Exploring the Mechanism of Directional Production of Characteristic Compounds by Interaction between Fish Myofibrillar Protein and Key Lipids with Different Saturations

Lipid saturation and protein oxidation influence the types and amounts of volatile and nonvolatile compounds by affecting lipid oxidation. This study examined three reaction modes: systems containing only fatty acids with three different saturations, only myofibrillar proteins (MPs), or their combinations. Sensomics (including volatilomics) and metabolomics were used to analyze these systems. Results showed that MPs enhanced saturated fatty acid oxidation, suppressed unsaturated fatty acid double-bond oxidation, and adsorbed volatiles from unsaturated fatty acid thermal oxidation. MPs promoted secondary oxidation to generate short-chain volatiles. The volatile products derived from stearic acid (SA) were mainly dominated by C6-C8 compounds, while oleic acid (OA) was mainly dominated by C7-C10 compounds, and linoleic acid (LA) was mainly dominated by C5-C8 compounds. The concentrations of volatile compounds followed the order: LA (14,061.66 ng/g) > OA (11,943.52 ng/g) > MPs-LA (2,224.45 ng/g) > MPs-OA (154.63 ng/g) > MPs-SA (28.00 ng/g) > SA (24.11 ng/g) > MPs (0.73 ng/g). Through multivariate statistical analysis, hexamethylenetetramine was identified as a differential metabolite specifically associated with the reaction between SA and MPs. This compound may act as an intermediate, potentially playing a regulatory role in flavor formation. Additionally, α-methyl-dl-phenylalanine and triethylene glycol were found to be differential metabolites in the reaction between LA and MPs. This study systematically explained how characteristic volatile and nonvolatile compounds were formed and transformed. The research findings provided important theoretical support for the flavor regulation of fish products, promoting innovative development in the food industry regarding flavor quality enhancement.