The process of making preserved eggs mainly involves the selection of raw eggs, soaking in material liquid, taking out inspection, coating with mud, and packing and storage. Among them, hydrogen must be used in the soaking process. Sodium oxide (NaOH) and metal ions.

The purpose of adding NaOH to the soaking liquid is to make the liquid alkaline and promote the coagulation and alkalization of egg whites and egg yolks; while the main purpose of adding metal compounds is to combine with the sulfur ions produced by the decomposition of proteins in the eggs. The formation of insoluble salt sulfide blocks the pores of the eggshell, hindering the continued penetration of OH- into the egg, causing "alkali damage" to the preserved egg in the later stage, causing the coagulated protein to reprogram into a liquid state.

The traditional craft of preserved eggs uses lead oxide to provide metal ions. Therefore, in the process of lead ions decomposing long-lasting sulfide ions with the protein in the egg to generate insoluble salt sulfide, which blocks the pores of the eggshell, the lead ions It also penetrated into the preserved eggs.

Many studies have confirmed that lead has a huge toxic effect on the human body, mainly damaging the nervous system and affecting children's memory, language, motor ability and learning ability. Therefore, more and more lead-free processes are used to make preserved eggs. The lead-free process means that lead compounds are not used to provide metal ions during the processing of preserved eggs, but zinc, iron, copper ions or a combination of these ions are used to provide metal ions.

However, it should be noted that lead-free preserved eggs does not mean that preserved eggs are completely lead-free, because in the nature we live in, the air, soil, and water will contain trace amounts of lead. These lead will be present in the ingredients we cannot make preserved eggs. The missing ingredient - fresh eggs. Extended information

According to the inspection and analysis of relevant food experts, there are only 400-500 bacteria on the eggshells of clean pineapples, while there are as many as 140 million to 400 million bacteria on the shells of dirty pineapples. These If a large number of bacteria enter the egg through the pores of the eggshell, eating such preserved eggs will cause poisoning.

When purchasing preserved eggs, you should pay attention to the fact that after being peeled off, the egg whites are dark brown and transparent, with a certain degree of toughness; while contaminated preserved eggs are light green and have poor toughness. It is easy to loosen, so you must not eat such preserved eggs.

The bacteria that contaminate the preserved eggs are mainly Salmonella, which enters the human body with the preserved eggs and causes inflammation in the mesentery. After the bacteria fission, they produce highly toxic endotoxins, which can lead to human poisoning. symptom.

Experiments have proven that Salmonella will die immediately at a high temperature of 100°C, 5 minutes at 70°C, and 15-30 minutes at 60°C. Therefore, when eating suspicious preserved eggs, you can steam the shelled eggs at high temperature for about 5 minutes and let them cool before eating safely. The suitable temperature for the growth of Salmonella is 20℃-37℃, and the temperature in summer and autumn is just within this range, so people must pay special attention to preventing poisoning from preserved eggs.

Preserved eggs contain more minerals than duck eggs, but have slightly lower fat and total calories. They can stimulate the digestive organs, increase appetite, promote the digestion and absorption of nutrients, neutralize gastric acid, cool and lower blood pressure. It has the effects of moistening the lungs, nourishing yin and stopping bleeding, cooling the intestines, stopping diarrhea and lowering blood pressure. In addition, preserved eggs also protect blood vessels.

Reference: Preserved Egg_Baidu Encyclopedia