Oil-water Interface Research Articles

The conformational modification of myofibrillar protein by magnetic field improves its emulsification properties

This study investigated the effect of different magnetic field treatments (0, 3, 6, 9, 12 mT) on the structure and emulsification properties of myofibrillar protein (MP). The results showed that the emulsion stabilized by MP with 3, 6, 9 mT magnetic field treatments possessed higher emulsifying ability, storage stability and apparent viscosity, since magnetic field induced the structural unfolding of MP and exposed the hydrophobic groups (the surface hydrophobic increased from 30.10 to 43.73 μg). Meanwhile, the magnetic field treatments decreased the MP particle size from 1752.00 to 1278.67 nm, which was favorable for the diffusion and adsorption of proteins at the oil-water interface, thus improving the MP emulsification ability and stability. Furthermore, the 9 mT magnetic field-treated MP had the best ability to emulsify oil droplets with a more uniform and smaller emulsion size from 28.593 to 23.443 μm. However, high-intensity magnetic field treatment (12 mT) caused MP particles to aggregate and the hydrophobic binding sites to be buried, which was not conducive to encapsulating oil droplets.

The two-faced functionality of birch glucuronoxylan in an emulsion-based carrier of vitamin D3

Emulsions are commonly used to fortify beverages with oil-soluble nutrients. Such emulsions must be physically stable, prevent the cargo nutrient from chemical degradation, and release the nutrient at the right time during digestion. Wood hemicelluloses, with their proven capability in producing nanoemulsions and preventing oil oxidation, have the potential to facilitate such a fortification method. These hemicelluloses are unique, as the presence of residual lignin was proven essential in their functionality. However, the structural interplay between the residual lignin and the polysaccharide fraction at the oil-water interface is unknown, including their effects on the storage stability and digestibility of a loaded bioactive compound. We studied the performance of emulsions stabilized by two grades of birch glucuronoxylans (GX) as vessels for vitamin D3. Both GXs showed similar protective performance to methylcellulose regardless of the lignin content during storage and the gastric phase of digestion. The unrefined GX, which contained larger lignin moieties, delayed the release of vitamin D3 during intestinal digestion. We concluded that the interface is primarily built of a polysaccharide layer with the lignin moieties facing towards the oil phase. We have thus highlighted the potential of GX-stabilized emulsions as carriers of vitamin D3. Additionally, these results advance the understanding of lignin-polysaccharide interplay towards a rationalized strategy in biorefining of wood hemicelluloses, for which the ratio of lignin-to-polysaccharide can be adjusted during extraction and post-extraction treatments to obtain a tailor-made emulsifier for various emulsion-based products.

Dynamic interfacial adsorption and emulsifying performance of self-assembled coconut protein and fucoidan mixtures

The functional properties of protein are affected by their aggregation behavior and morphology. In this study, the self-assembled coconut protein aggregates with specific morphology, including small amorphous aggregates (WLA), spherical-like aggregates (SLA) and rod-like aggregates (RLA), were regulated to form. The self-assembled process resulted in a decrease in fluorescence intensity and an increase in the surface hydrophobicity of coconut protein. Fucoidan was added to improve the stability of protein solutions, and the interfacial adsorption behavior was evaluated by dilatational rheology analysis. The results showed that the aggregation state of coconut protein affected its ability to reduce surface tension, and the interfacial layers mainly exhibited elastic property at oil-water interface (tanφ < 0.5). For macroscale analysis, the emulsions based on self-assembled coconut protein exhibited smaller droplet size, better rheological properties and centrifugal stability, especially WLA and RLA. This study may provide a reference to inspire the utilization of self-assembled coconut protein in the food industry.

