Japan's Exacting Science of Safety Inspection
Checking for cracks (C) Nabel
Checking for blood spots with red and green diodes (C) Nabel
The rapid-response intelligent robot packs eggs into cartons (C) Nabel
Rotating "fingers" (C) Hans Sautter
The robot seals the packages ready for shipping (C) Hans Sautter
The next step is to make sure there are no cracks in the shells. Sixteen hammers weighing just 0.8 grams give the eggs a gentle tap as they make their way along a conveyor belt of rollers. If the egg gives off a clean "tock" sound, it passes the test—no cracks. But if the sound is muffled and dull, there may be problems. Of course, there would be no sense in hitting the eggs so hard that they break—the hammers are set so that they merely brush gently against the eggshells. It is not easy to make a judgment based just on the sound, since the size of the egg and the thickness of the shell vary from one egg to the next. Japan’s super technology can detect cracks with 95% accuracy.
Once the eggs have been checked for cracks, the machine inspects them to make sure that there is no dirt left on the outside of the eggs, and tests for bloodspots. Occasionally a bloodspot is caused by a burst blood vessel or similar accident in the ovaries (the part of the hen where the eggs are stored). It's not actually dangerous to eat an egg with a bloodspot, but in Japan eggs with bloodspots are not considered fit for human consumption, so they have to be weeded out before the eggs go on sale. How is it possible to check inside the egg without breaking the shell? If you cover a flashlight with your hand, your fingertips will glow red. This is because the hemoglobin inside your blood absorbs blue and green light, so that only the red light penetrates your hand. The egg machine works on the same principle. The machine carries out a spectroscopic analysis of the light as it comes through the shell, studying the wavelengths of the light to see if any is being absorbed by blood. If there is even a tiny spot of blood in the egg, this test will find it.
After the check is finished, the eggs are weighed and sorted by size. The next stage in the process is the rapid-response intelligent robot. The robot keeps a constant watch on the number of eggs in each section. Once a lot of eggs have built up in a certain size category, the robot zips over and sucks up enough eggs to fill six packages of ten. The robot puts the eggs in their cartons and seals the packages ready for shipping.
It's very important to move the eggs very carefully even after the work is finished. The Japanese machine uses some of the most advanced technology in the world to make sure that the eggs don't break: from the auto-loader that sucks up the eggs and moves them almost instantly, to the rotating "fingers" that can collect and move a specific single egg without the need to stop the conveyor belt.
(Updated in January 2011)