Stable Pickering Emulsions Research Articles

Smart antimicrobial system based on enzyme-responsive high methoxyl pectin-whey protein isolate nanocomplex for fresh-cut apple preservation

The increase in pectin methylesterase (PME) activity on fresh-cut apple surface can smartly trigger the controlled release of bactericidal agents encapsulated within intelligent responsive Pickering emulsions. In this study, we developed a PME-responsive nanocomplex (W-H-II) to stabilize Pickering emulsion containing thyme essential oil (TEO), preserving fresh-cut apples. W-H-II, formed by heat-induced whey protein isolate (WPI) and high methoxyl pectin (HMP) (pH 4.5, 85 °C, 15 min, WPI:HMP ratio 1:2), exhibited good pH stability due to the stabilizing effects of hydrophobic, hydrogen bonding, and electrostatic interactions. The presence of PME triggered the demethylation of HMP within W-H-II, conferring PME response characteristics. Subsequently, a bacteriostasis experiment with pectinase-producing Bacillus subtilis provided evidence of PME-triggered TEO release from W-H-II-stabilized Pickering emulsion. Furthermore, microscopy techniques were employed to verify the demulsification behavior of the emulsion when PME activity ranged from 0.25 to 2.50 U mL−1. Finally, the PME-responsive TEO Pickering emulsion effectively preserved fresh-cut apples. Stored for 6 days at 5 °C and 10 °C, as the PME activity on the apple surface increased, the decay rate of the coated group was 0 %, with a total colony count below 3.0 log CFU g−1. This study introduces a novel intelligent preservation strategy for storing fresh-cut apples.

Pickering emulsions as an effective route for the preparation of bioactive composites: A study of nanocellulose/polyaniline particles with immunomodulatory effect

Several studies have reported on application of cellulose particles for stabilizing Pickering emulsions (PE). Here we employ an original approach that involves using these particles as a part of advanced composite colloids made of conducting polymer polyaniline (PANI) and cellulose nanocrystals (CNC) or nanofibrils (CNF). PANI/cellulose particles were prepared using oxidative polymerization of aniline in situ in the presence of CNC or CNF. The type and amount of celluloses (CNC vs CNF) and concentration of precursors (aniline monomer and oxidant) used in the reaction determined properties of the colloidal particles, such as size, morphology and content of PANI. The particles demonstrated intriguing biological characteristics, including no cytotoxicity, antibacterial activity against Staphylococcus aureus and Escherichia coli, antioxidant activity and related immunomodulatory activity. For the first time, such composites were used to successfully stabilize oil-in-water PE with undecane or capric/caprylic triglyceride oils. The properties of the emulsions were determined by the PANI/cellulose particles and oil used. The key finding of the study is the demonstrated ability of PANI/cellulose particles to stabilize PE, as well as the excellent antioxidant activity and ROS scavenging action originating from PANI presence, indicating potential of such systems for use in biomedicine, particularly for wound healing.

Improved sustained-release properties of ginger essential oil in a Pickering emulsion system incorporated in sodium alginate film and delayed postharvest senescence of mango fruits

The insufficient water vapor barrier and mechanical capacity of sodium alginate (SA) film limited its application in fruit preservation. Herein, cellulose nanocrystals (CNCs) were used to stabilize Pickering emulsion. Then, we prepared SA composite films. Ginger essential oil (GEO) was loaded as antimicrobials and antioxidants. Finally, the application on mangos were investigated. Compared to coarse emulsion, Pickering emulsion and its film-formation-solution showed more stable system and larger droplet size. The emulsion significantly changed the properties of SA film. Specifically, CNCs improved the thermal, tensile, and barrier properties of the film and GEO enhanced the ultraviolet-visible light barrier capacity. Additionally, the SA/CNC film possessed a homogeneous micromorphology which had a sustained-release effect on GEO, thus maintaining high postharvest quality and long-term bioavailability for mangos. In conclusion, the film prepared via Pickering emulsion showed satisfactory properties which had great potential in fruit preservation.

