Average Droplet Size Research Articles

Emulsifying properties of pea protein/guar gum conjugates and mayonnaise application

SummaryModified plant protein may be used as a healthy and more functional emulsifier in food products. The objective of this study was to evaluate the emulsifying properties of functionally enhanced pea protein (i.e. pea protein conjugated with guar gum, G‐PPI) and its potential application to mayonnaise, compared with unmodified pea protein. Emulsions containing G‐PPI were prepared at different pH, salt concentrations, protein concentrations and oil/water ratios. Mayonnaise samples were prepared using the pea proteins or egg yolk powder. Various characteristics of the emulsions, including droplet size, apparent viscosity, viscoelasticity and microstructure, were analysed. The emulsions with G‐PPI had significantly increased stability of up to 89.4% and apparent viscosity of up to 48.62 mPa.s. The G‐PPI emulsion had a smaller average droplet size of 934.4 nm at pH 7 compared with the PPI emulsion (stability 62.7%, apparent viscosity 22.8 mPa.s and droplet size 1664.8 nm). The pH, NaCl concentration, protein concentration and oil/water ratio greatly affected the emulsifying properties. The G‐PPI mayonnaise at higher protein concentrations (6 or 8%) exhibited excellent emulsifying and rheological properties. The modified pea protein through the green modification process with natural polysaccharides could be used as a safe and functional emulsifier in different emulsified foods.

Anticancer activity of Zingiber ottensii essential oil and its nanoformulations.

Zingiber ottensii, is widely used in Asian traditional remedies for the treatment of many diseases. The present study explores anticancer activity of Z. ottensii essential oil (ZOEO) and its nanoformulations. ZOEO obtained from hydrodistillation of Z. ottensii fresh rhizomes was analysis using gas chromatography mass spectroscopy. Zerumbone (25.21%) was the major compound of ZOEO followed by sabinene (23.35%) and terpene-4-ol (15.97%). Four types of ZOEO loaded nanoformulations; nanoemulsion, microemulsion, nanoemulgels, and microemulgel, were developed. The average droplet size of the nanoemulsion and microemulsion was significantly smaller than that of the nanoemulgel and microemulgel. Comparison with other essential oils of plants of the same family on anticancer activity against A549, MCF-7, HeLa, and K562, ZOEO showed the highest cytotoxicity with IC50 of 43.37±6.69, 9.77±1.61, 23.25±7.73, and 60.49±9.41 μg/mL, respectively. Investigation using flow cytometry showed that ZOEO significantly increased the sub-G1 populations (cell death) in cell cycle analysis and induced cell apoptosis by apoptotic analysis. The developed nanoformulations significantly enhanced cytotoxicity of ZOEO, particularly against MCF-7 with the IC50 of 3.08±2.58, 0.74±0.45, 2.31±0.91, and 6.45±5.84 μg/mL, respectively. Among the four nanoformulations developed in the present study, nanoemulsion and microemulsion were superior to nanoemulgel and microemulgel in delivering ZOEO into cancer cells.

Development of softgel capsules containing cyclosporine a encapsulated pine essential oil based self-microemulsifying drug delivery system

In this study, a new self-microemulsifying drug delivery system (SMEDDS) based on pine essential oil has been designed and successfully developed to load cyclosporine A (CsA), a poorly water-soluble immunosuppressant, for oral CsA softgel manufacturing. SMEDDS were prepared from pine essential oil and Capmul MCM as oily phases, Kolliphor RH 40 as surfactant, polyethylen glycol 400 as co-surfactant/co-solvent and none volatized co-solvent utilizing the pseudo-ternary phase diagrams. CsA SMEDDS loading 9.09% of CsA, dispersed in aqueous environments (water, pH 1.2, 4.5 and 6.8 buffers), presented an average droplet size of about 160 nm with polydispersity index (PdI) below 0.25, and were stable after 6 h of self-emulsification. Cytotoxicity of CsA SMEDDS on LLC-PK1 cells demonstrated that CsA SMEDDS had an IC50 value greater than that of the reference product, suggesting product safety against nephrotoxicity. CsA SMEDDS was filled into oval-5 soft gelatin capsules (softgels) containing 0.5% glycine which could avoid the cross-linking process. Additionally, CsA SMEDDS softgels presented the in vitro release profiles equivalent to that of Sandimmun Neoral® at pH 1.2, 4.5 and 6.8. Therefore, the pine essential oil based SMEDDS was considered to be potential and suitable for developing softgels to enhance the oral bioavailability of CsA.

