Mechanism of flavor changes in Northern Pike (Esox lucius) during refrigeration revealed by UHPLC-MS metabolomics and GC-IMS

Northern pike (Esox lucius) is a high-value aquatic product whose flavor changes during cold storage directly impact consumer acceptance and market competitiveness. However, the underlying mechanisms of these flavor changes remain unclear. To address this, this study employed gas chromatography-ion mobility spectrometry (GC-IMS) combined with metabolomics to systematically analyze the dynamic changes in volatile aroma compounds and differential metabolites of Esox lucius during cold storage. The results revealed a significant decline in sensory characteristics, including odor, color, texture, muscle elasticity, cohesiveness and overall acceptability as storage time increased. The key volatile compounds (VOCs) including 3-methylbutanal, pentanal, 3-methyl-2-butenal, 2-methylpropanal, 3-methyl-1-butanol, isopropanol, (E)-2-hexen-1-ol, 1-butanol, and 1-propanol were identified by GC-IMS. These compounds were found to play critical roles in flavor changes. Additionally, a total of 657 differential metabolites were identified, among which 528 metabolites were observed to be upregulated and 129 were found to be downregulated throughout the period of cold storage. Metabolomic analysis highlighted purine metabolism, cysteine and methionine metabolism, and glycerophospholipid metabolism as the three primary metabolic pathways related to flavor changes. A potential metabolic network associated with these changes was constructed. This study not only elucidated the metabolic mechanisms underlying flavor changes in Esox lucius during cold storage but also provided essential theoretical for flavor control and quality preservation of aquatic products.