Heteroprotein complex between soy protein isolate and lysozyme: Protein conformation, lysozyme activity, and structural characterization.

Heteroprotein complexes are formed by electrostatic interactions of oppositely charged proteins in a purely aqueous environment. Understanding the relationship between their structural and functional properties will contribute to their tailor-made applications. Therefore, this study investigated the protein conformation, assembling structure, and enzyme activity of soy protein isolate/lysozyme (SPI/LYS) complexes at mass ratios of 2:1 (soluble complex) and 1:1.3 (stoichiometric ratio). Electrostatic complexation increased the surface hydrophobicity of complexes. Their surface hydrophobicity decreased with increasing NaCl concentrations and reached the theoretical values at the critical salt concentration of 200 mM NaCl. Electrostatic complexation did not decrease the LYS activity (∼43,000 units/mg). SPI/LYS complexes exhibited flocculated structures in which the two proteins were unevenly distributed; these were typical amorphous complexes. High dilution disassembled these complexes over 5 µm into particles of ∼100 nm, and NaCl reduced the size of these particles. Immobilized water was detected in the complexes formed by particle flocculation.

Freeze-thaw-stable high internal phase emulsions stabilized by soy protein isolate and chitosan complexes at pH 3.0 as promising mayonnaise replacers.

The development of cholesterol-free mayonnaise has attracted increasing interest in the food colloid field, due to the potential health concerns as a result of consumption of cholesterol-rich mayonnaise. One effective strategy in this regard is to substitute or partially substitute egg yolk with other organic emulsifiers and stabilizers, without affecting the quality of the product. In the work, we reported an effective strategy to fabricate high freeze-thaw-stability high internal phase emulsions (HIPEs), using complexes of a heated soy protein isolate (SPI) and chitosan (CS) at pH 3.0 as the emulsifiers and stabilizers. The SPI/CS complexes, formed even at a very low CS-to-SPI ratio, e.g., 1:10, showed a high capacity to stabilize HIPEs with a high freeze-thaw stability. Increasing the CS-to-SPI ratio in the complexes resulted in a progressive strengthening of gel network in the corresponding HIPEs, together with a gradual improvement of emulsification performance. The gel network of the HIPEs stabilized by the SPI/CS complexes was mainly maintained by the inter-droplet noncovalent interactions involving the CS molecules. The presence of CS also progressively increased the percentage of adsorbed proteins at the interface, and decreased the surface coverage of proteins at the interface. The high freeze-thaw stability of such HIPEs might be unrelated to the ice crystal formation during the freezing, and was more likely associated with the strong steric repulsion contributed to the adsorbed CS molecules between different droplets. The results indicated that the complexation of heated SPI and CS could provide an effective strategy to facilely fabricate outstanding freeze-thaw-stability HI PEs as potential mayonnaise replacers.

Heteroprotein Complex Coacervate Based on ß-Conglycinin and Lysozyme: Dynamic Protein Exchange, Thermodynamic Mechanism, and Lysozyme Activity.

Heteroprotein complex coacervate (HPCC) is a liquid-like protein concentrate produced by liquid-liquid phase separation. We revealed the protein dynamic exchange and thermodynamic mechanism of ß-conglycinin/lysozyme coacervate, and clarified the effect of HPCC on protein structure and activity. ß-conglycinin and lysozyme assembled into coacervate at pH 5.75-6.5 and assembled into amorphous precipitates at higher pH. As the pH dropped from 8 to 6, the number of binding sites of the complex decreased in half, and the desolvation degree corresponding to the entropy gain was greatly reduced, conducing to the formation of coacervates rather than precipitates. The coacervates achieved the unique dynamic exchange by exchanging proteins with the diluted phase, making the uniform distribution of proteins in coacervates. The lysozyme activity was completely retained in ß-conglycinin/lysozyme coacervates. These results proved that ß-conglycinin-based heteroprotein complex coacervate is a feasible method to encapsulate and enrich active proteins in a purely aqueous environment.

Assembled milk protein nano-architectures as potential nanovehicles for nutraceuticals.

