Synergistic modification of tilapia-chicken composite gelatin via Mg2+ Cross-linking: A sustainable alternative to porcine gelatin

Conventional mammalian gelatins like porcine gelatin (PG) face limitations due to zoonotic disease risks and religious concerns. This study proposes a synergistic strategy combining tilapia skin gelatin (FG) and chicken skin gelatin (CG) with MgCl 2 modification to develop a sustainable modified composite gelatin as a PG alternative. At an optimal CG:FG mass ratio of 1:2.5, the composite gelatin (F-C) achieved physicochemical properties comparable to PG in gel strength, viscosity, and elasticity. This equivalence is attributed to hydrogen bonding bridges compensating for amino acid differences between FG and CG. Notably, unmodified F-C exhibited higher hardness (1218 g) and chewiness (492 g) but lower cohesiveness (0.41) than PG (777 g, 432 g, and 0.58, respectively). Modification with 20 μmol/L MgCl 2 significantly reduced the hardness and chewiness of F-C while increasing its cohesiveness, ultimately approaching the overall physicochemical profile of PG. Fourier transform infrared spectroscopy confirmed that Mg 2+ -mediated electrostatic cross-linking optimized peptide chain packing density within the composite framework. Atomic force microscopy revealed the disappearance of chain-like nanostructures and a significant increase in spherical nano-aggregate size post-modification. The dual mechanisms of amino acid complementation via hydrogen bonding and nanostructural optimization via Mg 2+ cross-linking provide a novel approach for constructing advanced composite gelatins. • Optimal chicken skin: tilapia skin gelatin mass ratio was 1:2.5, achieving comparable gel strength and viscosity to PG. • Hydrogen-bond bridging compensates amino acid deficits between gelatin sources. • Synergistic modification of Mg 2+ (20 μmol/L) to further enhance the properties of composite gelatin. • FTIR and AFM revealed enhanced peptide packing and larger nano-aggregates post-modification.