Elemental metabolomics: New analytical tools for food valorization and authentication

Elemental metabolomics studies the concentration, distribution, and speciation of macro, trace, and toxic elements in organisms. The elemental fingerprint is related to internal factors, such as the genome and diseases, or external factors, such as diet and environment. Therefore, elemental fingerprinting can be used for food authentication because the elemental fingerprint of a food varies depending on its geographical origin, cultivation or feeding methods, processing, or exposure to anthropic sources. Sustainability and food quality are the two most important aspects and challenges for the future of the food industry. In this context, new analytical methods are required to monitor food quality, safety, and authenticity. This work aims to develop, optimize, and validate several analytical methods to use elemental metabolomics in food authentication. Elemental analysis was performed using inductively coupled plasma mass spectrometry (ICP-MS). Sample preparation was performed by microwave acid digestion using single reaction chamber technology, and each method was optimized by experimental design. Multivariate analysis was used for data processing. The developed methods were used to study three food matrices of great importance for the economy of the region of Sardinia (Italy): honey, dairy sheep products and rice. The elemental fingerprinting of honey allowed the differentiation of the samples according to their botanical and geographical origin, as well as the evaluation of the levels of trace and toxic elements. Dairy sheep products were analyzed to study the influence of food processing. Pecorino Romano DOP and Pecorino Sardo DOP were accurately discriminated based on the cheese-making process. Moreover, the results highlighted the high content of many nutritional minerals that can be declared in the cheese label. The influence of irrigation methods on arsenic translocation and speciation was investigated. The results showed that sprinkler irrigation allows to minimize the total arsenic concentration and speciation is mainly influenced by irrigation methods than rice genotype. In conclusion, several ICP-MS methods were optimized and accurately validated for the analysis of elements in food. Therefore, these methods were used to investigate the influence of geographical origin, botanical origin, processing methods, seasonality, irrigation methods and genotypes on the elemental fingerprints of foods.