Chitosan spatial positioning dictates thermal reconstruction pathways and performance in myofibrillar protein...

Fat-substitute pre-emulsions must retain stability during thermal processing of emulsified meat products, yet how initial interfacial architecture governs heat-induced restructuring remains unclear. Here, three emulsions with chitosan (CS) and myofibrillar protein (MP) interfacial architectures-MP/CS composite co-adsorbed layer, CS-MP bilayer (CS outer, MP inner), and MP-CS bilayer (MP outer, CS inner)-were subjected to thermal treatment at 60-90 °C. Crucially, interfacial loading analysis speculated distinct thermal reconstruction pathways for the three architectures: expansion-interstitial filling for MP/CS, a balanced mode for CS-MP, and molecular extension for MP-CS. These mechanisms were further validated by cryo-scanning electron microscopy and small-angle X-ray scattering fractal analysis. Multi-scale rheology-encompassing bulk-, interfacial-, and micro-rheological measurements-consistently shows that emulsion performance (viscosity, elasticity, and nonlinear deformation resistance) is highly correlated with CS spatial positioning across all thermal conditions. Multiple light scattering measurements revealed that all three architectures achieved optimal stability at 80 °C. After reconstruction, MP/CS interface exhibited the highest interfacial cooperativity and deformation resistance; the CS-MP bilayer showed balanced improvement; and the MP-CS bilayer, although enhanced at 80 °C, degraded severely upon overheating. These findings demonstrate that CS spatial organization determines thermal reconstruction pathways and multi-scale performance, guiding design of pre-emulsions for thermally processed meat products.