Application of NIRs coupled with PLS and ANN modelling to predict average droplet size in oil-in-water emulsions prepared with different microfluidic devices

In this study, the potential of microfluidic systems with different microchannel geometries (microchannel with teardrop micromixers and microchannel with swirl micromixers) for the preparation of oil-in-water (O/W) emulsions using two different emulsifiers (2 % and 4 % Tween 20 and 2% and 4 % PEG 2000) at total flow rates of 20–280 μL/min was investigated. The results showed that droplets with a smaller average Feret diameter were obtained when a microfluidic device with tear drop micromixers was used. To predict the average Feret diameter of O/W emulsion droplets, near-infrared (NIR) spectra of all prepared emulsions were collected and coupled with partial least squares (PLS) regression and artificial neural network modelling (ANN). The results showed that PLS models based on NIR spectra can ensure acceptable qualitative prediction, while highly non-linear ANN models are more suitable for predicting the average Feret diameter of O/W droplets. High R2 values (R2validation greater than 0.8) confirm that ANNs can be used to monitor the emulsification process.

Structural and rheological properties of mung bean protein emulsion as a liquid egg substitute: The effect of pH shifting and calcium

The objective of this study was to develop functional egg substitutes using mung bean protein (MBP) through pH12-shifting modification and calcium addition. The influence of pH12-shifting and Ca2+ ions on emulsion stability and the physical properties of MBP-based emulsion gels were elucidated in a neutral (pH 7) composite system (7.2% MBP and 10% canola oil). Results showed that the pH12-treated MBP emulsions were stable even after 5-day storage at 25 °C. The pH12-shifting significantly decreased the average emulsion droplet size from 524 nm in emulsion of native MBP to 422 nm. The emulsion samples were further heated at 95 °C to induce the formation of gels. With the calcium addition of 0 or 5 mM, the pH12 MBP emulsion did not form self-supporting gels. In the presence of 10–20 mM Ca2+, emulsion gels prepared with pH12-treated MBP exhibited a uniform and compact network structure. The gel hardness, water-holding capacity, and water distribution of pH12-treated MBP emulsion gels were superior to that of the native MBP samples. This study demonstrated MBP-based emulsion gels can be improved by pH12-shifting treatment in combination with calcium addition, resulting in a similar texture to egg, hence, the potential to develop MBP-based egg substitutes.

Fabrication of Microfiber-Templated Microfluidic Chips with Microfibrous Channels for High Throughput and Continuous Production of Nanoscale Droplets

A polydimethylsiloxane (PDMS) microfluidic chip with well-interconnected microfibrous channels was fabricated by using an electrospun poly(ε-caprolactone) (PCL) microfibrous matrix and 3D-printed pattern as templates. The microfiber-templated microfluidic chip (MTMC) was used to produce nanoscale emulsions and spheres through multiple emulsification at many small micro-orifice junctions among microfibrous channels. The emulsion formation mechanisms in the MTMC were the cross-junction dripping or Y-junction splitting at the micro-orifice junctions. We demonstrated the high throughput and continuous production of water-in-oil emulsions and polyethylene glycol-diacrylate (PEG-DA) spheres with controlled size ranges from 2.84 μm to 83.6 nm and 1.03 μm to 45.7 nm, respectively. The average size of the water droplets was tuned by changing the micro-orifice diameter of the MTMC and the flow rate of the continuous phase. The MTMC theoretically produced 58 trillion PEG-DA nanospheres per hour without high shear force. In addition, we demonstrated the higher encapsulation efficiency of the PEG-DA microspheres in the MTMC than that of the microspheres fabricated by ultrasonication. The MTMC can be used as a powerful platform for the large-scale and continuous productions of emulsions and spheres.

Effect of salinity on the characteristics, pH-triggered demulsification and rheology of crude oil/water nanoemulsions

The interest in utilizing nanoemulsions in a number of industrial applications is growing rapidly because of their superiority over conventional emulsions. Therefore, the formulation of highly stable crude oil-in-water nanoemulsions with different salinity (i.e., NaCl) levels is preseented in this study. Despite the observed extreme emulsion stability, zeta potential of the nanoemulsions decreased with increasing the salt concentration as a result of the charge screening effect induced by NaCl addition. Charge screening effect and, accordingly, the weakening of the electrostatic repulsion range and strength resulted in an increase in the average droplet size and also in a wider size distribution as the salinity level in the nanoemulsions increased. Additionally, the nanoemulsion viscosity also increased with increasing the salt concentration, however, the increase was marginal (except at 20 g/L NaCl). One interesting and unprecedented observation reported herein is the change in the nanoemulsion flow behavior from shear-thinning to Newtonian and then to shear-thickening as the applied shear rate increased. Nonetheless, at a salt concentration of 20 g/L NaCl, the shear-thickening behavior disappeared. Another important finding is that the presence of NaCl made the on-purpose destabilization of these stable nanoemulsions through the addition of NaOH or HCl (i.e., pH-alteration induced demulsification) more effective.

