Oil-water interfacial behavior of soy β-conglycinin–soyasaponin mixtures and their effect on emulsion stability

Interfacial Properties and Structure of Emulsions and Foams Co-Stabilized by Span Emulsifiers of Varying Carbon Chain Lengths and Egg Yolk Granules

Interfacial properties significantly influence emulsifying and foaming stability. We here explore the interfacial behavior of egg yolk granules (EYGs) combined with various Span emulsifiers (Span 20, 40, 60, 80) to assess their solution properties, interface dynamics, and effects on emulsifying and foaming stability. The results unveiled that as the Span concentration increased, particle size decreased from 7028 to 1200 nm, absolute zeta potential increased from 4.86 to 9.26 mv, and the structure became increasingly loosened. This loose structure of EYGs-Span complexes resulted in reduced interfacial tension (γ), higher adsorption rate (Kd), and improved interfacial composite modulus (E) compared with native EYGs. These effects were more pronounced with shorter hydrophobic chain Spans but diminished with longer chain lengths. Enhanced interfacial properties contributed to better emulsification and foaming stability, with EYGs-Span complexes displaying increased emulsifying ability and stability compared with natural EYGs. Emulsifying and foaming stability improved in the order of Span 20 > Span 40 > Span 60 > Span 80 as the Span concentration increased. The correlation analysis (p > 0.05) indicated that emulsifying stability was positively associated with interfacial composite modulus and negatively correlated with particle size. Consequently, EYGs-Span composites demonstrate considerable potential for use as effective emulsifiers in food industry applications.

Soy protein isolate-xanthan gum complexes to stabilize Pickering emulsions for quercetin delivery

This study aimed to prepare soy protein isolate-xanthan gum complexes (SPI-XG) at pH 7.0 and as emulsifiers to prepare Pickering emulsions for delivering quercetin (Que). The results showed that SPI-XG exhibited a gel network structure in which protein particles were embedded. Fourier transform infrared spectroscopy (FTIR) and molecular docking elucidated that SPI-XG formed through hydrogen bonding, hydrophobic, and electrostatic interactions. Three-phase contact angle (θo/w) of SPI-XG approached 90° with biphasic wettability. SPI-XG adsorbed at the oil-water interface to form an interfacial layer with a gel network structure, which prevented droplet aggregation. Following in vitro simulated digestion, Que displayed higher bioaccessibility in SPI-XG stabilized Pickering emulsions (SPI-XG PEs) than SPI stabilized Pickering emulsions. In conclusion, SPI-XG PEs were a promising system for Que delivery.

Encapsulation and characterization of ω-3 medium- and long-chain triacylglycerols microencapsulated with different proteins as wall materials

In this study, ω-3 medium- and long-chain triacylglycerols (MLCTs) microcapsules with excellent performance were obtained using soy protein as the wall component to address the oxidation-related problems of MLCTs. Additionally, the effect of soy, whey, or pea proteins on microcapsules in terms of the changes in their structure and physicochemical properties was investigated. The results showed that the small particle size, low PDI (polydispersity index) and zeta potential, fast adsorption rate, and low interfacial tension of these protein-based samples fabricated through the O/W template method were conducive to maintaining the integrity of microcapsules during spray-drying. The microcapsules, characterized by a spherical shape, exhibited superior encapsulation efficiency of 94.56%, surpassing the findings of previous investigations. Overall, these microcapsules exhibited long-term storage stability and low controllable release rates, which could be utilized as carriers for liposoluble actives.

Effect of fat addition on the characteristics and interfacial behavior of chicken white soup emulsion from chicken skeleton

The effects of varying fat additions (0 %, 1.0 %, 1.5 %, 2.0 %, and 2.5 %) on characteristics and interfacial properties of chicken white soup emulsion from stewing chicken skeleton were investigated. The results revealed that the chicken white soup emulsion obtained with the 2.0 % fat addition had smaller D3,2 (1.889 μm), D4,3 (2.944 μm), and higher absolute zeta potential value (23.32 mV). Viscosity values were higher for the 2.0 % fat addition compared to the other treatment groups. Techniques like scanning electron microscopy, laser confocal, and atomic force microscopy demonstrated that oil droplets and particles in the soup were smaller and more evenly dispersed with the 2.0 % fat addition. Moreover, the 2.0 % fat group exhibited higher interfacial protein concentration of 207.56 mg/m2. Lastly, low field NMR images confirmed that the stability of the soup was enhanced with a 2.0 % fat addition. This research offers a foundational understanding for producing highly stable chicken white soup.

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.

