If you are involved in commercial poultry egg production, then you have probably heard a lot about egg grading.
The grade of an egg normally depends on the amount of air that is contained in the interior of the egg cell along with the density of the yolk and the albumen. If the air cell is small, it will have a rounder yolk and a firmer egg white and this will mean a fresher egg. A fresher egg generally has a higher quality grade.
But you might have noticed from your supermarket shelves that the grade of the egg also depends on the source or how it has been raised. The “cage-free” or free range eggs generally have a AA grade while a pasture raised egg will most likely have a grade “A”. This has to do with the quality of the egg and the production environment.
Pastured eggs are generally regarded as more nutritious and of better quality than eggs from the caged birds.
The main weakness of the commercially farmed eggs is that they have a small air cell by the time they reach the processing area. This is because the barn where the chickens lay their eggs is generally on the same property as the centre where the eggs will be processed.
The air cell is small for eggs that have just been laid and taken to the next door for storage. The grade AA will be granted to these kinds of eggs irrespective of their nutrition content. In this case, the “quality” refers to the freshness of the eggs.
Passing the eggs through multiple procedures will end in they being graded as A. This is because it has taken longer to take the eggs from the barn or nesting areas to the processing centre. The extra days that it takes to carry out various kinds of processing such as hand-held collection, packaging and transportation will allow more air to gather in the cells of the eggs thus losing their grade. They will thus be of a lower grade.
There are also grade B of eggs. These do not just meet the right standards. They might be smaller in size, have abnormal sizes and with no limit of the size of the air cells in the eggs.
The grade of the egg generally has nothing to do with its nutrition. It has everything to do with its size and freshness or more generally, the amount of time it took to process the eggs before being taken to the market.