Droplets deposition and harvest-aid efficacy for UAV application in arid cotton areas in Xinjiang, China

With the development of Unmanned Aerial Vehicle (UAV) sprayers, the application of low-volume spraying of harvest-aid and other agrochemicals to cotton using UAVs is becoming a new agronomic trend worldwide. The effect of spray volume and canopy density for UAV spraying is significant but was rarely studied. In this study, five representative spray volumes were explored to examine the effect of spray volume on deposition and harvest-aid efficacy for cotton using a UAV sprayer. To explore the effect of canopy density, similar tests were carried out in a field located nearby with a lower leaf area index (LAI). A conventional trailer boom sprayer was selected for comparison. Different spray volumes had a significant effect on defoliation, but had no significant effect on boll opening and fiber quality. A higher defoliation rate was achieved in the lower LAI field. The total rate of defoliation using the UAV was inferior to the boom sprayer in the high LAI field for lower deposition and defoliation rate in the lower canopy. Considering the deposition, defoliation rate, and working efficiency, a spray volume of 15.0 L/hm2 with an average droplet size of 150 μm is recommended for UAV application. Keywords: UAV, droplets deposition, spray volume, canopy density, leaf area index, defoliation, boll opening rate DOI: 10.25165/j.ijabe.20221505.6425 Citation: Wang G B, Wang J H, Chen P C, Han X Q, Chen S D, Lan Y B. Droplets deposition and harvest-aid efficacy for UAV application in arid cotton areas in Xinjiang, China. Int J Agric & Biol Eng, 2022; 15(5): 9–18.

Development of a Semi-Empirical Model for Droplet Size Determination of a Three-Channel Spray Nozzle for Pellet Coating Based on the Optical Method Concept

The purpose of this study was to investigate the droplet size obtained with a three-channel spray nozzle typically used in fluid bed devices and to construct a semi-empirical model for prediction of droplet size. With the aid of a custom-made optical method concept, the impact of the type of polymer and solvents used through dispersion properties (viscosity, density, and surface tension), dispersion flow rate, atomization pressure, and microclimate pressure on droplet size was investigated. A semi-empirical model with adequate predictability for calculating the average droplet size (R2 = 0.90, Q2 = 0.73) and its distribution (R2 = 0.84, Q2 = 0.61) was constructed by employing dimensional analysis and design of experiments. Newtonian and non-Newtonian dispersion and process parameters on laboratory and on production scale were included, thereby enabling constant droplet size irrespective of the scale. Based on the model results, it would be possible to scale-up the atomization process (e.g., coating process) from laboratory to production scale in a systematic fashion, regardless of the type of solvent or polymer used. For the system investigated, this can be performed by understanding the dispersion properties, such as viscosity, density, and surface tension, as well as the following process parameters: dispersion flow rate, atomization, and microclimate pressure.

A Method for the Segregation of Emulsion Inner Phase Droplets Using Imbibition Process in Porous Material

The process of forming an emulsion is an energy-consuming process. The smaller the internal phase droplets we want to produce and the closer the droplets are in size to each other (monodisperse), the more energy we need to put into the system. Generating energy carries a high economic cost, as well as a high environmental footprint. Considering the fact that dispersive systems are widely used in various fields of life, it is necessary to search for other, less-energy-intensive methods that will allow the creation of dispersive systems with adequate performance and minimal energy input. Therefore, an alternative way to obtain emulsions characterized by small droplet sizes was proposed by using an imbibition process in porous materials. By applying this technique, it was possible to obtain average droplet sizes at least half the size of the base emulsion while reducing the polydispersity by about 40%. Oil-in-water emulsions in which vegetable oil or kerosene is the oily phase were tested. The studies were carried out at three different volume concentrations of the emulsions. Detailed analyses of diameter distributions and emulsion concentrations are presented. In addition, the advantages and limitations of the method are presented and the potential for its application is indicated.