Catalyst-free selective oxidation of C(sp3)-H bonds in toluene on water

The anisotropic water interfaces provide an environment to drive various chemical reactions not seen in bulk solutions. However, catalytic reactions by the aqueous interfaces are still in their infancy, with the emphasis being on the reaction rate acceleration on water. Here, we report that the oil-water interface activates and oxidizes C(sp3)-H bonds in toluene, yielding benzaldehyde with high selectivity (>99%) and conversion (>99%) under mild, catalyst-free conditions. Collision at the interface between oil-dissolved toluene and hydroxyl radicals spontaneously generated near the water-side interfaces is responsible for the unexpectedly high selectivity. Protrusion of free OH groups from interfacial water destabilizes the transition state of the OH-addition by forming π-hydrogen bonds with toluene, while the H-abstraction remains unchanged to effectively activate C(sp3)-H bonds. Moreover, the exposed free OH groups form hydrogen bonds with the produced benzaldehyde, suppressing it from being overoxidized. Our investigation shows that the oil-water interface has considerable promise for chemoselective redox reactions on water without any catalysts.

Multifunctional ceramifiable silicone foam for smart fire fighting

The development of multifunctional silicone foam with high fire safety is of great significance to realize intelligent fire protection but challenging. Herein, a multifunctional ceramifiable fire-retardant silicone foam (MCSF) was fabricated by Ti3C2Tx nanosheet (MXene), multiwalled carbon nanotube (MWCNT), γ-aminopropyltriethoxysilane (APTES), Karstedt catalyst (Pt) and vinyl dimethylsiloxane via water–oil interface induced self-assembly and dehydrogenation foaming at room temperature. MCSF possessed low density and good mechanical properties. Its improved thermoelectric performance and sensitive fire-warning capability of MCSF were attributed to the skeleton supporting effect and unique electron transport effect between MWCNT and MXene. When being burned, MCSF was able to trigger the fire-warning system within 2.4 s and repeatedly alarm the fire reignition. Furthermore, owing to the synergism between APTES and Pt, MCSF exhibited good ceramization performance. When encountered high temperature, the MCSF surface rapidly ceramized, generating a ceramic-like barrier layer to block the further flame ablation, and it quickly self-extinguished after removing from flame. Besides, MCSF showed impressive thermal insulation and durable piezoresistive sensing. This work provides a new strategy for the preparation and application of multifunctional fireproof polymer foams.

Preparation of protein-polyphenol-polysaccharide ternary complexes to regulate the interfacial structure of emulsions: Interfacial behavior and emulsion stability

This study investigated the effect of protein-polyphenol-polysaccharide ternary complexes prepared from polysaccharides with different charges on emulsion stability. Sodium alginate (ALG), chitosan hydrochloride (CHC) and oat β-glucan (OG) were used as representational polysaccharides. The interfacial rheology showed that CHC increased the adsorption rate of WPI-rutin complexes at the oil-water interface, while ALG and OG reduced the adsorption rate. Furthermore, WPI-Rutin-CHC complexes effectively reduced the interfacial tension from 11.16 mN/m to 9.41 mN/m. Compared with other ternary complexes, the oil-water interface layer composed of WPI-Rutin-CHC complexes had the highest interfacial viscoelasticity and mechanical strength. Moreover, the emulsion prepared by WPI-Rutin-CHC complexes had the lowest instability index (0.17) and the smallest droplet size (660 nm), indicating the highest stability among all the emulsions. The microstructure results indicated that the thick interfacial layer was observed in WPI-Rutin-CHC emulsion, while thin interfacial layers were found in other emulsions. These results revealed the stability mechanism of emulsions prepared by ternary complexes and provided guidance for the preparation of stable emulsions.

Effects of non-covalently bound polyphenols/vitamins on the structure and functional characteristics of egg yolk powder

