Correlation between interfacial layer properties and physical stability of food emulsions: current trends, challenges, strategies, and further perspectives

Improve the chitosan particle-stabilized oil-water interface by dual reinforcement and its effect on the structure and properties of emulsion

This study investigated the enhancement of chitosan particle-stabilized oil-water interface stability by incorporating cinnamaldehyde in the oil phase and sodium alginate in the water phase. The effects of varying concentrations of these additives on emulsion microstructure and stability were examined. Sodium alginate and cinnamaldehyde contributed to a thicker, more uniform interface. The Schiff base reaction between chitosan and cinnamaldehyde improved particle adsorption and stability, while electrostatic interactions between sodium alginate and chitosan formed a multilayer interface. This dual-strengthening mechanism resulted in emulsions with smaller droplet sizes, improved storage stability, and enhanced centrifugal stability and oil binding capacity. At a 1.5:1:5 ratio of sodium alginate/chitosan/cinnamaldehyde, the droplet size was minimized to 31.33 μm and remained stable during storage. The emulsion showed no oil phase leakage after centrifugation, and the oil binding capacity increased from 52.5 % to 85.4 %. This study provides a novel approach to improve chitosan particle-stabilized emulsion stability.

Plant-based whipping cream: A promising sustainable alternative to dairy products

Future food is dedicated to transforming the traditional production model of the food industry, making people and the planet healthier, and addressing the challenges facing humanity. The development of plant-based foods is one of the core contents of future food and an important way to achieve green and low-carbon development of the food industry. A prevailing food trend in the dairy industry is the demand to develop various plant-based alternatives to dairy products. Plant-based whipping cream is a complex emulsion-foam system that can be transformed from an oil-in-water emulsion structure to a triphasic (solid-liquid-gas) foam structure by whipping, which should achieve a subtle balance between emulsion stability, whipping destabilization, and foam re-stabilization. This review aims to understand the science and technology underlying the development of plant-based whipping cream. The initial focus is on the fundamental principle of stabilization and destabilization of plant-based whipping cream, as the development of successful products depends on understanding their physicochemical basis. Three main processing technologies for the manufacture of plant-based whipping cream are then introduced: homogenization, sterilization, and tempering. Besides that, the role of the basic ingredients in plant-based whipping cream is highlighted, including vegetable fats, plant proteins, low-molecular-weight emulsifiers, and thickeners. In order to quantify and compare the quality attributes of different plant-based whipping cream products under standardized conditions, we provide an overview of characterization methods to evaluate emulsion stability, whipping destabilization, and foam re-stabilization of plant-based whipping cream. Subsequently, the legislations and regulations related to plant-based whipping cream products are introduced to cater to their market development. Finally, the current challenges faced by plant-based whipping cream are highlighted. This review aims to provide a guidance for researchers and manufacturers in related industries.

Relationship between fat crystallization, interfacial properties and qualities of whipped cream: Effect of lactic acid esters of monoglycerides

This study investigated the effects of lactic acid esters of monoglycerides (LACTEM) on the fat crystallization, interfacial properties, and their relationship with the qualities of whipped cream. LACTEM promoted the formation of moderate size fat crystals at low concentrations (≤0.10 wt%). Furthermore, LACTEM could be coexisted with interfacial proteins, which in turn induced two-dimensional crystals, and thereby reducing the interfacial tension and increasing the interfacial elastic modulus. The addition of LACTEM resulted in smaller particle size and higher apparent viscosity in emulsions, and higher firmness and lower serum loss were observed in whipped cream. At high concentrations (>0.10 wt%), the larger and sparser fat crystals were observed. However, LACTEM was still coexisted with, rather than replace the interfacial proteins. LACTEM induced coarser volume phase crystals instead of interfacial crystals, which resulted in increased emulsion particle size and decreased apparent viscosity. The firmness decreased and serum loss increased in whipped cream.

Host-guest interfacial recognition of alginate-based β-cyclodextrin/dendrobine supra-amphiphiles reinforced the physicochemical stability and sustained-release properties of Pickering emulsions

Achieving high bioavailability of dendrobine (DDB) necessitates the development of simplified available and efficient delivery systems. Pickering emulsions (PEs) derived from biomass represent a promising option. However, the physicochemical properties of PEs interfacial films were insufficient to prevent DDB leakage, thereby reducing bioavailability. Herein, a supramolecular host-guest interfacial recognition strategy was proposed in-situ between amphipathic sodium alginate-functionalized cyclodextrin (SAE-CD) and hydrophobic DDB at oil-water interface, further forming the SAE-based supra-amphiphiles to efficient stabilize the high internal phase Pickering emulsions (HIPPEs) with gel-like characteristics. A multiscale methodology was empolyed to investigate the interfacial assembly behavior and emulsification properties of supra-amphiphilic SAE-CD/DDB interfacial system, focusing on molecular interactions, interfacial adsorption, and overall stability. Notably, the SAE-CD/DDB-based supramolecular assembly/disassembly behaviors could be self-adjusted for regulating the aggregation particle size and thickness of interfacial self-assembled films. The SAE-CD/DDB co-stabilized HIPPEs exhibited favorable drug release capabilities, enabling sustained effects of DDB. Overall, the SAE-CD/DDB co-stabilized HIPPEs demonstrated excellent properties in terms of stability, drug loading capacity, and sustained release performance, highlighting their potential for in oral delivery and sustained-release systems.

A promising perspective to boost the utilizability of oil bodies: Moderate regulation and modification of interface

Oil bodies (OBs), as natural oil storage organelles, can be obtained and utilized directly by simple extraction, thereby satisfying consumer demand for plant-derived green foods. The unique topological structure of the phospholipid-protein membrane renders OBs controllable and resistant to environmental stres, demonstrating their promising prospects for applications. As natural self-assemblies, the nutrient distribution, composition, and structural characteristics of OBs can be modified in multiple ways, including the genetic improvement and various processing techniques, to meet diverse application requirements. Generally, the utilization of OBs (e.g., processing stability, emulsifying, digestion, etc.) is closely related to their interfacial properties, but the associated studies have not been systematically reviewed. In this paper, we systematically review the structural and interfacial characteristics of OBs for the first time, encompassing their biosynthetic pathways and the structure-function relationship critical to their processability and bioavailability In particular, targeted improvement methods were also discussed. The underlying mechanisms of the physicochemical stability of OBs were primarily related to the interfacial modulation, including linkages between density, charge, and the number of protein-phospholipid salt bridges, as well as the quantity and structure of extrinsic proteins. The membrane compactness, enzyme binding sites, and aggregation of OBs in gastrointestinal tract significantly impact their digestion and subsequent metabolic fate. In summary, moderate interfacial modification, by altering the interactions between membrane components and retaining some extrinsic proteins, may be a promising approach to boost the stability and functionality of OBs.

Enhancing the quality of fat-reduced pork batter with soybean protein-chitosan nanoparticles based Pickering emulsion

This study aimed to investigate the impact of substituting pork back fat with Pickering emulsion (PE) stabilized by soybean protein isolate-chitosan (SPI-CH) nanoparticles on the quality of pork batters. Cooking loss, rheological properties, water distribution, microstructures, texture, color, and oxidative stability of pork batters were evaluated. The results revealed that replacing fat with PE led to a reduction in fat content and an increase in moisture content, as well as higher L* and b* values (P < 0.05). Furthermore, the substitution resulted in improved gel performance by enhancing rheological properties and texture, reducing water mobility and cooking loss, as well as effectively inhibiting lipid and protein oxidation in pork batters. However, no significant differences were observed in sensory acceptability. The findings suggest that using SPI-CH nanoparticles as a stabilizer for PE presents significant potential as a nutritionally improved fat alternative in meat products, offering enhanced functional characteristics.

