Oil Phase Concentration Research Articles

Enhancement of Pickering effect of ovalbumin with bacterial cellulose nanofibers prepared by electron beam irradiation and encapsulation of curcumin

In this study, the enhancement of Pickering effect of ovalbumin (OVA) with bacterial cellulose nanofibers (BCNFs) prepared by electron beam irradiation was investigated and the environmental stability of oil-in-water Pickering emulsions stabilized by OVA/BCNFs complexes was explored by varying ratios of OVA/BCNFS (1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1) and oil phase concentrations (10 %, 20 %, 30 %, 40 %, 50 %, 60 %). Droplet sizes of Pickering emulsions were decreased with the increase of the proportion of BCNFs, while the viscosity and storage modulus (G') of Pickering emulsions were increased. The gel strength of Pickering emulsions was positively correlated with the oil phase content. Pickering emulsions stabilized by OVA/BCNFs complexes were endowed excellent environmental stability under varying pH, ionic strength, and thermal conditions. Moreover, after encapsulating curcumin in Pickering emulsions, the retention rates of curcumin were improved significantly during room temperature, UV light, and thermal treatment. The present study would contribute to the advancement of novel protein/polysaccharide stabilizers and offer novel insight for investigating the stability of Pickering emulsions and delivering lipophilic bioactive compounds.

Chickpea protein stabilized Pickering emulsions: As a novel mayonnaise substitute

This study investigates the characteristics of chickpea protein-stabilized Pickering emulsion transformed into a mayonnaise-like product, and examines the effects of altering the oil phase (65–73%) and high-pressure homogenization (0–300 Bar) on its appearance, rheological properties, thixotropy, particle size distribution, and freeze-thaw stability. The results reveal that with an increase in oil phase content or homogenization pressure, the chickpea protein emulsion undergoes a transition from an unstable to a densely packed state, exhibiting gel-like behavior with a significant rise in viscoelasticity and a gradual reduction in particle size. Augmenting the oil phase leads to a decrease in protein chain length and oil droplet size. Within the experimental range, when the chickpea protein content is 5%, and the oil phase is 69%, or when the oil phase is 65% with a homogenization pressure of 40 Bar, the emulsion demonstrates an optimal appearance and rheological properties closely resembling commercial mayonnaise products. This achievement represents a significant milestone in formulating emulsions that closely mimic the characteristics of prevalent mayonnaise products in the market.

Experimental investigation on forced imbibition characteristics of shale oil reservoir based on nuclear magnetic resonance method

After large-scale fracturing of shale reservoirs, the fracturing fluid will imbibe in the reservoir. In order to clarify the characteristics of imbibition and the distribution characteristics of crude oil in the stage of forced imbibition, this paper selects the core of some blocks in Qinghai and Gulong areas to carry out the shale forced imbibition experiment. Nuclear magnetic resonance technology is used to monitor the variation of crude oil. And the influence of core permeability and contact angle on forced imbibition is further analyzed. The results of the study show that the shale has a strong imbibition effect on the fracturing fluid. The content of oil phase in the core decreases, and the phenomenon of oil-water replacement occurs. Priority porosity for fracking fluids exists in the process of imbibition, where fracturing fluid preferentially enter smaller pores and can cause a short-term increase in the oil phase content in larger pores. With the continuous process of imbibition, the rate of imbibition oil gradually slowed down, and the fracturing fluid gradually permeates evenly into the rock sample. Both permeability and wettability affect the imbibition capacity of fracturing fluid in the forced imbibition stage.

Synthesis and Characterization of Emulsifiers Based on the Maillard Reaction and Its Application in Stabilized DHA Algal Oil Nanoemulsions.