The egg yolk powder (EYP) was modified in this study by incorporating the tea polyphenols (TP), rosemary extract (RE), curcumin (CC), ascorbic acid (AA), and vitamin E (VE) to create the complex of polyphenols/vitamins-EYP. The structure, flavor, and emulsification properties of the complex were investigated. The results demonstrated that the addition of these five substances enhanced the flavor of EYP. Among them, VEP (EYP modified by VE) exhibited the flavor profile closest to EYP, while TPP (EYP modified by TP) had the most different flavor compared to EYP. This was because VE could induce secondary and tertiary structural changes in EYP and exposed more functional groups for binding with volatile flavor compounds such as hexanal, 1-octen-3-ol, and benzaldehyde, thereby improving the overall flavor of EYP. However, due to its larger molecular weight (1099.62 Da), VE exhibited the limited degree of interaction with EYP, thereby enabling it to preserve the overall flavor profile of EYP. On the other hand, TP possessed most active hydroxyl groups, which easily interacted with EYP, forming new complexes that significantly altered its flavor characteristics. Among the five modified powders, VEP had the highest emulsification, but it was still lower than that of EYP. This was because the particle size of VEP (1592.75 nm) was higher than that of EYP (821.88 nm), which was not conducive to the rapid movement to the oil-water interface, resulting in the reduced emulsification.

Molecular dynamics simulation of wax micro-structure characteristics in the oil-water emulsion

As a key issue in the flow assurance of wax-containing crude oils, the microscopic mechanism of wax deposition in multiphase pipelines is still unclear. Based on macroscopic experimental data, two forms of crystallized wax have been found under an oil-water emulsion, including adsorbed wax on the interface of water droplets and suspended wax in the bulk oil phase, which are the important factors influencing wax deposition. However, the micro-formation mechanism of the adsorbed & suspended wax is not elucidated. In this work, molecular dynamics simulations are used to investigate the micro-structure characteristics of the adsorbed & suspended wax in the oil-water emulsion containing surfactant Span60. A method is proposed to quantitatively calculate the distributions of the adsorbed & suspended wax and the percentage of wax adsorption area at the oil-water interface. The results indicate that surfactant with the hydrophilic end will insert into the water phase and the trailing hydrophobic end stretching will point to the oil phase during co-crystallizing with wax molecules. Meanwhile, the interface tension is further reduced by tilting the adsorbed wax tail chain to enhance the adsorption stability. Based on the complicated influence of surfactants on wax adsorption, the quantitative distribution characteristics of the adsorbed & suspended wax in the oil-water emulsion are complex under different wax carbon numbers and surfactant/wax contents. This microscopic investigation of wax distribution in oil-water emulsion can support the establishment of better strategies for solving the wax deposition problem in multiphase flow.

Complexation of locust bean gum and κ-carrageenan microgels, from aqueous phase to oil-water interface

Although polysaccharide microgels exhibit potential as clean-label emulsifiers, the stability of emulsions in commercial application is still a challenge. The current work points out that specific complexation between polysaccharide molecules and polysaccharide microgels can benefit the interfacial adsorption of polysaccharide microgels and emulsion stability. The complexation of κ-carrageenan microgels (KCMs) and locust bean gum (LBG) was investigated for the first time, which was evaluated by visual appearance, rheological behavior, thermal stability, and microscopic morphology. Results indicate the low concentration of LBG promotes the clustering of KCMs, whereas high concentration of LBG can envelop and segregate KCMs. Subsequent blending with LBG could enhance the interfacial adsorption of KCMs, and multi-layers are observed when LBG concentration exceeds 0.3 wt%. LBG can obviously decrease the emulsion droplets size and improve the storage stability of emulsions, KCMs + LBG (0.2–0.5 wt%) stabilized emulsions could keep stable after three consecutive freeze-thaw cycles. Based on the specific complexation between KCMs and LBG, the layer-by-layer emulsification could be achieved. This strategy can inspire other polysaccharide microgel emulsifiers, which could be a feasible solution for improving the stability of polysaccharides microgels stabilized emulsions.

Numerical simulation of residual oil distribution characteristic of carbonate reservoir after water flooding

