An egg is composed of three layers: the yolk, the egg white, and the shell. The yolk solidifies at a temperature of 68°C—71°C, while the egg white solidifies at 62°C—64°C. When boiling an egg, if the heat is too high, the egg white, which has a lower solidification temperature, will quickly solidify and become hard on the outside. This then prevents heat from continuing to transfer to the yolk, affecting the solidification of the yolk, which has a higher solidification temperature. This results in a cooked egg white with an undercooked yolk. If boiled for too long, the proteins will denature excessively, making the egg very hard, which is not only unpleasant to eat but also affects digestion and absorption.
Therefore, there is a proper method for boiling eggs. First, place the eggs in cold water in the pot, then heat slowly. Once the water comes to a boil, turn off the heat after about two minutes. Let the eggs sit in the hot water for five to six minutes, then remove them and give them a quick rinse with cold water before they are ready to eat.