Relationship between Soybean Protein Isolate and Textural Properties of Texturized Vegetable Protein

To identify the ideal soybean protein isolate for texturized vegetable protein processing, the effect of different soybean protein isolates on texturized vegetable protein composition was studied. Three different types of soybean protein isolates were selected and analyzed for functional properties (water holding capacity (WHC), emulsifying properties, foaming properties), amino acid content, and protein secondary structure. Then, using the same formulation, the soybean protein isolates were extruded to produce texturized vegetable protein, and its textural properties, degree of texturization, microstructure, free sulfhydryl (free SH), and disulfide (S-S) content were determined. Lastly, a correlation analysis was performed to examine the connection between soybean protein isolates and texturized vegetable proteins. After correlation analysis, the soybean protein isolate functional properties that affect the textural properties of the texturized vegetable protein were as follows: the emulsifying property affected the hardness, adhesiveness, springiness, gumminess, and chewiness of the texturized vegetable proteins; and the foaming property affected the gumminess, chewiness, and the degree of texturization of the texturized vegetable proteins. In addition, 16 amino acids including threonine (Thr), methionine (Met), and arginine (Arg) affect texturized vegetable proteins, mainly with respect to adhesiveness, springiness, and free SH. The effects of secondary structure (α-helix, random coil) on texturized vegetable proteins were degree of texturization, resilience, and cohesion, respectively. Therefore, choosing the soybean protein isolate with better emulsifying and foaming properties provides a more suitable approach for processing texturized vegetable protein.

Study on the Stability Mechanism of Peanut OBs Extracted with the Aqueous Enzymatic Method

In this study, the internal relationships among oil bodies (OBs), the protein-phospholipid interactions in aqueous phase, oil-water interface behavior, and the stability of reconstituted OBs were analyzed from the bulk phase, interface, and macro perspectives, and the stability mechanism of OBs was discussed. OB proteins and phospholipids were combined through hydrophobic and electrostatic interactions, resulting in the stretching of protein conformation. OB proteins and phospholipids act synergistically to increase interface pressure and the rate of increase in interface pressure with relatively stable elastic behavior, which is beneficial to the formation and stability of interfacial films. When OBs were reconstituted by an OB protein-phospholipid complex system, phospholipids bound to OB proteins through hydrophobic and electrostatic interactions. OB proteins and phospholipids uniformly covered the oil droplet surface of reconstituted OBs to form a stable interfacial film, which maintained the stability of OBs. The addition of phospholipids significantly reduced the particle size of OBs prepared by OB proteins in a dose-dependent manner, and particle size decreased with the increase in phospholipid content (p < 0.05). Phospholipids increased the net surface charge, enhanced electrostatic repulsion, and improved the physicochemical stability of reconstituted OBs. The stability mechanism elucidated in this study provides a theoretical basis for the demulsification of peanut OBs.

Quantitative analysis and interfacial properties of mixed pea protein isolate-phospholipid adsorption layer

Proteins and low-molecular-weight (LMW) surfactants are widely used for the physical stabilization of many emulsion-based food products. This study investigated the oil-water interfacial behavior between pea protein isolate (PPI) and phospholipid (PL). The emulsions prepared with different concentrations of PPI and PL were stabilized by their synergetic or competitive adsorption at the oil-water interface. In addition, the quantitative proteomics results could illustrate the displacements of proteins by PL. The result showed that the vicilin (7S) could be preferentially displaced by PL. Meanwhile, the results of quartz crystal microbalance with dissipation (QCM-D) indicated the high affinity of legumin (11S) with PL, suggesting that the legumin possessed higher interfacial affinity to prevent interfacial displacement. This research could help us to understand the interaction and competitive adsorption between plant proteins and LMW surfactants profoundly, which could promote the development of plant protein-based emulsion beverage with improved stability.

The development process of plant-based meat alternatives: raw material formulations and processing strategies

With the rapid growth of the world's population, the demand for meat is gradually increasing. The emergence and development of plant-based meat alternatives (PBMs) offer a good alternative to solve the environmental problems and disease problems caused by the over-consumption of meat products. Soybean is now the primary material for the production of PBMs due to its excellent gelation properties, potential from fibrous structure, balanced nutritional value, and relatively low price. Extrusion is the most widely used process for producing PBMs, and it has a remarkable effect on simulating the fibrous structure of real meat products. However, interactions related to phase transitions in protein molecules or fibrous structures during extrusion remain a challenge. Currently, PBMs do not meet people's demand for realistic meat in terms of texture, taste, and flavor. Therefore, the objectives of this review are to explore how to improve fiber structure formation in terms of raw material formulation and processing technology. Factors to improve the taste and texture of PBMs are summarized in terms of optimizing process parameters, changing the composition of raw materials, and enriching taste and flavor. It will provide a theoretical basis for the future development of PBMs.