Comparison of volatility characteristics and temperature-dependent density, surface tension, and kinematic viscosity of n-butanol-diesel and ABE-diesel fuel blends

Climate strategies and targets are impossible to meet with the continuously expanding energy and transportation sectors without renewable liquid fuels. Butanol is a potential alternative fuel, however, its production cost is currently high. Therefore, acetone-butanol-ethanol (ABE), an intermediate fermentation product, can also be used as fuel, which is economically more competitive. This paper provides temperature-dependent measurement data of material properties of various n-butanol and ABE blends with EN 590 diesel fuel. The key findings are the following. Distillation curves and initial boiling points match up to 25% volume fraction of biofuel for n-butanol and ABE blends. Initial boiling point decreases exponentially with biofuel content and has no considerable change above 25% and 50% biofuel volume fraction for n-butanol and ABE blends, respectively. Curve fitting was performed for initial boiling point, density, surface tension, and kinematic viscosity data to provide an empirical model for simulations. The simple mixing rule was applicable to density and surface tension. Nissan-Grunberg equation for viscosity is only recommended with the binary interaction parameter that is negative for n-butanol and positive for ABE blends. Ohnesorge number has a minimum at 25% n-butanol volume fraction, showing a minimum in average droplet size, which is optimal for clean operation.

Controllable regulation of emulsion stability by a pH-responsive zwitterionic/anionic surfactant system

In order to improve the recovery of crude oil and realize rapid demulsification of produced fluid, a pH-responsive zwitterionic/anionic surfactant system was proposed. The pH-responsive zwitterionic/anionic surfactant system consists of zwitterionic surfactant EAB (erucic amide carboxylic betaine) and anionic surfactant SDS (sodium dodecyl sulfate). By adjusting the pH value, the protonation degree of EAB could be controlled. Accordingly, the interaction between surfactants in the mixed system could be strengthened or weakened in neutral environment (pH = 6–8) or acidic conditions (pH = 2–4), respectively. In consequence, transformation between the emulsification and demulsification states for the emulsions stabilized by zwitterionic/anionic surfactant system could be effectively controlled by variation of the pH values. Meanwhile, the interfacial tension, average droplet size, microstructure and stability analysis of the mixed system emulsifying at various pH values were studied. For the emulsion stabilized by the pH-responsive zwitterionic/anionic surfactant system, the droplets size was evenly distributed and the average particle size was the lowest when the molar ratio of EAB to SDS was 4:6, whilst the average particle size increased significantly once the pH value was reduced down to 2 or 3. Above all, this study provides a new approach for the development of chemical flooding agents for enhancing oil recovery.

Observational comparative study in Kühni and ORC agitated columns for the mechanism and performance of molybdenum extraction under various hydrodynamic conditions

The present work is expressed to interpret the hydrodynamic parameters of rotation extraction columns in the reactive and non-reactive systems. The solvent extraction technique has been utilized for optimizing the transportation of molybdenum ions to the organic phase in two agitated columns (ORC and Kühni columns). Dispersed phase volume fraction, average droplet diameter, slip velocity, size distribution, and ions permeability of the aqueous phase have been investigated in terms of changing the operational variables including the agitation rate, flow rate of the inlet dispersed and continuous phases, column geometry, and reaction conditions. By considering the reactive and non-reactive conditions, the responses investigated indicated that the alteration in the agitation rate and reaction systems on the hydrodynamic parameters is considerable in comparison with the column geometry as well as both phase flow rates. Previous experimental research works for anticipating the drop behavior, holdup values, and slip velocity of droplets in different rotary columns have been reviewed and several new models have been derived by considering the geometric parameters and reactive or physical systems. The solvent extraction findings showed that the rotary extraction columns could be utilized as a suitable mass transfer device for chemical reaction systems.

