Mechanism Of Emulsion Stabilization Research Articles

Effect of stigmasterol and polyglycerol polyricinoleate concentrations on the preparation and properties of rapeseed oil-based gel emulsions

Emulsion gels mimic the rheological properties of solid and semi-solid fats, offering a viable solution to replace conventional fats in low-fat food formulations. In this study, gel emulsions stabilized with stigmasterol (ST) and polyglycerol polyricinoleate (PGPR) complexes were prepared. Initially, we examined the effect of the ST/PGPR complex on the mechanism of gel emulsion stabilization. Our findings revealed that the gel emulsion formulated with 3% PGPR and ST exhibited a robust structure, effectively stabilizing the entire system and ensuring uniform distribution, and increasing ST concentration led to greater stability of the gel emulsion system. Stability assessments demonstrated that gel emulsions containing 3% PGPR and varying ST concentrations exhibited remarkable thermal stability and effectively delayed oil oxidation. These results underscore the high stability of gel emulsions stabilized with the ST/PGPR complex, highlighting their potential as a margarine substitute.

A microfluidic and Langmuir approach to unveil the interplay between hydroxypropyl methylcellulose and zein nanoparticles on the stability of Pickering emulsions

Utilizing microfluidic technology and Langmuir trough, the study investigated how hydroxypropyl methylcellulose (HPMC) interact with zein nanoparticles (ZNPs) at interfaces and their collective impact on emulsion stability. Herein, microchips were designed with varying adsorption channel lengths to study the effect of adsorption kinetics on the coalescence stability, while Langmuir assessments provided insights into particle adsorption kinetic and film properties of emulsion stabilization mechanisms. Results suggested that HPMC's incorporation expedited ZNPs' rearrangement rates at the interface, especially at low concentrations, resulting in a synergistic reduction in interfacial tension. However, at high HPMC concentration, a competitive adsorption scenario emerged between ZNPs and HPMC, leading to increased interfacial tension and instability. Microfluidic analyses of droplet coalescence, alongside Langmuir-derived interfacial rheology data, revealed that while a small amount of HPMC significantly bolstered emulsion stability by enhancing viscoelastic properties of interfacial film, an excess of HPMC inversely affected these parameters, diminishing film elasticity and thus, the emulsion's coalescence resistance. The adsorption kinetic and the interaction on interface of HPMC and zein particles were analyzed via microfluidic and LB technology in this study, which will not only expand our current strategies for interface engineering of emulsions, but also deepens our understanding of the interplay between mixed particle system adsorption properties, interfacial rheology, and Pickering composite emulsion stability.

Adsorption mechanism of asphaltenes and surfactants at oil-water interface: based on dissipative particle dynamics method

The study of emulsion stabilization mechanisms is of great importance in the field of crude oil extraction, transportation and processing. In order to further investigate the roles of asphaltenes and surfactants in the emulsion stabilization process, the adsorption mechanisms of asphaltenes and surfactants at the oil-water interface were investigated using dissipative particle dynamics. The results show that: the asphaltene interfacial film gradually becomes thicker before the saturation adsorption of asphaltene molecules at the oil-water interface, and the interfacial tension decreases with the increase of the number of molecules until it reaches the equilibrium state; different surfactant molecules have different influences on the interface, and the calculations of the radial distribution function and the interfacial tension show that H2T4 molecules have a stronger effect than H4T4 at the oil-water interface and have stronger surface activity. H2T4 reaches saturation adsorption capacity faster than H4T4 and has higher interfacial efficiency. The asphaltene-surfactant composite system can stabilize the oil-water interface more effectively. Competitive and synergistic effects of asphaltene and surfactant in the process of interfacial adsorption. When the concentration of surfactant in the composite system is low, there is a synergistic effect between the two in the interfacial adsorption process; when the concentration of surfactant is high, there is a competitive effect between the two in the synergistic adsorption process. The surfactant H4T4 has both interfacial adsorption and self-aggregation in the competitive adsorption process. This paper provides ideas for exploring the kinematic laws of molecular behavior in the stabilization mechanism of crude oil emulsions.

