Analysis of wild and farmed salmon using 13C solid-state NMR and MRI directly on fillet tissue

Abstract

Developments in feed composition and technologies cause a continuous change in farmed salmon fatty acid composition and quality. Hence, fast and direct techniques for the analysis of salmon are desirable. Here, it is demonstrated that ¹³C Magic Angle Spinning (MAS) NMR spectroscopy can quantify the most relevant fatty acids in salmon fat within 40 minutes without use of chemical extractions. The method is optimized with regard to parameters affecting the total spectral acquisition time and accuracy. Farmed and wild Atlantic salmons are compared to illustrate the effects of a natural and synthetic diet on their quality and fat composition. ¹³C T₁ relaxation reveals that the fatty acid composition in farmed salmon fat results in significantly different lipid packing compared to that in wild salmon, with possible negative impacts on the quality. Further, micro-MRI is applied to obtain complementary data on fillet quality and fat distribution.