German and Italian researchers have used a proteomics based assay to distinguish wild from farmed salmon. A total of 13 farmed and 13 wild Canadian salmon (Salmo salar) species were extracted and digested with trypsin. The peptide digest was analysed by an optimised LC- MS system(quadrupole time-of-flight mass spectrometer) followed by statistical analysis based on principal component (PC) analysis.This untargeted approach, using a data-independent acquisition MS scheme, demonstrated the ability to effectively discriminate salmon belonging to the two classes. Furthermore, selected peptides showing high loadings on PC1 could represent potential targeted candidate peptide markers able to discriminate farmed from wild-type salmon.
Characterisation of the lipid component of seafood products based on chromatography-mass spectrometry techniques has been reported as a promising approach to differentiate farmed from wild-type products. In this study, Italian researchers used a fast method based on Direct Analysis in Real Time (DART) coupled to High Resolution Mass Spectrometry (HRMS) based on a single stage Orbitrap mass analyser, integrated by Principal Component Analysis (PCA), to discriminate wild-type from farmed salmon of Salmo salar species. Obtaining the 30 most intense signals (all referred to fatty acids, FA) detected in negative ion DART-HRMS spectra of the lipid extracts of salmon fillets [26 wild-type from Canada, 74 farmed from Canada (25), Norway (25) and Chile (24)] were considered as the variables for PCA. In agreement with other studies, three saturated (14:0, 16:0 and 18:0) FA, along with unsaturated ones having 20 or 22 carbon atoms, were found as the main discriminating variables for wild-type salmons, whereas FA with compositions 18:1, 18:2, 18:3 and several oxidised forms arising from them were found to have a significantly higher incidence in farmed salmon. The methodology was tested against 6 samples of farmed Norwegian salmon, which were all correctly classified.
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