Potato starch/naringenin complexes for high-stability Pickering emulsions: Structure, properties, and emulsion stabilization mechanism

In this study, potato starch (PS)/naringenin (NAR) complex was prepared, and its properties and emulsification behavior were evaluated. The experimental results demonstrated that NAR successfully formed a complex with PS molecules through hydrogen bonds and other non-covalent interactions. The emulsifying capacity (ROV) of PS/NAR complex with 16 % composite ratio was 0.9999, which was higher than PS (ROV = 0.3329) (p < 0.05). Based on particle property analysis and molecular dynamics simulation, the mechanism of improving the emulsification performance might be the action of the benzene ring of NAR and intermolecular hydrogen bonding. In addition, the stability of the Pickering emulsions with PS/NAR complexes as emulgators was significantly improved. The emulsifying and rheological behavior of starch-based Pickering emulsions could be adjusted by changing the proportion of the complexes. Results demonstrated that the PS/NAR complexes might be a prospective stabilizer of Pickering emulsions based on starch material and might expand the use of PS in edible products.

The influence of α and α′ subunits on SPI Pickering emulsions based on natural hybrid breeding varieties

In this study, food-grade protein nanoparticles (Wild-NPs, α-lack-NPs, α′-lack-NPs, and (α + α′)-lack-NPs) were organized as emulsion stabilizers via thermal induction. The effects of α and α′ subunits in soybean protein isolate (SPI) on Wild nanoparticle Pickering emulsion (Wild-NPPEs), α-lack nanoparticle Pickering emulsion (α-lack-NPPEs), α′-lack nanoparticle Pickering emulsion (α′-lack-NPPEs) and (α + α′)-lack nanoparticle Pickering emulsion ((α + α′)-lack-NPPEs) were investigated. The Pickering emulsion stabilization mechanism indicated that the α′-lack-NPs particle size, surface hydrophobicity, and contact angle were mostly comparatively large. Therefore, the absence of the α′ subunit made the desorption of protein nanoparticles at the oil and water interface require higher energy. Through the hydrophobic interaction between molecules, the structure and properties of the emulsion were improved, showing good stability. The existence of α′-lack-NPPEs leads to the formation of a gel-like network in the emulsion, which increases the viscosity of the emulsion and makes the network structure of the emulsion more uniform and denser.

PH and redox dual-responsive Pickering emulsion based on silica nanoparticles and novel ferrocene surfactant

Responsive Pickering emulsions capable of responding to external stimuli have been extensively studied, however, there are few studies on double-responsive Pickering emulsions. Here in, a novel ferrocene surfactant (FcACUa) was synthesized and combined with aminated silica nanoparticles (0.5 wt%) to stabilize pH and redox sensitive smart Pickering emulsions. The carboxyl groups act as pH-sensitive parts, while ferrocene serves as the redox-responsive center. Stability and pH/redox response performance of the emulsions were investigated through various methods, such as the contact angle, macroscopic states, creaming index, microscopic images, droplet size distributions, etc. All atom molecular dynamics and dissipative particle dynamics simulations were used to probe the distribution of nanoparticles and surfactant at the water-oil interface, as well as to reveal the stabilization and pH/redox response mechanisms of the Pickering emulsions. Pickering emulsions can be reversibly switched between stable and unstable by adding HCl and NaOH or adding H2O2 and N2H4·H2O. After five pH-induced cycles, the emulsion shows no significant degradation or morphological changes. However, for the redox induced emulsification demulsification process, the size of the emulsion drops increases with the increase of the number of cycles. This work provides insights into the Pickering emulsion stabilization mechanism and the regulation mechanisms of pH and redox stimulation, which may have potential value in emulsion polymerization, biphasic catalysis, and oil and gas transportation.

Correlationship between self-assembly behavior and emulsion stabilization of pea protein-high methoxyl pectin complexes treated with ultrasound at pH 2.0

This study investigated the effects of ultrasound on the self-assembly behavior of pea protein (PP)-high methoxyl pectin (HMP) complexes at pH 2.0 through transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and intrinsic fluorescence analysis. The emulsion stabilization mechanism of PP-HMP treated with ultrasound (PP-HMP-US) was also elucidated. The results indicated that ultrasound increased the emulsifying activity index (EAI) and emulsifying stability index (ESI) of PP-HMP. Moreover, PP-HMP-US-based emulsions formed small, dispersed oil drops, which were stable during storage. PP-HMP- and PP-HMP-US-based emulsions did not demonstrate any creaming. The TEM results revealed that ultrasound can regulate the self-assembly behavior of PP and HMP to form spherical particles with a core–shell structure. This structure possessed low turbidity, a small particle size, and high absolute zeta potential values. The FTIR and intrinsic fluorescence spectra demonstrated that ultrasound increased the α-helix and β-sheet contents and exposed the tryptophan groups to more hydrophilic environments. Ultrasound also promoted the PP-HMP self-assembly through electrostatic interaction and improved its oil–water interfacial behavior, as indicated by the EAI and ESI values of PP-HMP-US-based emulsions. The current results provide a reference for the development of an innovative emulsifier prepared by ultrasound-treated protein–pectin complexes at low pH.

