USDA Pressure Chamber Makes Egg Microcracks Shine
February 13, 2009
A prototype pressure chamber and
camera system that finds very small cracks, called microcracks, in fresh
eggshells has been developed by Agricultural
Research Service (ARS) scientists.
The device could help the fresh egg industry find microcracks that can often
go undetected during grading, according to scientists at the agency's
Safety and Quality Research Unit (ESQRU) and
and Safety Assessment Research Unit (QSARU), both in Athens, Ga.
The ARS team that developed the device included food technologist
Jones at ESQRU and engineers
Lawrence, Seung Chul Yoon and
Park, image analyst
Heitschmidt, and technician
Savage at QSARU. Both units are part of the ARS
B. Russell Research Center.
The technology emulates human graders who squeeze the egg along suspected
cracks to see if it opens. A prototype chamber was built that uses a brief
negative pressure to slightly pull the eggshell outward to expose any existing
cracks that may be present, without causing cracks in intact eggs. The camera
system then takes a picture before and while the crack is opening to
"see" if the shell is cracked.
According to Lawrence, the system detected 99.4 percent of eggshell cracks
while recording almost no false positives--only 0.3 percent. In comparison,
professional human graders had an 85.8 percent crack detection rate and 1.2
percent false positives.
Currently, many high-speed egg-processing plants use high-frequency analysis
to "listen" for cracks, while other plants use human graders visually
inspecting eggs with a bright light source in a low-light environment. But
there hasn't been a reliable method for finding microcracks.
Microcracks are so small they can escape even the most experienced human
grader's eye at the processing plant. Unfortunately, microcracks grow over time
and are often easily visible by the time they reach consumers at market. Cracks
are a safety concern, because they potentially create a pathway for pathogens
such as Salmonella to enter the egg. The crack detection system would support
the efforts of human graders to ensure high-quality eggs reach consumers.
more about this research in the February 2009 issue of Agricultural
ARS is the principal intramural scientific research agency of the
U.S. Department of