Food metagenomics: Next generation sequencing identifies species mixtures and mislabeling within highly processed cod products

Abstract

Molecular identification of processed food products can be challenging due to the presence of unknown animal products or a blend of two or more species. However, with the development of high-throughput DNA sequencing methods (i.e. Next-Generation Sequencing) and DNA molecular markers libraries (e.g. DNA barcodes), it is possible to identify species using a powerful approach called metagenomics. Processed cod products, such as cakes and restaurant dishes, are very appreciated around the world and are an expensive seafood product in Brazil. Cod products are very prone to mislabeling since only four species can be legally labeled as “bacalhau” (cod) under Brazilian legislation: Gadus macrocephalus, Gadus morhua, Gadus ogac, and Boreogadus saida. The Ministry of Agriculture, Livestock and Food Supply is responsible for the inspection and certification of such products by providing an inspection stamp number (namely S.I.F.). We analyzed twenty-two processed cod products (i.e. cod pieces, frozen cakes, vacuum packaged cooked meals, a restaurant dish, and fast food cod cakes) labeled as “Bacalhau”, purchased from supermarkets, local stores, fast food outlets, and one restaurant in the city of Belo Horizonte, Brazil, with and without a S.I.F. stamp number. A mixture of two or more species were found within 31% of all products. Here, we report a mislabeling rate of 41% (N = 9) within highly processed cod products, but misidentification was less frequently found within products possessing a S.I.F stamp (4.5%). This is the first report of a metagenomic approach testing governmental certification programs and mislabeling of highly processed seafood products.