Xu X., Tsachidou B., Fortuin J., You L., Odelli D., Soukoulis C.
Applied Food Research, vol. 6, n° 2, art. no. 102396, 2026
This study reports on the design and characterisation of thermo-reversible gelatine hydrogels incorporating beeswax-structured oil-in-water emulsions (BOGEs) as novel 3D-printable food inks. BOGEs were prepared by varying the sunflower oil to beeswax (SFO:BW) mass fraction (1:0, 3:1, 1:1, 1:3 and 0:1) at a fixed lipid loading (10% wt.) within a 4% wt. gelatine matrix. The BOGEs were evaluated in terms of microstructure, thermophysical properties, small (SAOS) and large amplitude oscillatory shear (LAOS) rheological behaviour, instrumental hardness, and 3D printability. CLSM images revealed a progressive transition from an emulsion-filled to a bigel-like microstructure with increasing beeswax content, driven by partial crystallisation and percolation of lipid droplets. Beeswax incorporation progressively suppressed the gelatine hydrogel fusion enthalpy (from 1.39 to 0.19 J g<sup>−1</sup>), indicating that wax crystal lattices govern the supramolecular organisation of the gelatine network. SAOS tests showed that BW enhanced the elastic modulus, with a critical solid fat content threshold (Φ<sub>c</sub> = 0.294) above which lipid droplet percolation provided an additional structural reinforcement. LAOS characterisation revealed a type III nonlinear viscoelastic response, with delayed yielding and enhanced structural integrity at higher BW fractions. Instrumental hardness measurements confirmed the active filler role of BW at mass fractions ≥0.5. 3D printing assessment demonstrated that intermediate SFO:BW ratios (3:1 and 1:1) afforded the highest printing fidelity, combining favourable extrusion flow with adequate post-deposition shape retention. Overall, the results demonstrate that BOGEs can effectively tailor the structure–function properties of gelatine hydrogels, enabling the development of multiphase food inks suitable for extrusion-based 3D printing applications.