Product diversification to boost the sustainability of the shrimp processing industry: The case of shrimp-waste driven chitosan-based food Pickering emulsion stabilizers

Diversifying the product portfolio of the shrimp processing industry using its waste streams could contribute to its environmental sustainability and economic resilience. Considering that this study aimed to increase the commercial value of shrimp shell waste by using chitosan extracted from these wastes as a food emulsion stabilizer. More specifically, chitin was extracted from shrimp shell waste, and chitosan was then prepared from chitin by deacetylation. The findings showed that the extraction efficiency and degree of deacetylation of chitosan were 23% and 83%, respectively. After that, stearic acid was added to chitosan chains to improve its emulsifying properties. Then, the chitosan/stearic acid–stabilized flaxseed oil and olive oil emulsions were prepared in three oil ratios (20, 40 and 60%). The interfacial structure study showed that compared to flaxseed oil droplets, the olive oil droplets’ surface was better covered with the chitosan/stearic acid nanogels. Moreover, the rheological study indicated a stronger gel-like structure in olive oil emulsions than the flaxseed oil emulsions, particularly at 60% oil. The dried emulsions indicated that the olive oil was encapsulated better than flaxseed oil by the chitosan-based particles, and less oil leakage was observed for dried olive oil emulsions. Better encapsulation of olive oil with chitosan/stearic acid nanogels could be attributed to the higher polarity and viscosity of olive oil compared to flaxseed oil and the greater similarity of olive oil fatty acid profile with stearic acid attached to chitosan. In general, these findings showed that the stabilizer developed from shrimp shell waste is suitable for stabilizing emulsions containing more polar oils with less degree of unsaturation. The results obtained could contribute to enhancing the sustainability of the shrimp processing industry by diversifying its product portfolio.

Development by emulsion templating of a novel Tunisian clay-polyvinyl alcohol/extra-virgin olive oil scaffold with antibiofilm properties

A biobased porous scaffold with antibacterial and antioxidant properties was developed using the emulsion templating method. This technique represents a new route for the development of porous materials with controllable pore size. To take into account the environmental and economic aspects, polyvinyl alcohol (PVA) was chosen as the polymer matrix, raw Tunisian clay as the Pickering emulsion stabilizer, and extra virgin olive oil (EVOO) as the oil phase. PVA is often chosen for producing wound dressings that create a moist environment and consequently promote healing. Clay was used as a barrier against bacteria and as emulsifier due to its nanoscale and layered structure. In EVOO, the polyphenolic compounds have antioxidant activity and fatty acids have a plasticizer role. X-ray fluorescence, X-ray diffraction and Fourier transform infrared spectroscopy were used to analyze the raw clay. Then, the obtained films were structurally and chemically characterized, and their performance, antimicrobial activity against Pseudomonas aeruginosa, and antioxidant activity were evaluated. The emulsion characterization showed that clay addition influenced the emulsion type and increased the emulsion stability index to 98%, even after 3 months of storage. This was explained by the irreversible adsorption of clay platelets on the droplet surface that formed a rigid shell to prevent coalescence. The film characterization demonstrated that the oil: water ratio did not influence the surface porosity, although it affected the pore size uniformity and interconnection. Conversely, shortening the curing time improved the surface porosity. The resulting PVA-clay/EVOO scaffold displayed an exceptional performance, including high mechanical strength (∼2.1 MPa), interconnected porous structure with a size ranging from few µm to > 30 µm, and hydrophobic properties (∼90° ± 2). In addition, it showed antiadhesive and antibiofilm activities against P. aeruginosa. Therefore, this scaffold could be used for the early prevention of biofilm formation during wound healing and is a promising candidate for the controlled release of drugs and potentially for various applications in soft tissues.