Nanoencapsulation of hydrophobic nutraceuticals with food ingredients has become one of topical research subjects in food science and pharmaceutical fields. To fabricate food protein-based nano-architectures as nanovehicles is one of effective strategies or approaches to improve water solubility, stability, bioavailability and bioactivities of poorly soluble or hydrophobic nutraceuticals. Milk proteins or their components exhibit a great potential to assemble or co-assemble with other components into a variety of nano-architectures (e.g., nano-micelles, nanocomplexes, nanogels, or nanoparticles) as potential nanovehicles for encapsulation and delivery of nutraceuticals. This article provides a comprehensive review about the state-of-art knowledge in utilizing milk proteins to assemble or co-assemble into a variety of nano-architectures as promising encapsulation and delivery nano-systems for hydrophobic nutraceuticals. First, a brief summary about composition, structure and physicochemical properties of milk proteins, especially caseins (or casein micelles) and whey proteins, is presented. Then, the disassembly and reassembly behavior of caseins or whey proteins into nano-architectures is critically reviewed. For caseins, casein micelles can be dissociated and further re-associated into novel micelles, through pH- or high hydrostatic pressure-mediated disassembly and reassembly strategy, or can be directly formed from caseinates through a reassembly process. In contrast, the assembly of whey protein into nano-architectures usually needs a structural unfolding and subsequent aggregation process, which can be induced by heating, enzymatic hydrolysis, high hydrostatic pressure and ethanol treatments. Third, the co-assembly of milk proteins with other components into nano-architectures is also summarized. Last, the potential and effectiveness of assembled milk protein nano-architectures, including reassembled casein micelles, thermally induced whey protein nano-aggregates, α-lactalbumin nanotubes or nanospheres, co-assembled milk protein-polysaccharide nanocomplexes or nanoparticles, as nanovehicles for nutraceuticals (especially those hydrophobic) are comprehensively reviewed. Due to the fact that milk proteins are an important part of diets for human nutrition and health, the review is of crucial importance not only for the development of novel milk protein-based functional foods enriched with hydrophobic nutraceuticals, but also for providing the newest knowledge in the utilization of food protein assembly behavior in the nanoencapsulation of nutraceuticals.

Nano-architectural assembly of soy proteins: A promising strategy to fabricate nutraceutical nanovehicles.

Use of protein-based nanovehicles has been well recognized to be one of the most effective strategies to improve water dispersibility, stability and bioavailability of nutraceuticals or bioactive ingredients. Thanks to their health-benefiting effects and unique assembly behavior, soy proteins seem to be the perfect food proteins for fabricating nanovehicles in this regard. This review presents the state-of-art knowledge about the assembly of soy proteins into nano-architectures, e. g., nanoparticles, nanocomplexes or nanogels, induced by different physicochemical strategies and approaches. The strategies to trigger the assembly of soy proteins into a variety of nano-architectures are highlighted and critically reviewed. Such strategies include heating, enzymatic hydrolysis, pH shift, urea or ethanol treatment, reduction, and static high pressure treatment. The self-assembly behavior of soy proteins (native or denatured) is also reviewed. Besides the assembly of proteins alone, soy proteins can co-assemble with polysaccharides to form versatile nano-architectures, through different processes, e.g., heating or ultrasonication. Finally, recent progress in the development of assembled soy protein nano-architectures as nanovehicles for hydrophobic nutraceuticals is briefly summarized. With the fast increasing health awareness for natural and safe functional foods, this review is of crucial relevance for providing an important strategy to develop a kind of novel soy protein-based functional foods with dual-function health effects from soy proteins and nutraceuticals.

Heteroprotein complex coacervation: Focus on experimental strategies to investigate structure formation as a function of intrinsic and external physicochemical parameters for food applications.

