Why do boiled eggs burst? What are the reasons

Boiling eggs and bursting the shell is usually caused by a sudden release of pressure inside the egg. The main reasons are insufficient freshness of eggs, excessive heating speed, high water temperature, slight cracks in the eggshell, and incomplete thawing of eggs.

1. Insufficient freshness of eggs

Eggs stored for a long time will gradually expand their internal air chamber, and the adhesion between egg white and eggshell membrane will weaken. When heated, the gas inside the chamber expands and easily breaks through the weak parts of the eggshell. The fresh egg chamber is smaller and the egg white is viscous, which can better buffer the thermal expansion pressure.

2. Heating speed too fast

Directly placing refrigerated eggs in boiling water can cause a large temperature difference between the inside and outside of the eggshell. The expansion rate of eggshells is slower than the internal substances when heated, and the instantaneous steam pressure cannot be released in a timely manner. Suggest slowly heating the pot with cold water to ensure even heat transfer.

3. If the water temperature is too high [SEP], the continuously boiling water will produce violent bubble impacts, exacerbating the local stress on the eggshell. When the water temperature exceeds 100 degrees Celsius, the vaporization rate of water inside the egg accelerates, and the pressure suddenly increases, making it easy to break through the eggshell. Maintaining a slightly boiling water temperature is safer.

4. There are subtle cracks in the eggshell.

Invisible cracks generated during transportation or storage can reduce the strength of the eggshell. When heated, the crack becomes a pressure release point, causing a burst phenomenon. Before cooking, the integrity of the eggshell can be checked with a light to remove any damaged eggs.

5. Incomplete thawing of eggs

Frozen eggs contain ice crystals that can damage the structure of the eggshell membrane. If the thawing is not complete, direct heating can cause the water vapor formed by the melting of the ice crystals to suddenly burst the eggshell. Frozen eggs should be slowly thawed in the refrigerator for at least 12 hours before cooking.

To prevent boiled eggs from bursting, it is recommended to use fresh eggs and restore them to room temperature in advance. After adding cold water to the pot, maintain the water temperature at around 90 degrees Celsius. During the cooking process, gently stir with a spoon to ensure even heating. Adding a small amount of salt or white vinegar to water can help proteins solidify quickly, forming a protective layer to reduce the probability of shell explosion. If a large amount of cooking is required, it is more secure to use a steamer to heat it separately from water. Immediately supercooling boiled eggs can not only prevent overcooking caused by residual heat, but also help separate the eggshell from the protein for easy peeling.