Keeping your eggs safer--in a flash
By Sharon Durham
Agricultural Research Service, Information Staff
You've heard of lightning in a bottle, but how about lightning in a box?
That's the effect that Agricultural Research Service scientists create when they look for very small cracks in chicken eggs. Nobody wants to buy a carton of eggs only to find that some are cracked. But tiny cracks, called micro-cracks, can be so small that sometimes even an experienced egg inspector's eye misses them at the processing plant. Unfortunately, the micro-cracks grow over time, and by the time the eggs reach the supermarket, those cracks can be pretty big.
The shell protects the egg from contamination, so detecting cracks is important. Fortunately, eggs are carefully inspected in commercial plants before consumers buy them.
But, as we said earlier, even the most experienced inspectors, or "graders," can miss a micro-crack. So the egg industry could really use a better way to detect micro-cracks--one that is simple and inexpensive, and works with large batches of eggs. ARS scientists found a solution.
The scientists built a device that helps find those hard-to-see cracks. The scientists are food technologist Deana Jones at the ARS Egg Safety and Quality Research Unit; engineers Kurt Lawrence, Seung Chul Yoon and Bosoon Park, image analyst Jerry Heitschmidt, and technician Allan Savage at the Quality and Safety Assessment Research Unit. Both research units are part of the Richard B. Russell Research Center in Athens, Georgia.
ARS has filed an application for the technology. You can learn more from the ARS Science For Kids story "I Am an Inventor!" A patent is a short write-up that describes an invention. A patent includes background information, drawings, and models or pictures of the invention (roll-over definition).
Lawrence's technology uses a pressure chamber, specialized camera, and computer program to create a lightning-like flash that makes even the tiniest cracks obvious. The chamber is a sealed container that uses pressurized gas to "suck" the eggshell gently outward. An early version of the chamber was built for a single egg, but the scientist quickly expanded it to a 15-egg chamber, and then to a 20-egg chamber. To test the chamber, Lawrence got 1,000 white-shell table eggs from a nearby egg processing facility, brought them to the laboratory, and let them reach room temperature to copy real processing conditions.
Many of the experimental eggs were rolled around to cause micro-cracks, then were immediately examined by human graders and scored as either intact or cracked. The eggs were later placed in the chamber for imaging and re-graded for comparison. The results were surprising: 99.6 percent accuracy overall. "In comparison, the professional human graders had an overall accuracy of 94.2 percent on these hard-to-see micro-cracked eggs," Lawrence says. "These results are much better than anyone had achieved earlier.
"This could very well give egg graders a tool they can use to consistently identify cracked eggs for removal from the processing line while not removing intact eggs," Lawrence says.