Carbonate reservoirs are characterized by abundant reserves and are currently focal points for development in oil and gas producing regions such as the Ahdab oilfield, Tarim Basin, Sichuan Basin, and Ordos Basin. The primary method for exploiting carbonate reservoirs is waterflooding. However, due to the complex pore structure and pronounced heterogeneity of carbonate rocks, the waterflooding process often leads to an unclear distribution of remaining oil and low waterflooding recovery efficiency, significantly impacting the stable and high production of carbonate reservoirs. This paper presents a two-phase flow model of oil and water in distinct pore structures by integrating fluid flow equations and interface tracking equations. It visually represents the waterflooding process at the pore scale, elucidates the distribution and formation mechanism of remaining oil, and discusses the mechanism of microscopic displacement efficiency change. The study reveals that: 1) After waterflooding, the distribution patterns of remaining oil can be categorized into dead-end remaining oil, pressure balance remaining oil, wall-bound remaining oil, Jamin effect remaining oil, and water-encapsulating remaining oil, which are governed by microscopic pore structure, wettability, and preferential flow paths; 2) From the perspective of actual reservoir displacement efficiency, intergranular pores &amp;gt; intergranular dissolved pores &amp;gt; visceral foramen &amp;gt; mould pore, with this trend being more pronounced under hydrophilic wetting conditions; 3) Given the oil-wet to strong oil-wet wettability characteristics of these carbonate rocks, capillary forces pose significant resistance during waterflooding. The conclusion underscores the importance of leveraging the reservoir’s microscopic pore structure and wettability characteristics for actual oil wells, elucidating the evolutionary law of the mechanical mechanism of oil-water interface advancement, clarifying oil-water percolation characteristics at the pore scale, and understanding the microscopic displacement physical mechanism, all of which are crucial for guiding the design of schemes aimed at enhancing reservoir recovery efficiency.

CO2-switchable emulsion with controllable stability and viscosity based on chitosans and cetyltrimethylammonium bromide

Emulsions have extensive applications in food, cosmetics, and agriculture, while the requirements for emulsions differ in various fields. It is a challenge for one emulsion to satisfy multiple requirements in different applications. Herein, CO2-switchable emulsions with controllable stability and viscosity were prepared by a mixture of chitosans (CS) and CTAB. After adding low concentrations of CTAB (e.g. 0.5 mM), the viscous Pickering emulsions stabilized by CS alone were converted into moderate-viscous Pickering emulsions due to the competition adsorption between CS aggregates and CTAB at the oil-water interface. The transformation of emulsion types (such as Pickering and conventional emulsions) and the emulsion's stability and viscosity were controlled by CO2/N2 trigger. Furthermore, at high CTAB concentrations (≥ 0.8 mM), a novel long-term stable conventional emulsion was obtained after the CS aggregates at the oil-water interface were entirely replaced by CTAB. Compared with other stimuli, CO2 is recognized as a green trigger that doesn't cause contaminations in the system, which has potential applications in organic synthesis and polymerization. Our strategy provides a simple and effective method to smartly control the properties of the emulsions (such as the emulsion type, stability, and viscosity), obtaining an intelligent emulsion to meet different requirements in many applications.

Dispersion of polyacrylamide and graphene oxide nano-sheets for enhanced oil recovery

Hydrolysed polyacrylamide (HPAM) is widely used in enhancing oil production during tertiary flooding processes by improving the sweep efficiency . However, HPAM faces many challenges under high-temperature and high-salinity conditions mainly caused by the degradation. To overcome these challenges, incorporation of approprioate nanoparticles into HPAM solutions have been recently suggested to enhance its performance during the enhanced oil recovery (EOR) process. The current study specifically investigated the potential of amphiphilic graphene oxide (GO) in enhanicng the performance of HPMA. Its influences on HPAM in terms of the surface activity at the oil-water interface, the mobility behaviour, and the effectiveness in oil recovery were examined. The results revealed that adding up to 0.8 wt% of GO into HPAM reduced the oil-water interfacial tension (IFT) from 62.54 mN/m to 42.78 mN/m, and the contact angle (CA) from 71.08º to 68.84º, while in the mean time increasing the viscosity from 9.07 mPas to 16.49 mPas. Furthermore, the pilot core-flooding study demonstrated that with an addition of 0.8 wt% GO, HPAM achieved higher oil recovery rate (i.e., 76.83 %) than that of the pure HPAM (i.e., 67.39 %). The improved oil recovery performance was attributed to a better mobility ratio, resulting from the increased viscosity of the composite and reduced IFT, which was facilitated by the amphiphilic behaviour of GO, as supported by the desirability model.

