Lab test can authenticate hazelnuts, a food fraud hotspot

Researchers in Germany have identified a lab technique that can identify the geographic origin of hazelnuts – which have big pricing variations depending on their source country that open up opportunities for fraudsters.

Hazelnuts (Corylus avellana L) from some regions of Italy, for example, have Protected Designation of Origin (PDO) status and so command higher pricing, creating an incentive for economically-motivated food fraud, for example substituting cheaper nuts for the premium products.

The trade in counterfeits is also made easier by a complex global production chain and, while not specifically affected by regulatory initiatives like the European Deforestation Regulation (EUDR), some sources have been linked to unsavoury practices like bonded and child labour among farmers.

Now, scientists from the University of Hamburg's Institute of Food Chemistry have published a paper in the Journal of Food Composition and Analysis which describes the development of a method for hazelnut origin determination based on two approaches to inductively coupled plasma-mass spectrometry (ICP-MS).

ICP-MS is a highly sensitive analytical technique for liquids that measures and identifies elements in a sample, detecting them at parts-per-trillion levels, but has been challenging to apply to nuts due to the generally low element concentrations in such high-fat foods and the need for labour-intensive chemical digestion procedures to generate a liquid sample for testing.

The team deployed an ICP-MS technique based on solution nebulisation (SN-ICP-MS) to create whole element profiles of 244 hazelnut samples from five different countries that are significant producers – Germany, Italy, Georgia, France and Türkiye – over three harvest years.

Using SN-ICP-MS – which relies on chemical digestion – they were able to show accuracy of up to 92.1 per cent in identifying the country of origin for samples.

However, they refined the process further by using laser ablation as an alternative to chemical digestion (LA-ICP-MS), a technique that is greener as it uses fewer hazardous reagents such as nitric acid and hydrogen peroxide and is also time- and cost-saving.

It had the added advantage of hiking the accuracy of prediction to 100 per cent and – while the technique still needs some refinement – "the advantage of reducing the effort for sample preparation to almost none and also shortening the measurement time cannot be denied," write the authors of the paper.

Photo by Monika Grabkowska on Unsplash