Stable isotope and trace element analysis for tracing the geographical origin of the Mediterranean mussel (Mytilus galloprovincialis) in food authentication

Determining the geographical origin of seafood is crucial for regulators and fishing industries who seek to prevent commercial fraud, enforce food safety regulations and ensure high standards in sustainable fisheries management. Hence, we have investigated the potential of stable isotope ratio analysis (SIRA) and trace element fingerprinting (TEF), both individually and in combination, to trace the geographical origin of farmed M. galloprovincialis mussels harvested from eight different regions, located in the Mediterranean Sea, the European Atlantic coast and the Chilean Pacific coast. Particularly, carbon and nitrogen isotope ratios of mussel tissue (n = 179) and concentrations of 16 trace elements in shells (n = 100) were measured. Results show that significant differences exist in the chemical signatures of mussels harvested at different locations, and particularly among those belonging to different marine regions. Random forest (RF) classification method based on combined data (n = 64) revealed the best prediction accuracy correctly assigning 97% of individuals to their harvest location. The most relevant elements for provenance discrimination were δ13C, δ15N, Pb, Ba, Mn, and Al. Our results support the possibility for developing a reliable origin assignment tool based on stable isotopes and trace element analyses with global uses in seafood traceability and food safety.