Effects of pH-shifting treatments on the emulsifying properties of rice protein isolates: Quantitative analysis of interfacial protein layer

For the limitation of poor solubility and interfacial adsorption capacity of rice protein isolates (RPI), in this work the effects of pH-shifting treatments on the emulsifying properties of RPI were investigated. The results showed that the particle size of the emulsion stabilized by alkaline pH-shifting treated RPI was smaller than that stabilized by acid pH-shifting treated RPI. In addition, the RPI-10 stabilized emulsion showed a more uniform particle size distribution, which was explained by its high emulsifying activity and stability (EAI: 49.5 m²/g, ESI: 59.5 min). The interface rheology results showed that the alkaline pH-shifting treatment could promote the protein rearrangement and subsequently formed interface film with higher rate of protein penetration and rearrangement. The quantitative analysis of adsorbed proteins in the RPI-10 stabilized emulsion showed that glutelin-type isoforms as major proteins in RPI were increased at the oil-water interface for their balanced distribution of the hydrophilic and hydrophobic amino acid group. These quantitative and interfacial rheology analysis could improve deep understanding of the interfacial properties of pH-shifting treated RPI, and promote the development of application in grain protein stabilized emulsion.

Thoroughly review the recent progresses in improving O/W interfacial properties of proteins through various strategies

Along with the future food market developing world widely, the personalized nutrition and rational function food design are found to be urgently attracted. Oil in a water (O/W) emulsion system has an excellent ability to maintain nutraceuticals and thus plays a promising role in producing future functional foods. Understanding the interfacial related mechanisms involved are essential for improving the quality of food products. Protein can effectively reduce interfacial tension and stable immiscible phases. The interfacial properties of proteins directly affect the emulsion qualities, which have gradually become a prospective topic. This review will first briefly discuss the interfacial-related fundamental factors of proteins. Next, the paper thoroughly overviewed current physical and chemical strategies tailored to improving the interfacial and emulsion properties of proteins. To be summarized, a higher flexibility could allow protein to be more easily unfolded and adsorbed onto the interface but could also possibly form a softer interfacial film. Several physical strategies, such as thermal, ultrasound and especially high-pressure homogenization are well applied to improve the interfacial properties. The interfacial behavior is also altered by various green chemical strategies, such as pH adjustment, covalent modification, and low molecular weight (LMW) surfactant addition. These strategies upgraded emulsion properties by increasing adsorption load, accelerating diffusion and adsorption rate, associated with lowering interfacial tension, and promoting interfacial protein interactions. Future researches targeted at elucidating interfacial-bulk protein interactions, unraveling interfacial behavior through in silico tools, exploring connection between interfacial-industrial processing properties, and clarifying the interfacial-sensory-digestive relationships of O/W emulsions is needed to develop emulsion applications.

Research Progress of Food-Grade High Internal Phase Pickering Emulsions and Their Application in 3D Printing

High internal phase Pickering emulsion (HIPPE) is a type of emulsion stabilized by solid particles irreversibly adsorbed on an interfacial film, and the volume fraction of the dispersed phase (Φ) is larger than the maximum packing volume fraction (Φ_max). Proteins, polysaccharides, and their composite particles can be used as good particle stabilizers. The contact angle can most intuitively demonstrate the hydrophilicity and hydrophobicity of the particles and also determines the type of emulsions (O/W or W/O type). Particles' three-phase contact angles can be adjusted to about 90° by compounding or modification, which is more conducive to emulsion stability. As a shear thinning pseudoplastic fluid, HIPPE can be extruded smoothly through 3D printer nozzles, and its high storage modulus can support the structure of printed products. There is huge potential for future applications in 3D printing of food. This work reviewed the biomacromolecules that can be used to stabilize food-grade HIPPE, the stabilization mechanism of the emulsions, and the research progress of food 3D printing to provide a reference for the development of advanced food products based on HIPPE.

