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The citrus fiber based high internal phase emulsions (HIPEs) containing 75 wt% sunflower oil with high heat stability, good freeze-thawing recovery and ultralow tribological property are developed in this study. The corn peptides particles and corn peptides functionalized soluble fiber facilitate to construct interfacial architecture and insoluble fiber filled in continuous phase to prevent creaming, resulting stable HIPEs at acidic condition (pH3.0). The HIPEs exhibit excellent thixotropic recovery (above 90%), good heat stability (95 °C for 20 min) and freeze-thawing (−40 °C for 24 h/25 °C for 5 h) recovery properties. The emulsion with high citrus fiber concentration shows ultralow friction property in comparison with the egg-based commercial mayonnaise, which means that these products might provide more creaminess and smoothness sensory attribute than egg-based mayonnaise. The citrus fiber based HIPEs could find potential applications in the development of plant-based egg alternatives with interesting oral sensation. Image 109381 • Citrus fibers and corn peptides based high internal phase emulsions is constructed. • HIPEs exhibit excellent thixotropic recovery and good heat stability. • HIPEs show ultralow friction properties in comparison with egg-based mayonnaise. [ABSTRACT FROM AUTHOR]

Abstract In the present work, we studied the influence of particle size and charge density on the structure formation and rheological property of high internal phase emulsion gels (HIPE-gels) stabilized with zein/tannic acid complex particles (ZTPs). The size (68 and 108 nm) and charge density (+38, +20, and +1 mV) of ZTPs were controlled by adjusting the pH during the preparation of the particles and in the respective particle suspensions. Extensive centrifugation of the emulsions stabilized by those ZTPs resulted in stable HIPE-gels with an oil content ranging between 72 and 87% (w/w) and a particle concentration of 0.7–1.4% (w/w) only. Microscopy showed that even at these high oil volume fractions, limited coalescence between the oil droplets occurred. A decrease in the particle size resulted in a decrease in the oil content in the HIPE-gels, due to a more efficient particle network in the continuous phase. This increased the storage modulus of the HIPE gels, indicating that this particle network plays an important role for the gel strength. When increasing the interactions between the particles (by lowering the charge density), the gel strength increased even further. It was noted that the gel strength was independent of the oil content, suggesting that the oil droplets do not contribute a lot to the gel strength. These HIPE-gels with tunable rheological property may have various applications in industry. Graphical abstract The structure formation and rheological behavior of the high internal phase emulsion gels stabilized with zein/tannic acid complex particles (ZTPs) can be tuned by changing the particle size and charge density. Image 1 Highlights • Zein particles were used to stabilize high internal phase emulsions (HIPEs). • The HIPEs had an oil volume fraction of 72–87% and a protein content of 0.7–1.4%. • The storage moduli of these HIPEs were between 13000 and 27000 Pa. • The rheological behavior of HIPEs can be tuned by changing the particle properties. [ABSTRACT FROM AUTHOR]

In this paper, we report the structure formation and rheological properties of Pickering emulsions stabilized with zein/tannic acid complex particles (ZTPs) over a wide range of particle concentration (1–5%, w/v) and oil content (5–60%, v/v). Microscopy shows that the ZTPs provide stabilization at the droplet interfaces, and that excess ZTPs provide a particle network in the continuous phase to give a solid-like structure to the ZTPs-stabilized emulsions (ZTPEs). The low frequency dependency of G′ and low values for tan δ imply that ZTPEs have very elastic networks. The storage modulus (G′) of ZTPEs increases in a power-law manner with increasing particle concentration ( c p ) and oil content ( φ ), which can be scaled as G’ ∼  c p n and G’ ∼  φ m , respectively. The exponent n decreases with an increase of oil content, and m decreases with increase of particle concentration. This indicates that the structure of the network depends on both the particle concentration and the oil content. The difference in the network structure is also seen in the critical strain γ co , since three regimes are observed: for φ  ≤ 20%, γ co decreases with an increase in particle concentration; for 30% ≤ φ  ≤ 50%, γ co increases with increasing particle concentration; and for φ  = 60%, γ co is almost independent on the particle concentration. The results show that the microstructure and rheological properties of ZTPEs can be tuned by changing both the particle concentration and oil content, which may provide interesting features for various applications in industry. [ABSTRACT FROM AUTHOR]

