Have you ever looked at a carton of eggs in the grocery store and wonder what it meant by AA, A, and all the other information on there? Egg grading is the process by which eggs are labeled based on quality. Though many people believe that the AA and A rankings mean size, they don't. It is the quality of the egg that gives it that ranking. Sure, they may not look as beautiful as the eggs you'd see in a show, but that doesn't mean that they aren't the highest quality produced in the egg farm.
So what exactly is grading? It is a a classification that is determined by interior and exterior quality, as mentioned above, and designated by the letters AA, A and B. The USDA provides a grading service and if you see the USDA official shield on the cartoon, it means that the eggs have been graded under Federal USDA supervision. Though this is not mandatory, other eggs must be packed under state regulations that meet or exceed those that are federal. Some states have stricter guidelines for their eggs and have seals of their own that indicate that their eggs are produced inside the state and constantly being checked for quality.
When being graded, the eggs are checked for both interior and exterior quality and then sorted by size, but size does not affect in which category they are placed. You can have a huge B quality egg but a tiny AA egg.
Judging the exterior of the egg is the first step in the grading process. Shell color isn't a factor, but graders will look for cleanliness, soundness, texture and shape. Eggs must be clean to pass, but are allowed a small amount of staining in B Grade. They must have sound, unbroken shells- any eggs with cracks or unsound shells are restricted. Ideally, the egg shell is oval with one end larger than the other, thick and without any bumps. Abnormal shells- misshapen, bumpy, ridged, thin or rough- are permissible for B grade eggs.
The interior is harder to inspect without breaking the eggs open. In most cases, the candling method is used. Candling is the holding up of the egg to a light source to check the interior. The other method is the Haugh unit system which requires the eggs to be broken. Albumen (the egg white) is looked at first and judged based on clarity, firmness and thickness. If it is clear, there will not be any spots, discolorations or foreign bodies. When rotated, the yolk should swing freely towards the shell and have a distinct outline. The thicker the albumin, the less movement, however, and a thick albumin receives a higher grade than a thin albumin. Yolk quality is determined by distinctness of outline, size, shape and lack of blemishes, mottling, germ development and blood spots.
Air cells may not exceed 1/8th inch depth in high quality eggs. While this is considered in grading, however, it does not necessarily relate to freshness. In order to judge freshness you should always observe the dates on the carton.
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