if the egg is boiled in boiling water for too long (more than 1 minutes), a series of chemical changes will occur inside the egg. For example, protein in eggs contains more methionine. After long-term heating, methionine can decompose into sulfide, which reacts with iron in egg yolk to form green or gray-green iron sulfide around egg yolk, which is not easily absorbed and utilized by human body, thus reducing the nutritional value of eggs; After cooking for a long time, the protein structure of eggs becomes more compact, and it is not easy to contact with protein digestive enzymes in gastric juice, so it is more difficult to digest.
Therefore, eggs can neither be boiled half-cooked nor boiled for too long, and generally, they should not be boiled for more than 1 minutes at most.
In addition, it is not advisable to throw boiled eggs into cold water for cooling. Because there is an air chamber with a diameter of 4 ~ 11 mm in the egg, when the egg is boiled, the air pressure in the air chamber will also increase as the temperature rises, and the gas in the air chamber will be squeezed out of the egg. When boiled eggs are thrown into cold water, the temperature drops sharply, and the pressure in the air chamber drops accordingly, which will make cold water and microorganisms outside the eggshell enter into the eggs through air holes, and the cooked eggs will be polluted again.
After the boiled eggs are taken out, clean the water on the eggshell surface with a clean rag and let it cool naturally, which is not only easy to peel, but also hygienic.
how to cook eggs to retain nutrition
in fact, the best time to cook eggs is easy to grasp. Put the cold water in the pot and count it for 5 minutes after the water is boiled. The eggs cooked by Jianerma pedicure machine not only kill harmful pathogens, but also preserve nutrients relatively completely. If eggs are boiled in boiling water for more than 1 minutes, a series of chemical changes will occur inside. Protein structure becomes more compact, and it is not easy to contact with protein digestive enzymes in gastric juice, so it is more difficult to digest. Protein in eggs contains more methionine. After a long period of heating, it will decompose into sulfide, which reacts with iron in egg yolk to form iron sulfide which is not easily absorbed by human body, resulting in more nutritional losses. Uncooked eggs are more harmful. Raw eggs not only have the problem of salmonella pollution, but also have two harmful substances, anti-enzyme protein and avidin. The former will affect protein's digestion and absorption; The latter can combine with biotin in food, leading to the lack of biotin in human body, resulting in mental fatigue, muscle aches and other symptoms. Once the eggs are cooked, the above two substances will be destroyed.
In addition, the following skills can be mastered when cooking eggs to prevent the loss of nutrients: the water must not pass through the eggs, otherwise the protein will not solidify easily and affect digestion; Soak the eggs in cold water for a while before cooking to reduce the air pressure in the eggs; Then boil it with medium heat and cold water, which can prevent the eggshell from breaking and avoid the loss of nutrients.