Study on the hydrate growth characteristics and rheology of silica-containing sand water-in-oil emulsion system

Understanding the transportability of silica-sand-containing hydrate slurries is crucial for production safety of non-consolidated natural gas hydrate reservoirs, especially when solid-state fluidization technology is utilized. Despite some research on silica sand and marine sediments’ influence on hydrate formation kinetics, rheological studies are scarce for systems with silica sands. The formation process of cyclopentane hydrates under the coexistence of hydrophilic silica particles and surfactants were observed. The effects of the concentration and particle size of silica sands as well as the water cut and surfactant concentration of emulsion on the rheological properties of hydrate slurries were investigated using a rheometer. The results indicated: (1) Hydrophilic sand aggregates were entrapped in water droplets, indirectly affecting the oil–water contact area due to the increase in water droplet volume, which was conducive to the combination of alkanes and water molecules to form a hydrate shell; silica particles provided nucleation sites at the oil–water interface to promote the adsorption and aggregation of cyclopentane molecules. (2) The synergistic effect of silica sand and surfactants significantly shortened the induction time of hydrates and increased the viscosity of the slurry. As the concentration of silica sand (1 wt%, 5 wt%, 10 wt%) increased, the induction time of hydrate formation decreased by 44.8 min. Within the concentration range below 5 wt%, the viscosity of the slurry increased as the concentration increased, with an amplitude of 13830.7 mPa·s. The induction time of hydrate formation decreased with increasing silica sand particle size (2 μm, 6.5 μm, 12 μm), but the size of silica sand particles had no significant effect on the viscosity of the slurry. (3) Hydrate slurries in all systems exhibited shear-thinning behavior. There was no obvious relationship between the yield stress of slurry under different silica sand concentrations. However, the yield stress of the slurry was inversely proportional to the size of silica sand particles. The yield stress decreased by 141.13 Pa when the size of silica sand particles increased from 2 μm to 12 μm. Overall, this study highlighted the influence of silica sand presence on flow safety assurance in solid-state fluidization technology.

Mechanism of discoloration of Antarctic krill oil upon storage: A study based on model systems

The reddish-orange color of Antarctic krill oil fades during storage, and the mechanism remains unclear. Model systems containing different combinations of astaxanthin (ASTA), phosphatidylethanolamine (PE), and tocopherol were subjected to accelerated storage. Among all groups containing ASTA, only the ones with added PE showed significant fading. Meanwhile, the specific UV–visible absorption (A470 and A495) showed a similar trend. Peroxide value and thiobarbituric acid reactive substances increased during storage, while ASTA and PE contents decreased. Correlation analysis suggested that oxidized PE promoted fading by accelerating the transformation of ASTA. PE content exceeded the critical micelle concentration (1μg/g) indicating the formation of reverse micelles. Molecular docking analysis indicated that PE also interacted with ASTA in an anchor-like manner. Therefore, it is speculated that amphiphilic ASTA is more readily distributed at the oil-water interface of reverse micelles and captured by oxidized PE, which facilitates oxidation transfer, leading to ASTA oxidation and color fading.

Whipped cream stabilized by faba bean protein isolate microgel particles substituted for sodium caseinate: Whipping performance and foam stabilization analysis

In this study, faba bean protein isolate microgel particles (FPIMPs) were used as substitutes for sodium caseinate in whipped cream ingredients, the effect of FPIMPs on properties of emulsion system before whipping and foam system after whipping was investigated, and the stabilization mechanisms of whipped cream systems stabilized by FPIMPs and sodium caseinate, respectively, were analyzed and compared. Elevated levels of FPIMPs facilitated the cross-linking and flocculation of oil droplets in the emulsions, which further promoted the formation of gel-like networks, leading to a larger average particle size and higher viscoelasticity. Meanwhile, the firmness, shaping ability, and shape retention ability of whipped creams were gradually enhanced with the increase of FPIMPs content. The quality of whipped creams with FPIMPs concentrations of 0.8% and above was comparable to that of commercial whipped cream. Tribological results showed that the coefficient of friction of whipped creams was roughly negatively correlated with the concentration of FPIMPs, and the lubricating properties of whipped creams with high FPIMPs concentrations (>0.8%) were better than those of commercial whipped cream. The oil-water interface film with high mechanical strength formed by FPIMPs made the FPIMPs-stabilized whipped creams more resistant to whipping than sodium caseinate-stabilized whipped cream, delaying the occurrence of excessive whipping phenomenon. This work has important implications for expanding the application of faba bean protein isolate in food systems, as well as provides new strategies for the development of healthier plant-based whipped creams.