Interfacial characteristics and digestive kinetics of emulsions fabricated by composite potato and whey protein

Partial substitution of animal protein with plant protein can reduce animal protein consumption and carbon emissions. This study investigated the effects of potato protein (PP) and whey protein (WP) ratios (10/0, 9/1, 7/3, 5/5, 3/7, 1/9 and 0/10, w/w) on the interfacial characteristics and digestive kinetics of composite protein emulsions for substituting WP with PP. Increasing the PP proportion improved the dynamic surface pressure of mixed protein at the oil/water interface while decreasing the interfacial layer dilatational elasticity. Furthermore, a high PP proportion increased the particle size, ζ-potential value, adsorbed protein amount, surface protein load and apparent viscosity of the emulsions. Confocal laser scanning microscopy confirmed that the increased PP proportion led to interfacial protein aggregation, thereby forming a thick and complete interfacial layer. Moreover, it improved the emulsion stability index. In addition, increasing the PP proportion slowed down the release of free fatty acids, but did not influence the release of total and individual fatty acids. Based on emulsification characteristics and digestion rate, the optimal PP/WP radio was found to be 7/3. The findings support the possible use of plant proteins in food items as substitutes for animal proteins.

The polysaccharide-based nanoemulsions: Preparation, mechanism, and application in food preservation-A review

The stability and bioavailability of antioxidant, antibacterial, and other bioactive substances could be improved through nanoemulsion systems, as a result, nanoemulsion technology has become popular in food preservation. Polysaccharides are green polymers, their renewability, richness, safety, and functionality determine broad application prospects. Polysaccharide-based nanoemulsion coatings with good waterproofness, and mechanical and biological properties are found to effectively prevent or delay water loss, respiration, gas exchange, and microbial corruption of fruits, vegetables, and meat products, and they will be an important innovative technology for sustainable development in the future. The structural and functional properties of polysaccharides that could stabilize nanoemulsions have been discussed, and the preparation methods, physicochemical properties, stability, and formation mechanism of nanoemulsions have been summarized in this review. In addition, the preparation methods of polysaccharide-based nanoemulsion coatings are summarized, the application and preservation mechanisms in fruits, vegetables, and meat products have been introduced, and future perspectives have been discussed. At present, the related researches mainly focus on the bactericidal activity and the sensory quality of food products, while the in-depth research is unclear, this review provides ideas for the subsequent research on polysaccharide-based nanoemulsions for food preservation.

Research Advances for Protein-Based Pickering Emulsions as Drug Delivery Systems

Nanotechnologically engineered protein-based carriers have attracted considerable attention in the pharmaceutical field due to the advantages of superior biocompatibility, tunability and good emulsifying properties. Recently, protein-based Pickering emulsions (PPEs) systems with multi-level structures have been introduced as innovative colloidal delivery systems for advanced drug encapsulation, protection, delivery and controlled release. Natural source protein nanoparticles are promising candidates to provide a wide range of functional performances and interfacial properties in the preparation and stabilization of Pickering emulsions. Herein, this review summarizes the development of PPEs in drug delivery systems, focusing on the research progress concerning the aspects of protein particle preparation methods, formation mechanisms and rational design principles, emphasizing the relationship between protein particle structure and functional properties. To further understand the interfacial behavior in protein nanoparticle stabilized emulsion, the mesoscopic dissipative particle dynamics (DPD) simulations were discussed, which bridges the gaps between macroscopic time and length scales, as well as molecular-scale simulations on particles and oil/water interface systems. The structure-effect relationship between the tunable physicochemical properties of protein-based interface design, which leads to the effective loading, stimuli-responsiveness for the controlled release and multiple delivery, was then summarized. Finally, the opportunities and challenges for the future development of PPEs for drug delivery are discussed. This review aims to provide a reference for the further application of PPEs as advanced drug delivery systems.

Measuring interactions between Pickering emulsion droplets coated with casein-chitosan complex using optical tweezers

Emulsions stabilized by protein/polysaccharide complexes have attracted great interest. However, the emulsion properties and interactions between droplets at the microscale require further investigation. In this work, the interaction forces between two rice bran oil droplets stabilized by casein-chitosan complexes, with a diameter of 3 ± 0.1 μm (pH 5.54 and no-salt), were measured under different aqueous conditions (pH and ionic strength) using optical tweezers. The measured force curves exhibited consistency with the interfacial layer conformation and interfacial charge, as determined through fluorescence spectroscopy and zeta-potential analysis. Furthermore, atomic force microscopy (AFM) and optical microscopy were employed to characterize the morphology and structural evolution of the emulsions under varying environmental conditions. Our results provide a useful method for studying the interaction forces between Pickering emulsion droplets with pN force resolution and reveal the correlation between interfacial layer properties and physical stability, offering deep insights into the stabilization mechanism of Pickering emulsions.

Fabrication and characterization of emulsion stabilized by tannic acid/soluble potato starch complexes

In this study, the influence of tannic acid (TA)/soluble potato starch (PS) mass ratio and PS concentration on TA/PS complexes and emulsions stabilized by TA/PS complexes were studied. The size, hydrophobicity and emulsifying properties of TA/PS complexes were all controlled by TA/PS mass ratio and PS concentration. In detail, the hydrophobicity of PS (θow = 48°) improved after complexing with TA to form TA/PS complexes (θow max = 64°). The emulsions size decreased and then increased with increasing TA/PS ratio. Additionally, the emulsifying properties of TA/PS complexes improved by increasing PS concentration. Analysis of the interfacial tension after adsorption equilibrium (0.25 mass ratio, TA/PS complexes (13.03 mN/m), TA (14.21 mN/m) and PS (20.25mN/m)), TA and PS had a synergistic effect of stabilizing the oil-water surface. Among them, TA mainly played a role in emulsifying property, and PS mainly played a role of stabilization. All emulsions exhibited obvious creaming. However, at high PS concentration or TA/PS ratio, the creaming was prevented by formed smaller emulsion size, interface complexes networks or high viscosity (Increased from 0.004 to 0.060 Pa.s). It showed that TA/PS complexes can act as emulsifiers to improve the physical and oxidative stability of emulsions, making them suitable for delivering oxidation-sensitive fat-soluble bioactive compounds.

Utilizing carboxymethyl cellulose to assist soy protein isolate in the formation of emulsion to deliver β-carotene: Exploring the correlation between interfacial behavior and emulsion stability

This study investigated the effects of carboxymethyl cellulose (CMC) adsorption on the interfacial properties of soy protein isolate (SPI) and its correlation with emulsion stability. The findings revealed that SPI-CMC emulsions exhibited reduced zeta potential and particle size compared with SPI emulsion alone. Molecular docking analysis suggested that the enhanced stability of SPI-CMC emulsions was primarily due to hydrogen bonding and electrostatic interactions between SPI and CMC. Notably, the encapsulation efficiency of β-carotene in SPI-CMC emulsions increased by 47.74 % at pH 4.0 with 0.4 % CMC and by 39.55 % at pH 5.0 with 0.5 % CMC compared to SPI emulsion. Stability analyses demonstrated that at pH 4.0, the SPI-CMC interfacial layer formed by hydrogen bonding and electrostatic interactions effectively protected β-carotene from external degradation factors. At pH 5.0, steric hindrance facilitated the formation of a SPI-CMC network structure, increasing the path length for oxidants to reach the oil droplet interface. These distinct binding mechanisms in SPI-CMC emulsions effectively prolonged oil droplet digestion and regulated the release of free fatty acids. The resulting emulsion exhibited slow and sustained lipid release and digestion kinetics, making it a suitable model for designing sustained-release nutritional supplements.

Interfacial properties of whey protein hydrolysates monitored by quartz crystal microbalance with dissipation

Whey protein hydrolysate (WPH) can be used to develop hypoallergenic foods. However, the stabilization mechanism of WPH-stabilized emulsion is not fully understood. Here, a real-time quartz crystal microbalance with dissipation monitoring (QCM-D) was used in conjunction with a rheometer to investigate the interfacial properties of WPH. Initially, the properties of WPH with different (6 %, 8 %, 10 %, 12 % and 14 %) degree of hydrolysis (DH) were investigated. 8 %-WPH demonstrated superior emulsifying (11.49 m2/g, 81.34 min) and foaming properties (14.00 %, 7.78 %). Subsequently, the stability of different WPH-stabilized emulsions were examined. 8 %-WPH emulsion exhibited the lowest centrifugal precipitation rate (4.50 %) and Turbiscan stability index (2.24). Additionally, the 8 %-WPH promoted the adsorption and retention of molecules at the interface, which effectively reduced the interfacial tension. QCM-D measurement further proved that the 8 %-WPH possessed excellent adsorption mass and viscoelasticity. Finally, we characterized the interface-adsorbed WPH. The 8 %-WPH exhibited the highest surface hydrophobicity (1072.60) and flexibility (0.22). Notably, the 8 %-WPH showed the highest β-sheet (41.11 %). This led to stronger interactions between neighboring interfacial WPH molecules, which protected the emulsion droplets from destabilizing factors. Nevertheless, excessive hydrolysis (10 %-14 %) caused WPH molecules aggregation, which consequently diminished the viscoelasticity of the interfacial film and the emulsion stability.