The aim of this study was to optimize the formation of sodium caseinate (CS) and gum arabic (GA) complexes through the Maillard reaction and to evaluate their effectiveness in improving the emulsification properties and stability of docosahexaenoic acid (DHA) nanoemulsions. First, the best target polysaccharides were selected, and the best modification conditions were determined using orthogonal experiments. Secondly, the response surface experiments were used to optimize the preparation process of the emulsion. The stability, in vitro digestion characteristics, and rheological characteristics of the emulsion prepared by means of CS-GA were compared with the emulsion prepared using a whey protein isolate (WPI). After the orthogonal test, the optimal modification conditions were determined to be a reaction time of 96 h, a CS-GA mass ratio of 1:2, a reaction temperature of 60 °C, and a degree of grafting of 44.91%. Changes in the infrared (IR), Raman, ultraviolet (UV), and endogenous fluorescence spectra also indicated that the complex structure was modified. The response surface test identified the optimal preparation process as follows: an emulsifier concentration of 5 g/L, an oil-phase concentration of 5 g/L, and a homogenization frequency of five, and the emulsion showed good stability. Therefore, the use of a nanoemulsion as a nanoscale DHA algal oil delivery system is very promising for extending the shelf life and improving the stability of food.

Formation conditions of soy protein isolate-carrageenan complex particles and their stabilization effect on the relationship between structure and rheology of emulsions

This study investigated the formation conditions of the soy protein isolate (SPI)/κ-carrageenan (κCG) complex particles (SCP) and their stabilization effect on the structure and rheology of emulsions over the range of SCP concentration (Cp, 0.5%–2.5%, w/v) and oil phase content (φ, 10%–60%, v/v). By conducting turbidity titration of SPI/κCG mixtures with different ratios and ionic strengths, we observed the formation of soluble complexes in all samples at pH 6.0. The saturation complex ratio of SPI/κCG at pH 6.0 was 1:0.2 using isothermal titration calorimetry, and thermal complex with saturation ratio to form SCP as stabilizers could prepare emulsions with smaller droplet size in comparison of other ratios. Microstructure showed that SCP provided stabilization at the interface, and excess SCP formed network in the bulk phase to give solid-like emulsions. Furthermore, the power-law relationships of G′ with particle concentration (G' ∼ Cpn) and oil content (G' ∼ φm) was established. The exponent n and m decreased with increase of Cp and φ, indicating structure of SCPEs depends on Cp and φ. The G'/G″ crossover strain (γco) is indicator of breakdown of emulsion structure. For φ ≤ 20%, γco slightly decreased with increasing Cp; For 30%<φ<50%, γco increased with increasing Cp; For φ = 60%, γco significantly decreased with increasing Cp. In summary, these findings indicate the structure and rheology of soy protein-based emulsion can be regulated by controlling the formation condition of SCP and altering the SCP concentration and oil content.

Stability and 3D-printing performance of high-internal-phase emulsions based on ultrafine soybean meal particles

There are numerous studies on the application of soybean whey protein in three-dimensional (3D) printing. In this study, the effects of soybean meal particles (5%, 6%, 7%, 8%, 9%, and 10%) and oil-phase concentrations (70%, 72%, 74%, 76%, and 78%) on the stability and 3D-printing performance of a soybean-meal-based high-internal-phase emulsion were investigated. The results showed that the particle size of the emulsion decreased with increasing soybean meal particle concentration, and that increasing the concentration of the oil phase improved the viscoelasticity of the emulsion. Rheological tests further showed that the higher storage modulus of the emulsion indicated better support and stability. The emulsion with 8% soybean meal-particles and 76% oil-phase concentration exhibited the best printing effect. This study provides an effective solution for the preparation of stabilized high-internal-phase emulsions of soybean meal particles suitable for 3D printing.

