NMR-based metabolomic approach for the assessment of traceability, authenticity, and quality of food products

Currently, two substantial concepts are gaining importance in the food field of knowledge, namely, authenticity and traceability. Food adulteration is becoming a central issue for many players in the food industry, such as stakeholders, institutions, regulatory bodies, and consumers, due to an increased availability and easy access to a range of different food products, which it is focusing the attention of consumers demand to high-quality and authentic products, with special attention to the place of origin. Highly developed targeted analytical methods and regulated tools are used to assess the authenticity of food products; however, they possess undeniable disadvantages. These methods investigate just one characteristic decided a priori and neglect the product in its entirety, which make them ineffective strategies due to increasingly sophisticated adulterations. The foods considered for this study were selected based on the most common sources of food fraud of the so called “Made in Italy” products. One of the most counterfeited Italian food commodities is extra-virgin olive oil (EVOO). An in-depth inspection of the literature about the assessment of its quality and authenticity has revealed that it is a well and deeply studied issue. Many works with different approaches are already published, considering targeted and untargeted approaches, and chromatography and spectroscopic techniques. Nuclear magnetic resonance (NMR) is also highly used in this field, due to its high level of reproducibility and simple sample preparation. For these reasons, this topic was covered with a thorough scientific review. Grana Padano cheese is always among the leading positions in adulteration rankings, and it was the second investigated food in this study. Grana Padano cheese was firstly discriminated from its competitors and other non-PDO (non-Protected Designation of Origin) labeled cheeses. The counterfeiting issue is especially acute when the cheese is in the shredded form because no trademark logo fire-marked on the crust or other authentication signs can be recognized. Samples of Grana Padano cheese, its Italian competitors and foreign non-PDO samples were analyzed with NMR spectroscopy and multivariate analysis to obtain a statistical model able to discriminate Grana Padano cheese from all the other cheeses. Then, another important aspect about cheese, ripening, was considered. Grana Padano cheese is in fact sold with three different aging steps, that also affect its price. Mislabeling about ripening can possibly occur, and for this reason we have decided to proceed with the ripening investigations, to find possible “biomarkers” of the different aging stages. To accomplish this task, another dataset of authentic PDO Grana Padano samples with different ripening ages was analyzed. Both the aqueous and lipid fraction extracted from the samples were considered in order to obtain a holistic view of the samples during maturation. In the end, bactofugation, an additional production step has been considered. Since the production of Grana Padano cheese is strictly controlled by specification rules, the modification of such rules needs further studies to avoid modifications of the organoleptic and nutritional characteristics of the product. For this reason, the additional centrifugation step to remove microorganisms and spores was studied by the comparison of the profile of “traditional” Grana Padano samples with samples produced with bactofugation step and the results were challenging. The resulting differences were mainly affecting the aqueous fraction, which is the major responsible for the organoleptic properties. These results can be helpful for the Consortium for the discussion whether to include this step in the disciplinary or not. A preliminary study on another food commodity, blueberries, was completed, which investigated the differences among four different varieties and with varying storage times. The aim of this investigation was the application of NMR-based metabolomics to highlight differences among varieties with a fast and simple analysis and try to identify compounds potentially sensitive to storage time, as a tool for breeders to understand possible degradation pathways.