Full length articleCOI barcode-HRM as a novel approach for the discrimination of hake species

- HRM analysis targeting COI barcode was developed for hake species differentiation.
- Five Merluccius species were discriminated in distinct clusters.
- Real-time PCR assay targeting COI gene allowed detecting hake DNA down to 0.2-20 pg.
- The method was successfully applied to analyse processed seafood samples.
- Results suggest adulterations based on the substitution of labelled species.

Hake species of Merluccius genus represent an important group of fish commonly sold all over the world. Therefore, they are highly prone to be adulterated, particularly the substitution of M. merluccius by other species with lower market value. The present work intended the development of a highly sensitive methodology for the rapid detection and differentiation of hake species based on mini-barcoding of cytochrome c oxidase subunit I (COI) gene combined with high resolution melting (HRM) analysis. The method allowed the full discrimination of M. merluccius, M. productus, M. hubbsi, M. capensis and M. paradoxus with high levels of confidence. Real-time PCR assay targeting COI mini-barcode provided a high sensitive tool to detect hake species down to 0.2-20 pg of DNA with adequate performance parameters. The application of the COI-HRM approach to 45 fish-containing foods showed that two samples did not comply with the declared species, suggesting mislabelling or species substitution. These findings highlight the need of controlling processed fish-containing foods and the feasibility of the proposed tool for their authentication at trace levels.