Heat and Mass Transfer Characteristics of Oily Sludge Thermal Desorption

Oily sludge is a loose material containing solid and multiple liquid components. Thermal desorption is an efficient method of disposing of liquids from oily sludge. Most existing studies have mainly discussed the effect of some external process parameters on thermal desorption, with little discussion on the heat transfer characteristics and the variation in the wet component mass of oily sludge under heating. Small-scale experiments have been performed to measure the rise in temperature and liquid phase content change of the sludge during heating. The temperature rise rate increases with material density and increases faster during the initial heating stage, while it slows down as the liquid phase evaporates. The adhesive shear stress is determined by measuring the pulling force of the test rod, which decreases with decreasing water content and increases significantly with decreasing oil phase content. Heat transfer and energy distribution models have been developed to calculate the rise in the temperature of materials and the evaporation of contained liquids. The heat and mass transfer processes are obtained from simulation calculations by taking the initial material with a mass content of 25% water and 10% oil under a heating temperature of 500 °C. When the heating time reaches 135 min, the drying region reaches the boundary of the test container, at which the material temperature exceeds 350 °C. During the evaporation of different liquid-phase components, there are multiple segments in the corresponding temperature curves. The processing time and heat source temperature can be reasonably determined by analyzing the temperature rise of the material, and the effect of the disposal of liquids from oily sludge can be predicted by analyzing the changes in liquid content. The results may guide the formulation of process parameters for engineering project schemes for oily sludge disposal.

Specialized fat-and-oil emulsion food systems for the prevention of hyperlipidemia and obesity

The development of specialized fat-and-oil emulsion food systems for the prevention of hyperlipidemia and obesity is an important task of health concern in the Russian Federation. The aim of the study was to develop specialized fat-and-oil emulsion food systems for the prevention of hyperlipidemia and obesity, the distinctive features of which are the presence of functional ingredients and bioactive compounds that meet modern safety requirements, have a hypolipidemic effect and influence on body weight. Material and methods. As a source of fucoxanthin, an oil extract from the thallom (stratum) of the annual Undaria pinnatifida brown algae was used, obtained by re-extraction with soy oil for 8 hours from a glycerin extract (extractant - 60% glycerin solution, the duration of the process - 8 h). The determination of organoleptic parameters was carried out at a temperature of 20 °C 12 h after manufacture using standard methods. Organoleptic parameters were determined in the following sequence: consistency, appearance, color, smell, taste. Physical and chemical characteristics (mass content of fat, moisture, egg products in terms of dry yolk, acidity in terms of acetic acid, emulsion stability), acid and peroxide values were studied by standard methods. Fatty acid analysis of lipids was performed by gas-liquid chromatography. The fucoxanthin content was determined by spectrophotometric method. Results. The presented formulations of lipid compositions as the fat base of specialized oil-fat emulsion food systems for the prevention of hyperlipidemia and obesity included Schizochytrium sp. microalgae oil in a mass fraction of 3-6% as a source of ω-3 polyunsaturated fatty acids (PUFAs) (eicosapentaenoic and docosahexaenoic acids). An oil extract of U. pinnatifida brown algae in a mass fraction of 48-54% was used as a source of fucoxanthin. The total content of PUFA was significantly high - at least 73%, ω-6 PUFA prevailed (48.0-49.1%). However, the high content of ω-3 PUFA (at least 25%) should be also noted. The ratio of ω-3 to ω-6 PUFA was 1:1.72-1:1.90, which is atypical for individual vegetable oils traditionally used as the fat phase in fat-and-oil emulsion systems. The fucoxanthin content in the presented lipid compositions was 6.4-7.2 mg/100 ml. Edible fat-and-oil emulsion food systems for the prevention of hyperlipidemia and obesity (mayonnaise and mayonnaise sauces) with a given ratio of ω-3:ω-6 PUFA containing eicosopentaenoic and docosahexaenoic acids, as well as fucoxanthin, have been obtained. The extract of U. pinnatifida brown algae, containing fucoxanthin, significantly slowed down the processes of lipid oxidation and hydrolysis, as evidenced by changes in the peroxide and acid values of fat isolated from specialized fat-and-oil emulsion systems for the prevention of hyperlipidemia and obesity. Conclusion. Specialized fat-and-oil emulsion food systems for the prevention of hyperlipidemia and obesity (mayonnaise and mayonnaise sauces with different oil phase content), containing fucoxanthin, having an optimized fatty acid composition, a given ratio of ω-3:ω-6 PUFA, high content of essential PUFA (eicosopentaenoic and docosohexaenoic acids) are safe food products with traditional organoleptic characteristics and specified physical and chemical parameters.

