Why do eggs develop air pockets when stored long?

Question

Learn what that air pocket at the end of an egg is. Discover why it gets larger over time as the egg ages and loses moisture.

Answer 1

Eggs develop air pockets over time because moisture and carbon dioxide escape through the porous shell, and air enters to replace the lost volume. This process is accelerated by warmer temperatures and lower humidity.

Detailed Explanation:

An eggshell, while seemingly solid, is actually porous, containing thousands of tiny pores. These pores allow for the exchange of gases, which is crucial for the developing chick if the egg is fertilized. However, even in unfertilized eggs, this porosity plays a role in how the egg ages.

When an egg is first laid, it contains a small air cell, usually located at the larger end of the egg. Over time, two main processes contribute to the growth of this air cell:

1. Moisture Loss: The egg's contents, primarily water, gradually evaporate through the shell. This evaporation is influenced by the surrounding environment's humidity. Drier air pulls more moisture out of the egg.

2. Carbon Dioxide Escape: Freshly laid eggs contain carbon dioxide. As the egg ages, this carbon dioxide also escapes through the shell.

As moisture and carbon dioxide leave the egg, air is drawn in through the pores to equalize the pressure. This incoming air fills the space left behind, causing the air cell to expand. The larger the air cell, the older the egg generally is. A very large air cell can indicate that the egg is no longer fresh.

Pro Tip:

Store eggs in their original carton in the coldest part of your refrigerator (usually the back) to minimize temperature fluctuations and slow down moisture loss, thus keeping them fresher for longer. Avoid storing them in the refrigerator door, where temperatures are less consistent.