Mechanism of phospholipid regulated thermal aggregation of myosin in emulsified meat systems: Protein-lipid co-assembly and molecular thermodynamics.

This study investigated the role of phospholipids in myosin thermal aggregation in emulsified meat systems by constructing a myosin-phospholipid model and combining thermal analysis, spectroscopy, aggregation characterization, microscopy, and molecular dynamics simulation at 70 °C. The presence of phospholipids was associated with a continuous thermal response of the complex system, reflecting coupled myosin conformational transitions, protein-lipid interactions, and hydration changes during heating. As temperature increased (25-70 °C), the system shifted from a dispersed state to aggregates, with significant increases in turbidity, surface hydrophobicity, and particle size (P < 0.05), and decreases in solubility and free sulfhydryl content (P < 0.05), indicating myosin unfolding, hydrophobic exposure, and intermolecular cross-linking. Spectroscopic analysis revealed that approximately 50 °C was critical for structural transition, with α-helix loss and coordinated changes in the amide backbone, hydrogen-bonding/hydration environment, aromatic residue microenvironment, and phospholipid PO₂- headgroups. Microscopy showed that small, dispersed particles transformed into clustered aggregates, suggesting phospholipid incorporation or binding within protein aggregation regions. Molecular dynamics indicated that phosphatidylcholine stably bound myosin and promoted a more compact, low-energy conformation (ΔG bind = -56.96 kcal/mol), mainly through van der Waals and nonpolar interactions, with transient hydrogen bonds assisting. Overall, phospholipids modulated myosin thermal aggregation by regulating hydration and hydrogen bonding via polar headgroups and binding exposed hydrophobic regions via hydrophobic chains, thereby promoting protein-lipid co-assembled aggregate formation.