Possible application of green algae as emulsifiers in foods and nutritional supplements

The high protein content (43.4 %) and the ability of dietary fiber in Spirulina (Arthrospira platensis) to retain water or vegetable oil make the alga suitable for use as an emulsifier in colloidal or emulsion systems. This study aimed to investigate the influence of Spirulina (Arthrospira platensis) (4%, 8%, 12%) as emulsifier on the physical and thermodynamic stability of model emulsions by determining parameters such as Gibbs energy, enthalpy, and entropy. Thermodynamic stability was estimated spectrophotometrically, and physical stability was determined by the Kozin method. It was shown that increasing the Spirulina concentration leads to a decrease in Gibbs free energy and an increase in the physical stability of all emulsions (20%, 40%, 60% oil phases) that are finely dispersed and microscopically determined. The highest percentage of retained emulsion (100 %) was at 12 % Spirulina with an oil phase content of 40 % or 60 %. From a rheological point of view, emulsions with Spirulina at 20 % oil phase showed plastic body behavior, and those with 40 % and 60 % oil phase showed pseudo-plastic behavior.

Optimization of Clove Oil Nanoemulsions: Evaluation of Antioxidant, Antimicrobial, and Anticancer Properties

Clove essential oil is traditionally used as an anesthetic, analgesic, or insecticide, and recently, its applications as an antimicrobial, antioxidant, or anticancer agent have been explored. Nanoemulsions are thermodynamically unstable dispersions (d &lt; 100 nm) produced by mixing two immiscible phases, which, in many cases, improve the stability and biological activities of functional ingredients for pharmaceutical, cosmetic, or food applications. This research optimized the formation of clove essential oil nanoemulsions by employing response surface methodology. The surfactant concentration was minimized by modifying the percentage of clove oil (0–100%), surfactant content (1–4%), and oil phase content (0–20%). In the optimum conditions, a nanoemulsion (93.19 ± 3.92 nm) was produced using 1.0% surfactant and 2.5% oil phase of which 50.7% was clove essential oil. The optimized nanoemulsion was stable in rapid stability tests (centrifugation, freezing–thawing, and heating–cooling), but its average droplet size increased during storage at different temperatures. The nanoemulsion contains a phenolic content equivalent to 736 mg gallic acid/mL. However, the antioxidant capacity of the essential oil (IC50 = 0.78 µg/mL) was dismissed in the nanoemulsion (IC50 = 2.43 µg/mL). The antimicrobial activity of the nanoemulsion showed strain–dependent behavior with MIC ranging from 0.0468 to 0.75 mg/mL, where E. coli and S. typhimurium were the most susceptible pathogenic bacteria. Finally, nanoencapsulation of clove oil showed higher in vitro cytotoxic activity against Caco–2 cancer cells (227 μg/mL) than free clove essential oil (283 μg/mL), but nanoemulsion (306 μg/mL) was less effective than oil (231 μg/mL) in the HT–29 line. This research shows the potential of clove essential oil nanoemulsions for developing biological therapies to treat diseases.

From an oil with “antifoaming” properties to stabilization for foam: A novel approach for establishing a long-term stable foam system

Can a foam be synergistically stabilized by particles and oil? Sure it can. A new strategy for preparing “capillary foam” based on whey protein isolate particles (WPs) was designed by co-stabilization with coconut oil (CO) to improve foam stability. Unique aspect of the “capillary foam” presented here was the protein particle-facilitated diffusion of the minority oil around the bubble. The foamability and foam stability were evaluated based on size, ζ-potential, and surface wettability of particles, as well as different oil phase concentrations. Foam stability was significantly improved in the presence of a minor amount of CO (1%, v/v). The size and hydrophobicity of the particles become important factors in determining the stability of the “capillary foam”. The oil/water contact angle (θo/w) of the particles was close to 90° at pH 5.0, which makes it easier for particles to adsorb at the oil/water interface compared to the air/water interface, thus facilitating the formation of the special structure of the “capillary foam” with high stability. The distribution of the oil phase around the bubble surface raised with the increase of oil phase mass fraction, although the stability decreases slightly. This strategy provides useful tips and achieves a fundamental breakthrough, which means that the new idea of “capillary foam” is promised to furnish a new solution to the challenge of food foam stability.