Surfactant-free cellulose filaments stabilized oil in water emulsions

There has been significant interest over recent years in the production and application of sustainable and green materials. Among these, nanocellulose has incurred great interest because of its exceptional properties and wide range of potential applications, including in Pickering emulsions. However, the production cost of these cellulosic materials has limited their application. In this study, the capability of a new type of cheaper cellulosic material, cellulose filaments (CFs), in formulating stable oil in water Pickering emulsions was investigated and compared with three conventional nanocelluloses, namely cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs) and TEMPO-oxidized CNFs (TEMPO-CNFs). Results showed that CFs can provide stable surfactant-free emulsions over wide ranges of salt concentration (0–500 mM) and pH (2–10), as indicated by the near-constant oil droplet size and dewatering index of the emulsions. This is due to the ability of CFs to strongly adsorb to the oil and water interface, as evidenced by Cryo-SEM and visualized through labelled CFs with engineered carbohydrate-binding module (CBM2a) conjugated with green fluorescent protein (CBM2a-eGFP) under fluorescent microscopy. Compared to the emulsions stabilized by other types of nanocelluloses, the CF-stabilized emulsion demonstrated a larger average droplet size and comparable (with CNFs) or better (than CNCs and TEMPO-CNFs) stability, which is partially attributed to the higher viscosity of continuous phase in the presence of CFs. The results of this study demonstrate the use of CFs as a novel and cheaper cellulosic material for stabilizing emulsions, which opens the door to a range of markets from the food industry to engineering applications.Graphical abstract

Study of In/GaAs nanodroplet formation in conditions of non-stationary supersaturation during droplet epitaxy

In this paper, we present the results of kinetic Monte Carlo study of the In/GaAs growth by droplet epitaxy in conditions of non-stationary vapor supersaturation. These conditions allow achievement of the independent control of size and surface density of nanostructures. The material redistribution is realized on the surface when indium deposition is interrupted and leads to a decrease in the critical thickness of droplet formation. An average droplet size increases with increase in interruption time whereas the surface density decreases. However, additional nucleation within the wetting layer can also be observed during the growth interruptions, which makes it possible to increase the surface density of droplets.

Pore-scale dynamic behavior and displacement mechanisms of surfactant flooding for heavy oil recovery

Surfactant flooding is widely used in enhanced heavy oil recovery. It is important to understand the mechanisms involved in different stages of surfactant flooding at the pore scale. First, the effects of surfactant flooding at different surfactant concentrations were evaluated, and the optimal concentration was determined by analyzing the interfacial tension (IFT), emulsification states, turbiscan stability index (TSI), and viscosity reduction rate. Then, the microscopic displacement mechanism at different stages of the surfactant flooding of heavy oil was visualized by a microscopic visualization model. Furthermore, the residual oil was classified. The optimal surfactant concentration was found to be 0.5 wt%. At this concentration, the IFT was only 0.092 mN/m, the average droplet size of O/W emulsion is 7.1 μm, and the viscosity reduction rate was as high as 99.37%. The surfactant flooding process occurred in three stages. The main mechanisms in the initial stage are cutting emulsification and stable displacement. Temporary blocking in the small throat resulted in a change in the diversion ratio, Further, the cutting and tension-fracture effects of the small throat on the heavy oil droplets and the stretching effect on the adhered oil film were found to be the main mechanisms of middle stage. The main mechanisms of the last stage were the pulling, peeling, and swirling–carrying effects of surfactant flooding on the heavy oil in the stagnant zone, which were controlled by the large throats. Moreover, liquid-flow carrying, and emulsification-cutting effects in the pore system controlled by the small throats. The primary residual oil did not flow migrate throughout the development process. Further, secondary residual oil was generated by the plugging of heavy oil droplets at very small throats, resulting in a diversion ratio of zero. The results are highly significat for optimizing surfactant flooding for enhanced oil recovery technology and the development of high-efficiency surfactants.

Experimental study of the rheological properties and stability of highly-concentrated oil-based emulsions

This study presents a systematic investigation of viscosity and rheological properties of several dozen emulsions and nanoemulsions. The concentration by volume of the oil in emulsions varied from 20% to 80%. Low-viscosity mineral oils were used for emulsion formation and an aqueous solution of calcium chloride was used as the second medium. The volumetric concentration of emulsifiers varied from 1.5% to 4.5%. Three types of mineral oil, as well as various emulsifiers, are considered. The effect of the volumetric content and base oil type, the emulsifier type and concentration and the ultrasonic treatment duration on colloidal stability, rheological properties and droplet size of the resulting emulsion has been studied. It is shown that emulsions are considered to be non-Newtonian fluids with apparent elastic properties at oil concentration less than 35 vol%. All other things being equal, the average droplet size in the emulsion increases with an increase in the base oil viscosity. The use of ultrasonic treatment makes it possible to reduce the average droplet size in the emulsion by 4.5 times and to reduce its viscosity by 1.5 times.

