Grading an egg

The Poultry Division administers many programs pertaining to eggs.  The programs include:

USDA Shell Egg Surveillance
Massachusetts Seal Program
Quality assurance grading of consumer shell egg product sold within the Commonwealth

The USDA Shell Egg Surveillance Program is a Federal program administrated by the USDA Agricultural Marketing Services (AMS). Massachusetts is contracted by AMS to inspect all hatcheries, egg grading stations and shell egg producer/packers with 3000 birds or more. Massachusetts state inspectors conduct quarterly inspections at these premises.

The Massachusetts Seal Program allows producers of Massachusetts eggs participating in the inspection program to market their product using the Mass Seal Logo.

Quality Assurance Grading of Consumer Shell Egg Product involves on sight grading of egg product at consumer outlets. This is done by Department inspectors on a random basis.

General Information about Egg Grading

Egg Quality Grade

The interior and exterior quality of an egg, referred to as the grade (AA, A, B), is determined by a process called candling. The candling light allows the user to grade the interior quality of the egg.

The following combination of factors is used to determine the grade of an egg:

  • Distinctness of the yolk shadow outline.The shadow of the yolk outline cast on the shell, when the egg is twirled in the candling process is one of the best indicators of interior quality. As the egg ages the whites lose carbon dioxide and moisture causing them to become thinner, allowing the yolk to spin more freely in the egg. This creates a more clearly defined shadow of the yolk, when the egg is candled.
  • Air Cell.The size of the air cell is another factor used to determine the grade of the egg. When an egg is first laid, it has a very small air cell or none at all. As the internal temperature of the egg drops, the liquids contract more than the shell. As a result of this contraction, the inner membrane separates from the outer to form an air space. As the egg ages this air cell becomes bigger due to the escape of gas and evaporation of water from the egg.
  • Blood and Meat Spots can also be detected by the candling light. The presence of large spots will downgrade an egg.
  • Surface cracks on the shell are also easier to detect when candling.

Egg Weights

The weight standards are as follows:

  • A dozen Jumbo eggs should weigh approximately 30 oz. or more
  • A dozen Extra Large eggs should weigh approximately 27 oz. or more
  • A dozen Large eggs should weigh approximately 24 oz. or more
  • A dozen Medium eggs should weigh approximately 21 oz. or more

If you have any questions or suspect that eggs you have purchased do not meet the grade and size requirements, please call 617-626-1796 for more information.