The Protein Composition Changed the Quality Characteristics of Plant-Based Meat Analogues Produced by a Single-Screw Extruder: Four Main Soybean Varieties in China as Representatives

Plant-based meat analogues (PBMs) are increasingly interesting to customers because of their meat-like quality and contribution to a healthy diet. The single-screw extruder is an important method for processing PBMs, and the characteristics of the product are directly affected by the composition of the raw materials; however, little research focuses on this issue. To explore the effect of protein composition on the quality characteristics of PBMs produced by a single-screw extruder, four soybean varieties used in China (Heihe 43 (HH 43), Jiyu 86 (JY 86), Suinong 52 (SN 52), and Shengfeng 5 (SF 5)) were selected. The 11S/7S ratios for these varieties ranged from 1.0: 1 to 2.5: 1 in order to produce PBMs with different protein compositions. The structure, processing, nutrition, and flavor characteristics were explored to analyze their differences. The results showed that protein composition affected the structure of PBMs, but the correlation was not significant. Meanwhile, a lower 11S/7S ratio (HH 43) did not prove to be a favorable characteristic for the processing of PBMs. From the perspective of nutrition and flavor, it seems acceptable to use a moderate 11S/7S ratio (JY 86 and SN 43) to produce PBMs. This study proved that the protein composition of raw materials affects the characteristics of PBM products produced by a single-screw extruder. To produce PBMs of higher quality, soybeans with a markedly different 11S/7S ratio should not be selected.

Mechanism of interactions between soyasaponins and soybean 7S/11S proteins

In this study, the proteins glycinin (11S) and β-conglycinin (7S) were mixed with soyasaponin (Ssa) Ab/Bb to form a composite system. We used fluorescence and synchronous fluorescence spectra to demonstrate the changes in the surrounding environment and the structure of the proteins. Dynamic interface behavior analysis showed the possible interface behavior induced by the composite system. The interactions between Ssa and the proteins, along with the mode of action, were analyzed by molecular docking. The interactions between Ssa and soy protein increased with the change in concentration. The interactions between the two proteins were mediated by tryptophan (Trp) and primarily involved hydrogen bonds, which changed the microenvironment and loosened the protein structure. These results helped in understanding the mechanism underlying the interactions between Ssa Ab/Bb and 7S/11S. Furthermore, these results highlighted the theoretical fundamentals for the future applications of composite systems as surfactants in the food industry.

A hierarchical emulsion system stabilized by soyasaponin emulsion droplets

Oil/water (O/W) emulsion droplets coated with soyasaponin (Ssa) were used as emulsifiers to prepare emulsions with hierarchical configurations (2.82 μm). Ssa is a natural triterpenoid with amphiphilic properties and an excellent emulsifying activity. Stable O/W emulsions were prepared and characterized using an ultrasonic method at a Ssa concentration of 2.5 wt%. The resultant hierarchical emulsions were further prepared using O/W droplets as emulsifiers. It was observed that the stability of the hierarchical emulsions changed with alterations to the ratio of O/W droplets to the oil phase. As the number of droplets increased, the more the surface area of the hierarchical emulsion was covered. Additional observations included a decreased particle size, increased negative charge and viscoelastic behavior, and enhanced emulsion stability. The emulsion was most stable when the O/W droplet addition was 29%. The addition of O/W droplets continued to increase, and there was an imbalance in the ratio of O/W droplets to the oil phase; the excess O/W droplets induced instability in the emulsion, resulting in a degradation of the emulsion quality. We monitored hierarchical emulsions with different concentrations of emulsifiers for 30 days, and the results indicated that hierarchical emulsions could meet the demand for long-term storage. This provides a new theoretical basis for the construction and application of complex emulsion systems.

Impact of rutin on the foaming properties of soybean protein: Formation and characterization of flavonoid-protein complexes

The aims of present study were to determine the impact of rutin complexation on the ability of soybean protein isolates (SPI) to form and stabilize foams and its mechanism. At pH 7.0, the foaming capacity and foaming stability of the rutin-SPI complexes (28.33% and 14.22%) was appreciably changed when compared with that of SPI alone (19.64% and 32.95%). The improvement in foaming properties was mainly attributed to decrease gas bubble size and increase interfacial thickness as suggested by light microscopy analysis. UV-visible spectroscopy showed that the absorption peak of the SPI was increased and red shifted after complexation with rutin. ITC confirmed that there was an interaction between rutin and SPI. This interaction was hydrophobic interaction and the binding process was entropy driven. This study shows that the foaming properties of plant-based proteins can be improved by forming complexes with flavonoids, which may be useful for foaming agents in foods.

Effect of glycosylation with sugar beet pectin on the interfacial behaviour and emulsifying ability of coconut protein

The aim of the present study was to investigate the effect of glycosylation with sugar beet pectin (SBP) on the interfacial behaviour and emulsifying ability of coconut protein (CP). The physical stabilities of the emulsions were predicted by transmission variation, droplet distribution and zeta potentials. The results showed that SBP-CP-stabilized emulsions showed better stability during centrifugation than those stabilized by CP because SBP-CP reduced the degree of variation in the CP transmission profile. The adsorption kinetics of all emulsifiers at the oil-water interface were determined to investigate the relationship between the interfacial behaviour and emulsion stability. The presence of SBP considerably reduced the adsorption rate of CP (0.698 mN/m/s^1/2) and hampered the development of a highly viscoelastic network at the oil-water interface. The values of the dilatational elastic modulus (E_d = 19.477 mN/m) and dilatational viscous modulus (E = 19.719 mN/m) were approximately equal, indicating that the adsorption process was mainly dominated by elastic behaviour. Additionally, the SBP-CP interaction enhanced the dilatational property of the CP-absorbed layer.