Competition between hydrogen bonding and electrostatic repulsion in pH-switchable emulsions

Electrostatic interactions and hydrogen bonding play important roles in the stabilization of self-assembled systems. However, the competition between hydrogen bonding and electrostatic repulsion in emulsions hasn’t been reported. Herein, we report on electrostatic repulsion overcoming hydrogen bonding in oil-in-water (O/W) emulsions prepared by the mixture of escin and hydrophilic silica nanoparticles triggered by pH, in which the location of the nanoparticles is reversibly transformed from being adsorbed at the oil–water interface to being dispersed in the continuous phase. Escin adsorbs on silica particles in alkaline solution by its hydroxyl groups to endow the particles with surface activity, yielding a stable Pickering emulsion. However, such adsorption via hydrogen bonding is reversed by electrostatic repulsion between carboxylate ions and negatively charged silica particles after escin was converted to sodium aescinate. Demulsification occurred after silica particles reverted to being hydrophilic, which could further co-stabilize the oil-in-dispersion (OID) emulsions with sodium aescinate through electrostatic repulsion after re-homogenization. Pickering or OID emulsions with high internal phase volume fraction could also be obtained. This strategy is universal for O/W emulsions stabilized by nanoparticles and similarly charged surfactants with a polar headgroup near the nonionic functional group, e.g. silica plus polyoxyethylene lauryl ether carboxylate. This work aids in understanding the role of electrostatic repulsion and hydrogen bonding in stabilizing emulsions and sheds light on the design of smart surfactants for practical applications.

Interfacial properties and structure of Pickering emulsions co-stabilized by different charge emulsifiers and zein nanoparticles

The stability of Pickering emulsions can be improved by the synergistic action of colloidal particles and small molecule emulsifiers. In addition, the interaction between particles and different charge emulsifiers at the interface may result in different interfacial film structures, thus affecting the stability of Pickering emulsions. However, little is currently known about the impact of emulsifier charge on the fabrication and characteristics of these co-stabilized Pickering emulsions. Herein, we investigated the influence of Pickering emulsions co-stabilized by zein nanoparticles and anionic (quillaja saponin, QS), non-ionic (Tween 80), or cationic (lauroyl arginate ethyl hydrochloride) emulsifiers on the interfacial properties. The adsorption kinetics and rheological behavior of the molecular emulsifiers at oil/water interfaces were studied. Changes in interfacial structure and adsorption behavior were studied by confocal laser scanning microscopy (CLSM), and quartz crystal microbalance-dissipation (QCM-D) analysis. The dynamic interface characteristics showed that QS has good emulsification performance. The CLSM images indicated that the emulsifier charge impacted the interfacial structure of the Pickering emulsions. The combination of QS and zein nanoparticles formed a coating at the oil/water interface that was denser than for the other two emulsifiers, which improved the stability of the Pickering emulsions. QCM-D revealed that the interfacial film formed by anionic emulsifiers and zein nanoparticles was the thickest (about 6.6 nm). Moreover, anionic emulsifiers and zein nanoparticles stabilized Pickering emulsions provided the best protection against curcumin. These results may be important for optimizing the performance of Pickering emulsions in the food and pharmaceutical industries.

Structure and surface properties of ozone-conjugated octenyl succinic anhydride modified waxy rice starch: Towards high-stable Pickering emulsion

In the present work, a dual-modified waxy rice starch (OOWRS) fabricated with OSA and ozone was successfully used to stabilize the O/W Pickering emulsion. The molecular structure, surface properties, and underlying stabilizing mechanism were systematically investigated. The results showed that oxidation occurring on the surface of OSA-modified waxy rice starch (OSAWRS) resulted in the presence of indentations and cracks. The relative crystallinity of starch was generally decreased with increasing degree of oxidation. Due to the introduction of carbonyl and the variation in surface structure, the hydrophobicity and acidity of OSAWRS were significantly enhanced after the ozone treatment. Remarkably, OOWRS stabilized Pickering emulsion exhibited a feature of typical O/W emulsion, and the 0.5 h and 1 h OOWRS emulsion exhibited a more uniform droplet size as well as a higher surface potential. We also noted that a weak-gel network was formed within the OOWRS emulsion system as the hydrophilic starch chains played a bridging role. Two reasons for the improved stability of the emulsion were the special gel structure and the enhanced electrical repulsion among the droplets. This research provides that ozone-conjugated OSA modification is a promising strategy for improving the emulsion ability of starch-based Pickering emulsions.