Stable water in water (W/W) emulsions of guar rich droplets dispersed in an amylopectin rich continuous phase (G/A) and the inverse (A/G) can be achieved by adding gelatin and inducing microphase separation of the latter by cooling. In this research, the effect of gelatin on the emulsion stability was further studied by storing the emulsions at 10, 20 and 25 °C. The visual aspect, the microstructure, and the viscosity of the emulsions were investigated at different times during storage at different temperatures and pH. It was found that depending on the conditions, the gelatin phase wetted the interface or formed small discrete microdomains that adsorbed at the interface and dispersed in the bulk phases. The observed differences in morphology and stability are related to the interplay of the rates of aggregation, phase separation of gelatin, which itself depend on the gelatin concentration, temperature and pH. Emulsions could be prepared in this manner that were stable for at least one week and remained visually homogeneous. We believe that this is a promising method to stabilize W/W emulsions as long as the components of the emulsion are incompatible with aggregated gelatin. • Water in water (W/W) emulsions were stabilized by adding gelatin. • Microphase separation of gelatin in the W/W emulsions was induced by cooling. • Either a gelatin layer or discrete gelatin domains formed at the W/W interface. • The stability is related to the rates of gelatin aggregation and phase separation. • The stability could be tuned by gelatin concentration, temperature and pH. [ABSTRACT FROM AUTHOR]

Abstract The aim of this study was to assess the effect of oil type and solvent quality on the structure formation and rheological properties of zein-stabilized oil-in-glycerol emulsion gels. To change the interactions within the system, four types of oil (medium chain triglyceride (MCT) oil, sunflower oil, extra virgin olive (EVO) oil, and castor oil) with different polarity were used, and the solvent quality was modified by temperature and water addition. In all cases, emulsion gels were obtained with G' > G''. At each protein concentration and oil content, the gel strength and crossover strain γ co increased with an increase in oil polarity, indicating the formation of a stronger gel structure and higher stability against structure breakdown. These results are related to the fact that a higher oil polarity decreases the oil-protein hydrophobic interactions and thereby increasing the interactions between the proteins to form a strong network in the continuous phase. In addition, water addition to the continuous phase enhanced the gel strength and the resistance against structure breakdown for more apolar MCT oil, while the opposite results were observed for the more polar castor oil. The zein-based emulsion gels showed a thermo-responsive behavior, and different responses in structure collapse and rearrangements during heating and cooling were found for different oils. These simple approaches form an interesting route to tune the rheological properties of zein-based emulsion gels. Graphical abstract The structure formation and rheological behavior of the zein stabilized oil-in-glycerol emulsion gels can be tuned by changing the interplay between the different interactions within the system. Image 101 Highlights • Zein self assembles to form oil-in-glycerol emulsions gels. • Gel strength and crossover strain increase with an increase in oil polarity. • Water addition enhances the gel strength and crossover strain for more apolar oil. • Water addition decreases the gel strength and crossover strain for more polar oil. • The thermo-responsive behavior can be tuned by the oil type. [ABSTRACT FROM AUTHOR]

In the present work, the influence of hydrophobicity of zein/tannic acid complex particles (ZTPs) on the rheological behavior of ZTP-stabilized emulsion gels is described. The hydrophobicity of the particles was controlled by the incorporation of different amounts of hydrophilic tannic acid, while retaining a similar particle size. The resulting ZTPs with varying hydrophobicity were successfully used to form emulsion gels with similar oil droplet size. With a decrease in the hydrophobicity of ZTPs, the storage modulus (G′) of emulsion gels increased, while tan δ and the frequency dependence decreased, indicating the formation of a stronger gel network. The crossover strain, γ co , increased with a decrease in the hydrophobicity of ZTPs, indicating the gel network becomes more resistance against breakdown. In all cases, G′ increased in a power-law manner with an increase in protein concentration (G' ∼  c p n ) and oil content (G' ∼  φ m ). The exponent n and m decreased with decreasing particle hydrophobicity, indicating that hydrophobic interactions between particles within the particle network in the continuous phase and the oil droplets provide a relatively larger contribution to the gel strength for emulsion gels stabilized by ZTPs with higher hydrophobicity. Increasing the oil polarity provided a lower gel strength for emulsions stabilized by particles with high hydrophobicity, while it increased the gel strength for particles with low hydrophobicity. The results show that the rheological behavior of ZTP-stabilized emulsion gels can be tuned by changing the particle hydrophobicity and oil polarity, which provide interesting features for various applications in the food industry. [ABSTRACT FROM AUTHOR]

