The reason why eggshells break is because the egg white and yolk inside the shell expand with heat and become larger in volume, and when the volume of the egg white and yolk is larger than the capacity of the shell, the shell will be "squeezed". The secret to avoiding breakage is to "cook cold eggs in boiling water".

The proteins in the egg shrink when they solidify. If the egg is heated quickly, when the outer layer of the egg white expands with heat, the inner layer is still cold and doesn't expand, so the total amount of expansion is relatively small, and the increased capacity of the egg shell as well as the capacity of the air chambers in the egg will be able to withstand it and won't be broken. Continue to heat, the internal began to heat expansion, the outer layer of egg white has solidified and contracted, the total expansion is also smaller, the shell will not break.

Boiled egg tips

1, soak.

Before boiling eggs, it is best to soak the eggs in cold water for a while, and then put them into a pot of cold water to boil, so that the eggshell is not easy to break. Of course, this is only one of the ways to keep the shape of the egg intact.

2, fire.

Boiled eggs if the fire, easy to cause rapid expansion of air in the eggshell and lead to eggshell cracking; if the use of small fire, and prolonged the time to cook the eggs, and it is not easy to grasp the degree of good eggs old and tender. Practice has proved that boiled eggs to medium heat is most suitable.

3, stirring.

In order to make the egg yolk solidified in the middle of the egg white, should be in the egg in the pot with a hand spoon constantly stirring in one direction, so that the water in the pot was swirling and turning until cooked.