In most commercial operations, eggs drop automatically from the hens’ cages to a conveyor belt below where they are taken to a machine for washing. To clean and sanitize the eggs, a machine washes them in water heated to more than 90°F with a special cleaning solution. Once the eggs are washed, they are rotated as they pass by to look for dirt spots. If an egg is detected with dirt spots, the egg is routed back to the washer. In some cases, oil is used to protect shell eggs and is applied in a manner that prevents egg contamination and preserves egg quality.
The contents of the egg are examined without cracking the shell. The condition of the shell, albumen and yolk are all checked. Inferior eggs are removed.
In modern operations, to detect shell cracks, eggs are checked sonically. In a matter of seconds, tiny probes tap each egg 16 times and ‘listen’ for the sound it makes. A fully intact egg has a high pitch and a sustained ring. A thud indicates a crack and the egg won’t be packed.
Once washed and determined whole, the eggs are packaged and shipped. Each package must be determined to be clean and in good condition, mold free and without offensive odors, and sufficiently strong and durable to protect eggs from damage during normal distribution.
Throughout the collection and washing process, eggs must be kept at an average ambient temperature of 60° F or below, but must be brought to 45°F or colder within 36 hours after collection. After being processed and packaged they must be kept at an average ambient temperature of 45°F or colder at all times, including while they are being transported. At no time should the eggs be frozen.