Responsive dual-structured emulsions and gel emulsions have attracted more and more attention due to their complex microstructures, on-demand responsive properties, and controlled release of active cargoes. In this work, the effect of monoglyceride (MG)-based oil phase structuring on the formation and stability, structural properties, and thermoresponsive and cargo release behavior of gel emulsions stabilized by glycyrrhizic acid (GA) nanofibrils were investigated. Owing to the formation of GA fibrillar networks in the aqueous phase and MG crystalline networks in the oil phase, a stable dual-structured gel emulsion can be successfully developed. The microstructure of the dual-structured gel emulsions largely depended on the concentration of MG in the oil phase. At low MG concentrations (1–2 wt%), the larger formed and lamellar MG crystals may pierce the interfacial fibrillar film, inducing the formation of partially coalesced droplets. In contrast, at high MG concentrations (4 wt% or above), the smaller MG crystals with enhanced interfacial activity can lead to the formation of a bilayer shell of GA nanofibrils and MG crystals, thus efficiently inhibiting the interfacial film damage and forming a jamming structure with homogeneously distributed small droplets. Compared to pure GA nanofibril gel emulsions, the GA−MG dual-structured gel emulsions showed significantly improved mechanical performance as well as good thermoresponsive behavior. Moreover, these stable GA−MG gel emulsions can be used as food-grade delivery vehicles for encapsulating and protecting hydrophobic and hydrophilic bioactive cargoes. They also have great potential as novel and efficient aroma delivery systems showing highly controlled volatile release. The dual-structured emulsion strategy is expected to broaden the applications of natural saponin GA-based gel emulsions in the food, pharmaceutical, and personal care industries. [ABSTRACT FROM AUTHOR]

The naturally occurring saponins exhibit remarkable interfacial activity and also possess many biological activities linking to human health benefits, which make them particularly attractive as bifunctional building blocks for formulation of colloidal multiphase food systems. This review focuses on two commonly used food-grade saponins, Quillaja saponins (QS) and glycyrrhizic acid (GA), with the aim of clarifying the relationship between the structural features of saponin molecules and their subsequent self-assembly and interfacial properties. The recent applications of these two saponins in various colloidal multiphase systems, including liquid emulsions, gel emulsions, aqueous foams and complex emulsion foams, are then discussed. A particular emphasis is on the unique use of GA and GA nanofibrils as sole stabilizers for fabricating various multiphase food systems with many advanced qualities including simplicity, ultrastability, stimulability, structural viscoelasticity and processability. These natural saponin and saponin-based colloids are expected to be used as sustainable, plant-based ingredients for designing future foods, cosmetics and pharmaceuticals. [ABSTRACT FROM AUTHOR]

Water-in-water emulsions were formed by mixing aqueous solutions of the neutral polysaccharides guar and amylopectin. The effect of adding gelatin B on emulsions, both of a dispersed guar rich phase in a continuous amylopectin phase and the inverse, were investigated using confocal scanning laser microscopy as a function of the gelatin concentration between 0.25 and 1.5 wt% and the pH between pH 4 and pH 6. Gelatin was found to phase separate upon cooling below about 25 °C in a narrow pH range around pH 5 both in the pure guar phase and in the pure amylopectin phase forming distinct spherical domains. The phase diagram was established as a function of the gelatin concentration and the pH. In the emulsions, the gelatin phase separated first at the interface between the two phases forming a continuous layer at the droplet surface. In some conditions the layer persisted, but in others it broke up into distinct domains. Excess gelatin phase separated in the bulk amylopectin phase, particularly when it was the continuous phase. The gelatin redispersed into the bulk phases when the emulsions were heated to 30 °C. [Display omitted] • Gelatin phase separates during cooling in guar and amylopectin solutions. • Phase separation depends on the pH and is favored by aggregation of gelatin. • W/W/W emulsions can be formed in-situ using guar/amylopectin/gelatin. • Gelatin forms distinct domains or a continuous layer around dispersed droplets. • The formation of the gelatin layer on cooling is reversed by heating. [ABSTRACT FROM AUTHOR]

