To enhance the functional properties of walnut protein isolate (WalPI), hydrophilic whey protein isolate (WPI) was selected to formulate WalPI-WPI nanoparticles (nano-WalPI-WPI) via a pH cycling technique. These nano-WalPI-WPI particles were subsequently employed to stabilize high internal phase Pickering emulsions (HIPEs). By adjusting the mass ratio of WalPI to WPI from 9:1 to 1:1, the resultant nano-WalPI-WPI exhibited sizes ranging from 70.98 to 124.57 nm, with a polydispersity index of less than 0.326. When the mass ratio of WalPI to WPI was 7:3, there were significant enhancements in various functional properties: the solubility, denaturation peak temperature, emulsifying activity index, and emulsifying stability index increased by 6.09 times, 0.54 °C, 318.94 m2/g, and 552.95 min, respectively, and the surface hydrophobicity decreased by 59.23%, compared with that of WalPI nanoparticles (nano-WalPI), with the best overall performance. The nano-WalPI-WPI were held together by hydrophobic interactions, hydrogen bonding, and electrostatic forces, which preserved the intact primary structure and improved resistance to structural changes during the neutralization process. The HIPEs stabilized by nano-WalPI-WPI exhibited an average droplet size of less than 30 μm, with droplets uniformly dispersed and maintaining an intact spherical structure, demonstrating superior storage stability. All HIPEs exhibited pseudoplastic behavior with good thixotropic properties. This study provides a theoretical foundation for enhancing the functional properties of hydrophobic proteins and introduces a novel approach for constructing emulsion systems stabilized by composite proteins as emulsifiers.

The primary significance of this work is that the commercial yeast proteins particles were successfully used to characterize the high internal phase Pickering emulsions (HIPPEs). The different sonication time (0,3,7,11,15 min) was used to modulate the structure and interface characteristics of yeast proteins (YPs) that as Pickering particles. Immediately afterward, the influence of YPs particles prepared at different sonication time on the rheological behavior and coalescence mechanism of HIPPEs was investigated. The results indicate that the YPs sonicated for 7 min exhibited a more relaxed molecular structures and conformation, the smallest particle size, the highest H0 and optimal amphiphilicity (the three-phase contact (θ) was 88.91°). The transition from extended to compact conformations of YPs occurred when the sonication time exceeded 7 min, resulting in an augmentation of size of YPs particles, a reduction in surface hydrophobicity (H0), and an elevation in hydrophilicity. The HIPPEs stabilized by YPs particles sonicated for 7 min exhibited the highest adsorption interface protein percentage and a more homogeneous three-dimensional (3D) protein network, resulting in the smallest droplet size and the highest storage (G\'). The HIPPEs sample that stabilized by YPs particles sonicated for 15 min showed the lowest adsorption protein percentage. This caused a reduction in the thickness of its interface protein layer and an enlargement in the droplet diameter (D [3,2]). It was prone to droplet coalescence according to the equation used to evaluate the coalescence probability of droplets (Eq (2)). And the non-adsorbed YPs particles form larger aggregation structures in the continuous phase and act as \"structural agents\" in 3D protein network. Therefore, mechanistically, the interface protein layer formed by YPs particles sonicated 7 min contributed more to HIPPEs stability. Whereas the \"structural agents\" contributed more to HIPPEs stability when the sonication time exceeded 7 min. The present results shed important new light on the application of commercial YPs in the functional food fields, acting as an available and effective alternative protein.

In this study, high internal phase Pickering emulsions (HIPPEs) stabilized by protein-polysaccharide complexes were used as inks for food-grade three-dimensional printing (3DP). The complexes (RCs) structured by synergistic interactions between rice proteins (RPs) and carboxymethyl cellulose (CMC) displayed outstanding biphasic wettability with excellent ability to reduce the oil/water interfacial tension. The interfacial structures formed by RCs provided a steric barrier and sufficient electrostatic repulsion, preventing droplet coalescence against heating treatment as well as long-term storage. Moreover, the rheological behaviors of the HIPPEs can be tuned by the substitution degree (DS) of CMC for tailorable hydrophobic/hydrophilic properties of RCs, allowing their controllable injectability and printability during 3DP. The HIPPEs stabilized by RCs with a DS 1.2 showed the most favorable printing resolution, hardness, adhesiveness, and chewiness. Associating the hydrophobic RPs with hydrophilic CMC, our study enabled on-demand amphiphilicity of RCs for effective stabilization of HIPPEs that can be manipulated for 3DP.

In this study, the anti-solvent precipitation and a simple complex method were applied for the preparation of bacterial cellulose nanofiber/soy protein isolate (BCNs/SPI) colloidal particles. Fourier transform IR (FT-IR) showed that hydrogen bonds generated in BCNs/SPI colloidal particles via the anti-solvent precipitation were stronger than those generated in BCNs/SPI colloidal particles self-assembled by a simple complex method. Meanwhile, the crystallinity, thermal stability, and contact angle of BCNs/SPI colloidal particles via the anti-solvent precipitation show an improvement in comparison with those of BCNs/SPI colloidal particles via a simple complex method. BCNs/SPI colloidal particles via the anti-solvent precipitation showed enhanced gel viscoelasticity, which was confirmed by dynamic oscillatory measurements. Furthermore, high internal phase Pickering emulsions (HIPEs) were additionally stable due to their stabilization by BCNs/SPI colloidal particles via the anti-solvent precipitation. Since then, HIPEs stabilized by BCNs/SPI colloidal particles via the anti-solvent precipitation were used for the delivery of curcumin. The curcumin-loaded HIPEs showed a good encapsulation efficiency and high 2,2-diphenyl-1-picrylhydrazyl (DPPH) removal efficiency. Additionally, the bioaccessibility of curcumin was significantly increased to 30.54% after the encapsulation using the prepared HIPEs. Therefore, it can be concluded that the anti-solvent precipitation is an effective way to assemble the polysaccharide/protein complex particles for the stabilization of HIPEs, and the prepared stable HIPEs showed a potential application in the delivery of curcumin.

High internal phase Pickering emulsions (HIPPEs) have attracted intensive interest for their great potential in foods, cosmetics, and biomedical applications. However, the relatively poor biodegradability and biocompatibility of inorganic and synthetic particulate emulsifiers greatly limit their practical applications. Here, a kind of biobased nanoparticles, namely dialdehyde amylopectin/chitosan complex nanoparticles (DAPCNPs), were fabricated by Schiff base reaction between dialdehyde amylopectin and chitosan with the assistance of ultrasonication treatment. The resultant DAPCNPs were employed to stabilize O/W HIPPEs with various oils, such as toluene, cyclohexane, styrene and edible rapeseed oil. Moreover, the resultant DAPCNPs-stabilized HIPPEs showed high stability under various environmental stresses (80 °C; 20 mM and 100 mM aqueous NaCl solutions). Furthermore, porous scaffolds were also fabricated by freeze-drying cyclohexane-in-water HIPPEs stabilized by DAPCNPs after the introduction of polyvinyl alcohol (PVA) into the continuous phase. These findings would give inspiration for designing polysaccharides-based nanoparticles to stabilize HIPPEs and improve their practical applications.