ISAAC – Innovative SeAfood AuthentiCation: DNA-Based Solutions to Promote Safety and Sustainability in the Global Supply Chain

In recent years, processed seafood products have become increasingly appreciated by consumers as a practical, affordable, and widely accessible way to benefit from the nutritional properties of fish. However, the processed seafood sector is characterized by highly fragmented and globalized supply chains which, combined with the loss of species-specific morphological traits during processing, facilitates the occurrence of fraudulent practices, such as the substitution or the inclusion of undeclared species, particularly in mixed fish products. In this context, strengthening systems for processed seafood authenticity, safety, and transparency has become increasingly critical. DNA metabarcoding, made possible by the advent of high-throughput sequencing (HTS) technologies, currently stands as the only molecular approach capable of reliably authenticating potentially multi-species seafood products. In the absence of standardized analytical protocols, targeted methodological evaluations are needed to guide its implementation and fully utilize its potential. Within this framework, the objective of the ISAAC – Innovative SeAfood AuthentiCation doctoral thesis was to contribute to the development of effective DNA metabarcoding strategies for the authentication of processed seafood products. In-silico primer assessments, followed by in-vitro applications, provided insights that support the definition of robust multi-marker approaches. Species composition analyses of products sourced from European retailers and in different supply chain stages revealed frequent mismanagement of raw materials by global processors, the presence of harmful species, and gaps in labelling regulations. Considering the outcomes of this thesis, DNA metabarcoding for seafood authenticity can be considered as a sufficiently mature approach to be adopted by various stakeholders across the supply chain, particularly when based on the “gold-standard” Illumina platform. While further methodological refinements may still enhance its performance in the coming years, DNA metabarcoding already represents a robust solution to ensure food safety, prevent species substitution fraud, and contribute to ongoing efforts toward the sustainable use of marine resources.