Interaction of curcumin with four types of gelatins in nanoparticles: Mechanism and application for emulsion stabilization

The research of the interaction between proteins and functional active substances in the protein nanoparticles is a research hotspot in the field of food science. Gelatin type had a significant effect on the structural and functional properties of gelatins. Herein, the interaction mechanism of curcumin with four types of gelatins (bovine bone gelatin, BBG; cold water fish skin gelatin, CFG; fish gelatin, FG; and porcine skin gelatin, PSG) and the structural and functional properties of gelatin/curcumin nanoparticles were explored. All four types of gelatins could be applied to prepare gelatin/curcumin nanoparticles with an amorphous state of curcumin. The nanoparticle sizes were not dependent on the molecular weight of gelatins. The stability of gelatin/curcumin nanoparticle solutions was dependent not on the nanoparticle size but on the gelatin type. The binding affinity between gelatins and curcumin was dependent on gelatin type and the number of binding sites was nearly 1. The main binding forces to form gelatin-curcumin nanoparticles were hydrogen bonds, Pi-alkyl interaction, and Pi-anion interaction. The nanoparticulation increased the surface hydrophobicity of BBG, FG, and PSG, whereas it decreased the surface hydrophobicity of CFG. The nanoparticulation increased the surface tension of gelatins and decreased the dynamic interfacial tension of gelatins. The functional properties were dependent on both gelatin type and nanoparticulation. CFG/Cur nanoparticulation could not change the creaming stability, whereas other gelatins/curcumin nanoparticulation significantly increased creaming stability than the corresponding gelatins. This work provided the basic knowledge to illustrate the interaction and application of protein nanoparticles for Pickering emulsion stabilization.

Controlled oxidation and digestion of Pickering emulsions stabilized by quinoa protein and (-)-epigallocatechin-3-gallate (EGCG) hybrid particles

In this study, we prepared Pickering emulsions stabilized by quinoa protein isolate (QPI) and (-)-epigallocatechin-3-gallate (EGCG) non-covalent hybrid particles using ultrasonic emulsification technique and demonstrated lipid oxidation and in vitro digestion process of Pickering emulsions. The interaction forces between QPI and EGCG were characterized using fluorescence spectroscopy, isothermal titration calorimetry, and Fourier transform infrared spectroscopy. Results indicated that the non-covalent QPI/EGCG hybrid particles were formed mainly via hydrophobic interactions, hydrogen bonds, and electrostatic interactions at pH 5. Then, the QPI/EGCG non-covalent hybrid particles were applied to modify the Pickering emulsion with ultrasonic homogenization. The rheological experimental results showed that the energy storage modulus (G′) was higher than the loss modulus (G″), indicating that the emulsion had solid-like properties. As a physical barrier, interfacial layer fabricated by antioxidant QPI/EGCG hybrid particles limited lipid oxidation at 60 °C for 15 days. At 37 °C, the QPI/EGCG hybrid particles stabilized Pickering emulsions with robust antioxidant interfacial structure limited the lipid digestion under simulated gastrointestinal tract (gastric, small intestine phases). Thus, EGCG and quinoa proteins were more resistant to free radical oxidation and gastrointestinal digestion with the assistance of ultrasound. It provides a basis for better development of food and drug delivery systems by fully utilizing the antioxidant properties of plant polyphenols.

Construction of whey protein gels prepared by three methods to stabilize high internal phase Pickering emulsions loaded with CoQ10 under different pH.