The effect of enzymatic deamidation on the solubility and emulsifying properties of walnut protein isolate

BACKGROUND

Alkaline-extracted walnut protein isolates (WPI) exhibit limited solubility, which poses challenges for their application in the food industry. The present study investigated the effects of protein-glutaminase (PG) deamidation on the physicochemical characteristics, solubility and emulsifying properties of WPI.

RESULTS

The deamidation process of WPI was monitored by assessing the release of free ammonia and the reduction in solution turbidity. PG deamidation significantly increased the surface charge of WPI and modified its surface hydrophobicity with increasing deamidation degree (DD), resulting in a gradual improvement in solubility by approximately 50-70%. Furthermore, the emulsifying capacity of deamidated WPI (DeWPI), specifically at 0.25 h (DeWPI0.25, DD 7%) and 9 h (DeWPI9, DD 23%), was evaluated for stabilizing low internal phase emulsions (LIPEs) and high internal phase emulsions (HIPEs). LIPEs stabilized by WPI and DeWPI0.25 exhibited significant flocculation of oil droplets, leading to decreased stability against heat, salt treatment and storage compared to those stabilized by DeWPI9. DeWPI-stabilized HIPEs showed a 2-2.5-fold higher storage modulus compared to those stabilized by WPI. However, HIPEs stabilized by DeWPI0.25 displayed higher flow stress and flow strain compared to DeWPI9-stabilized HIPEs. Overall, DeWPI-stabilized HIPEs demonstrated relatively high physical stability against storage, heat treatment and high ionic strength.

CONCLUSION

PG deamidation significantly enhanced the solubility and influenced the emulsifying properties of WPI in a manner dependent on the DD. © 2024 Society of Chemical Industry.

Interfacial Properties and Visualization of Emulsions Stabilized by Temperature-Triggered Bovine Bone High-Temperature Hydrolysate

Temperature is an important factor affecting the stability of emulsified products. This study explored how the typical temperatures in the industry (55, 70, and 85 °C) influence the stability of bovine bone high-temperature hydrolysate emulsion by modulating the interfacial properties. The results showed that heat treatment at 70 °C could improve the interfacial properties. In terms of structure, treatment at 70 °C facilitated the unfolding of the interfacial protein α-helix to the β-turn and β-sheet. Moreover, the interface was relatively smooth at 70 °C, while holes appeared at 55 and 85 °C. In addition, the disulfide bond promoted cross-linking, and the hydrogen bond strengthened the interfacial network. However, the cross-linking was seriously damaged at 85 °C. The most improved emulsion stability (the smallest droplet size, no aggregation) was observed at 70 °C. The lower interfacial protein concentration and layer thickness at 55 and 85 °C were insufficient to cover all oil-water interfaces, resulting in droplet aggregation. Our results demonstrated that heat treatment at different temperatures could change the interfacial properties, which was the main reason for the difference in emulsion stability.

Exploration of Pea Protein Isolate-Sodium Alginate Complexes as a Novel Strategy to Substitute Sugar in Plant Cream: Synergistic Interactions Between the Two at the Interface

This study aims to explore the feasibility of using pea protein isolate (PPI)/sodium alginate (SA) complex as a sugar substitute to develop low sugar plant fat cream. Firstly, this study analyzed the influence of SA on the structure and physicochemical properties of PPI and evaluated the types of interaction forces between PPI and SA. The addition of SA effectively induces the unfolding and structural rearrangement of PPI, causing structural changes and subunit dissociation of PPI, resulting in the exposure of internal-SH groups. In addition, the addition of SA increased the content of β-folding in PPI, making the structure of PPI more flexible and reducing interfacial tension. The ITC results indicate that the binding between PPI and SA exhibits characteristics of rapid binding and slow dissociation, which is spontaneous and accompanied by heat release. Next, the effect of PPI/SA ratio on the whipping performance and quality of low sugar plant fat creams was studied by using PPI/SA complex instead of 20% sugar in the cream. When using a PPI/SA complex with a mass ratio of 1:0.3 instead of sugar, the stirring performance, texture, and stability of plant fat cream reach their optimum. Finally, the relevant analysis results indicate that the flexibility and interface characteristics of PPI are key factors affecting the quality of cream. This study can provide theoretical support for finding suitable sugar substitute products and developing low sugar plant fat cream.

Investigation of Emulsifying Properties and Stability of Fish Gelatin and Tea Saponin Complex Emulsion System

In this study, environmental stability, rheological properties, and structural characterization of co-stabilized emulsions using fish gelatin (FG) and tea saponin (TS) were investigated. The results demonstrated that the addition of TS significantly enhanced the emulsifying properties of FG, and the FG-TS0.1% emulsion had the smallest particle size. TS and FG co-stabilized emulsions provided resistance to salt and high temperatures. Optical microscopy and CLSM showed that the addition of TS made FG more effectively adsorb at the oil-water interface, leading to the formation of more uniform oil droplet sizes. Additionally, the addition of TS increased the viscosity of FG emulsions, which reduced emulsion flocculation. Results of intrinsic fluorescence, FTIR, and surface hydrophobicity revealed that the addition of TS altered the secondary structure of FG, enhancing surface hydrophobicity and improving emulsification. In conclusion, the moderate addition of TS significantly enhanced the emulsification and rheological properties of FG, suggesting new potential applications for FG in various industries.

Ultrasonic combined pH shifting strategy for improving the stability of emulsion stabilized by yeast proteins: Focused on solubility, protein structure, interface properties

In this study, the improvement mechanism of yeast proteins (YPs) with the ultrasonic and pH shifting treatment on the emulsion stability was investigated through the solubility, protein structure and interface behavior of YPs. Compared with only pH shifting or ultrasound treatment, the solubility of YPs with the combined treatment of ultrasonic and pH shifting was increased significantly. The soluble protein content of pH-U400 reached 85.51 %. The results of YPs structure demonstrated that the β-sheet, α-helix and disulfide bonds contents of YPs with the combined treatment first declined and subsequently increased with increasing ultrasonic power, under alkaline conditions. The fluorescence intensity and surface hydrophobicity first increased and then declined. The more flexible protein structure endowed pH-U400 with lower interfacial tension, higher interfacial diffusion, penetration and reorganization rate, and interfacial protein concentration. The pH-U400 showed the best emulsifying properties (emulsifying activity index was 27.05 m2/g, emulsifying stability index was 31.27 min) and could prepare smaller and more uniform emulsion droplet. The results of multiple light scattering demonstrated that emulsion stabilized by pH-U400 showed the best stability. These results revealed the stability mechanism of emulsions stabilized by YPs and provided guidance for further development of practical YPs products in the food industry.

Ultrasound-induced food protein-stabilized emulsions: Exploring the governing principles from the protein structural perspective

Consumers' growing demand for healthy and natural foods has led to a preference for products with fewer additives. However, the low emulsifying properties of natural proteins often necessitate the addition of emulsifiers in food formulations. Consequently, enhancing the emulsifying properties of proteins through various modification methods is crucial to meet modern consumer demands for natural food products. High-intensity ultrasound offers a green, efficient processing technology that significantly improves the emulsifying properties of proteins. This study explores how ultrasound treatment enhances the stability of protein-based emulsions by modifying protein structures. While ultrasonic treatment does not significantly affect the primary structure of proteins, it influences the secondary, tertiary, and quaternary structures depending on the type of protein, ultrasound parameters (type, intensity, and time), and treatment conditions. The results suggest that ultrasound treatment reduces α-helix content, decreases protein particle size, and increases β-sheet content, surface hydrophobicity, free sulfhydryl groups, and zeta potential, leading to a more stable protein-based emulsion. The reduced particle size and increased flexibility of proteins induced by ultrasound enable more rapid protein adsorption at the oil-water interface, resulting in smaller emulsion droplets. This contributes to the emulsion's improved stability during storage. Future research should focus on the large-scale application of ultrasonic treatment for protein modification to produce high-quality, natural foods that meet the evolving needs of consumers.