3D printing has been applied to create nutritious foods with tailored textures for the elderly. However, the edible materials that possess the elastoplastic properties and shear-thinning behavior required for direct-write 3D printing are limited. In this study, we developed a simple approach to fabricate Spirulina emulsion gels as edible 3D printable material by exploiting depletion attraction between emulsion droplets. By controlling the volume ratio of continuous and oil phases, mixing highly viscous Spirulina slurry and vegetable oil could form self-standing oil-in-water emulsion gels with elastoplastic rheological properties. Also, adding food polysaccharides into the continuous phase could act as depletants to drive the formation of emulsion gels. Auto-fluorescence spectroscopy and microscopy were employed to characterize the interfacial protein compositions of the emulsion, showing that phycobilisome (PBS) particles might play a dominant role in the formation of Spirulina emulsions. The depletion attraction could drive the adsorption of PBS particles onto the droplet interface, and the particle-armored droplets in the dispersed phase connected into a percolating droplet cluster, resulting in arrested dynamics and gelation. Overall, this novel approach can be applied by exploiting depletion attraction and opens up possibilities for using high-solids viscous food slurries to produce personalized 3D-printed foods. [Display omitted] • Self-standing emulsion gel is formed by mixing Spirulina slurry with vegetable oil. • PBS particles may play a dominant role in the formation of Spirulina emulsion. • Depletion attraction drives the adsorption of PBS particles onto droplet interface. • Particle-armored droplets are connected into a percolating cluster for gelation. • Polysaccharides as depletants modify the rheological properties of Spirulina emulsion. [ABSTRACT FROM AUTHOR]

Double emulsion is the most common multiple emulsion with compartmentalized internal structure. It can be used for delivery of both hydrophilic and hydrophobic bioactives and fat reduction in foods. However, conventional approach for stable double emulsion preparation often requires high dosage of synthetic surfactants (e.g., polyglycerol polyricinoleate, PGPR) and complicated two-step emulsification process. Herein, we report a facile approach to create stable double emulsion using particular emulsifier of edible chitosan/soy β-conglycinin (7S) complex nanoparticles via one-step emulsification. By modulating chitosan/7S complex ratio of particles and algal oil content in oil phase, water-in-oil-in-water (W/O/W) Pickering double emulsion was generated in most cases. The dominant mechanism for one-step generation of Pickering double emulsion can be attributed to the polyunsaturated fatty acids (PUFA) in algal oil. The binding of PUFA on particle surface contributes to hydrophobization of the chitosan/7S complex nanoparticles, leading to stabilization of W/O interface. Moreover, stability of the resultant Pickering double emulsions is correlated to particle contact angle. When using nanoparticles with chitosan/7S complex ratio of 1:2 and oil phase containing 40 wt% algal oil, particle contact angle at O/W interface is near 90°, which is the optimum condition to produce highly stable Pickering double emulsion. This facile approach for the fabrication of stable double emulsion is promising for a wide range of applications, particularly in food field. [Display omitted] • A W/O/W Pickering double emulsion was fabricated via one-step emulsification strategy. • Edible chitosan/7S complex particles were used as the interfacial stabilizers. • PUFA in algae oil could modulate particle wettability. • The resultant W/O/W Pickering double emulsion was stable over 50 days. [ABSTRACT FROM AUTHOR]

