How Eggs Are Classed and Graded

The grading of eggs is done with a series of tests where the eggs are examined for various qualities such as size and weight. There are three grades of eggs, which are Grade A, Grade B, and Grade C, in Canada. The grades in the US differ slightly by name only, as Grade A, Grade AA and Grade B. Grade A eggs are sold to consumers but the other Grades are for commercial uses.

In order to grade the eggs, they are first washed to make sure they are spotless then they are sent to be candled. Candling, which is usually performed by hand, examines the contents of the egg. This is done by passing the eggs past a light which allows the shell to be viewed internally. The conditions of the shell, the white, and the yolk, are checked for cracks and air pockets. In modern egg operations, the eggs are checked for cracks with the use of sonic sound. Tiny probes tap the egg a total of 16 times to accurately detect any blemishes in the shell. If a crack is found, a thud will indicate the egg is below standard and will be removed. An egg that is perfect will have the machine produce a high pitched sound. The candling or scanning allows the technician to see the size of the air pocket, cracks in the shell, and the centering of the yolk. This is what will later divide the eggs into different grades.

Once it has been determined the egg is worthy of carrying on, it then goes to be graded and weighed. The weight is done by the carton, not the individual egg, and computer controlled sensors weigh each egg over 60 times in less than one second. There is only a 3 ounce difference per one dozen eggs of a different size so the accuracy of the weight of each carton is important.

Grade A: The egg is found in perfect condition. The shell is not cracked at all, is fully clean, and the yolk is round and centered in a firm white with a minimal air pocket. These eggs will be processed for shipping to retail stores for consumers to buy.

Grade B: This egg also has an un-cracked shell but may have a rough texture. The white will be watery/thin and the yolk somewhat flat. These eggs are saved for commercial uses such as selling to bakeries or for processing into other foods like making mayonnaise or noodles.

Grade C: Eggs with this grade likely have a cracked shell, loose yolk, and very thin white. This will only be sold to commercial processors as use as an additive for other products.

Sometimes during the cleaning and other processes, eggs will get broken or punctured. These will be added to the Grade C eggs to be used in processed foods. The eggs are all broken by special machines at a "breaking station," where they are then pasteurized. The eggs are pasteurized by heating the eggs liquid form to a very high temperature in order to kill any harmful bacteria and micro-organisms. Once the pasteurization process has been completed, further processing of the egg is done and then packaged in liquid, frozen or dried/powdered form for sale. Preservatives or flavorings, and food coloring may be added before selling to companies who will use the processed eggs for production of food or condiments as well as such things as shampoos, pet food, and in adhesives.

Technology has played a significant role in the production of eggs. Now, all eggs are able to be used in a variety of food areas, while the best eggs are provided directly to the consumer.