A smart material: Multi-stimulus-responsive composite microspheres prepared via RAFT polymerization as recyclable pickering emulsifiers and their application in stabilizing real oil phases

The development of smart composites to sustainably separate and recover oil from oily water had attracted much attention. In this study, tri-block (P(LMA-b-NIPAM-b-AA)) polymer brushes were controllably “grown on” the Fe3O4 surface by three-step surface-initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization to prepare Fe3O4-P(LMA-b-NIPAM-b-AA) (MNPLNA) magnetic nanospheres with interfacial activity. The MNPLNA nanospheres were characterized to demonstrate the triple response of pH, temperature and magnetism. Meanwhile, the comparison experiments showed that the MNPLNA nanospheres with tri-block structure had excellent interfacial activity. Then, the O/W type of Pickering emulsion was prepared by using MNPLNA nanospheres as the particle emulsifier. The size variation pattern of Pickering emulsion was comprehensively investigated by adjusting the concentration of nanospheres, oil-water ratio, electrolyte concentration and polarity of oil phase. Pickering emulsions were controllably separated by the action of an external magnetic field, and could be reversibly switched at least 10 cycles between emulsified and broken states under the trigger of pH and temperature. In addition, MNPLNA nanospheres exhibited excellent emulsification properties for stabilizing variety of real oil phases (e.g., canola oil, kerosene, diesel and crude oil). Based on this, MNPLNA nanospheres were applied as smart multifunctional materials in simulated kerosene-containing wastewater separation. MNPLNA nanospheres could be used to recover kerosene with high recovery rate after 10 separation cycles under the stepwise action of pH, temperature and magnetic field.

The formation and temperature stability of microemulsion emulsified by polyoxyethylene ether surfactant

The effect of polyoxyethylene chain length on the formation and temperature stability of W/O microemulsion emulsified by polyoxyethylene ether surfactant is investigated by dissipative particle dynamics simulation (DPD) on the mesoscopic level. The results show that W/O microemulsions can be formed by three polyoxyethylene chain length ether nonionic surfactants with decreasing the water-oil ratio equal to increasing the oil phase content. However, W/O microemulsion is most easily formed by diethylene glycol monododecyl ether (H1T2) with the smallest oxyethylene base.The results of temperature stability show that W/O microemulsion emulsified by H1T2 has better stability resistant to high or low temperature. In addition, the interfacial tension of the W/O microemulsion system is the lowest, the end-to-end distance of the surfactant molecule is smallest, and the molecular chain is the most curved at the water-oil interface. The theoretical simulation results can guide the formation of the W/O microemulsion induced by polyoxyethylene ether nonionic surfactant, and provide the guidance for its practical application.

High internal phase emulsions stabilized by pea protein isolate-inulin conjugates: Application as edible inks for 3D printing

High internal phase emulsions (HIPEs) are soft materials that can be designed to contain nutrients and active agents. As a result, they are being explored for their potential application as edible inks in 3D food printing applications. However, the rheological characteristics of HIPEs are often unsuitable for this purpose, resulting in unsatisfactory precision and resolution performance during 3D printing. This study aims to overcome these problems by creating HIPEs with improved rheological properties by using pea protein-inulin glycosylation products as plant-based emulsifiers. These conjugates were prepared from pea protein isolate (PPI) and inulin by glycosylation using a combined ultrasound/pH-shift method. The oil phase of these emulsions consists of omega-3 rich algal oil and lemon oil. We showed that stable HIPEs could be formed at an oil phase content of 80%. At this oil content, the oil droplets were uniform and stable, and the emulsions exhibited higher storage modulus. Compared to PPI alone or physical mixture of PPI and inulin, PPI-inulin conjugates formed oil droplets with smaller diameters and better uniformity, as well as thicker and denser biopolymer coatings. Compared with protein alone, the rheological analysis demonstrated that the HIPEs formulated with PPI-inulin conjugates had a higher viscosity, higher elasticity, higher recovery rate, and better thixotropy, indicating that they had physiochemical characteristics suitable for edible inks applications. This was confirmed by using the HIPEs as edible inks to 3D print model food objects. In conclusion, the pea protein-inulin conjugates fabricated in this study can be used as plant-based emulsifiers to form edible inks based on HIPEs. In principle, a range of nutrients and other bioactive agents could be incorporated into these inks for personalized nutrition applications.