Active coatings of thermoplastic starch and chitosan with alpha-tocopherol/bentonite for special green coffee beans

The quality of green coffee beans (GCBs) is possibly affected by storage conditions. Edible polymer coatings for GCBs can help preserve flavors and improve shelf life of GCBs. This study aimed to incorporate α-tocopherol, a powerful antioxidant, in thermoplastic starch [TPS] and chitosan [TPC] and determined the best cavitation energy (960-3840 J·mL-1) using an ultrasonic probe. Then, we evaluated the incorporation of bentonite (0% and 2% m/m) and α-tocopherol (0% and 10% m/m) in the best energy cavitation/biopolymer combination. The TPS and TPC coatings demonstrated good adherence to the GCBs, measured by surface energy. The dispersion of α-tocopherol in TPC, with cavitation energy 960 J·mL-1, promoted greater stability (greater zeta potential), thereby increasing antioxidant activity by 28% compared to TPS, therefore, was selected for a second stage. Incorporation of 2% bentonite into the TPC, with 10% α-tocopherol, resulted in a 3.7 × 10-10 g·m-1·s-1·Pa-1 water vapor permeability, which is satisfactory for prevented of moisture gain during storage. The compressive load showed values of 375 N to the non-coated GCB and around 475 N with the insertion of coatings to the GCB. Thus, a TPC/α-tocopherol/bentonite combination, dispersed with 960 J·mL-1 energy, was highly effective in the development of biopolymeric coatings for the GCBs.

Optimization of the Emulsifying Properties of Food Protein Hydrolysates for the Production of Fish Oil-in-Water Emulsions

The incorporation of lipid ingredients into food matrices presents a main drawback-their susceptibility to oxidation-which is associated with the loss of nutritional properties and the generation of undesirable flavors and odors. Oil-in-water emulsions are able to stabilize and protect lipid compounds from oxidation. Driven by consumers' demand, the search for natural emulsifiers, such as proteins, is gaining much interest in food industries. This paper evaluates the in vitro emulsifying properties of protein hydrolysates from animal (whey protein concentrate) and vegetal origin (a soy protein isolate). By means of statistical modelling and bi-objective optimization, the experimental variables, namely, the protein source, enzyme (i.e., subtilisin, trypsin), degree of hydrolysis (2-14%) and emulsion pH (2-8), were optimized to obtain their maximal in vitro emulsifying properties. This procedure concluded that the emulsion prepared from the soy protein hydrolysate (degree of hydrolysis (DH) 6.5%, trypsin) at pH 8 presented an optimal combination of emulsifying properties (i.e., the emulsifying activity index and emulsifying stability index). For validation purposes, a fish oil-in-water emulsion was prepared under optimal conditions, evaluating its physical and oxidative stability for ten days of storage. This study confirmed that the use of soy protein hydrolysate as an emulsifier stabilized the droplet size distribution and retarded lipid oxidation within the storage period, compared to the use of a non-hydrolyzed soy protein isolate.

Interfacial Properties and Emulsification of Biocompatible Liquid-Liquid Systems

A comparative study is reported on the interfacial properties of a set of surfactants and is discussed in terms of the effects on the features of the corresponding oil-water emulsions. The surfactants are saponin, Tween 80 and citronellol glucoside (CG), while the oil is Miglyol 812N—A Medium Chain Triglyceride (MCT) oil. Due to their high biocompatibility, all these compounds are variously utilized in food, cosmetic or pharmaceutical products. Among the surfactants, which are all soluble in water, CG presents also an important solubility in oil, as shown by the measured partition coefficient. For these systems, dynamic and equilibrium interfacial tensions and dilational viscoelasticity are measured as a function of the surfactant concentration and analyzed according to available adsorption models. In order to compare these results with the time evolution of the corresponding emulsions, the actual surfactant concentration in the matrix phase of the emulsion is accounted for. This may differ significantly from the nominal concentration of the solutions before dispersing them, because of the huge area of droplets available for surfactant adsorption in the emulsion. Using this approach allows the derivation of the correlations between the observed emulsion behavior and the actual surfactant coverage of the droplet interface.