Nano-eggshell calcium enhances low-salt pork myosin emulsion gels via sustained Ca2+ release and particle filling.

Abstract

To alleviate the loose network and low water-holding capacity (WHC) of low-salt myosin emulsion gels, myosin was utilized as the matrix to formulate emulsions, which were subsequently gelled via heat induction. Nano eggshell calcium (NEC, 0-1.25%) was then incorporated, and the synergistic effects of Ca2+ sustained release and nanoscale particle-mediated pore-filling on emulsion stability and gel network formation were evaluated. As NEC increased, the emulsifying activity index (EAI) was raised from 6.77 to 14.76 m2/g, and the emulsion stability index (ESI) was raised from 85.96% to 96.19% (P < 0.05). Mean particle size was increased (P < 0.05). At 1% NEC, protein solubility was reduced to 51.9% (P < 0.05), surface hydrophobicity was increased (P < 0.05), and zeta potential reached -15.4 mV; the droplet distribution was the most compact and uniform. In gels, the highest whiteness, hardness, and WHC were obtained at 1% NEC, and cooking loss was reduced to 8.29% (P < 0.05). Low-field nuclear magnetic resonance (LF-NMR) showed conversion of free water to immobilized and bound water. Fourier transform infrared (FT-IR) and intrinsic fluorescence indicated improved secondary and tertiary structures, and Differential scanning calorimetry (DSC) showed the highest thermal stability. Rheology and scanning electron microscopy (SEM) confirmed enhanced viscoelasticity and the densest, most uniform network at 1% NEC. The gel framework was reinforced by particle adsorption and pore filling, while protein aggregation was enhanced by charge shielding and ionic bridging from released Ca2+, jointly improving gel structural stability.