The egg industry is a highly developed and technical industry. To achieve success, the producer must be something of a scientist, a nutritionist, an engineer and a businessman.
On a modern poultry farm, eggs are gathered daily. They are then graded according to quality and weight. The quality of the eggs is determined by means of the candling method without having to break the shell. Each egg rotates under a harsh light. The quality of the egg yolk the white and the air space are monitored and eggs that don't conform to requirements are thrown out.
The Fresher the Better
The quality of an egg is determined by the size of the air space. As the egg deteriorates, the air space expands. Placing it in a bowl of salt water can test the freshness of an egg. The fresh egg will lie on its side on the bottom, an egg one week old will lie on the bottom at an angle and eggs of two to three weeks will stand upright.
Fresh egg: the yolk will form a nice firm dome while the egg white will lie stiff and firm around the yolk.
Not-so-fresh egg: the yolk will appear flat and the white will appear watery.
3-week+ egg: the membrane around the yolk tears and the yolk spreads. The white is completely watery.
The sizes in which eggs are marketed are as follows:
+ JUMBO Eggs with a mass of more than 66g (purple)
+ EXTRA LARGE Eggs with a mass of 59g to 66g (red)
+ LARGE Eggs with a mass of 51g to 59g (blue)
+ MEDIUM Eggs with a mass of 43g to 51g (green)
+ SMALL Eggs with a mass of 33g to 43g (black)
These grade standards are set and enforced by the Directorate of Agricultural Product Standards. Inspectors of the Directorate follow up all complaints with regard to egg mass.