Rapid collagen peptide mass fingerprinting as a tool to authenticate Pleuronectiformes in the food industry

Reliable species identification of specimens in the food chain is crucial for detecting mislabelling fraud. While visual identification, DNA-analyses, and proteomic approaches have been used in the past, this research provides an alternative proteomic technique that has been trialled here to identify tissue samples from species within the order Pleuronectiformes (flatfish). Previously, archaeological research has used peptide mass fingerprinting to identify fish remains to species by extracting collagen Type I preserved in bones. As this type of collagen can also be found in the fins, skin and muscle of fishes (types of tissue that can be found throughout the food chain), collagen peptide mass fingerprinting has been applied here to identify modern fish specimens to species. In this study, MALDI-ToF MS peptide fingerprints are obtained from enzymatic digestion of collagen Type I from fin (or skin if fin was not available) and muscle tissues from six specimens of Pleuronectiformes. Using the already available diagnostic collagen peptide biomarkers for flatfish, all six specimens could be identified to the correct species for each of the tissue types. We recommend using this rapid approach for future screenings of modern flatfish in the food chain to detect mislabelling fraud, and also in more general applications of modern ecological studies of this order. It is likely that the methods can be applied to other Actinopterygian fishes.