Synergistic enhancement of thermal stability and digestibility in thermally processed Myofibrillar proteins via glycation and l-glutamic acid supplementation

This study systematically investigated the synergistic effects of l-glutamic acid supplementation and nonenzymatic glycation on the thermal stability and in vitro digestibility of heat-treated myofibrillar proteins (MPs). Compared to native MPs, the combined treatment effectively enhanced their thermal stability, as evidenced by a reduction in aggregate particle size from 131.57 μm to 68.31 μm at 90 °C, an increase in solubility from 2.13 % to 52.48 % at 90 °C, and phase separation was only observed in the combined treatment group at temperatures exceeding 70 °C. As the temperature increased, MP solubility declined modestly from 60.61 % to 52.48 %, with distinct phase separation observed only at 70 °C. Protein profiling, two-dimensional Fourier-transform infrared (2D FT-IR) spectroscopy, and micromorphological analysis revealed that l-glutamic acid promoted the depolymerization of MPs through electrostatic repulsion and interacted with exposed sulfhydryl and hydrophobic groups to form oligomeric precursors prior to aggregation. Concurrently, increased steric hindrance from expanded dextran binding sites inhibited disulfide cross-linking and hydrophobic interactions. The resulting aggregates exhibited a less compact structure, which facilitated protease accessibility and enhanced enzymatic hydrolysis. This increases the in vitro digestibility at 90 °C from 64.97 % for native MPs to 78.5 %. These findings support the development of low-sodium, thermally stable, and digestible meat protein-based liquid foods.