Gliadin/Konjac glucomannan particle-stabilized Pickering emulsion for honokiol encapsulation with enhanced digestion benefits

Owing to the limited availability of biocompatible, edible and natural emulsifiers, the development of Pickering emulsions applicable to the food industry still confronts challenges. Moreover, Honokiol (HNK), due to its poor stability and susceptibility to oxidation, most of the existing delivery systems are centered on injection administration routes and relatively complex in preparation, posing significant challenges for industrialization. In this research, a Pickering emulsion system stabilized by gliadin and konjac glucomannan composite particles (GKPs) was constructed using the pH cycling method and was employed for the delivery of HNK. Under the conditions of a 1:2 mass ratio of the composite particles at pH 4 and an oil phase fraction of 50 %, the storage stability of HNK was effectively enhanced, attaining a retention rate of 84.88 % ± 0.78 % at 4 °C for 14 days. In simulated in vitro digestion, this emulsion system effectively mitigated the degradation of HNK, achieving a bioavailability of 66.94 % ± 4.05 % and increasing the release of free fatty acids. Pickering emulsions stabilized by GKPs may provide a useful means of delivery of bisphenol lignans.

Prolamin-pectin complexes: Structural properties, interaction mechanisms and food applications

Prolamin, a class of plant protein mainly derived from grains, and pectins, complex-structured polysaccharides, are natural biological macromolecules with versatile functional properties. The interactions between prolamins and pectin have been widely studied and applied, demonstrating that both covalent and non-covalent interactions play pivotal roles in the formation of prolamin-pectin complexes. These interactions impart exceptional physicochemical and functional properties to the complexes. This review also details the main applications of prolamin-pectin complexes, including emulsions, nanoparticles, hydrogels and films. The similarities in their reaction principles are based on the interaction of complexes that improve their physicochemical and functional properties, while the difference lies in the specific modes of action, involving the emulsifying properties, self-assembly properties, gelling properties and film-forming properties of prolamin and pectin. By delving into the intricate mechanisms underlying prolamin-pectin interactions and their diverse applications in the food industry, this review offers valuable insights for advancing the development and utilization of these complexes.

Enhancing the physical and oxidative stability of hempseed protein emulsion via comparative enzymolysis with different proteases: Interfacial properties of the adsorption layer

Effects of enzymolysis by seven proteases (Alcalase, Bromelain, Flavourzyme, Papain, Pepsin, Protamex, and Trypsin) with distinct cleavage specificities on the emulsification performance of hempseed protein (HPI) and its correlation with the structural and interfacial characteristics were explored in this study. Upon enzymolysis, a remarkable decrease in α-helix and β-turn was observed in resultant hydrolysates (HPH), accompanied by a rise in β-sheet and random coil, notably by Alcalase, Bromelain, Papain, and Trypsin. Overall, proteolysis led to noticeable reductions in surface hydrophobicity and total sulfhydryls as well as a redshift in intrinsic fluorescence, with Papain showing the most pronounced effects, possibly due to its higher hydrolysis degree (4.00 %). Interestingly, among the seven HPHs, Papain-HPH with the highest solubility (67.4 %) and smallest molecular weight exhibited compromised interfacial activity, lowest emulsifying activity (EAI, 1.67 m2/g), and highest creaming index (CI, 64 %). Contrastively, Trypsin hydrolysis significantly improved the interfacial activity, albeit causing a notable decrease in interfacial viscoelasticity of the absorbed layers. Consequently, Trypsin yielded the best EAI (10.5 m2/g) and emulsion stability (CI, 4 %); yet, the smallest emulsion droplets with homogeneous distribution and high apparent viscosity were spotted. Additionally, the oxidative stability of emulsions was conspicuously enhanced, contingent upon the antioxidative capacity of HPHs.

Effects of Maillard Reaction Durations on the Physicochemical and Emulsifying Properties of Chickpea Protein Isolate

This study investigated the physicochemical and emulsifying properties of chickpea protein isolate (CPI)-citrus pectin (CP) conjugates formed via the Maillard reaction across varying reaction durations. CPI and CP were conjugated under controlled dry-heating conditions, and the resulting conjugates were characterized by measuring their particle size, zeta potential, solubility, thermal stability, surface hydrophobicity, and emulsifying properties. The results showed that as reaction duration increased, the particle size and zeta potential of the CPI-CP conjugates increased significantly, reaching a maximum particle size of 1311.33 nm and a zeta potential of -35.67 mV at 12 h. Moreover, the Maillard reaction improved the solubility, thermal stability, and hydrophobicity of the CPI. Glycosylation increased the emulsifying activity index (EAI) and emulsifying stability index (ESI) of the CPI to 145.33 m2/g and 174.51 min, respectively. Optimal emulsions were achieved at a protein concentration of 1.5 wt% and a 10% volume fraction of the oil phase. The Maillard reaction promoted the interfacial protein content and the thickness of the interfacial layer while decreasing the droplet size and zeta potential of the emulsion. Additionally, the emulsion prepared with CPI-CP-12 h showed outstanding long-term stability. These results demonstrate that a moderate Maillard reaction with CP effectively enhances the physicochemical and emulsifying characteristics of CPI.

All-aqueous synthesis of alginate complexed with fibrillated protein microcapsules for membrane-bounded culture of tumor spheroids

Water-in-water (W/W) emulsions provide bio-compatible all-aqueous compartments for artificial patterning and assembly of living cells. Successful entrapment of cells within a W/W emulsion via the formation of semipermeable capsules is a prerequisite for regulating on the size, shape, and architecture of cell aggregates. However, the high permeability and instability of the W/W interface, restricting the assembly of stable capsules, pose a fundamental challenge for cell entrapment. The current study addresses this problem by synthesizing multi-armed protein fibrils and controlling their assembly at the W/W interface. The multi-armed protein fibrils, also known as 'fibril clusters', were prepared by cross-linking lysozyme fibrils with multi-arm polyethylene glycol (PEG) via click chemistry. Compared to linear-structured fibrils, fibril clusters are strongly adsorbed at the W/W interface, forming an interconnected meshwork that better stabilizes the W/W emulsion. Moreover, when fibril clusters are complexed with alginate, the hybrid microcapsules demonstrate excellent mechanical robustness, semi-permeability, cytocompatibility and biodegradability. These advantages enable the encapsulation, entrapment and long-term culture of tumor spheroids, with great promise for applications for anti-cancer drug screening, tumor disease modeling, and tissue repair engineering.

Interfacial engineering of Pickering emulsions stabilized by pea protein-alginate microgels for encapsulation of hydrophobic bioactives

This study aims to investigate the effects of interfacial layer composition and structure on the formation, physicochemical properties and stability of Pickering emulsions. Interfacial layers were formed using pea protein isolate (PPI), PPI microgel particles (PPIMP), a mixture of PPIMP and sodium alginate (PPIMP-SA), or PPIMP-SA conjugate. The encapsulation and protective effects on different hydrophobic bioactives were then evaluated within these Pickering emulsions. The results demonstrated that the PPIMP-SA conjugate formed thick and robust interfacial layers around the oil droplet surfaces, which increased the resistance of the emulsion to coalescence, creaming, and environmental stresses, including heating, light exposure, and freezing-thawing cycle. Additionally, the emulsion stabilized by the PPIMP-SA conjugate significantly improved the photothermal stability of hydrophobic bioactives, retaining a higher percentage of their original content compared to those in non-encapsulated forms. Overall, the novel protein microgels and the conjugate developed in this study have great potential for improving the physicochemical stability of emulsified foods.

