Fabrication of double-network emulsion gels to emulate bovine adipose tissue and application in 3D printing ink

Developing fat alternatives that can effectively mimic animal adipose tissue is crucial for enhancing the quality of plant-based meat and supporting sustainable food production. This study introduces a 3D-printable emulsion gel composed of sodium alginate and κ-carrageenan, designed to replicate the structural and thermal properties of real animal fat. Emulsion gels were formulated with varying concentrations of κ-carrageenan (0 %, 1 %, 2 %, 3 %), and their physicochemical characteristics were evaluated using SEM, CLSM, FTIR, and rheological analysis. As the κ-carrageenan concentration increased, the gels exhibited denser microstructures, smaller oil droplet sizes, and stronger network formation. These changes enhanced thermal stability, with the 3 % κ-carrageenan sample demonstrating a gradual melting behavior above 80 °C—closely resembling the thermal response of bovine adipose tissue during cooking. To assess printability, rheological parameters critical to extrusion-based 3D food printing were analyzed across three process stages: extrusion (viscosity, yield stress), recovery (3ITT), and self-support (frequency sweep). The gelation temperature increased with κ-carrageenan content, indicating that optimal printing temperatures must be tailored to each formulation. 2D and 3D printing trials confirmed that matching printing temperature to the gelation point was key to achieving accurate deposition and shape fidelity. Overall, these findings highlight the potential of the proposed emulsion gel system to enhance the quality of plant-based meat analogues by closely mimicking the structural and thermal behaviors of animal fat, while also offering practical insights into optimizing the 3D printability of lipid-based foods formulated with hydrocolloids.