Segregative phase separation of gelatin and tragacanth gum solution and Mickering stabilization of their water-in-water emulsion with microgel particles prepared by complex coacervation

This study aimed to investigate the segregative interaction of gelatin (G) and tragacanth gum (TG) and the stabilization of their water-in-water (W/W) emulsion by G-TG complex coacervate particles. Segregation was studied at different pHs, ionic strengths and biopolymer concentrations. Results showed that incompatibility was affected by increasing the biopolymer concentrations. So, three reigns were demonstrated in the phase diagram of the salt-free samples. NaCl significantly changed the phase behavior via enhancement of self–association of polysaccharide and changing solvent quality due to the charge screening effect of ions. The W/W emulsion prepared from these two biopolymers and stabilized with G-TG complex particles was stable for at least one week. The microgel particles improved emulsion stability by adsorption to the interface and creating a physical barrier. A fibrous and network-like structure of the G-TG microgels was observed by scanning electron microscopy images suggesting the Mickering emulsion stabilization mechanism. It was confirmed that the bridging flocculation between the microgel polymers led to phase separation after the stability period. Biopolymer incompatibility investigation is a useful tool to obtain beneficial knowledge for preparation new food formulation, especially no contain oil emulsions for low- calorie diets.

Determination of the Emulsion Stabilization Mechanisms of Quaternized Glucan of Curdlan via Rheological and Interfacial Characterization

Interfacial-active quaternized glucan of curdlan (QCD) with different degrees of substitution (DS) was prepared and used as stabilizers of oil-in-water (O/W) emulsions at different concentrations. The adsorption behavior of QCDs, rheology of bulk emulsions and interfacial films, emulsion morphology, and stability were investigated. The emulsifying capacity of QCD was essentially related to the viscoelastic features of the interfacial film and the continuous phase and the electrostatic repulsion among oil droplets. QCD molecules with different DS form structurally different interfacial films. The high-DS QCD formed a viscously predominant interfacial film with certain hydrophobicity, whereas the low-DS QCD molecules formed an elastically predominant film characterized by hydrogen bonds among adsorbed chains. The structuralization of low-DS QCD molecules through physical cross-linking in bulk and interfacial films at high concentrations was conducive to emulsion stability. Excess QCD chains in the bulk formed a weak gel-like network, further hindering the movement of droplets in the emulsions. Relevant emulsification and stability mechanisms were proposed. Finally, the stability of curcumin encapsulated in O/W emulsions was evaluated.

Interfacial characteristics of artificial oil body emulsions (O / W) prepared using extrinsic and intrinsic proteins: Inspired by natural oil body

In order to explore the stabilization mechanisms of intrinsic protein (IP) and extrinsic protein (EP) in natural oil-bodies, the effects of adding EP and IP in different relative proportions on the stability, interfacial characteristics, and digestibility of artificial oil body (AOB) emulsions were studied. The stability test results showed that the AOB emulsion prepared using 40% EP/60% IP exhibited the highest ζ-potential (−36.3 mV) and storage stability. According to the results of interface properties, competitive adsorption occurred at the interface in the emulsions prepared using IPs and EPs. Furthermore, by measuring the bioavailability of free fatty acids and curcumin during the digestion process, it was elucidated that 40% EP/60% IP developed a stable interfacial membrane, which facilitated the targeted release of curcumin in the intestine and yielded higher bioavailability. These results lay the foundation for clarifying the stabilization mechanism of natural oil body emulsions from an interfacial perspective.

