Covalent reinforcement drives hierarchical multiscale structure–function integration in hybrid chicken–plant protein systems during extrusion-based 3D printing
Hybrid protein systems produced by simple blending often lack the hierarchical structural organization required to reproduce the physicochemical coherence of native muscle tissues. In this study, transglutaminase-mediated ε-(γ-glutamyl)lysine cross-linking was introduced to promote structural integration in hybrid chicken–plant protein systems. Covalent reinforcement, together with plant-derived non-covalent interactions, stabilized an intermediate protein network and facilitated extrusion-guided alignment, resulting in anisotropically aligned fibrous structures with improved fascicle-like structural coherence. The reinforced systems exhibited reduced shrinkage, enhanced processing stability, and anisotropic mechanical resistance following extrusion and thermal treatment. Importantly, these structural modifications were achieved without reducing essential amino acid availability or simulated protein digestibility. Multivariate analysis further revealed coordinated multiscale relationships linking molecular interactions, hierarchical structural organization, and mechanical performance. These findings demonstrate that covalent reinforcement can simultaneously enable structural optimization and nutritional preservation in hybrid protein systems designed for extrusion-based 3D food structuring.