Regulated the aggregation of bile salts by β-Cyclodextrin and Tangeretin at the oil-water interface for inhibiting lipid digestion

Our previous research has demonstrated that the changes in oil-water interface properties during dietary digestion have a significant impact on the digestion and absorption of lipids. In this study, these methods of interfacial tension, microscopic examination, isothermal titration calorimetry (ITC), molecular dynamics (MD) simulations, and free fatty acid (FFA) release were used to evaluate the effect and mechanism of assembly behavior of tangeretin (TAN) and β-cyclodextrin (β-CD) at the oil-water interface on the rate of lipid digestion. The results showed that the combination of β-CD and TAN at the oil-water interface made the interfacial tension first increase and then decrease with the increase of TAN: β-CD ratios (M: M, 1:1–20). The self-assembled structure formed by the interaction of TAN and β-CD can produce stronger interaction with bile salts, which makes bile salts flocculate at the oil-water interface. The FFAs release experiment showed that a TAN: β-CD molar ratio of 1:8 exerted the highest inhibitory (34.92%) effect on lipid digestion. Furthermore, the results from ITC and MD simulations confirmed that BS exhibited stronger binding affinity with the TAN/β-CD complex. These results suggested that the TAN/β-CD complex caused the bile salts to prematurely gather at the oil-water interface, thereby thickening the interfacial layer, hindering the displacement of bile salts and lipase between droplets, and ultimately impeding lipid digestion. This study emphasized the promising potential of the synergistic effect between cyclodextrin and flavoring molecules in inhibiting lipid digestion, proposing a novel avenue for the development of reduced-fat foods with enhanced health benefits.

Study of Interfacial Properties of Anionic–Nonionic Surfactants Based on Succinic Acid Derivatives via Molecular Dynamics Simulations and the IGMH Method

Surfactants are widely used in fields such as oil recovery and flotation. The properties and mechanisms of surfactants can be effectively studied using molecular dynamics (MD) simulations. Herein, the aggregation behavior of surfactants was studied at the oil–water interface by MD simulation, and the micro-morphology of surfactants was analyzed under a low concentration and saturated state at the oil–water interface, respectively. The visualization results of the MD simulation showed that DTOA was saturated at the oil–water interface at 120 surfactant molecules, whereas 160 surfactant molecules were required for BEMA. In addition, the effect of surfactant concentration on the interfacial thickness and hydrogen bond distribution was studied, with the inflection point of hydrogen bond distribution identified as a characteristic parameter for surfactant saturation at the oil–water interface. The aggregation behavior of their hydrophobic and hydrophilic chains at the oil–water interface was qualitatively assessed using order parameters. Finally, the aggregation state of surfactants in salt-containing systems was studied, and it was found that the surfactants could effectively adsorb magnesium ions and calcium ions at the oil–water interface. However, the curve of the number of hydrogen bonds varies greatly, with a possible reason being that BEMA has a different coordination manner with diverse metal ions. This study provides some original insights into both the theoretical study and practical application of anionic and nonionic surfactants.

