Development of innovative analytical strategies for the geographical and varietal authentication of food products highly susceptible to fraud

[eng] Due to globalization and the expansion of food supply chains, food fraud has become a global issue, especially for high-value foods such as olive oil and nuts. These products are highly valued for their nutritional benefits and sensory properties, which are strongly influenced by their varietal and geographical origin. Driven by economic gain, they are often mislabelled to exploit premium prices associated with specific regions or varieties. The problem is exacerbated by ineffective official control methods, posing both economic risks and significant threats to public health. This doctoral thesis aims to develop and validate new analytical methodologies to verify the geographical and varietal authenticity of high-value foods, specifically virgin olive oil, hazelnuts, and pine nuts. To achieve this, isotopic and metabolic marker-based methods were used, including both target and untargeted approaches. For virgin olive oil, two methods were compared: sesquiterpene hydrocarbon fingerprinting and stable isotopes of carbon (C), hydrogen (H), and oxygen (O). Sesquiterpene fingerprinting proved more effective, offering greater sensitivity, specificity, and robustness for both geographical and varietal authentication. For hazelnuts, a method to analyse stable isotope ratio of O, and C and H of fatty acids was developed alongside three untargeted metabolic methods: triglyceride, unsaponifiable fraction, and spectroscopic fingerprinting. While the isotopic method distinguished between regions with different pedoclimatic conditions, the metabolic methods proved superior. Triglyceride fingerprinting achieved lower accuracy but was fast and simple and consequently suggested for screening. Conversely, fingerprinting of the unsaponifiable fraction was more laborious but offered higher accuracy as a confirmation method. Combining these methods enhanced efficiency reducing workload. Finally, the spectroscopic method, being simpler, faster and more accurate than triacylglycerol analysis, was also a suitable screening method. For pine nuts, strontium isotopic analysis failed to differentiate Mediterranean from Asian pine nuts, demonstrating that a single isotopic marker is inadequate for complex geographic authentication. However, terpene fingerprinting was successful in distinguishing Mediterranean pine nuts from other origins, proving to be a direct and efficient authentication method. Overall, metabolic fingerprinting methods have shown superior effectiveness for the geographical and varietal authentication of these foods, positioning them as suitable support tools to official control methods. However, limitations related to their transferability and the lack of standardized validation protocols are their main current challenges.