Jammed Pickering Emulsion Gels

Emulsion gels with specific rheological properties have widespread applications in foods, cosmetics, and biomedicines. However, the constructions of water-in-oil emulsion gels are still challenging, due to the limited interactions available in the continuous oil phase. Here, a versatile strategy is developed to prepare a new type of emulsion gels, called Jammed Pickering emulsion gels (JPEGs). In the JPEG system, SiO2 NPs in the oil phase serve as colloidal surfactants to stabilize water-in-oil Pickering emulsions, while positively-charged NH2-PEG-NH2 molecules in the water phase cross-link negatively-charged SiO2 NPs at the water/oil interface, making NP-stabilized water droplets hard to deform and thus jamming the emulsion system to form emulsion gels. The strategy to prepare JPEGs is versatile and applicable to diverse oil phases. The designed JPEGs possess many advantages, including good biocompatibility for widespread applications, shear-thinning rheological properties for easy processing, good stability Over a wide temperature range and Against centrifugation, good adhesion to wet tissues for tissue engineering, and well-controlled sustained release Under intestinal conditions. The developed JPEGs are demonstrated to be a promising delivery platform and the strategy to achieve JPEGs will trigger more innovations of material design.

Formation of whey protein, pectin, and chlorogenic acid ternary complexes and their application in emulsions

Physicochemical properties, stability, and digestive behavior of lycopene-loaded emulsions prepared by ternary complexes fabricated with different mixing sequences based on whey protein isolate (WPI), high methoxyl pectin (HMP), and chlorogenic acid (CA) were investigated. Spectroscopic and molecular docking analyses confirmed the non-covalent interactions among the compounds within the ternary complexes, as well as the conformational changes in the protein induced by the mixing sequence. The interfacial tension (6.92-9.44 mN/m) influenced by the different mixing sequences of WPI, HMP and CA was HMP-CA-WPI > WPI-CA-HMP > WPI-HMP-CA, and the size of emulsions stabilized by HMP-CA-WPI was approximately 10 nm larger than that of the other two. Complexes with mixing sequence of HMP, CA and WPI outperformed in antioxidant properties (Ferric reducing power absorbance 0.43, ABTS∙ radical scavenging activity 66.04 %), lycopene retention rate (after UV irradiation 85.11 %, after thermal treatment 83.15 %), and storage stability of emulsions than those prepared by WPI-HMP-CA and WPI-CA-HMP. Emulsions stabilized by different ternary complexes showed similar free fatty acid release profiles (39.62 %-41.59 %) and lycopene bio-accessibility (28.87 %-29.94 %) during digestion. This study mat offer novel insights for the rational utilization in emulsions of ternary complexes based on proteins, polysaccharides, and phenolic acids.

Improving the emulsifying properties and oil-water interfacial behaviors of chickpea protein isolates through Maillard reaction with citrus pectin

The limited adsorption capability of chickpea protein isolates (CPI) at the oil-water interface restricts its application in emulsions. This study aimed to improve the emulsifying properties and interfacial behaviors of CPI through Maillard reaction with citrus pectin (CP). The research findings showed that the covalent linking of CP with CPI caused the unfolding of the molecular structure of CPI, exposing more hydrophobic groups. Consequently, the CPI-CP conjugates exhibited improved emulsifying properties. Emulsions stabilized by CPI-CP conjugates after 12 h of glycosylation demonstrated the smallest droplet sizes (1.73 μm) and the highest negative zeta potentials (-54.7 mV). Glycosylation also improved the storage and environmental stability of these emulsions. Interfacial adsorption kinetics analysis revealed the lower interfacial tension (13.94 mN/m) and faster diffusion rates of the CPI-CP conjugates. Furthermore, interfacial dilatational rheology analysis indicated that the CPI-CP conjugates formed an interfacial layer with a higher viscoelastic modulus (33.214 mN/m) and predominant elastic behavior. The interfacial film of CPI-CP conjugates showed excellent resistance to amplitude and frequency variations, enhancing emulsion stability. Thus, this study demonstrates that moderate glycosylation enhances interfacial performances and improves emulsion stability of CPI, providing new insights into the mechanisms by which CPI stabilizes emulsions.

Pickering Emulsion Stabilized by Different Concentrations of Whey Protein-Cress Seed Gum Nanoparticles

Nanoparticles based on food-grade materials are promising materials to develop Pickering emulsions for food applications. Initially, this study focuses on the development of nanoparticles through the utilization of a soluble complex of whey protein concentrate (WPC) and cress seed gum (CSG), which were modified by calcium chloride (CaCl2) as a cross-linker. The response surface methodology was used to investigate the impact of different concentrations of WPC (1-4% w/v), CSG (0-1% w/v), and CaCl2 (1-3 mM) on particle size, polydispersity index (PDI), and Zeta potential. The optimum conditions for the production of CSG-WPC nanoparticles (WPC-CSG NPs) were 0.31% (w/v) CSG, 1.75% (w/v) WPC, and 1.69 mM CaCl2, resulting in nanoparticles with average size of 236 nm and Zeta potential of -22 mV. Subsequently, oil-in-water (O/W) Pickering emulsions were produced with different concentrations of WPC-CSG NPs in optimum conditions. The contact angles of the WPC-CSG NPs were 41.44° and 61.13° at concentrations of 0.5% and 1%, respectively, showing that NPs are suitable for stabilizing O/W Pickering emulsions. Pickering emulsion viscosity rose from 80 to 500 mPa when nanoparticle concentration increased from 0.5% to 1%. Results also showed that WPC-CSG NPs enable stable O/W Pickering emulsions during storage and thermal treatment, confirming that protein-polysaccharide NPs can provide a sufficient steric hindrance.

Quercetin encapsulation and release using rapid CO2-responsive rosin-based surfactants in Pickering emulsions

Emulsion-based delivery systems are extensively employed for encapsulating functional active ingredients, protecting them from degradation, and enhancing bioavailability and release efficiency. Here, a CO2-responsive surfactant synthesized from rosin displays rapid responsiveness to CO2 at room temperature, transitioning reversibly switches between active and inactive states multiple times. The dual tertiary amines on the rosin rigid structure contributes to its CO2 sensitivity. When in its active cationic form, in conjunction with silica nanoparticles, it exhibits desired Pickering emulsification performance across various oil phases. In the Pickering emulsion loaded with quercetin, the encapsulation efficiency and loading efficiency reached 80.50% and 0.69%, respectively, with stability lasting at least 30 days. The system provides robust protection for quercetin against external factors, such as UV and heat, revealing sustained release effects. This study investigated the potential of using rosin-based CO2-responsive surfactants alongside nanoparticles to design stable Pickering emulsion systems for active substance encapsulation and sustained release.

Ultrasound-assisted fabrication of chitosan-hydroxypropyl methylcellulose nanoemulsions loaded with thymol and cinnamaldehyde: Physicochemical properties, stability, and antifungal activity

This study investigated the influence of chitosan (CH) and hydroxypropyl methylcellulose (H), along with ultrasound power, on the physicochemical properties, antifungal activity, and stability of oil-in-water (O/W) nanoemulsions containing thymol and cinnamaldehyde in a 7:3 (v/v) ratio. Eight O/W formulations were prepared using CH, H, and a 1:1 (v/v) blend of CH and H, both with and without ultrasonication (U). Compared to untreated samples, U-treated nanoemulsions had lower droplet sizes (433-301 nm), polydispersity index (0.42-0.47), and zeta potential (-0.42-0.77 mV). The U treatment decreased L* and b* values, increased a* color attribute values, and increased apparent viscosity (0.26-2.17) at the same shear rate. After 28 days, microbiological testing of nanoemulsions treated with U showed counts below the detection limits (< 2 log CFU mL-1). The U-treated nanoemulsions exhibited stronger antifungal effects against R. stolonifer, with the NE/CH-U and NE/CH-H-U formulations demonstrating the lowest minimum inhibitory and fungicidal concentrations, measured at 0.12 and 0.24 μL/mL, respectively. On day 28, U-treated nanoemulsions demonstrated higher ionic, thermal, and physical stability than untreated samples. These findings suggest that the stability and antifungal efficacy of polysaccharide-based nanoemulsions may be improved by ultrasonic treatment. This study paves the way for innovative, highly stable nanoemulsions.

