10 Mind-Blowing Facts About the Science of Boiling an Egg Perfectly

6. The Ice Bath Secret: Thermal Contraction Power

Why plunge boiled eggs immediately into ice water? It’s not just to stop the cooking. This rapid temperature drop – thermal shock in reverse – causes the egg white and yolk to contract slightly faster than the shell. This minute contraction helps pull the egg away from that clingy inner shell membrane we just discussed. The result? A small gap forms, making the shell significantly easier to slip off cleanly, preserving the smooth surface of your perfectly cooked egg white.