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A team from the University of Barcelona is leading a study that improves the technology available to identify the geographical origin and variety of hazelnuts, and thus avoid commercial fraud and food safety problems linked to the consumption of these nuts.

Food fraud, a problem that can affect a number of commonly consumed products, generates high economic losses and also influences the relationship of trust between suppliers and consumers.

The new strategy presented by the UB team explores the application of fingerprinting analysis of triglycerides to determine the geographical and varietal origin of the product. This fast and effective procedure can identify the origin and variety of more than 80% of the samples and helps to complement the results provided by the technique of fingerprinting the unsaponifiable fraction, described by the team in a previous study.

Professors Stefania Vichi and Alba Tres lead the study, in the journal Food Chemistry, which is part of a doctoral thesis carried out by researcher Berta Torres, from the UB's Faculty of Pharmacy and Food Sciences, the Nutrition and Food Safety Research Institute (INSA) and the Food and Nutrition Torribera Campus.

The study also includes the participation of UB experts Soriana B. Nicotra and Francesc Guardiola, as well as Mercè Rovira and Agustí Romero, from the Institute of Agrifood Research and Technology (IRTA), under the collaboration within the TRACENUTS project.

A rapid technique for an initial screening of samples

The triglyceride fingerprinting technique provides an effective tool for rapid initial screening of specimens, allowing for the quick selection of samples that are clearly classified as genuine or fraudulent. For the more doubtful ones—which are in a zone of uncertainty around the threshold of separation between authentic and fraudulent ones—it is proposed to use the technique of unsaponifiable lipid fraction fingerprinting, which was described in a previous paper.

This methodology is based on the analysis of several lipid compounds that are minorities in hazelnuts. Thanks to the extension of the sample database with new geographical regions and harvests, this study has validated that the unsaponifiable fraction technique achieves an accuracy of more than 94% to identify the origin and variety of hazelnuts, and exceeds the results obtained with the triglyceride method. This high percentage of success consolidates it as a key tool for detecting fraudulent samples, although, due to its complexity, it is proposed as a confirmation technique.

In both cases, the analytical data are approached using the lipid fingerprinting technique, a state-of-the-art data processing methodology for authenticating food products. This approach allows the lipid compound profiles to be treated as a unique fingerprint of each hazelnut variety or geographical origin. In this way, it is possible to look for similarities in this fingerprint between fruits of the same variety or origin, as well as differences with other hazelnut samples of different varieties or origins.

The results not only validate two efficient techniques for food authentication, but also open up new perspectives for applying the technique in other areas of food control, thus strengthening consumer and producer confidence in product traceability.

Infrared spectroscopy to determine the geographical origin and variety of hazelnuts

Near infrared (NIR) and mid-infrared (MIR) spectroscopy techniques can also expand the range of fast and efficient authentication methodologies available to prevent food fraud. This follows from the team's paper in the journal Spectrochimica Acta Part A, the first scientific study to systematically compare spectroscopic techniques to determine the authenticity of hazelnut variety and geographical origin, carried out in collaboration with experts Vincent Baeten and Juan Antonio Fernandez-Pierna from the Walloon Agricultural Research Center in Gembloux (Belgium).

These methodologies, which require a very short analysis time and minimal or no sample treatment, could potentially be applied in situ and are added to those that the team has successfully developed in this area of research to prevent food fraud. The results of this study demonstrate that the NIR technique can be suitable for authenticating the geographical and varietal origin of hazelnuts, as it correctly classifies more than 95% of the samples.