Impact of hydrophilic substances on Ostwald ripening in emulsions stabilized by varied hydrophilic group surfactants

This study investigated the impact of water-soluble substances on Ostwald ripening in emulsions stabilized by surfactants with different head groups (Brij S20 and Tween 60). Adding ≥20% (w/w) corn oil to the oil phase effectively inhibited Ostwald ripening of n-decane emulsions due to compositional ripening. The presence of glucose, maltose, or glycerol in the aqueous phase of the emulsions decreased the Ostwald ripening rate, regardless of emulsifier type. However, the impact of propylene glycol depended on emulsifier type, accelerating Ostwald ripening in Brij S20-stabilized emulsions but having little effect in Tween 60-stabilized emulsions. This effect was mainly attributed to the ability of propylene glycol to alter interfacial characteristics. When emulsions were fabricated with a mixture of n-decane and corn oil, glucose and maltose were still effective in inhibiting Ostwald ripening, but glycerol lost its ability. These results have important implications for formulating emulsion-based delivery systems with enhanced shelf life.

Phase inversion regulable bigels co-stabilized by Chlorella pyrenoidosa protein and beeswax: In-vitro digestion and food 3D printing

Algal proteins are an emerging source of functional foods. Herein, Chlorella pyrenoidosa protein (CPP)/xanthan gum-based hydrogels (HG) and beeswax-gelled oleogels (OG) are adopted to fabricate bigels. The phase inversion of bigels can be regulated by the ratio of OG and HG: As the OG increased, bigels turn from OG-in-HG (OG/HG) to a semicontinuous state and then HG-in-OG (HG/OG). In OG/HG bigels (OG ≤ 50 %), hydrophilic CPP acts as the emulsifier at the interface of OG and HG, while beeswax emulsifies the system in HG/OG bigels (OG = 80 %). A semicontinuous bigel appears during the transition between HG/OG and OG/HG. The increase of OG can enhance the viscoelasticity, hardness, adhesiveness, chewiness, and thermal stability. OG/HG bigels exhibit stronger thixotropic recovery and oil-holding capacity than HG/OG bigels. In the in-vitro digestion and food 3D printing, the high specific surface area and the highest thixotropic recovery caused by the emulsion structure of the OG/HG bigel (OG = 50 %) are conducive to the release of free fatty acids and molding of 3D-printed objects, respectively. This study provides a new approach to structure the gelled water-oil system with CPP and helps to develop edible algal proteins-based multiphase systems in food engineering or pharmacy.

Galacto-oligosaccharides modified whey protein isolate ameliorates cyclophosphamide-induced immunosuppression

The effect of whey protein isolate (WPI)- galacto-oligosaccharides (GOS)/fructo-oligosaccharides (FOS) conjugates on RAW264.7 cells, and further the effect of WPI-GOS conjugates on CTX-induced immunosuppressed mice were investigated. Compared to WPI-FOS conjugates, WPI-GOS conjugates exhibited deeper glycation extent, more pronounced structural unfolding and helix-destabilizing, and obviously improved functional indicators of RAW264.7 macrophages. In addition, WPI-GOS conjugates also repaired immune organ and intestinal barrier and increased IL-1β and IFN-γ levels in immunosuppressed mice. The alteration of gut microbiota induced by WPI-GOS conjugates changed the serum metabolites, causing the activation of NFκB pathway, which strengthens the immune system. The activation of NFκB pathway maybe associated with the mTOR signal pathway and ABC transporters. However, the precise mechanisms by which NFκB pathway interacts with mTOR signal pathway and ABC transporters to modulate the immune response need for further research.

The non-covalent and covalent interactions of whey proteins and saccharides: influencing factor and utilization in food

During the application of Whey proteins (WPs), they often have complex interactions with saccharides (Ss), another important biopolymer in food substrate. The texture and sensory qualities of foods containing WPs and Ss are largely influenced by the interactions of WPs-Ss. Moreover, the combination of WPs and Ss is possible to produce many excellent functional properties including emulsifying properties and thermal stability. However, the interactions between WPs-Ss are complex and susceptible to some processing conditions. In addition, with different interaction ways, they can be applied in different fields. Therefore, the non-covalent interaction mechanisms between WPs-Ss are firstly summarized in detail, including electrostatic interaction, hydrogen bond, hydrophobic interaction, van der Waals force. Furthermore, the existence modes of WPs-Ss are introduced, including complex coacervates, soluble complexes, segregation, and co-solubility. The covalent interactions of WPs-Ss in food applications are often formed by Maillard reaction (dry or wet heat reaction) and occasionally through enzyme induction. Then, two common influencing factors, pH and temperature, on non-covalent/covalent bonds are introduced. Finally, the applications of WPs-Ss complexes and conjugations in improving WP stability, delivery system, and emulsification are described. This review can improve our understanding of the interactions between WPs-Ss and further promote their wider application.

Gelatin-nanocellulose stabilized emulsion-filled hydrogel beads loaded with curcumin: Preparation, encapsulation and release behavior

In this study, the curcumin was firstly encapsulated in gelatin (GLT) and/or cellulose nanocrystals (CNC) stabilized emulsions, then further mixed with sodium alginate (SA) to form emulsion-filled hydrogel beads loaded with curcumin (Cur). The Cur-loaded emulsions showed a droplet size of 20.3-24.4 μm with a uniform distribution. Introducing CNC and/or SA increased the viscosity of emulsions accompanied by viscoelastic transition, while the modulus was reduced due to destruction of GLT gel. Cur was doubly immobilized in the hydrogel beads with >90 % of encapsulation efficiency. The results of simulated gastrointestinal tract experiments revealed that the beads possessed a good pH sensitivity and controlled release behavior to prolong the retention of Cur in the gastrointestinal tract. After 6 h of UV irradiation, the Cur-loaded emulsion-filled hydrogel beads showed a higher antioxidant activity than that of pure Cur, effectively delaying the photodegradation of Cur. In addition, the beads had better stability in aqueous and acidic environments, which was favorable for prolonging the release of Cur. These results suggest that the emulsion-filled hydrogel beads have great potential for the delivery of lipophilic bioactive molecules.

Effects of Emulsifiers on Physicochemical Properties and Carotenoids Bioaccessibility of Sea Buckthorn Juice

The need to improve the physicochemical properties of sea buckthorn juice and the bioavailability of carotenoids is a major challenge for the field. The effects of different natural emulsifiers, such as medium-chain triglycerides (MCTs), tea saponins (TSs) and rhamnolipids (Rha), on the physical and chemical indexes of sea buckthorn juice were studied. The particle size of sea buckthorn juice and the carotenoids content were used as indicators for evaluation. The effects of different addition levels of MCT, Rha and TS on the bioavailability of carotenoids in sea buckthorn juice were investigated by simulating human in vitro digestion tests. The results showed that those emulsifiers, MCT, Rha and TS, can significantly reduce the particle size and particle size distribution of sea buckthorn juice, improve the color, increase the soluble solids content, turbidity and physical stability and protect the carotenoids from degradation. When the addition amount of Rha was 1.5%, the total carotenoids content (TCC) of sea buckthorn juice increased by 45.20%; when the addition amount of TS was 1.5%, the total carotenoids content (TCC) of sea buckthorn juice increased by 37.95%. Furthermore, the bioaccessibility of carotenoids was increased from 36.90 ± 2.57% to 54.23 ± 4.17% and 61.51 ± 4.65% through in vitro digestion by Rha and TS addition, respectively. However, the total carotenoids content (TCC) of sea buckthorn juice and bioaccessibility were not significantly different with the addition of MCT. In conclusion, the findings of this study demonstrate the potential of natural emulsifiers, such as MCT, Rha and TS, to significantly enhance the physicochemical properties and bioavailability of carotenoids in sea buckthorn juice, offering promising opportunities for the development of functional beverages with improved nutritional benefits.

Influence of carboxymethyl cellulose on the stability, rheology, and curcumin bioaccessibility of high internal phase Pickering emulsions

Recently, there has been a focus on using biopolymer-based particles to stabilize high internal phase Pickering emulsions (HIPPEs) due to the notable advances in biocompatibility and biodegradability. In this work, the complex particles of peanut protein isolate and carboxymethyl cellulose (CMC) with various substitution degrees (DS; 0.7 and 0.9) and weight average molecular weights (Mw; 90, 250, and 700 kDa) were prepared and characterized as novel stabilizers. For the obtained four types of morphologically distinct particles, the complex particles formed by CMC (0.9 DS and 250 kDa) showed cluster structures with an average size of 1.271 μm, equally biphasic wettability with three-phase contact angles of 91.5°, and the highest diffusion rate at the oil-water interface. HIPPEs stabilized by these particles exhibited more elastic behavior due to the smaller tanδ and higher viscosity, as well as excellent thixotropic recovery properties and stability against heating, storage, and freeze-thawing. Furthermore, confocal laser scanning microscopy verified that these particles formed a dense interfacial layer around the oil droplets, which could resist flocculation and coalescence between oil droplets during in vitro digestion. The improved bioaccessibility of curcumin-loaded HIPPEs made these delivery systems potentially apply in functional foods.

