From DNA barcoding to nanoparticle-based colorimetric testing: a new frontier in cephalopod authentication

Food-item authentication and traceability is an issue of primary concern, due to both socio-economical and health implications. DNA-based methods are increasingly being recognised as powerful tools to assess the reliability of supplier labels for any type of food. This is especially true for products characterised by a short shelf life and high-processing supply chain, such as seafood. In this work, a DNA barcoding approach was applied to assess the accuracy of species labelling in 150 cephalopod seafood products sold in the Italian market. Overall, high levels of mislabelling in squid, cuttlefish, and octopus items were identified, and in some cases, even species not included in the current food Regulations. Additionally, an application of the recently developed naked-eye detection tool 'NanoTracer', consisting in the combination of DNA barcoding with gold nanoparticle-based, was demonstrated to authenticate common cuttlefish (Sepia officinalis) seafood. The primer pairs used to set the fast detection system for S. officinalis were designed based on the most comprehensive DNA barcoding (COI and 16s rRNA) datasets ever assembled for cephalopods, assuring the specificity of the method. 'NanoTracer' allowed a simple, rapid, accurate and cost-effective authentication, revealing its potential adaptability to any type of seafood and other food categories.