Mislabeling assessment and species identification by PCR-RFLP of mussel-based products (Mytilus spp.) sold on the Italian market

An Authentication Survey on Retail Seafood Products Sold on the Bulgarian Market Underlines the Need for Upgrading the Traceability System

Economically motivated or accidental species substitutions lead to economic and potential health damage to consumers with a loss of confidence in the fishery supply chain. In the present study, a three-year survey on 199 retail seafood products sold on the Bulgarian market was addressed to assess: (1) product authenticity by molecular identification; (2) trade name compliance to the list of official trade names accepted in the territory; (3) adherence of the list in force to the market supply. DNA barcoding on mitochondrial and nuclear genes was applied for the identification of whitefish (WF), crustaceans (C) and mollusks (cephalopods-MC; gastropods-MG; bivalves-MB) except for Mytilus sp. products for which the analysis was conducted with a previously validated RFLP PCR protocol. Identification at the species level was obtained for 94.5% of the products. Failures in species allocation were reconducted due to low resolution and reliability or the absence of reference sequences. The study highlighted an overall mislabeling rate of 11%. WF showed the highest mislabeling rate (14%), followed by MB (12.5%), MC (10%) and C (7.9%). This evidence emphasized the use of DNA-based methods as tools for seafood authentication. The presence of non-compliant trade names and the ineffectiveness of the list to describe the market species varieties attested to the need to improve seafood labeling and traceability at the national level.

Comparison of two commercial methods for smooth-shelled mussels (Mytilus spp.) species identification

Seafood international trade has increased the labeling requirements in standards and regulations to include product information that enable traders and consumers to make informed choices. The European Union (EU) Regulation No. 1379/2013 imposes the declaration of an official commercial designation and scientific names for all the fishery and aquaculture products to be offered for sale to the final consumers. DNA analyses are used to enforce this regulation and to test authenticity in processed foods. We compared the performance of two mono-locus approaches for species identification (SI) in 61 Mytilus mussels: the high-resolution melting analysis of the polyphenolic adhesive protein gene and the partial sequencing of the histone H1C gene. The H1C sequences were analyzed with five different methods. Both approaches show discrepancies in the identification of putative hybrids (0.0 < κ < 0.687 and 0.0 < MCC < 0.724). Excluding putative hybrids, methods show substantial to perfect agreement (0.772 < κ < 1.0 and 0.783 < MCC < 1.0). This study highlights the need to use standardized molecular tools, as well as to use multi-locus methods for SI of Mytilus mussels in testing laboratories.