Untargeted analysis of microbial metabolites and unsaturated fatty acids in salmon via hydrophilic-lipophilic...

The ability to detect spoilage and the nutrient content of salmon is critical for ensuring food safety and determining market value. In this paper, we document the development of a hydrophilic-lipophilic balanced solid-phase microextraction arrow that offers better extraction performance than two other commercial devices. The devices were also compared using two operational models: headspace microextraction and direct immersion. The multidimensional statistical analysis and heatmap analysis for the headspace microextractions showed that the content levels of volatile metabolites including hydrocarbons, alcohols, ketones, acids, amino acids, and ethers increased with longer storage times, indicating an increase in the activity of spoilage-associated bacteria, such as gram-negative bacteria. For the direct immersion tests, important nutrients, including lipids, sterols, and squalene, were directly extracted from the salmon fillets with high efficiency. Thus, the developed method provides a simple and easy time-domain monitoring strategy for testing the freshness and quality of salmon for consumers.