Addressing marketplace gilthead sea bream (Sparus aurata L.) differentiation by 1H NMR-based lipid fingerprinting

A complete NMR-based lipid fingerprinting protocol is described for the classification of farmed and wild adult gilthead sea breams having a commercial size (between 201.5 ± 25.2 g and 335.3 ± 21.8 g) and captured during the warm season (June-October). The presented approach is able to differentiate 68 fish sold in the Italian market between wild and farmed and reared fish in different off-shore sea cage farms in Sardinia (Italy) and imported from Greece. Sample selection, preparative protocol, NMR acquisition of lipid extracts and multivariate statistical analysis of experimental data carried out by means of principal component analysis (PCA) and orthogonal projection on latent structure-discriminant analysis (OPLS-DA), are thoroughly described. In addition, statistically meaningful confirmation of the observed clustering patterns was given by bootstrap statistical analysis. Bootstrap values associate the largest scores separation to the discrimination between Greek and Sardinian fish (100%), followed by the distinction between wild and farmed fish captured in Sardinia (90%). Finally, the less relevant but significant classification (68-57%) was achieved between sea breams reared in different Sardinian off-shore sea cage farms. Differential Metabograms show that polyunsaturated fatty acids, and in particular n − 3 fatty acids, differentiate farmed fish from wild counterparts.