Proteins are important components of foods, because they are one of the essential food groups, they have many functional properties that are very useful for modifying the physicochemical and textural properties of processed foods and possess many biological activities that are beneficial to human health. The process of heteroprotein complex coacervation (HPCC) combines two or more proteins through long-range coulombic interaction and specific short-range forces, creating a liquid-liquid colloid, with highly concentrated protein in the droplet phase and much more diluted-protein in the bulk phase. Coacervates possess novel, modifiable, physicochemical characteristics, and often exhibit the combined biological activities of the protein components, which makes them applicable to formulated foods and encapsulation carriers. This review discusses research progress in the field of HPCC in three parts: (1) the basic and innovative experimental methods and simulation tools for understanding the physicochemical behavior of these heteroprotein supramolecular architectures; (2) the influence of environmental factors (pH, mixing ratio, salts, temperature, and formation time) and intrinsic factors (protein modifications, metal-binding, charge anisotropy, and polypeptide designs) on HPCC; (3) the potential applications of HPCC materials, such as encapsulation of nutraceuticals, nanogels, emulsion stabilization, and protein separation. The wide diversity of possible combinations of proteins with different properties, endows HPCC materials with great potential for development into highly-innovation functional food ingredients.

Hofmeister Effect-Assistant Fabrication of All-Natural Protein-based Porous Materials Templated from Pickering Emulsions.

Porous materials derived from natural and biodegradable polymers have received growing interest. We demonstrate here an attractive method for the preparation of protein-based porous materials using emulsions stabilized by gliadin-chitosan hybrid particles (GCHPs) as the template, with the addition of gelatin and kosmotropic ions to improve the mechanical strength. The microstructure, mechanical properties, cytotoxicity, and fluid absorption behavior of porous materials were systematically investigated. This strategy facilitated the formation of porous materials with highly open and interconnected pore structure, which can be manipulated by altering the mass ratio of hexane or gelatin in the matrix. The Hofmeister effect resulted from kosmotropic ions greatly enhanced the Young's modulus and the compressive stress at 40% strain of porous materials from 0.56 to 6.84 MPa and 0.26 to 1.11 MPa, respectively. The developed all-natural porous materials were nontoxic to HaCaT cells; they also had excellent liquid (i.e., simulated body fluid and rabbit blood) absorption performance and advantages in resisting stress and maintaining geometry shape. The effects of different concentration amounts and type of salts in the Hofmeister series on the formation and performance of porous materials were also explored. Mechanical strength of porous materials was gradually enhanced when the (NH4)2SO4 concentration increased from 0 to 35 wt %, and the other four kosmotropic salts, including Na2S2O3, Na2CO3, NaH2PO4, and Na2SO4, also showed positive effects. This work opens a simple and feasible way to produce nontoxic and biodegradable porous materials with favorable mechanical strength and controllable pore structure. These materials have broad potential application in many fields involving biomedical and material science, such as cell culture, (bio)catalysis, and wound or bone defect healing.

Outstanding antioxidant pickering high internal phase emulsions by co-assembled polyphenol-soy ß-conglycinin nanoparticles.

This work reports a kind of novel antioxidant Pickering high internal phase emulsions (HIPEs; with an oil fraction, ϕ > 0.74) stabilized by soy ß-conglycinin (ß-CG) and polyphenol complex nanoparticles, as outstanding protective containers for lipophilic nutraceuticals. The nanoparticles with a representative polyphenol ((-)-epigallocatechin-3-gallate; EGCG) encapsulated were fabricated through an ethanol-mediated dissociation and re-assembly process of ß-CG, with greater particle size and higher surface hydrophilicity observed at higher initial EGCG concentrations. Using these co-assembled nanoparticles as sole stabilizers, a kind of HIPE gels with similar gel stiffness and microstructure, could be easily fabricated at ϕ = 0.8 and a protein concentration in the aqueous phase of 1.0 wt% using polyunsatuated fatty acid-rich flaxseed oil as the dispersed phase. These HIPE gels were extraordinarily stable against heating or long-term storage, but susceptible to freeze-thawing. The as-fabricated HIPEs showed an excellent protection to ß-carotene (encapsulated in oil phase) against heating, as well as an inhibition of lipid oxidation. The oxidation protection was in an EGCG concentration dependent manner. The results would be of interest for providing a novel strategy to fabricate functionalized Pickering HIPEs as potential containers or delivery systems for lipophilic nutraceuticals.

