Analytical technique can spot counterfeit eggs

A few years back, reports of counterfeit eggs being sold in China were all but written off as an urban myth, but it seems the problem is real – and researcher are looking into ways to detect the fraud.

Back in 2011 there was news of people in China complaining about artificially fabricated eggs, and there has been a steady stream of other cases reported in the intervening years of eggs with whites and yolks made from sodium alginate, gelatin and other chemical ingredients like colourings, with shells made of calcium chloride.

Fabricated eggs lack the nutritional value of real eggs, but more worryingly they pose a risk of severe side effects due to potentially hazardous chemical ingredients, including increased blood pressure, upset stomach, nausea, and vomiting.

It's remarkable that profit can be made on a low-value food item like an egg, but the fakes are apparently fairly easy to make and hard to distinguish from the real thing, often being introduced alongside real eggs in shipments to try to hide the scam.

Researchers in South Korea and the US have been looking at techniques that could be used to screen for fake eggs rapidly at an industrial scale and in a non-destructive way, and think that an approach based on Fourier transform infrared (FT-IR) spectroscopy could be the answer.

The team combined FT-IR spectra with statistical analyses for discriminating fabricated from real eggs, and concluded that the technique was 99% accurate.

They compared eggs bought at a market in South Korea to eggs they manufactured using off-the-shelf lab ingredients – sodium alginate, tartrazine for the yolk colouring, and calcium chloride for the shell.

"The entire fabrication process was conducted at room temperature and required 5 min to produce a single fabricated egg," write the authors, whose work is published in the journal Infrared Physics & Technology.

The study shows that it is feasible to build an advanced detection technique for fabricated eggs using FT-IR spectroscopy and multivariate analytical methods, they conclude.

"This research will be pursued further in the future using other varieties of egg samples to examine the potential of the developed model for detecting other adulterations of eggs in real-time samples."