In this article, we report the microstructure and rheological property of Pickering emulsions stabilised with zein nanoparticles prepared through phase separation from acetic acid solution. The fresh emulsions showed liquid-like behaviour and reasonable small droplet size. Interestingly, after 3 days of storage at 25° C, the emulsions changed into solid-like state. The viscosity remarkably increased, and the storage modulus was much larger than the loss modulus. These results indicate the formation of the gel-like network in emulsions. The droplet size also showed an obvious increase, while the big droplets could be disrupted into small ones in the presence of sodium dodecyl sulphate. The particle network in the continuous phase was seen in the confocal laser scanning microscopy. Therefore, it is suggested that the gel-like network is formed by the flocculation of oil droplets and particle network in continuous, mainly through the hydrophobic interactions between the particles. [ABSTRACT FROM AUTHOR]

[Display omitted] • GA nanofibrils are effective and robust stabilizer to make soft-solid emulsion foams. • Stability and structural properties of emulsion foams were controlled by oil phase polarity. • Emulsion foam with polar castor oil had denser network microstructure, higher mechanical strength, and lower friction coefficients. • Volatile limonene oil weakened structural stability and lubrication ability of emulsion foams. Novel supramolecular nanofibrils assembled from food-grade saponin glycyrrhizic acid (GA) are effective building blocks to make complex multiphase systems, e.g., emulsion foams. In this work, the effects of different oil phases (castor oil, sunflower oil, dodecane, and limonene) on the formation, stability and structural properties of long-lived emulsion foams prepared by GA nanofibrils (GNs) were investigated. The obtained results showed that soft-solid emulsion foams (4 wt% GNs) can be fabricated, independently of oil phase, and their structural properties, viscoelasticity, and tribological properties can be well tuned by oil phase polarity. Compared to the GNs aqueous foams, the presence of jammed emulsion droplets in the liquid channels and at the surfaces of bubbles can provide a higher bubble stability for emulsion foams. For more polar oil phase (castor oil), GNs showed a higher affinity to the oil–water interface with a lower interfacial tension, thus forming smaller oil droplets and bubbles, which leads to the higher mechanical strength, denser network microstructures, and lower friction coefficients of emulsion foams. However, the limonene foam exhibited weak storage stability and rheological properties, as well as the relatively low lubrication, which may be related to the formation of oil droplet aggregates and clusters induced by the volatility of limonene. GN-based emulsion foams are thermoresponsive, independently of oils, and the temperature-switchable process for the destabilization and regeneration of foams can be controlled and repeated. These emulsion foams based on natural saponin nanofibrils with tunable properties have potential sustainable applications in foods, pharmaceuticals, and personal care products. [ABSTRACT FROM AUTHOR]

• Dual-structured emulsion gels were made by GA nanofibrils and sitosterol-oryzanol mixtures. • Microstructure of emulsion gels strongly depended on sterols concentration. • Nonlinear rheological behaviors of emulsion gels were studied using LAOS tests. • The percolating emulsion gels were more elastic and resistant to large deformations. The linear and nonlinear rheological behaviors of heterogeneous emulsions gels made from natural glycyrrhizic acid (GA) nanofibrils and sitosterol-oryzanol mixtures (sterols) were investigated using small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS). The nonlinear rheological response was qualitatively analyzed using normalized Lissajous-Bowditch curves. The microstructure of the emulsion gels strongly depended on the concentration of sterols in the oil phase, and showed a percolated segregated network at 10–20 wt% sterols due to the partial coalescence of droplets, and a jamming transition without coalescence at higher sterols concentration of 30 wt%. The microstructure differences led to different linear and nonlinear viscoelastic behaviors of these emulsion gels. SAOS tests showed that the oil phase structuring by the sterols significantly enhance the viscoelasticity of GA nanofibril emulsion gels, and the percolating emulsion gels exhibited higher elasticity than the jammed emulsion gel, as evidenced by a lower damping factor and frequency power-law exponent. The data of crossover strain, phase angle, and the normalized Lissajous-Bowditch curves from LAOS tests further revealed that compared to the samples in a jammed state or without oil phase structuring, the emulsion gels with a percolating segregated network showed higher structural elasticity and thus were more resistant to large deformations, probably due to the slow relaxation of rigid, hydrodynamically interacting clusters of partially coalesced droplets. These findings could potentially aid in the design of novel emulsion gels, based on all-natural and sustainable building blocks, with specific textural and functional properties for foods, cosmetics, and pharmaceutical applications. [ABSTRACT FROM AUTHOR]