Emulsifying and emulsion stabilization mechanism of pectin from Nicandra physaloides (Linn.) Gaertn seeds: Comparison with apple and citrus pectin

The emulsifying and emulsion stabilization mechanism of three kinds of pectin (Nicandra physaloides (Linn.) Gaertn seeds pectin-NP, apple pectin-AP, and citrus pectin-CP) were compared in terms of emulsions system, interface layer and pectin structure. The results showed the emulsifying properties of NP was superior to AP and CP, which attributed to lower interfacial tension (∼15.57 mN/m) and better long-term stability to prepared emulsion. The long-term stability of NP emulsion ascribed to the higher emulsion viscosity, more uniform droplet size distribution, stronger electrostatic repulsion, and thicker interfacial layer. Structurally, the emulsifying activity of NP was mainly provided by acetyl and methyl groups, and the emulsifying stabilization was provided by the neutral monosaccharide side chains and ionized carboxyl groups. Therefore, the protein in pectin was not essential for the stabilization of oil-water interface, and the carbohydrate components played a crucial role in when especially lack of protein. Consider that the emulsifying properties of NP were independent of protein, it may be a potential natural emulsifier in resisting acid, ions, and heat.

Depletion stabilization of emulsions based on bacterial cellulose/carboxymethyl chitosan complexes

The regulation of the magnitude of the depletion effect is necessary for accurately predicting and explaining the emulsion stabilization mechanism. Herein, the bacterial cellulose/carboxymethyl chitosan (BC/CCS) complexes with tunable assembled behaviors were prepared and designed via electrostatic interaction. Specially, the emulsions stabilized by BC/CCS complexes exhibited excellent stability as compared with that stabilized by BC polymers alone. At pH 9.6, BC/CCS complexes in the continuous phase induced long-range depletion-stabilization effect to stabilize emulsions. Additionally, the magnitude of depletion effect of BC/CCS complexes could be improved by increasing BC concentration, and effectively stabilized emulsions. Furthermore, with the decrease to pH 7.0, the interfacial adsorption layers at the oil-water interface prevented oil droplets from agglomerating, but did not show better emulsion stability. These results clarified that the magnitude of the depletion effect could be controlled by altering BC-based complexes particles, which would be useful for the applications of emulsions in numerous fields.

Are micelles actually at the interface in micellar casein stabilized foam and emulsions?

Different casein preparations are used for stabilizing emulsions and foams. For systems made with aqueous micellar casein dispersions, the molecular and colloidal mechanisms responsible for the stabilization of oil-water and air-water interfaces have not been conclusively ascertained. Whether the micelles themselves, small casein aggregates, or individual casein molecules are at the interface is still an open question. Understanding these mechanisms is important for food industries to improve product formulations. We investigated the nonlinear rheology and microstructure of oil-water and air-water interfaces stabilized with casein micelle dispersions and their fractions. Our results convincingly show that the micelles themselves are not adsorbed at the interfaces. For air-water interfaces, the behavior appears to be dominated by β-casein, whereas the properties of oil-water interfaces are dominated by small casein aggregates. These findings are important to understand the stabilization mechanisms of emulsions and foams prepared with caseins or milk.

Ethyl cellulose nanoparticles as stabilizers for Pickering emulsions

Pickering emulsions stabilized by ethyl cellulose nanoparticles have recently received –great attention for their remarkable stability and numerous industrial applications. De- spite this, the exact stabilization mechanism of such Pickering emulsions is still not fully understood. Both the stabilization of the emulsion by particle adsorption at the inter- face and through network formation in the continuous phase (leading to a yield stress) have been suggested. In this work we study soybean oil-in-water emulsions stabilized by ethyl cellulose nanoparticles and find, by the use of confocal microscopy and interfa- cial tension measurements, that the main stabilization mechanism of this nanoparticle- stabilized emulsions is the adsorption of the particles at the interface, instead of forming a network in the continuous phase. At the same time, oscillatory rheology measurements reveal that the emulsions exhibit a yield stress well below the random close-packing limit for hard spheres, suggesting short-range interactions between the droplets caused by the presence of the particles at the interface. The presence of the particles at the interface in combination with the observed rheological behavior of an attractive emulsion gives a strong indication for a particle-bridged stabilized emulsions.

Emulsifying behavior between oil and water of flowback fluids from acidizing oil wells based on high-voltage electric field oil–water separation technology

Emulsion stabilization mechanism caused by the multiple actions of NaCl charges, polyacrylamide, and solid nanoparticles.