The aim of this study was to investigate the effect of whey protein gel particles (WPGPs) prepared by heat-induced method, enzyme cross-linking method and calcium ion cross-linking method on the structural properties and intrinsic linkage of their stable high internal phase Pickering emulsions (HIPPEs) under different pH conditions. The effects of different pH and preparation methods on the internal interaction forces, particle size, ζ-potential, wettability and secondary structure of gels was investigated. The results indicated that the construction of HIPPEs system was successfully constructed at pH 3, 5 or 7. The WPGPs stabilized HIPPEs can maintain stable state at 4°C for 28days. Coenzyme Q10 (CoQ10) loaded with HIPPEs increased the bioavailability from 13.2% to 79.4%, which was demonstrated in in vitro digestion experiments.

Comparative study of rheological properties and Pickering emulsion stabilizing capacity of nonenyl succinic anhydride and octenyl succinic anhydride modified amaranth starches

Functional properties and ability to stabilize Pickering emulsions of amaranth starch with the novel nonenyl succinic anhydride (NSA) modification and the widely used octenyl succinic anhydride (OSA) modification were compared. The NSA modification was more effective in altering the rheological properties of amaranth starches. NSA-modified amaranth starch showed significantly higher peak viscosity (7.13 Pa·s at DS of 0.02209) than the OSA-modified amaranth starch (6.10 Pa·s at DS of 0.03042). The gelatinization temperature, gelatinization enthalpy, and relative crystallinity of amaranth starch were more affected by the OSA than the NSA. The Pickering emulsions stabilized with NSA-modified starches had higher stability than those with the OSA-modified starches as characterized by particle size distribution, morphological, and rheological approaches. A lower degree of substitution by NSA than by OSA is needed to achieve a similar emulsification capacity. Thus, the NSA modification could be an efficient alternative to OSA modification in tailoring physicochemical and rheological functions, as well as stabilizing Pickering emulsions.

Structure and functionality of cinnamaldehyde/chitosan/gum Arabic complex particles

The work aims to study the effects of the mixing order of chitosan, gum Arabic and cinnamaldehyde and the concentration of cinnamaldehyde on the structure and functionality of complex particles. The results showed that non-covalent and Schiff base reactions occurred between cinnamaldehyde, chitosan and gum Arabic. When chitosan and gum Arabic (CS-GA-1:0.3) were mixed first, the complex particles were flat spherical and more compact and existed in aggregate state, with higher particle size, Zeta potential and wettability, and lower interfacial tension. When mixing cinnamaldehyde with chitosan or gum Arabic first (CS-CA-1:0.3 and GA-CA-1:0.3) and adding high concentration of cinnamaldehyde (CS-GA-1:0.9 and CS-GA-1:1.2), the structural compactness and morphological regularity of the complex particles got weakened, leading to the decrease in contact angle and increase in interfacial tension. All complex particles could be effectively used as Pickering emulsion stabilizers. When chitosan:cinnamaldehyde mass ratio reached 1:0.6 and below, the complex particles showed obvious antibacterial properties. The above results laid a foundation for the application of chitosan-based complex particles in the food and medical field.

Carboxylated chitin nanowhiskers enhanced stabilization of Pickering and high internal phase Pickering emulsions

Pickering emulsions stabilized by the emulsifiers derived from biobased materials have been widely used in food related fields. In the current study, Pickering emulsions possessing internal phase volume fractions (ɸ) from 0.5 to 0.8 were successfully prepared by mechanical emulsification methods using carboxylated chitin nanowhiskers (C-ChNWs) as the emulsifiers. C-ChNWs suspensions obtained by ammonium persulfate (APS) oxidation showed high stability and possessed a Zeta potential of −48.9 mV. FTIR and XRD analyses indicated the α-chitin crystal structure could be maintained following APS oxidation. The C-ChNWs could form a three-dimensional network structure at the interface and endow the emulsion with high stability and viscoelastic features. Morphology results demonstrated these were oil-in-water emulsions. Moreover, the prepared high internal phase Pickering emulsions (HIPPEs; ɸ >0.74) showed good texture characteristics for high-resolution 3D printing. This work further validated the potential of nanochitin derived from biomass as an outstanding Pickering emulsion stabilizer.