One-step fabrication of multifunctional high internal phase pickering emulsion gels solely stabilized by a softer globular protein nanoparticle: S-Ovalbumin.

A softer natural Pickering nanostabilizer, S-ovalbumin (S-OVA) was reported in this work, based on our previous researches about soft globular protein nanoparticles. Compared with native OVA, S-OVA has higher surface hydrophobicity, greater conformational flexibility and thinner tightly-bond water layer, which make it be unfolded more highly at the oil-water interface. However, S-OVA also possesses higher zeta-potential and thicker closely-surrounding water layer, offering it stronger electrostatic repulsion and steric hindrance between molecules and increased intramolecular cohesion. The improvements guarantee S-OVA undisintegrated particle structure and independent state on the interface and high refolding off the interface. The more flexible interior and firmer exterior together endow a higher softness to S-OVA. The HIPPE gels solely stabilized by S-OVA were fabricated using one-step shearing. These HIPPE gels own steady network structure mainly supported by bridging flocculation, strong self-supporting ability and moldability. The high storage stability and ability to inhibiting lipid oxidization provide the HIPPE gels an enormous potential in encapsulating and protecting volatile, easily-oxidized or dangerous organic liquids, during the storage and transportation. The attractive temperature responsiveness offers a high convenience to re-obtaining the organic liquids. And a re-encapsulation can be easily achieved via a re-shearing. The heat-enhanced gel intensity and moldability mean the HIPPE gels can be applied to produce dualistic gels or porous scaffolds with latent applications. These findings are helpful to explore more new Pickering stabilizers from the nature and extend the applications of HIPPEs in highly-demanded and high-tech industries.

Novel Soy ß-Conglycinin Core-Shell Nanoparticles As Outstanding Ecofriendly Nanocarriers for Curcumin.

The development of high-performance nanocarriers for nutraceuticals or drugs has become one of the topical research subjects in the functional food fields. In this work, we for the first time propose a novel and ecofriendly process to obtain a kind of nanostructured soy ß-conglycinin (ß-CG; a major soy storage globulin) as outstanding nanocarriers for poorly soluble bioactives (e.g., curcumin), by a urea-assisted disassembly and reassembly strategy. At urea concentrations > 4 M, the structure of ß-CG gradually dissociated into its separate subunits (α, α', and ß) and even denatured (depending on the type of subunits); after dialysis to remove urea, the dissociated subunits would reassemble into a kind of core-shell nanostructured particles, in which aggregated ß-subunits acted as the core while the shell layer was mainly composed of α- and α'-subunits. The core-shell nanoparticles were favorably formed at protein concentrations of 1.0-2.0 wt %. Curcumin crystals were directly introduced into the ß-CG solution at high urea concentrations (e.g., 8 M) and would preferentially interact with the denatured ß-subunits. As a consequence, almost all of the curcumin molecules were encapsulated in the core part of the reassembled core-shell nanoparticles. The loading amount of curcumin in these nanoparticles could reach 18 g of curcumin per 100 g of protein, which far exceeds those reported previously. The encapsulated curcumin exhibited a high water solubility, extraordinary thermal stability, and improved bioaccessibility, as well as a sustained release behavior. The findings provide a novel strategy to fabricate a kind of high-encapsulation-performance, organic solvent-free, and biocompatible nanocarrier for hydrophobic nutraceuticals and drugs.

Fabrication and Characterization of Novel Water-Insoluble Protein Porous Materials Derived from Pickering High Internal-Phase Emulsions Stabilized by Gliadin-Chitosan-Complex Particles.