Stabilization mechanism of reverse emulsions containing chromium (III): effect of interphase modification and dispersed phase viscosity

The stabilization mechanism of concentrated and highly concentrated emulsions containing chromium (III) sulfate colloidal solution as dispersed phase is presented. It is concluded that the internal interphase is stabilized mechanically by a chromium (III)—dodecyl sulfate complex formed during emulsion preparation. Moreover, the dynamic viscosity of the colloidal solution plays a significant role in emulsion stabilization. Both formation of a mechanically stable interphase and the viscosity of the colloidal solution depend drastically on the initial composition of the phases. To derive the corresponding stabilization mechanism, we quantify this dependency by employing empirical modeling of the maximum content of the dispersed phase, taken as a measure of the emulsion stability. Analysis of the model reveals a complex interplay of the stabilization and destabilization processes involved which depend on the mechanical properties of both the interphase and the disperse phase. In particular, we demonstrate that the highest content of the dispersed phase can be achieved when the initial composition of the phases favors the formation of a stiff interphase and the viscosity of the dispersed phase is sufficiently high.

Effect of ultrasound assisted emulsification in the production of Pickering emulsion formulated with chitosan self-assembled particles: Stability, macro, and micro rheological properties

Chitosan is not a good Pickering emulsion-stabilizer owing to its high hydrophilic properties at low pH. This study prepared chitosan self-assembled particles (pH chitosan = 6.6) stabilized Pickering emulsion by ultrasound assisted emulsification. The effects of ultrasound time on the microstructure, stability, macro and micro rheological properties of the Pickering emulsion were investigated, and the underlying mechanism of emulsion stabilization was also clarified. The chitosan particles were successfully adsorbed on the oil-water interface confirmed by the confocal laser scanning microscope (CLSM). After ultrasound treatment (20 kHz, 300 W, 1, 3, 5, 7, and 9 min), the droplet size and viscosity of the Pickering emulsion decreased. The macroscopic viscosity index (MVI), elasticity index (EI) of the Pickering emulsion decreased with the increase of ultrasound time, while the fluidity index (FI) was reversed. Ultrasound treatment improved the stability of Pickering emulsion observed by the turbiscan stability index (TSI) prior to 5 min. In conclusion, ultrasound assisted emulsification affected the stability of the Pickering emulsion mainly by affecting the particle size and viscosity of the emulsion. The chitosan self-assembled particles stabilized Pickering emulsion prepared by ultrasonic treatment (5 min) stabilized at room temperature at least for 60 days with no delamination.

Structural and emulsion stabilization comparison of four gelatins from two freshwater and two marine fish skins

This study analyzed the structural and emulsion stabilization properties of two freshwater and two marine fish skin gelatins: Chinese longsnout catfish skin gelatin (CLCSG), silver carp skin gelatin (SCSG), salmon skin gelatin (SSG), and Alaska pollack skin gelatin (APSG). Their gel strengths (Bloom values) were: 361 ± 1 (SCSG) > 253 ± 4 (CLCSG) > 69 ± 1 (SSG) > 36 ± 2 (APSG). Higher molecular weights and α/β subunit contents of gelatins might induce higher gel strengths. Both creaming and droplet stability were completely the same to the contents of imino acids, β-sheet percentages, and β-turn percentages, whereas they were completely the opposite to random coil percentages. The emulsion stabilization mechanisms involved an “fish skin source – protein chemical composition – protein secondary structure – protein functional properties – emulsion stability” route. This study provided useful knowledges for gelatin science and for the comprehensive utilization of aquatic by-products in gelatin industry.

Water-in-Water Emulsions, Ultralow Interfacial Tension, and Biolubrication

Water-in-Water Emulsions, Ultralow Interfacial Tension, and Biolubrication

Comparison of silver carp fin gelatins extracted by three types of methods: Molecular characteristics, structure, function, and pickering emulsion stabilization

High value-added utilization of different aquatic by-products is an increasingly urgent issue in aquatic science and industry. In this work, the effects of extraction methods on the molecular characteristics, structural properties, functional properties, and Pickering emulsion stabilization behaviors of silver carp fin gelatins were comprehensively studied. All the results showed molecular characteristics of silver carp fin gelatin was the key parameter to determine their functional properties such as wide gel strength range, excellent water-holding capacity, and excellent Pickering emulsion stabilization ability. The Pickering emulsion stabilization mechanisms of fin gelatins involved an “extraction method – protein molecular characteristics – fat-binding capacity – droplet structure – water phase properties – Pickering emulsion stability” route. This work could be helpful to understand the basic information on how the molecular characteristics determine the functions of gelatins. It would be also useful for the high value-added utilization of aquatic by-products and gelatins.