Effects of Extended Storage on
Eggs By Sharon
June 2, 2004
Egg quality and usefulness are safely maintained beyond the
sell-by date if the eggs are stored properly, according to
Agricultural Research Service scientists
in Athens, Ga.
ARS food technologists Mike Musgrove and Deana Jones with the
agency's Poultry Processing and Meat
Quality Research Unit tested the quality and functionality of table eggs
during a 10-week storage time, long beyond the current 30-day industry standard
for storing eggs on the store shelf. Properly refrigerated and handled, eggs
are considered safe for consumption for four to five weeks beyond the sell-by
Musgrove looked at bacteria like Salmonella, Escherichia,
Enterobacter, Klebsiella and Yersinia that can contaminate eggshells and--if
handled or processed improperly--remain on eggs when they reach the consumer.
However, Musgrove found that after washing and packaging, eggs showed no
bacteria of the Enterobacteriaceae family until the fifth week after
processing. Washing eggs according to current guidelines removes bacteria from
their surface, reducing the chances of microbes getting into the eggs once they
are cracked in preparation for consumption.
An egg's shell and membranes under the shell provide a barrier
that limits the ability of organisms to enter. A natural protective coating,
called the cuticle, helps to preserve freshness and prevent microbial
contamination of the egg. This coating is damaged or removed by processing, but
a thin layer of oil may be applied during processing to help preserve internal
quality. The eggs are then placed in cold storage and shipped.
Jones studied the functionality of the eggs during 10 weeks of
storage. Eggs are found in a wide range of foods, including baked goods and
mayonnaise. Over time, eggs can lose their ability to fluff up an angel food
cake or make creamy mayonnaise, but according to Jones, they didn't show a
marked decrease in quality during the 10-week test period.
about the research in the June issue of
ARS is the U.S. Department of
Agriculture's chief scientific research agency.