Pickering high internal-phase emulsions (HIPEs) and porous materials derived from the Pickering HIPEs have received increased attention in various research fields. Nevertheless, nondegradable inorganic and synthetic stabilizers present toxicity risks, thus greatly limiting their wider applications. In this work, we successfully developed nontoxic porous materials through the Pickering HIPE-templating process without chemical reactions. The obtained porous materials exhibited appreciable absorption capacity to corn oil and reached the state of saturated absorption within 3 min. The Pickering HIPE templates were stabilized by gliadin-chitosan complex particles (GCCPs), in which the volume fraction of the dispersed phase (90%) was the highest of all reported food-grade-particle-stabilized Pickering HIPEs so far, further contributing to the interconnected pore structure and high porosity (>90%) of porous materials. The interfacial particle barrier (Pickering mechanism) and three-dimensional network formed by the GCCPs in the continuous phase play crucial roles in stabilization of HIPEs with viscoelastic and self-supporting attributes and also facilitate the development of porous materials with designed pore structure. These materials, with favorable biocompatibility and biodegradability, possess excellent application prospects in foods, pharmaceuticals, materials, environmental applications, and so on.

Cellular Uptake and Intracellular Antioxidant Activity of Zein/Chitosan Nanoparticles Incorporated with Quercetin.

In this work, zein/chitosan nanoparticles (ZCPs-Q) were developed for encapsulating quercetin to overcome its lower water solubility and instability, and to concomitantly enhance its cellular uptake and intracellular antioxidant activity. This strategy enhanced quercetin solubility 753.6 and 9.95 times in water and PBS (7.4), respectively, and quercetin encapsulated in ZCPs remained stable after UV irradiation and heat treatment. ZCPs-Q could significantly attenuate AAPH induced erythrocyte hemolysis through the inhibition of ROS generation. It restored intracellular antioxidant enzyme (SOD and GSH-Px) activities to normal levels and inhibited intracellular malondialdehyde (MDA) formation. Simultaneously, ZCPs-Q showed a strong antioxidant activity in HepG2 cells with an EC50 value of 31.18 µg/mL, which was lower than free quercetin's 41.02 µg/mL. ZCPs enhanced the uptake efficiency of quercetin in Caco-2 cells, which contributed to the improvement of cellular antioxidant activities (CAA) evaluated with the CAA assay and AAPH-induced erythrocyte hemolysis assay. The designed route is particularly suitable for the encapsulation of water-insoluble nutraceuticals and for enhancing cell uptake and CAA.

Fabrication of Zein/Pectin Hybrid Particle-Stabilized Pickering High Internal Phase Emulsions with Robust and Ordered Interface Architecture.

Diets containing partially hydrogenated oils (PHOs) expose the human body to trans fatty acids, thus endangering cardiovascular health. Pickering high internal phase emulsions (HIPEs) is a promising alternative of PHOs. This work attempted to construct stable Pickering HIPEs by engineering interface architecture through manipulating the interfacial, self-assembly, and packing behavior of zein particles using the interaction between protein and pectin. Partially wettable zein/pectin hybrid particles (ZPHPs) with three-phase contact angles ranging from 84° to 87° were developed successfully. ZPHPs were irreversibly anchored at the oil-water interface, resulting in robust and ordered interfacial structure, evidenced by the combination of LB-SEM and CLSM. This situation helped to hold a percolating 3D oil droplet network, which facilitated the formation of Pickering HIPEs with viscoelasticity, excellent thixotropy (>91.0%), and storage stability. Curcumin in HIPEs was well protected from UV-induced degradation and endowed HIPEs with ideal oxidant stability. Fabricated Pickering HIPEs possess a charming application prospect in foods and the pharmaceutical industry.

Molecular Mechanism for Improving Emulsification Efficiency of Soy Glycinin by Glycation with Soy Soluble Polysaccharide.