Oil-in-Water Pickering Emulsions Stabilized with Nanostructured Biopolymers: A Venue for Templating Bacterial Cellulose.

Pickering emulsions (PEs) differ from conventional emulsions in the use of solid colloidal particles as stabilizing agents instead of traditional amphiphilic molecules. Nanostructured biopolymers (NBs) emerge as a promising alternative for PE stabilization owing to their remarkable biocompatibility, abundant availability, and low cost. To explore this potential, a study is herein presented, in which cellulose nanocrystals (CNCs), both type I and type II allomorphs, and chitin nanocrystals (ChNCs) were used for stabilizing oil-in-water PEs prepared by the use of ultrasound. Sunflower oil was selected as the oil phase as it offers the advantages of being edible, renewable, and inexpensive. By utilizing ζ-potential, static light diffraction, and visual observations, we determined the optimal oil/water ratio for each type of NB to obtain stable emulsions after 14 days. The optimized PEs were used to form bacterial nanocellulose composites through emulsion templating. To our knowledge, this study represents a pioneering work in exploiting oil-in-water PEs for this approach. Additionally, it entails the first utilization of nonmercerized type II CNCs as stabilizers for PEs, while also establishing a direct comparison among the most relevant NBs. The resulting composites exhibited a unique morphology, composed of larger pores compared to standard bacterial nanocellulose aerogels. These findings highlight the notable potential of NBs as stabilizers for PEs and their ability to generate green nanocomposites with tailored properties.

Improved antioxidant properties of pork patties by replacing fat with resveratrol-loaded MP-CS complex stabilized pickering emulsion.

The characterization and antioxidant ability of Res-loaded MP-CS stabilized Pickering emulsion, and its effects of fat reduction (25%, 50%, 75%, and 100%) in meat patties on pH, color, texture, cooking yield and antioxidant activity were investigated. Fat substitute using emulsion had no significant effect on pH and cooking yield. The addition of emulsion increased L* value and reduced a* value. a* value of meat patties with resveratrol added were higher than those without resveratrol group. Hardness and chewiness of meat patties with 25% and 100% fat replacement was lower than 50% and 75% fat replacement. The addition of emulsion could improve the network structure of meat patties and enhance oxidative stability. Oxidative stability of meat patties was improved by Res-loaded MP-CS stabilized Pickering emulsion. The results showed that MP-CS stabilized Pickering emulsion had great potential to be used as fat substitute for developing low-fat meat products, and the addition of resveratrol can improve the antioxidant ability of substitute fat meat products.

Phycocyanin/lysozyme nanocomplexes to stabilize Pickering emulsions for fucoxanthin encapsulation

Food-grade Pickering emulsions with plant proteins have attracted increasing interest in recent years. In this work, we report a type of phycocyanin (PC) electrostatic nanocomplex fabricated following a complexation between PC and lysozyme (Lys). The aim was to investigate toward investigating the performance of phycocyanin-Lysozyme (PC-Lys) nanocomplexes in stabilizing Pickering emulsions and protecting fucoxanthin (FX) from degradation. The properties of the PC-Lys nanocomplexes were characterized by 1H nuclear magnetic resonance (NMR) spectroscopy and three-phase contact angle. Using PC-Lys nanocomplexes as emulsifiers, Pickering emulsions were successfully prepared. Pickering emulsions stabilized by PC-Lys nanocomplexes generated a tight three-dimensional network structure, which increased the memory modulus and viscoelasticity of the emulsion. Furthermore, the produced Pickering emulsions considerably increased the chemical stability and bioavailability of FX. Overall, our study showed that PC-Lys nanocomplexes have the potential for use in Pickering emulsion construction with enhanced protective effects on loaded lipophilic ingredients.

