store eggs correctly?
After buying eggs, consumers should first select cracked or damaged eggs to eat. Eggs that are intact can be gently wiped clean with clean cloth or paper, and then stored with small heads down and big heads up — — This can make the yolk float and stick it under the air chamber, which can not only prevent microorganisms from invading the yolk, but also prolong the shelf life of eggs.
Eggs can be stored at room temperature for up to 10~15 days. When eggs are stored in the refrigerator, the optimum temperature is 2℃ ~ 8℃, and the shelf life of eggs can reach 40~45 days.
Cooked eggs can only be kept for 1~2 days in summer if they are kept at room temperature. Because of the high temperature in summer, boiled eggs provide a nutrient-rich culture medium for microorganisms in the air, and microorganisms reproduce quickly at high temperature, and eggs are prone to deterioration. If it is put in the refrigerator, it can be preserved for more than ten days without damaging the eggshell.
How about eating eggs raw?
In recent years, it is popular in society to eat raw eggs, especially hard-boiled eggs. It is suggested that we should be careful when eating raw eggs. Because the protein structure of raw eggs is dense, it is not easy to be digested and absorbed. However, the structure of the cooked egg protein becomes soft, which is easier to be digested and absorbed by the human body. More importantly, eating raw eggs is prone to food poisoning, and about 10% of fresh eggs carry pathogenic bacteria and parasitic eggs. In addition, some people like to eat eggs with boiling water, because the germs and parasitic eggs in eggs can not be completely killed, which is easy to cause diarrhea and parasitic diseases.
Can eggs be eaten if they have bacteria?
Both native eggs and foreign eggs are easily contaminated by bacteria, which makes people sick. The most common pathogen is Salmonella enteritidis. The contaminated eggs are colorless and tasteless and cannot be distinguished by the naked eye. Salmonella generally enters eggs in two ways. The first type occurs in the process of hen’s ovary formation. Salmonella usually enters chicken’s body through feed and drinking water, which can infect hen’s ovary and thus infect eggs before laying eggs. The second way is to carry the egg outside the body. Even if the egg is not infected in the hen, Salmonella in feces or soil may pollute the surface of the egg and even invade the egg from the pores of the eggshell.
Salmonella can be reduced by clean feed and water intake and keeping the environment clean in the production of eggs, and can be killed when cooked.
Boil, steam, fry and stir fry … … There are many ways to eat eggs. As far as the nutrient absorption and digestibility of eggs are concerned, boiled and steamed eggs are 100%, tender fried eggs are 98%, scrambled eggs are 97%, poached eggs are 92.5%, old fried eggs are 81.1%, and raw eggs are 30%~50%. From this point of view, boiled and steamed eggs should be the best way to eat.
In a word, it is the most nutritious and safest to eat eggs when they are cooked.
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