4-25. DETERIORATIVE CONDITION OF UNKNOWN CAUSE
In the case of a deteriorative condition of unknown cause, the veterinary officer
will make the decision as to whether a potential health hazard is present or not.
Section IV. DETERIORATIVE CONDITIONS IN SHELL EGGS
a. Responsibility. As a 91R20 veterinary food inspection specialist, you must
verify the presence of deteriorative conditions in shell eggs.
b. Storage and Handling. Because shell eggs are delicate, they must be
stored under controlled temperature and must be handled with care. Rough handling
may cause the shells to crack or leak or the air cells inside the eggs may break loose
and move about.
c. Importance of Humidity Control. Humidity must be maintained at an
accurate level. When it is too high, moisture develops on the eggs and sometimes
causes mold to grow inside the shell eggs. When it is too low, the shell eggs may
dehydrate on the inside.
d. Potential Deterioration During Storage. Because deterioration can take
place on the inside of shell eggs, the supply in storage may be in an advanced stage of
4-27. MICROBIAL SPOILAGE
When laid, the contents of the shell egg are generally free from bacteria. The
shell egg contents are protected by the shell and associated membranes and chemical
inhibitors in the egg albumen. Some of the components in the albumen that provide an
unfavorable medium for microbial growth include lysozyme, conalbumin, ovomucoid,
avidin, riboflavin, and others. (Although shell eggs have built-in natural protection as
just described, Salmonella has been found in freshly laid eggs. Therefore, it must be
assumed that all shell eggs are contaminated with this bacterium.) Deteriorative
conditions due to microbial growth that cause shell eggs to become inedible follow.
a. Black Rot. When viewed with a candling light, shell eggs with black rot are
virtually opaque. When broken out, the egg content has either a gelatinous yolk,
blackened throughout with a grey, watery albumen, or a dark brown, mealy yolk with a
dark brown albumen. The bacteria associated with this type of spoilage are species of
Proteus and Aeromonas.
b. White Rot. With white rot, threadlike shadows may be seen in the thin white.
In later stages, the yolk appears severely blemished when the shell egg is viewed with
the candling light. Upon opening, the egg yolk shows a crusted appearance and