They are supposedly “organic” – but is that really true? Researchers report that a yolk analysis using nuclear magnetic resonance spectroscopy can now precisely show whether chicken eggs actually come from organically kept hens. The respective type of farming is clearly reflected in patterns of the composition of certain ingredients. The process could therefore now benefit the protection of consumers and organic egg producers from fraudulent practices.
“How did the hens that gave me the eggs live?” This question is important to many consumers because animal welfare is important to them. That’s why they reach for products with the organic seal on the egg shelf in the supermarket because they promise that they come from hens that were treated relatively well. Consumers are also prepared to pay higher prices because organic production is known to be more complex than conventional production. But trust in the authenticity of organic products has suffered: there is a risk that black sheep in the industry will try to trick consumers into buying expensive organic products that actually come from conventional farming.
How an egg was produced should actually be recognizable by a stamp that must be placed on each egg. In Germany, four production methods are distinguished and graded by numbers according to the level of animal welfare: A “0” at the beginning of the code stands for “organic production”, a “1” for free-range farming, “2” means barn farming and “3” stands for the lower category of so-called small group farming. But labels are known to be forged: the stamps do not always guarantee the actual authenticity of the eggs. So far, fraudsters have also benefited from the fact that false declarations are difficult to prove.
Signatures of attitude in the egg yolk
However, this is exactly what the new method developed by a research team from the German Institute of Food Technology in Quakenbrück with the support of the Federal Ministry of Agriculture could now make possible. It is based on a special form of nuclear magnetic resonance spectroscopy: the 1H NMR spectroscopy analysis method can break down the composition of sample materials in detail. The researchers’ focus was on the so-called metabolome of the egg yolk: the totality of the metabolic products that a hen stores in the yolk during its formation.
First, the researchers examined the metabolome of a total of 4,500 yolks from eggs from the four different production methods. The profiles obtained were then subjected to a so-called linear discriminant analysis (LDA). Artificial intelligence was used to identify characteristic patterns in the molecular profiles that can be linked to the types of husbandry. The team then used new test eggs to check to what extent they actually produce a “fingerprint” that can be used for detection.
Precisely verifiable
It was shown that the organic farming of hens is reflected in a metabolite pattern in the egg yolk that differs significantly from that of conventional forms. The researchers report that the correct classification of eggs from conventional and organic farming achieves an accuracy of 99.9 percent. The individual sub-forms of farming can also be classified with high precision, the results show. The effectiveness of the concept is also shown in another interesting signature in the yolk profiles, the team reports: The eggs could even be classified with an accuracy of 98.4 percent to the various breeds of laying hens that are currently common in production.
The results now show great potential for application, say the researchers. The method is suitable for broad use in food monitoring. It could now reliably detect incorrectly declared eggs in random samples or in suspected cases. This could protect organic egg producers from unfair competition and protect retailers and the processing industry from scandals. Above all, however, such controls could strengthen consumer confidence in the authenticity of organic eggs and thus increase demand.
The German Institute of Food Technologies is therefore now calling on companies, associations and additional research institutions to get involved in order to advance the further development of the analytical method and its application.
Source: Federal Office for Agriculture and Food, Final report on the project