Don't get scrambled over eggs

Friday, 18 October, 2019

Don't get scrambled over eggs

A method has been developed in Europe to detect fraud in egg labels; while in Australia there are calls to phase out caged eggs.

In the European Union, eggs are labelled with a code starting with 0, 1, 2 or 3, depending on whether the hens are organically produced, free-range, floor-raised or caged, respectively. To prevent fraud and confirm the type of egg that the consumer buys actually corresponds to what is shown on the label, a team of researchers at the University of Santiago de Compostela (USC) in Spain have developed a technique to distinguish them with 100% accuracy by analysing the lipids of the yolk.

Organically produced eggs (certified by a regulatory council) or those laid by a free-range hen (which can be fed in the open air) are not the same in price or quality as those of birds raised on the floor of a closed henhouse or those that never leave a cage.

The USC method differentiates the four types of eggs at once. The technique consists of extracting the lipids from the yolk and analysing them by UV-VIS-NIR spectroscopy, ie, determining their absorption spectrum at ultraviolet (UV), visible (VIS) and near infrared (NIR) wavelengths. Details of the procedure have been published in the Food Chemistry journal1.

“Until now, the proposed methods only allowed a partial differentiation: for example, to discriminate between organic and conventional eggs, or between type 1, 2 and 3 eggs, but not all at the same time,” points out one of the authors, Manuel Vázquez, a USC professor at the Lugo campus, who emphasises: “Our method is the first one that allows a complete differentiation and with 100% accuracy.”

The authors worked with the hypothesis that the feeding and movement of the hens affects the composition of the yolk, so they extracted their lipids and determined the UV-VIS-NIR spectrum. With this information, they obtained chemometric models that made it possible to clearly distinguish the four types of eggs.

As for the detection of possible fraud to consumers, “For the time being, we have not ‘monitored’ the industry,” as Vázquez acknowledges, concluding: “It was not really our objective to inspect; that, in any case, will be up to the administration. We have developed this new tool, and now others will have to decide whether or not they want to use it to detect possible fraud.”

Phasing out caged eggs

Ahead of a parliamentary inquiry into use of battery caged eggs, the World Animal Protection is calling for support to phase out caged eggs. Findings from its recent research on consumer attitudes to battery cages in NSW revealed that more than 80% of NSW consumers don’t know that battery cages still exist in Australia, with no plans to phase them out. However, on a positive note, most NSW consumers (62%) said they always or almost always buy free-range eggs. And, almost half (48%) said they never or hardly ever buy caged eggs.

Rochelle Flood from World Animal Protection Australia said: “The Australian Government needs to take action to phase out battery cages, to avoid falling further behind nations who have already introduced regulations banning the practice. The European Union, New Zealand and some American states introduced battery cage phase-outs in 2012, so Australia is lagging behind.”

Australia’s state and federal agriculture ministers will be meeting early next year to consider an update to the standards and guidelines for poultry which have not been updated since the early 2000s. The current draft includes a phase-out of battery cages.


  1. Gema Puertas, Manuel Vázquez. “Fraud detection in hen housing system declared on the eggs’ label: An accuracy method based on UV-VIS-NIR spectroscopy and chemometrics”. Food Chemistry 288 (2019) 8–14.

Image credit: Example of an egg encoded with the number 2 (chicken raised on the floor)/Gema Puertas

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