Glycation with carbohydrates has been considered to be an effective strategy to improve the emulsifying properties of plant storage globulins, but the knowledge is inconsistent and even contradictory. This work reported that the glycation with soy soluble polysaccharide (SSPS) progressively improved the emulsification efficiency of soy glycinin (SG) in a degree-of-glycation (DG)-dependent manner. The glycation occurred in both the acidic (A) and basic (B) polypeptides to a similar extent. The physicochemical and structural properties of glycated SG samples with different DG values of 0-35% were characterized. The emulsifying properties of unglycated and glycated SG were performed on the emulsions at an oil fraction of 0.3 and a protein concentration in the aqueous phase, produced using microfluidization as the emusification process. The glycation with increasing the DG led to a progressive decrease in solubility and surface hydrophobicity but remarkably increased the magnitude of ζ-potential. Dynamic latter scattering and spectroscopic results showed that the glycation resulted in a gradual dissociation of the 11S-form SG at the quaternary level (into different [AB] subunits), in a DG-dependent way, while their tertiary ([AB] subunits) and secondary structure were slightly affected. Besides the emulsification efficiency, the glycation progressively accelerated the droplet flocculation and facilitated the adsorption of the proteins at the interface and formation of bridged emulsions. The results demonstrated that the improvement of the emulsification efficiency of SG by the glycation with SSPS was largely attributed to the enhanced conformation flexibility at the [AB] subunit level as well as facilitated formation of bridged emulsions. It was also confirmed that once the glycated SG adsorbed at the interface, it would readily dissociated into subunits; the dissociated [AB] subunits exhibited an outstanding Pickering stabilization. The findings would be of importance for providing new knowledge about the molecular mechanism for the modification of emulsifying properties of oligomeric globulins by the glycation with polysaccharides.

Ovalbumin as an Outstanding Pickering Nanostabilizer for High Internal Phase Emulsions.

There is still a debate about the effectiveness of native globular proteins to perform as Pickering-like stabilizers for oil-in-water high internal phase emulsions (HIPEs). In the work, we report one native globular protein (ovalbumin) with strong structural integrity and high refolding ability, exhibits an outstanding Pickering stabilization for HIPEs. Ultrastable gel-like HIPEs can be formed through a facile one-pot homogenization even at a concentration as low as 0.2 wt %. The HIPEs formed in the protein-poor regime are a kind of self-supporting and remoldable hydrogel consisting of bridging droplets. The formed HIPEs also exhibit other unique characteristics, such as extraordinary coalescence stability (against prolonged storage or heating), susceptibility to freeze-thawing, enhanced oxidation stability (to encapsulated bioactives), and inhibited vaporization of volatile oils. The findings would be of importance for extending the HIPEs to be applied in food, cosmetic, and petroleum industries.

Development of Pickering Emulsions Stabilized by Gliadin/Proanthocyanidins Hybrid Particles (GPHPs) and the Fate of Lipid Oxidation and Digestion.

This work attempted to engineer emulsions' interface using the special affinity between proline-rich gliadin and proanthocyanidins (PA), to develop surfactant-free antioxidant Pickering emulsions with digestive-resistant properties. This binding interaction between gliadin and PA benefited the interfacial adsorption of the particles to corn oil droplets. Pickering droplets as building units assembled into an interconnected three-dimensional network structure, giving the emulsions viscoelasticity and ultrastability. Oxidative markers in Pickering emulsions were periodically monitored under thermally accelerated storage. Lipid digestion and oxidation fates were characterized using in vitro gastrointestinal (GI) models. The interfacial membrane constructed by antioxidant particles served as a valid barrier against lipid oxidation and digestion, in a PA dose-dependent manner. Briefly, lipid oxidation under storage and simulated GI tract was retarded. Free fatty acid (FFA) fraction released decreased by 55% from 87.9% (bulk oil) to 39.5% (Pickering emulsion), implying engineering interfacial architecture potentially benefited to fight obesity. This study opens a facile strategy to tune lipid oxidation and digestion profiles through the cooperation of the Pickering principle and the interfacial delivery of antioxidants.

Development and characterization of novel antimicrobial bilayer films based on Polylactic acid (PLA)/Pickering emulsions.

Biodegradable food packaging is sustainable and has a great application prospect. PLA is a promising alternative for petroleum-derived polymers. However, PLA packaging suffers from poor barrier properties compared with petroleum-derived ones. To address this issue, we designed bilayer films based on PLA and Pickering emulsions. The formed bilayer films were compact and uniform and double layers were combined firmly. This strategy enhanced mechanical resistance, ductility and moisture barrier of Pickering emulsion films, and concomitantly enhanced the oxygen barrier for PLA films. Thymol loadings in Pickering emulsion layer endowed them with antimicrobial and antioxidant activity. The release profile of thymol was well fitted with Fick's second law. The antimicrobial activity of the films depended on film types, and Pickering emulsion layer presented larger inhibition zone than PLA layer, hinting that the films possessed directional releasing role. This study opens a promising route to fabricate bilayer architecture creating synergism of each layer.