Polysaccharide-dependent depletion strategy to fabricate pickering emulsion gels

Understanding the associations between polysaccharide depletion and emulsion gelation is of great importance for achieving stable Pickering emulsion gels, but there is inconsistency in the relevant studies. In this work, we report a versatile strategy, by using depletion attractions of anionic polysaccharides - hyaluronic acid and sodium alginate, to realize the gelation of Pickering emulsions stabilized with various particles of different characteristics. The depletion interactions imposed by different ratios of a polysaccharide were demonstrated to be conducive to the formation of emulsion gels. With a higher addition of polysaccharides, emulsions underwent (1) enhanced interfacial adsorption at weak depletion, (2) bridging flocculation at moderate depletion, and (3) depletion flocculation at high depletion, which all led to the arrested dynamics and gelation of Pickering emulsions. The prepared emulsion gels exhibited good stabilities and favorable rheological properties including high gel strength, shear sensitivity, and thermostability. The universality of this study was further confirmed by using different types of Pickering stabilizers as well as oil phases. The polysaccharide-dependent depletion provides a simple strategy to design Pickering emulsion gels with tunable rheological behaviors for varied purposes.

Modified coconut pulp particles: The potential candidate for stabilizing Pickering emulsions

Coconut pulp, a by-product of coconut milk extraction, was used to prepare Pickering emulsion–stabilizing particles by modification with citric acid (CA) through dry heat treatment. The treatment temperature (100, 120, and 140 °C) and CA concentration (0.7, 2.0, and 3.3 % w/v) were varied. Modification at 100 °C and high concentration of CA gave products with satisfactory appearance and surface characteristics. The product obtained by treatment at 3.3 % CA and 100 °C had a yellowish white color with a light and porous surface, 0.08 degree of substitution (DS), 70° water contact angle, −50 mv zeta potential, and an average particle size after homogenization of 8.4 µm. Unmodified CP powders could not stabilize the oil-in-water (O/W) emulsion, and phase separation occurred rapidly at 25 °C, while CP modified using 2.0 % and 3.3 % CA at 100 °C could stabilize the emulsion for at least 30 d. The oil droplet size decreased as the DS of the particles increased from 77.3 to 33.3 µm and 18.6 µm for the particles with DS of 0.046, 0.072, and 0.082, respectively. The higher hydrophobicity imparted by CA modification strongly affected the oil droplet size, while the negative surface charge of particles supported the uniform dispersion of free CP particles in the interspace among the oil droplets.

Fabrication and characterization of food-grade pea protein-ascorbic acid nanoparticles-stabilized Pickering emulsion

In this study, modified pea proteins (PP) were prepared by heat treatment, ultrasound, adjusting the pH to 9, and the addition of ascorbic acid (AA) to stabilize the Pickering emulsion (PE) with a 50% volume fraction of corn oil. The solubility of PP after different treatments was higher in all treatments than in the native state. FTIR and SDS-PAGE results confirmed that a covalent bond (Maillard reaction) was formed between PP and AA, which occurred more strongly in the heat-treated suspensions. The nanoparticles produced from ultrasonication of PP and the PP/AA complexes were able to stabilize the emulsion with a high volume fraction of oil as novel Pickering emulsifiers. In ultrasonicated PP and PP/AA complexes, the reduction of interfacial tension and particle size and increase of contact angle caused a significant improvement in the physical stability of the PE, which can be the result of regular placement of protein particles at the water-oil interface. The treatment corresponds to highly stable PE, heat-treated PP in the presence of AA in alkaline conditions (HPP.AA.pH), increased the contact angle of PP from ∼ 42 to 77, and decreased interfacial tension from ∼ 25 to 14. These PEs showed high physical and oxidative stability. According to CLSM images, the type of PE was oil in water, and PP particles surrounded the oil droplets. The results of this research could be effective in developing PP-based low-fat formulations with improved oxidative stability by utilizing different treatments, including ultrasonic treatment and/or complex formation between PP and AA.