Molecular Mechanism of the Impact of Lipid Oxidation Products (2,4-Decadienal) on the Conformation of Grouper (Epinephelus coioides) Myofibrillar Proteins During Refrigeration and its Implications on the Overall Protein Flavor

2,4-Decadienal (2,4-Dec) is one of the main oxidation products produced during the lipid oxidation process of grouper. Therefore, this study employed 2,4-Dec as a lipid oxidation product to explore its impact on protein conformation and the overall aroma development. The evaluation of fluorescence quenching behavior, Schiff base content, secondary, and microstructure of myofibrillar proteins (MP) revealed that 2,4-Dec played a promotive role in altering the conformation of MP and inducing oxidative degradation. Eight key volatile compounds (VOCs) associated with the overall flavor of MP were identified. Additionally, an analysis of six key differential metabolites and five metabolic pathways in the MP-aldehyde solution shed light on the crucial role of 2,4-Dec in influencing the conformation of MP. It was further explained that the production of these key VOCs might arise from the metabolism of arginine, proline, alanine, aspartate, glutamate, and beta-alanine, and potentially being products of arginine biosynthesis. Complementary molecular docking confirmed that hydrophobic interactions and hydrogen bonding were the primary driving forces behind the binding of 2,4-Dec with MP. This study unveils the molecular-level interaction between MP and aldehydes, providing valuable insights for regulating the flavor of grouper during storage.