(2) Moderately stained--B Quality. The shell of a moderately stained egg is
free from adhering dirt but has slight stains that do not appreciably detract from the
appearance of the egg. When the stain is localized, approximately 1/32 of the shell
surface may be moderately stained. When the moderately stained areas are scattered,
approximately 1/16 of the shell surface may be moderately stained. Eggs having more
than 1/16 of the shell surface slightly stained may be classified as Dirty.
(3) Dirty. A Dirty egg has adhering dirt, foreign material, or prominent or
moderate stains that cover more than 1/16 of the shell surface, if scattered, or more
than 1/32 of the shell surface, if localized.
b. Since Dirty eggs are downgraded, producers often clean eggs before
delivery. In the past, the military would not buy shell eggs that had been washed,
because the available methods were not adequate for proper sanitation. Now, however,
contractual documents permit cleaning shell eggs and specify the methods and
equipment to be used. At present, the only approved method is to wash them. The
numerous egg-washing machines on the market all work on much the same principles.
The eggs are scrubbed clean by brushes and detergents, then rinsed and air-dried.
Some machines wet down the eggs before scrubbing, to reduce the surface tension of
the dirt. Machines also vary in methods of using water. Some reuse the wash water,
adding additional water only to replace that lost in evaporation; others use fresh water
for each operation. Criteria for reusing the water for shell egg cleaning operations, to
include time and temperature requirements, can be located in the most current copy of
the USDA "Regulations Governing the Grading of Shell Eggs and US Standards,
Grades, and Weight Classes for Shell Eggs." Potable water is required for all rinse
c. The illustrations in figure 3-2 are intended as a guide. Also, the shell surface
measurements are not to be used as an actual measurement in grading. Graders
should learn to determine the area that constitutes these measurements and then judge
eggs having soiled shells against this mental picture.
d. It is difficult to visualize the gathering together of soiled areas and apply them
against a scale. However, if you, the grader, keep in mind that the total area of a
normal 2-ounce egg is about 10-1/2 square inches, 1/32 of the shell surface of a
2-ounce egg would measure approximately 9/16" x 9/16", 1/16 would measure about
13/16" x 13/16".
In giving consideration to shell color, it should be borne in mind that this factor
does not affect the quality of the egg and for this reason it is not considered in the US
standards of quality or grades. For many years, consumers in some areas of the
country have preferred white eggs, thinking, perhaps, that the quality is better than that
of brown eggs, while consumers in other areas have preferred brown eggs, thinking