Molecular Insights into the Mechanism of Caffeic Acid in Meat Color Improvement via Multispectral Spectroscopy and Molecular Dynamics Simulation

This study investigated the color-stabilizing effects of caffeic acid (CA) on meat and its interaction mechanism with myoglobin (Mb) using in situ and in vitro model assays, combined with physicochemical analyses, multi-spectroscopic techniques, molecular docking, and molecular dynamics (MD) simulations. Three 24-month-old Simmental crossbred steer carcasses were utilized, yielding 12 steaks (four per carcass). The steaks were divided into three treatment groups: a control (deionized water), 0.05% (w/v) CA, and 0.1% (w/v) CA. Samples were stored at 4 ± 0.5 °C for 7 days under simulated retail display conditions, overwrapped with polyvinyl chloride (PVC) film. Storage assays demonstrated that 0.1% CA significantly delayed beef browning and maintained its red color. Physicochemical analyses revealed that CA inhibited metmyoglobin (MetMb) formation by 6%, reduced Mb solubility, and decreased surface hydrophobicity by approximately 90%. Fluorescence spectroscopy confirmed that the interaction between CA and Mb was driven by hydrogen bonding and van der Waals forces, resulting in a static quenching mechanism with a binding constant of 259.41 × 103 L/mol at 293 K. Furthermore, UV–Vis and FT-IR spectroscopy indicated structural adjustments in Mb upon CA binding. Differential scanning calorimetry (DSC) showed an increased thermal denaturation temperature. Atomic Force Microscopy (AFM) showed CA-induced Mb aggregation. Consistently, molecular docking and MD simulations revealed that CA binds to the Mb molecule primarily through non-covalent interactions, such as hydrogen bonding. Collectively, these findings provide a theoretical basis for the application of CA as a natural color stabilizer in meat products.