Many people are accustomed to putting freshly boiled or steamed eggs directly into cold water to cool them down and to make them easier to peel. However, this method is not scientifically sound, and it is best not to soak boiled eggs in cold water.
While immersing a boiled egg in cold water does cool it down quickly, the difference in contraction between the inner shell membrane and the albumen membrane can create a gap, making the shell easier to peel. This approach, however, overlooks the fact that cold water contains a large number of bacteria. After being heated, the eggshell membrane that prevents bacteria from passing through is damaged. This means the shell's pores no longer block bacteria, allowing them to easily invade the egg.
The correct method is to add a small amount of salt to the water during the boiling process. Salt not only sterilizes and detoxifies but also causes the inner shell membrane and the albumen membrane to contract at different rates, creating a gap and making the shell easier to peel.