Physicochemical properties and biological safety of ferulic acid-grafted gelatin as a versatile food emulsifier: Studies in zebrafish and C. elegans.

Ferulic acid-grafted gelatin (Fg) was synthesized through the reaction with carbodiimide and evaluated for its potential as a clean-label, multifunctional food emulsifier. FTIR, UV-Vis, and NMR structural analyses demonstrated that amide linkages were effectively established between ferulic acid and gelatin. The grafting significantly enhanced the interfacial performance and the physicochemical characteristics. Visual and microscopic evaluations further confirmed that Fg formed stable and fine emulsions with reduced droplet size and improved dispersion stability compared to native gelatin. The interfacial tension decreased from 104.6 mN/m to 2.94 mN/m the zeta potential-21.4 mV and the emulsion droplet size was reduced to 0.89 μm, indicating an improvement in colloidal stability. The rheological analysis revealed notable shear-thinning properties, with the storage modulus (G) of Fg being 2.3 times higher than that of native gelatin, signifying enhanced network strength. Biological evaluations using Danio rerio (zebrafish) embryos and Caenorhabditis elegans confirmed the biosafety of Fg, showing survival rates exceeding 80 % at 0.5 IC₅₀ (0.155 mg/mL) and no noticeable teratogenic or behavioral anomalies. The results indicate that ferulic acid grafting improves the emulsifying effectiveness and biocompatibility of gelatin, supporting its potential application as a natural, functional biopolymer in clean-label food systems.