Monitoring of quality changes in salmon and salmon rest raw materials by NMR

Abstract

High-resolution nuclear magnetic resonance (HR-NMR) spectroscopy is extensively utilized to monitor the food quality. This chapter describes how HR-NMR can be an effective and comprehensive tool to assess the quality of Atlantic salmon though the analysis of water-soluble metabolites. A yet unpublished case study of salmon muscle NMR analysis performed by the authors is reported together with a description of the results of the most recent publications in the field. The onset of salmon rigor mortis is estimated by measuring the ATP/IMP ratio. It is described how to detect premortem stress by quantifying glucose, lactic acid, and other molecules. The procedures to assess freshness of various salmon fractions, such as K- and H-index, or the levels of nicotinamide adenine dinucleotide are compared and discussed. The fish safety is evaluated by monitoring the formation of biogenic amines. Salmon taste, flavor, odor, and nutritional value are also estimated by quantifying the main water-soluble metabolites. Finally, a new Umami index is proposed within the chapter, to estimate the level of fish palatability provided by the umami taste compounds.