OPTIMIZATION AND PHYSICAL CHARACTERIZATION OF QUERCETIN NANOEMULGEL FORMULA AS AN ANTIBACTERIAL AGENT

Objective: This research aims to optimize the quercetin nanoemulgel formula to improve quercetin solubility as an antibacterial agent. Methods: In this research, quercetin was formulated into nanoemulgel with the factorial design of three independent variables, the concentration of oil phase (virgin coconut oil), surfactant (Tween 80), and co-surfactant (Span 80). The nanoemulgel physical properties (viscosity, spreadability, transmittance value, zeta potential, and particle size) were tested. The data were evaluated using Minitab®18 software; if the p-value&lt;0.05, it is stated that there is a statistically significant difference in the formula, and the use of the response optimizer menu in the Minitab® 18 software determines the optimum formula with multiple responses. Results: The results showed that the concentration of quercetin used to inhibit the growth of Staphylococcus aureus was 2 mg/ml. The size of the particles had a mean of 62.487 nm, the polydispersity index had a mean of 0.365, and the percent transmittance had a mean of 95.533±0.113%. Measurements of the zeta potential had a mean of -26.712±0.154, with the viscosity and spreadability of the preparations made having a mean of 2495±0.250 cps and 4.795±0.028 cm. Conclusion: This study reported that the VCO amount of 3g, the tween amount of 12g and the span amount of 3.5g were found to be computational recommendations to achieve the optimum conditions only for percent transmittance value response.

Study of the Effect of Temperature on the Rheological Characteristics of Composite Fuel

The article is devoted to the study of the patterns of change in the rheological characteristics of composite fuels based on low-ash anthracite at a mass fraction of the solid phase of 40%, an oil phase concentration of Co = 49%, a water concentration of CH2O = 10%, and 1% of a chemical additive with an increase in temperature from 10 to 70 °C. It has been established that the dependence of the rheological characteristics of composite fuel on temperature indicators is complex. When the temperature changes from 20 to 30 °C, a plateau is observed (the change in the Kμt coefficient is ≈0.9), which has a significant deviation from the approximation dependence for calculating the Kμt coefficient. From the data obtained, it can be concluded that this type of fuel can successfully compete with traditional types of liquid fuel.

Pickering emulsions stabilized by reassembled oleosome protein nanoparticles for co-encapsulating hydrophobic nutrients

In this study, oleosome proteins were disassembled using guanidine hydrochloride to form shell-core colloidal particles (reassembled oleosome proteins, ROPs). These particles were then used to prepare a dual-compartment-structured Pickering emulsion to co-deliver curcumin (Cur) and vitamin D. The results showed that ROP can effectively encapsulate Cur inside the hollow structure. Moreover, at a Cur concentration of 100 μM, the ROP-Cur contact angle was 71.5°, which aids the preparation of stable Pickering emulsions. The most stable Pickering emulsion was then prepared by adjusting the ROP-Cur emulsifier and oil phase concentrations. The Pickering emulsion prepared with 2.0 mg/mL emulsifier and the addition of 10% oil phase displayed the best stability, with an average particle size, ζ-potential, and Turbiscan Stability Index of 2.2 μm, −31.5 mV, and 3.63, respectively. Notably, the emulsification process doesn't destroy the shell-like structure of ROP-Cur. Instead, it triggers the aggregation of ROP-Cur, which is finally adsorbed at the oil–water interface. Our designed strategy successfully affords double-compartment microdroplets and improves the storage stability of biologically active compounds.

