There is no air gap in the egg before the chicken is laid. The inner and outer shell membranes of the egg are adhered to each other. When the egg comes out, it cools and air begins to accumulate between these two membranes on the blunt side of the egg. On the first day of the egg, this air gap is between 4-5 millimeters. Depending on the weather, storage conditions and dwell time, this air gap in the egg becomes larger. As long as the egg loses water, the growth expands and deepens. In short, this event is stale egg. Though stale eggs have a large air gap, but it is wrong to call all eggs with a large air gap stale. Depending on some factors, the air gap may be large even if the egg is fresh. The air gap in stale eggs exceeds 12 millimeters.

It is possible to see the air gap when the egg is held to light. In general, the method used to understand the freshness of the egg at home is to leave the egg in cold water. If the egg collapses quickly at the bottom of the water, it is fresh, but if it slowly descends and stands upright, the egg begins to stale. But if the egg stays above the cold water, it's definitely stale.

Of course, the air gap in the eggs is made more professionally in laboratories. At the authorized laboratories, air gap determination studies are also carried out (for each 10 egg) within the scope of physical analyzes. During these studies, the standards published by local and foreign organizations are complied with. In the laboratories, not only the air gap, but also vitamins and nutritional values ​​are tested and analyzed.

The air gap of the eggs is also very important for the poultry farms. If the humidity of the hatched eggs is low, the egg loses water very quickly and causes the chick to die. If the humidity is too high, this time the egg loses very little water and causes chicks to die. Therefore, conditions should be provided that allow eggs to be stored without staling.