Conjugation of coconut protein with ferulic acid promotes interfacial adsorption and mitigates lipid oxidation in O/W emulsion

The formation of small droplets in emulsion systems promotes lipid oxidation, affecting their shelf life. In this study, ferulic acid was covalently grafted onto coconut protein (CPI) through alkaline treatment method. The structural characteristics, interfacial properties, emulsifying properties, and oxidative stability of emulsions prepared by coconut protein-ferulic acid covalent complexes (CPF) were investigated. The results showed that covalent grafting of ferulic acid could change the physicochemical properties of coconut protein, including altering protein secondary and tertiary structures, enhancing the absolute value of zeta potential and antioxidant activity [2, 2-diphenyl-1-picrylhydrazyl (DPPH•) and 2, 2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+)]. Meanwhile, the interfacial behavior of CPI and CPF was characterized by dissipative quartz crystal microbalance and dilatational rheology analysis. Compared to CPI, CPF could diffuse to the oil-water interface quickly (from 0.084 ± 0.002 to 0.154 ± 0.003 mN/m/s1/2), and formed a thick interfacial layer dominated by elasticity, which enhanced the centrifugal stability of CPF-stabilized emulsions and effectively inhibited lipid oxidation within a 15-day storage period. Our results clearly demonstrated that coconut protein-ferulic acid conjugated complexes could improve emulsion stability and mitigate lipid oxidation, owing to the strong electrostatic repulsion interaction and high diffusion rate at interface. These findings may provide comprehensive insights for the further design and development of protein-polyphenol covalent complexes in the food industry.

Pickering emulsion gel of polyunsaturated fatty acid-rich oils stabilized by zein-tannic acid green nanoparticles for storage and oxidation stability enhancement

HypothesisPoor storage stability and oxidative deterioration are the common drawbacks of edible oils rich in polyunsaturated fatty acids (PUFAs). We hypothesized that the natural zein/tannic acid self-assembly nanoparticles (ZT NPs) could be employed as stabilizers to anchor at the oil–water interface, thus constructing Pickering emulsion gel (PKEG) system for three types of PUFA-rich oils, soybean oil (SO), fish oil (FO) and cod liver oil (CLO), to improve the storage and oxidation stability. ExperimentsZT NPs were prepared by the anti-solvent coprecipitation method, and the three-phase contact angle, FT-IR, and XRD were mainly characterized. To observe the shell-core structure and oil–water interface details of SO/FO/CLO PKEGs by confocal laser scanning microscope and cryo-scanning electron microscope. Accelerated oxidation of FO was performed to assess the protective effect of PKEG on lipids. FindingsThe SO, FO, and CLO PKEGs stabilized by 2 % ZT NPs, with oil fraction (φ = 0.5–0.6), were obtained. PKEGs show high viscoelasticity, clear shell-core structure spatial network structure, and ideal storage stability. Under accelerated oxidation, the degree of oxidative rancidity of FO PKEG was obviously lower than that of free FO. Overall, this work opens up new possibilities for using natural PKEG to prevent oxidative deterioration and prolong the shelf-life of PUFA-rich oils.

High internal phase Pickering emulsions stabilized by egg yolk-carboxymethyl cellulose as an age-friendly dysphagia food: Tracking the dynamic transition from co-solubility to coacervates

Although protein-polysaccharide complexes with different phase behaviors all show potential for stabilizing high internal phase Pickering emulsions (HIPPEs), it is not clarified which aggregation state is more stable and age-friendly. In this study, we investigated and compared the stability and age friendliness of HIPPEs stabilized with egg yolk and carboxymethyl cellulose (EYCMC) in different phase behaviors. The results revealed differences in particle size, aggregation state, charge potential, and stability of secondary and tertiary structures of EYCMC. The behavior of EYCMC at the oil-water interface was mainly divided into three phases: rapid diffusion, permeation, and reorganization. The electrostatic interaction, kinetic hindrance, and depletion attraction were the mechanisms primarily involved in stabilizing HIPPEs by EYCMC. Rheological analysis results indicated that HIPPEs had excellent viscoelasticity, structural recovery properties and yield stress. HIPPEs were used in 3D printing, electronic nose testing, IDDSI testing and in vitro digestive simulations for the elderly, demonstrating a fine appearance, safe consumption and bioaccessibility of β-carotene. Soluble complexes showed the best stability and age friendliness compared to other aggregated forms. This study serves as a foundational source of information for developing innovative foods utilizing HIPPEs.