The mechanism of 3D-printed high internal phase Pickering emulsion gels improved by soybean protein isolate / bacterial cellulose co-assemblies

In this study, soybean protein isolate (SPI) / bacterial cellulose (BC) co-assemblies replicate the fibrous network structure in animal fat to stabilize the 3D-printed high internal phase Pickering emulsion (HIPPE) gels with excellent processing characteristics. The SPI/BC co-assemblies, structured through pH shifting treatment, displayed exceptional emulsification and gelation properties. The relevant results indicate that the SPI/BC coassemblies possess numerous hydrophobic and thiol groups on their surfaces. Within the HIPPE system, the SPI in its molten globular state combined with the thickening effect of BC provides a steric barrier that prevents oil droplet coalescence during heating and freeze-thaw storage. Moreover, the rheological behaviors of the HIPPE stabilized by SPI/BC co-assemblies have higher G', viscosity, and viscoelastic recovery. During the 3D printing process, the molten-globular SPI forms a complex well-aggregated three-dimensional network system, while BC acts as a dynamic filler, occupying the voids within the protein network structure, thus bolstering the hardness and elasticity of the HIPPE gels. These findings enhance our understanding that SPI/BC co-assemblies replicate the fibrous network structure to emulsify and solidify HIPPE gels, offering new insights into formulating plant oil gels as viable alternatives to animal fats.