The influence of ionic strength on the characteristics of heat-induced soy protein aggregate nanoparticles and the freeze-thaw stability of the resultant Pickering emulsions.

The improvement of the freeze-thaw stability of emulsions by interfacial engineering has attracted increasing attention in recent years. The present work investigated the potential of using soy protein isolate (SPI) aggregate nanoparticles as the Pickering stabilizers to improve the freeze-thaw stability of the resultant emulsions. SPI nanoparticles with different particle sizes and surface properties were fabricated through heating the SPI solutions (at a constant protein concentration of 2%, w/v) at 95 °C for 15 min, by varying the ionic strength (I) in the range of 0-500 mM. The nanoparticles fabricated at I values of 100-500 mM exhibited larger particle sizes and higher surface hydrophobicity, but poorer emulsification efficiency than those at I = 0.05 mM. The presence of NaCl during the nanoparticle fabrication resulted in the formation of a kind of gel-like emulsion with a high extent of droplet flocculation. The emulsion stabilized by SPI nanoparticles at I = 0.05 mM was highly susceptible to coalescence, flocculation and creaming upon freeze-thaw treatment, while those in the presence of NaCl exhibited excellent freeze-thaw stability. The much better freeze-thaw stability of the emulsions in the presence of NaCl (relative to that at I = 0.05 mM) was largely attributed to the gel-like network formation, rather than the salt itself. The results indicated that a kind of Pickering emulsion with excellent freeze-thaw stability, stabilized by heat-induced SPI nanoparticles, could be fabricated by heating the SPI solutions at I values of 100-500 mM. The findings would be of great relevance for providing important information about the development of food grade Pickering emulsions stabilized by protein-based particles, with potential applications in frozen food, or functional food formulations.

Development of antioxidant Pickering high internal phase emulsions (HIPEs) stabilized by protein/polysaccharide hybrid particles as potential alternative for PHOs.

We report for the first time the usage of mono-dispersed gliadin/chitosan hybrid particles as a particulate emulsifier for Pickering high internal phase emulsions (HIPEs) development. The hybrid particles with partial wettability were fabricated at pH 5.0 using a facile anti-solvent route. Stable Pickering HIPEs with internal phases of up to 83% can be prepared with low particle concentrations (0.5-2%). The hybrid latexes were effectively adsorbed and anchored at the oil-water interface to exert steric hindrance against coalescence. Concomitantly, the compressed droplets in Pickering HIPEs to form a percolating 3D-network framework endowed the emulsions viscoelastic and self-standing features. The protective effect of Pickering HIPEs on curcumin was confirmed, and the content of primary oxidation products in HIPEs was slightly lower than that in bulk oil. This work opens an attractive strategy to convert liquid oils to viscoelastic soft solids without artificial trans fats, as a potential alternative for PHOs.

Octenylsuccinate starch spherulites as a stabilizer for Pickering emulsions.

This study investigated structure and morphology of starch spherulites prepared from debranched waxy maize and waxy potato starches. Debranched waxy potato starch favored the formation of B-type crystals with longer branch chains (average chain length, 26.14), whereas A-type polymorphic aggregates were generated from debranched waxy maize under same recrystallization condition. Spherulites had smaller particle size distribution (D[3,2], ∼3.7µm), higher dissociation temperature (80-120°C) and crystallinity (80∼90%), compared to native waxy starches. Intact spherulites could be used as an edible particle emulsifier after modifying by octenylsuccinic anhydride (OSA). The emulsion produced using 2wt.% of octenylsuccinate (OS) starch spherulites as emulsifier was quite stable over 2months, and its Pickering emulsions displayed protective effect on stability of oil droplets.