Insight into oil-water interfacial adsorption of protein particles towards regulating Pickering emulsions: A review

Over the past decade, Pickering emulsions (PEs) stabilized by protein particles have been the focus of researches. The characteristics of protein particles at the oil-water interface are crucial for stabilizing PEs. The unique adsorption behaviors of protein particles and various modification methods enable oil-water interface to exhibit controllable regulation strategies. However, from the perspective of the interface, studies on the regulation of PEs by the adsorption behaviors of protein particles at oil-water interface are limited. Therefore, this review provides an in-depth study on oil-water interfacial adsorption of protein particles and their regulation on PEs. Specifically, the formation of interfacial layer and effects of their interfacial characteristics on PEs stabilized by protein particles are elaborated. Particularly, complicated behaviors, including adsorption, arrangement and deformation of protein particles at the oil-water interface are the premise of affecting the formation of interfacial layer. Moreover, the particle size, surface charge, shape and wettability greatly affect interfacial adsorption behaviors of protein particles. Importantly, stabilities of protein particles-based PEs also depend on properties of interfacial layers, including interfacial layer thickness and interfacial rheology. This review provides useful insights for the development of PEs stabilized by protein particles based on interfacial design.

Influences of carboxymethyl chitosan upon stabilization and gelation of O/W Pickering emulsions in the presence of inorganic salts

The objective of this study was to investigate the effects of carboxymethyl chitosan (CMCS) on the stabilization and gelation of oil-in-water (O/W) Pickering emulsions (PEs) with polyphenol-amino acid particles in the presence of inorganic salts. The results revealed that the CMCS-induced depletion interactions contributed to improving the emulsification ability and interfacial adsorption efficiency of polyphenol-amino acid particles as well as constructing the network structures in the continuous phase. These relevant changes collectively resulted in elevating stability, viscosity and moduli of PEs. The additional effects of different inorganic salts with varying additions were further investigated, and the addition-dependent phenomena were observed. At low additions of inorganic salts, the occurrence of the chelation of inorganic salts with CMCS consolidated the constructed network structure, favorable to the gelation of PEs. With increasing additions, this chelation effect became stronger which compromised the CMCS-induced depletion, gradually leading to destabilization of PEs. In terms of ion species, the more pronounced effect on emulsion stability was achieved with calcium ions than with potassium and iron ions. This study expects to provide a new perspective on the extending application of cationic CMCS for improving the stability of O/W PEs in the food industry.

Molecular modification of low-dissolution soy protein isolates by anionic xanthan gum, neutral guar gum, or neutral konjac glucomannan to improve the protein dissolution and stabilize fish oil emulsion

Herein, the effects of anionic xanthan gum (XG), neutral guar gum (GG), and neutral konjac glucomannan (KGM) on the dissolution, physicochemical properties, and emulsion stabilization ability of soy protein isolate (SPI)-polysaccharide conjugates were studied. The SPI-polysaccharide conjugates had better water dissolution than the insoluble SPI. Compared with SPI, SPI-polysaccharide conjugates had lower β-sheet (39.6 %-56.4 % vs. 47.3 %) and α-helix (13.0 %-13.2 % vs. 22.6 %) percentages, and higher β-turn (23.8 %-26.5 % vs. 11.0 %) percentages. The creaming stability of SPI-polysaccharide conjugate-stabilized fish oil-loaded emulsions mainly depended on polysaccharide type: SPI-XG (Creaming index: 0) > SPI-GG (Creaming index: 8.1 %-21.2 %) > SPI-KGM (18.1 %-40.4 %). In addition, it also depended on the SPI preparation concentrations, glycation times, and glycation pH. The modification by anionic XG induced no obvious emulsion creaming even after 14-day storage, which suggested that anionic polysaccharide might be the best polysaccharide to modify SPI for emulsion stabilization. This work provided useful information to modify insoluble proteins by polysaccharides for potential application.

Oriented Interpenetrating Capillary Network with Surface Engineering by Porous ZnO from Wood for Membrane Emulsification

Membrane emulsification technology has garnered increasing interest in emulsion preparation due to controllable droplet size, narrower droplet size distribution, low energy consumption, simple process design and excellent reproducibility. Nevertheless, the pore structure and surface engineering in membrane materials design play a crucial role in achieving high-quality emulsions with high throughput simultaneously. In this work, an oriented interpenetrating capillary network composed of highly aligned and interconnected wood cell lumens has been utilized to fabricate an emulsion membrane. A novel honeycomb porous ZnO layer obtained by a seed prefabrication-hydrothermal growth method was designed to reconstruct wood channel surfaces for enhanced microfluid mixing. The results show that through the unique capillary mesh microstructure of wood, the emulsion droplets were smaller in size, had narrower pore-size distribution, and were easy to obtain under high throughput conditions. Meanwhile, a well-designed ZnO layer could further improve the emulsion quality of a wood membrane, while the emulsifying throughput is still maintained at a higher level. This demonstrates that the convection process of the microfluid in these wood capillary channels was intensified markedly. This study not only develops advanced membrane materials in emulsion preparation, but also introduces a brand-new field for functional applications of wood.

Enhancing the stability of mung bean-based milk: Insights from protein characteristics and raw material selection

Plant-based milk (PBM) alternatives are gaining popularity worldwide as the change of consumers' nutritional habits and health attitudes. Mung beans, recognized for their nutritional value, have gained attention as potential ingredients for PBM. Nevertheless, mung bean-based milk (MBM) faces instability issues common to other plant-based milks. This study investigated the factors influencing MBM stability focusing on raw materials. We selected 6 out of 20 varieties based on their MBM centrifugation sedimentation rates, representing both stable and unstable MBM. Stable MBM exhibited distinct advantages, including reduced separation rate, smaller particle size, lower viscosity, fewer protein aggregates, higher soluble protein content, and increased consumer acceptance. Major nutritional components such as protein, starch, and lipids were not significant different between stable and unstable MBM varieties. The pivotal distinction may lay in the protein properties and composition. Stable MBM varieties exhibited significantly improved protein solubility and emulsion stability, along with elevated concentrations of legume-like acidic subunits, basic 7S proteins, and 28 kDa and 26 kDa vicilin-like subunits. The increasement of these proteins likely contributed to the improvement in protein characteristics that affect MBM stability. These findings offer valuable insights for raw material selection and guidance for future mung bean breeding to enhance mung bean milk production.

Pea protein [Pisum sativum] as stabilizer for oil/water emulsions

A map of stability for various water/oil/pea protein compositions has been plotted from the numerous reported results. Two clear regions of stability were identified. High internal oil phase emulsions with 70-80%, v/v oil content stabilized by total pea protein concentration <2.5%, w/v showed stability. Low oil content of 10-30%, v/v for a range of total pea protein concentrations >0.5%, w/v have also been identified as stable. Intermediate oil content and pea protein concentrations >4% w/v are unexplored regions and are likely to be areas of fruitful future research. The wide range of stability suggests that different stabilization mechanisms could be important for different compositions and careful consideration has to be taken to avoid oversimplification. Both stabilization with particles, i.e. Pickering emulsions, and protein unfolding have been suggested as mechanisms. The diverse way of describing stability makes it difficult to intercompare results in different studies. A summary of different oil types used have been presented and several properties such as dynamic viscosity, density, the dielectric constant and interfacial tension have been summarized for common vegetable oils. The type of vegetable oil and emulsion preparation techniques were seen to have rather little effect on emulsion stability. However, the different extraction methods and processing of the pea material had more effect, which could be attributed to changing composition of different proteins and to the states of aggregation and denaturing. Careful consideration has to be taken in the choice of extraction method and an increased understanding of what contributes to the stability is desirable for further progress in research and eventual product formulation.

