Construction of 3D printed reduced-fat meat analogue by emulsion gels. Part I: Flow behavior, thixotropic feature, and network structure of soy protein-based inks

The fabrication of high-quality low-fat 3D printed foods is strongly dependent on the development of shear-thinning, viscoelastic, and thixotropic ink with a monomodal particle size distribution. In this study, oil was partially or totally replaced with hydrophobically modified biosurfactants (acetylated starch, octenyl succinic anhydride starch, ethyl (hydroxyethyl) cellulose, and dodecenyl succinylated inulin) in a soy protein-based emulsion to produce the desired reduced-fat emulsion gels for potential applications in the 3D printing process. These reduced-fat emulsion gels exhibited pseudoplastic behavior with viscoelastic properties, where viscosity recovery, frequency crossover point, and storage modulus were found to increase with increasing biosurfactants ratio. Higher levels of surface-active biopolymers also yielded inks with lower creep compliance, a smaller droplet size having a more uniform distribution, and possessing improved structural strength and storage stability. Spherical droplets of inks with higher ratios of biosurfactants remained well dispersed. The differences in molecular weight and radius of gyration of biosurfactants accounted for the observed differences in flow behavior and emulsion stability, where inks including dodecenyl succinylated inulin and ethyl (hydroxyethyl) cellulose offered stable structures with strong gel-like properties compared to acetylated and octenyl succinic anhydride starches. All ink networks were also dynamic and recoverable, thus demonstrating the potential of these reduced-fat inks in 3D printing processes.