Free-range eggs cost considerably more than those laid by caged hens, so it’s not surprising that unscrupulous vendors would try to pass the latter off as the former. That’s why Spanish scientists have developed a new verification system, which is said to be completely accurate at determining an egg’s classification.
There are four types of eggs sold in the European Union, which are stamped with codes beginning with 0, 1, 2 or 3. These numbers indicate whether the hens were organically-raised, free-range, floor-raised or caged, respectively. Organic and free-range eggs are generally considered to be of better quality than the others, plus the production of them involves more work, so they’re accordingly priced higher.
Researchers from the University of Santiago de Compostela suspected that the yolks of eggs might be affected by the type of feed the hens were given, and by the amount that the birds were able to walk around. With that in mind, they proceeded to extract organic compounds known as lipids from eggs of known classifications, and then analyzed them via UV-VIS-NIR spectroscopy.
Sure enough, based on the amounts of ultraviolet (UV), visible (VIS) and near infrared (NIR) light that the lipids absorbed, it was found that eggs of different classes had different, specific spectral signatures. It is now hoped that once the technology is developed further, it could be used to detect fraudulently-labelled batches of eggs.
“Until now, the proposed methods only allowed a partial differentiation: for example, to discriminate between organic and conventional eggs,” says Prof. Manuel Vázquez. “Our method is the first one that allows a complete differentiation and with 100-percent accuracy.”
Spectral signatures used to check eggs’ credentials [New Atlas]