Exploring fungal bioemulsifiers: insights into chemical composition, microbial sources, and cross-field applications

The demand for emulsion-based products is crucial for economic development and societal well-being, spanning diverse industries such as food, cosmetics, pharmaceuticals, and oil extraction. Formulating these products relies on emulsifiers, a distinct class of surfactants. However, many conventional emulsifiers are derived from petrochemicals or synthetic sources, posing potential environmental and human health risks. In this context, fungal bioemulsifiers emerge as a compelling and sustainable alternative, demonstrating superior performance, enhanced biodegradability, and safety for human consumption. From this perspective, the present work provides the first comprehensive review of fungal bioemulsifiers, categorizing them based on their chemical nature and microbial origin. This includes polysaccharides, proteins, glycoproteins, polymeric glycolipids, and carbohydrate-lipid-protein complexes. Examples of particular interest are scleroglucan, a polysaccharide produced by Sclerotium rolfsii, and mannoproteins present in the cell walls of various yeasts, including Saccharomyces cerevisiae. Furthermore, this study examines the feasibility of incorporating fungal bioemulsifiers in the food and oil industries and their potential role in bioremediation events for oil-polluted marine environments. Finally, this exploration encourages further research on fungal bioemulsifier bioprospecting, with far-reaching implications for advancing sustainable and eco-friendly practices across various industrial sectors.

Noncovalent interactions between biomolecules facilitated their application in food emulsions' construction: A review

The use of biomolecules, such as proteins, polysaccharides, saponins, and phospholipids, instead of synthetic emulsifiers in food emulsion creation has generated significant interest among food scientists due to their advantages of being nontoxic, harmless, edible, and biocompatible. However, using a single biomolecule may not always meet practical needs for food emulsion applications. Therefore, biomolecules often require modification to achieve ideal interfacial properties. Among them, noncovalent interactions between biomolecules represent a promising physical modification method to modulate their interfacial properties without causing the health risks associated with forming new chemical bonds. Electrostatic interactions, hydrophobic interactions, and hydrogen bonding are examples of noncovalent interactions that facilitate biomolecules' effective applications in food emulsions. These interactions positively impact the physical stability, oxidative stability, digestibility, delivery characteristics, response sensitivity, and printability of biomolecule-based food emulsions. Nevertheless, using noncovalent interactions between biomolecules to facilitate their application in food emulsions still has limitations that need further improvement. This review introduced common biomolecule emulsifiers, the promotion effect of noncovalent interactions between biomolecules on the construction of emulsions with different biomolecules, their positive impact on the performance of emulsions, as well as their limitations and prospects in the construction of biomolecule-based emulsions. In conclusion, the future design and development of food emulsions will increasingly rely on noncovalent interactions between biomolecules. However, further improvements are necessary to fully exploit these interactions for constructing biomolecule-based emulsions.

Effects of protein concentration, ionic strength, and heat treatment on the interfacial and emulsifying properties of coconut (Cocos nucifera L.) globulins

This research aimed to investigate the effects of protein concentration (0.2 %-1.0 %), ionic strength (100-500 mM NaCl), and heat treatment (temperature: 80 and 90℃; time: 15 and 30 min) on the interfacial and emulsifying properties of coconut globulins (CG). When protein concentration was set at 0.2-0.6 %, the interfacial adsorption increased with the increasing of protein concentration. However, the lowest interfacial viscoelasticity was found when CG concentration was 0.6 %. When the protein concentration was higher than 0.6 %, the dilatational viscoelasticity increased with the increasing of protein concentration. The protein concentration showed positive effect on the emulsion stability of CG. The ionic strength showed positive effect on the interfacial adsorption but negative effects on the interfacial viscoelasticity and emulsion stability. Higher temperature and longer heating time brought worse interface behavior. The heated CG (90℃, 30 min) had the worst interfacial behavior but the best emulsion stability.

Effects of the Combination of Protein in the Internal Aqueous Phase and Polyglycerol Polyricinoleate on the Stability of Water-In-Oil-In-Water Emulsions Co-Encapsulating Crocin and Quercetin

This study aimed to diminish the reliance on water-in-oil-in-water (W/O/W) emulsions on the synthetic emulsifier polyglycerol polyricinoleate (PGPR). Considering the potential synergistic effects of proteins and PGPR, various protein types (whey, pea and chickpea protein isolates) were incorporated into the internal aqueous phase to formulate W/O/W emulsions. The effects of the combination of PGPR and protein at different ratios (5:0, 4:1, 3:2, 1:1 and 2:3) on the stability and encapsulation properties of W/O/W emulsions co-encapsulating crocin and quercetin were investigated. The findings indicated that the combination of PGPR and protein resulted in a slight reduction in the encapsulation efficiency of the emulsions, compared to that of PGPR (the control). Nonetheless, this combination significantly enhanced the physical stability of the emulsions. This result was primarily attributed to the smaller droplet sizes and elevated viscosity. These factors contributed to increased retentions of crocin (exceeding 70.04%) and quercetin (exceeding 80.29%) within the emulsions after 28 days of storage, as well as their improved bioavailability (increases of approximately 11.62~20.53% and 3.58~7.98%, respectively) during gastrointestinal digestion. Overall, combining PGPR and protein represented a viable and promising strategy for reducing the amount of PGPR and enhancing the stability of W/O/W emulsions. Notably, two plant proteins exhibited remarkable favorability in this regard. This work enriched the formulations of W/O/W emulsions and their application in the encapsulation of bioactive substances.

Strategies for improving loading of emulsion-based functional oil powder

Functional oil is type of oil that is beneficial to human health and has nutritional value, however, functional oils are rich in bioactive substances such as polyunsaturated fatty acids which are sensitive to environmental factors and are susceptible to oxidation or decomposition. Construction of emulsion-based oil powder is a promising approach for improving the stability and solubility of functional oils. However, the low effective loading of oil in powder is the main challenge limiting encapsulation technology. This manuscript focuses on reviewing the current research progress of emulsion-based functional oil powder construction and systematically summarizes the processing characteristics of emulsion-based oil powder with high payload and summarizing the strategies to enhance the payload of powder in term of emulsification and drying, respectively. The impact of emulsion formation on oil powder production is discussed from different characteristics of emulsions, including emulsion composition, emulsification methods and emulsion types. In addition, the current status of improving material loading performance by various modifications to the drying technology is discussed, including the addition of drying processing additives, changes in drying parameters and the effect of innovative technological means.

Surface Functionalization of Sugarcane-Bagasse-Derived Cellulose Nanocrystal for Pickering Emulsion Gel: Microstructural Properties and Stability Efficiency

An environmentally friendly Pickering stabilizer was developed by upcycling sugarcane bagasse (SCB) into a cellulose nanocrystal (CNC), which was subjected to surface modification by using quaternary ammonium compound to enhance its amphiphilic characteristics. The changes in microstructural properties of modified cellulose nanocrystal (m-CNC), such as surface functional group, thermal stability, surface morphology, elemental composition, and particle size distribution were investigated. Results indicated the success of quaternary ammonium compound grafting with the presence of a trimethyl-alkyl chain on the cellulose structure, while the m-CNC preserves the needle-like nanoparticles in length of ~534 nm and width of ~20 nm. The colloidal profile of m-CNC-stabilized oil-water emulsion gels with different concentrations of m-CNC (1-5 wt%), and oil:water (O:W) ratios (3:7, 5:5, 7:3) were examined. The emulsion gel stability study indicated that the optimal concentration of m-CNC (3 wt%) was able to stabilize all the emulsion gels at different O:W ratios with an emulsion index of >80% for 3 months. It is the minimum concentration of m-CNC to form a robust colloidal network around the small oil droplets, leading to the formation of stable emulsion gels. The emulsion gel with O:W ratio (3:7) with 3 wt% of m-CNC rendered the best m-CNC-oil-droplets dispersion. The m-CNC effectively retained the size of oil droplets (<10 μm for 3 months storage) against coalescence and creaming by creating a steric barrier between the two immiscible phases. Furthermore, the emulsion gel exhibited the highest viscosity and storage modulus which was able to prevent creaming or sedimentation of the emulsion gels.