Enhanced Gel Properties of Silver Carp (Hypophthalmichthys molitrix) Surimi through Hydroxycinnamic Acid-Mediated Interactions with Myosin S1: Insights from Molecular to Macroscopic Level

Enhancing the gel properties of surimi is critical for advancing aquatic protein product quality. This study demonstrates that hydroxycinnamic acids (HCAs), such as caffeic acid (CA), p -coumaric acid (PCA), chlorogenic acid (CGA), and rosmarinic acid (RA), significantly improve the texture, water-holding capacity, and flavor of silver carp ( Hypophthalmichthys molitrix ) surimi and myosin gels. RA incorporation resulted in the most significant increase in gel strength and WHC, without compromising whiteness. To elucidate the mechanistic basis of these improvements, the interactions between HCAs and myosin S1 were investigated. Microscale thermophoresis revealed RA as the strongest binder to myosin S1 ( k d  = 2.33 mM), followed by CA (9.25 mM), CGA (37.29 mM), and PCA (109.50 mM). Thermodynamic analyses and molecular simulations confirmed spontaneous binding mainly driven by hydrogen bonding or hydrophobic forces. HCA binding induced divergent structural effects: RA and CGA stabilized α-helical structures, enhancing intermolecular alignment of stabilized helices, while CA and PCA promoted partial unfolding, exposing hydrophobic residues. Both pathways elevated aggregation propensity, as evidenced by increased particle size and radius of gyration. Microrheology further demonstrated RA’s superior capacity to enhance myosin S1 elasticity and viscosity, correlating with its robust gel network formation. These findings elucidate how HCA-myosin S1 interactions underpin the observed improvements in gel properties, establishing RA as a potent natural modifier for surimi. The work provides a molecular blueprint for leveraging polyphenol-protein interactions to optimize texture, stability, and sensory attributes in aquatic products.