Thermoresponsive Alginate–Starch Composite Emulsion Gels for Mimicking the Thermal Softening Behavior of Animal Fat

Replacing animal fat in reduced-fat meat products and meat analogs remains challenging because animal fat provides lipids as well as structural and sensory functions. From a polymer materials perspective, hydrogel-based emulsion gels are promising structured fat mimetics because polymeric networks can immobilize liquid oil and provide solid-like mechanical properties. However, conventional alginate emulsion gels form heat-stable networks, limiting their ability to reproduce the thermal softening behavior of animal fat. In this study, thermoresponsive composite emulsion gels were designed by incorporating 4-α-glucanotransferase-treated potato starch (GTPS) into alginate-based emulsion gels via internal gelation and evaluated as porcine back fat mimetics.
GTPS exhibited a reorganized glucan-chain architecture associated with thermoreversible gel–sol behavior. Its incorporation into the alginate network produced a denser polymeric matrix with thicker pore walls, reduced effective pore volume, and improved oil droplet confinement. Increasing GTPS concentration enhanced stiffness, water-holding capacity, and heating stability, indicating reinforcement of the alginate–GTPS composite network.
Among the tested formulations, the 15% GTPS emulsion gel (GTPS15) showed the most pronounced thermoresponsive behavior, with G′ decreasing to approximately one-tenth of its initial value during heating and recovering upon cooling. Although its initial elasticity and softening temperature range differed from those of porcine back fat, GTPS15 approximated key aspects of the temperature-dependent softening–recovery behavior of animal fat. These findings suggest that alginate–GTPS composite emulsion gels can serve as thermoresponsive polymeric soft materials for developing lower-fat meat products with controlled thermal softening behavior.