Natural Amphiphilic Shellac Nanoparticle-Stabilized Novel Pickering Emulsions with Droplets and Bi-continuous Structures

Shellac is a natural amphiphilic substance, and its nanoparticles can be used to stabilize Pickering emulsions with droplets and bi-continuous structures. In this study, shellac nanoparticles (SNPs) were produced through the anti-solvent method, and these SNPs were used to produce a series of Pickering emulsions. Fourier transform infrared results showed that SNPs were generated through hydrogen bonding and hydrophobic effects. The contact angle of SNPs was 122.3°, indicating that hydrophobicity was their dominant characteristic. According to the results of confocal laser scanning microscopy, the Pickering emulsions stabilized by SNPs showed oil-in-water, bi-continuous structure, and water-in-oil characteristics, which were dependent on the oil-phase content. The resistance value of the emulsified part of these Pickering emulsion systems significantly increased at an oil-phase ratio of 80-90% (more than 105 MΩ), as compared with the 10-70% oil-phase content (around 1 MΩ). The viscosity of SNP-stabilized Pickering emulsions with bi-continuous structures was highest at 40% oil-phase content. The porous material prepared by using Pickering emulsions with bi-continuous structures as a template had an interconnected structure and was able to absorb both water and oil. This study indicated that these amphiphilic SNPs readily form bi-continuous structures and effectively stabilize Pickering emulsions with droplets. These SNPs are expected to have increased application in food and pharmaceutical industries.

Fabrication and characterization of nanoemulsions for encapsulation and delivery of vitexin: antioxidant activity, storage stability and in vitro digestibility.

Nanoemulsions were prepared as an encapsulation and delivery system for vitexin, a poorly water-soluble antioxidant. This study evaluated how the type and concentration of the dispersed oil phase and vitexin loading impacted droplet characteristics and nanoemulsion stability. The influences of storage temperature on antioxidant activity and in vitro gastrointestinal digestion on nanoemulsion stability were also investigated. Nanoemulsions prepared at different dispersed oil concentrations showed diverse characteristics and stability. Highest stability against droplet aggregation and phase separation with small oil droplets (< 150 nm) was observed for nanoemulsions prepared using 300 g kg-1 medium-chain triglyceride oil. These nanoemulsions are able to entrap and deliver vitexin with high encapsulation efficiency (88-90%) with no significant effect on emulsion stability. Vitexin-loaded nanoemulsions were stable during storage when refrigerated (4 °C) and at room temperature (25 °C) for up to 45 days with no effect on their antioxidant activity. Significantly delayed lipolysis rate and decreased extent of lipid digestion were observed in vitexin-loaded nanoemulsions. Stable vitexin-loaded nanoemulsions were successfully produced by high-pressure homogenization using a mixture of Tween 80 and lecithin as emulsifiers. Vitexin-loaded nanoemulsions stabilized with a mixture of these two emulsifiers were effective in retaining antioxidant activity during storage and protecting vitexin from changes during gastrointestinal digestion. Our results suggested that nanoemulsions were effective vitexin delivery systems for food applications. © 2022 Society of Chemical Industry.

Effects of Concentration of Soybean Protein Isolate and Maltose and Oil Phase Volume Fraction on Freeze-Thaw Stability of Pickering Emulsion.

There is growing interest in enhancing the freeze-thaw stability of a Pickering emulsion to obtain a better taste in the frozen food field. A Pickering emulsion was prepared using a two-step homogenization method with soybean protein and maltose as raw materials. The outcomes showed that the freeze-thaw stability of the Pickering emulsion increased when prepared with an increase in soybean protein isolate (SPI) and maltose concentration. After three freeze-thaw treatments at 35 mg/mL, the Turbiscan Stability Index (TSI) value of the emulsion was the lowest. At this concentration, the surface hydrophobicity (H0) of the composite particles was 33.6 and the interfacial tension was 44.34 mN/m. Furthermore, the rheological nature of the emulsions proved that the apparent viscosity and viscoelasticity of Pickering emulsions grew with a growing oil phase volume fraction and concentration. The maximum value was reached in the case of the oil phase volume fraction of 50% at a concentration of 35 mg/mL, the apparent viscosity was 18 Pa·s, the storage modulus of the emulsion was 575 Pa, and the loss modulus was 152 Pa. This research is significant for the production of freeze-thaw resistant products, and improvement of protein-stabilized emulsion products with high freeze-thaw stability.