Perfluorooctane sulfonate (PFOS) exposure of bovine oocytes affects early embryonic development at human-relevant levels in an in vitro model

Perfluorooctane sulfonate (PFOS) has been added to Stockholm Convention for global phase out, but will continue to contribute to the chemical burden in humans for a long time to come due to extreme persistence in the environment. In the body, PFOS is transferred into to the ovarian follicular fluid that surrounds the maturing oocyte. In the present study, bovine cumulus oocyte complexes were exposed to PFOS during 22 h in vitro maturation. Concentrations of 2 ng g-1 (PFOS-02) representing average human exposure and 53 ng g-1 (PFOS-53) relevant to highly exposed groups were used. After exposure, developmental competence was recorded until day 8 after fertilisation. Blastocysts were fixed and either stained to evaluate blastomere number and lipid distribution using confocal microscopy or frozen and pooled for microarray-based gene expression and DNA methylation analyses.PFOS-53 delayed the first cleavage to two-cell stage and beyond at 44 h after fertilisation (p < .01). No reduction of proportion blastocysts were seen at day 8 in either of the groups, but PFOS-53 exposure resulted in delayed development into more advanced stages of blastocysts seen as both reduced developmental stage (p = .001) and reduced number of blastomeres (p = .04). Blastocysts showed an altered lipid distribution that was more pronounced after exposure to PFOS-53 (increased total lipid volume, p=.0003, lipid volume/cell p < .0001) than PFOS-02, where only decreased average lipid droplet size (p=.02) was observed. Gene expression analyses revealed pathways differently regulated in the PFOS-treated groups compared to the controls, which were related to cell death and survival through e.g., P38 mitogen-activated protein kinases and signal transducer and activator of transcription 3, which in turn activates tumour protein 53 (TP53). Transcriptomic changes were also associated with metabolic stress response, differentiation and proliferation, which could help to explain the phenotypic changes seen in the blastocysts. The gene expression changes were more pronounced after exposure to PFOS-53 compared to PFOS-02. DNA-methylation changes were associated with similar biological functions as the transcriptomic data, with the most significantly associated pathway being TP53. Collectively, these results reveal that brief PFOS exposure during oocyte maturation alters the early embryo development at concentrations relevant to humans. This study adds to the evidence that PFOS has the potential to affect female fertility.

W/O emulsions generated by heavy oil in porous medium and its effect on re-emulsification

Water/hot water flooding and steam stimulation are usually used for heavy oil recovery. However, W/O emulsions are generated when heavy oil and water flow in porous medium of formations, which can seriously restrict the recovery effect in the middle or late stage. First, the influence of the W/O emulsion on efficient heavy oil recovery is analyzed by the production dynamics and produced fluid emulsified states of oilfields. Then, the W/O emulsion generation process during heavy oil entrapment and water flooding recovery was simulated. The effects of permeability, porous medium shearing distance and heavy oil viscosity on the emulsified state of W/O emulsions were studied. The properties of W/O emulsions were tested. Before reaching the final emulsified state, the lower the permeability and the longer the porous medium shearing distance, the more fully emulsified of the W/O emulsion. In the final emulsified state, the droplet sizes of the W/O emulsions generated by different viscosities of heavy oil are basically the same at the same water content. As the water content increases, the W/O emulsion droplet size grows first, then tends to stabilize, and finally stabilizes at between 2 and 3 μm. The viscosity of the W/O emulsion increases as water content increases and its viscosity increases significantly at high water contents. The lower the viscosity of dehydrated heavy oil is, the greater the increase of the viscosity of W/O emulsion increase. The viscosity of 70% the water content W/O emulsion is more than 15 times that of the dehydrated heavy oil. Finally, the effects of the water content, surfactant concentration, oil–water ratio on the emulsified state, droplet size distribution and its fluidity in porous medium were studied by simulating the re-emulsification process of W/O emulsion and surfactant solution. A W/O/W emulsion would formed by re-emulsification of the W/O emulsion and surfactant solution. As the water content of W/O emulsion increases, the droplet size of the W/O/W emulsion formed by re-emulsification increases, and its fluidity in porous medium decreases. The average emulsion droplet size (50% water content) after re-emulsification is 6.29 times that of emulsions formed by dehydrated heavy oil, and the apparent viscosity in porous medium is 15.05 higher. This study provides significant information for understanding the key issues in the efficient development of heavy oil reservoirs throughout their life time and the research and development of high-efficiency emulsion flooding systems.

In vitro digestion and bioaccessibility studies of vitamin E-loaded nanohydroxyapatite Pickering emulsions and derived fortified foods

Vitamin E is a lipophilic vitamin playing an essential role in human health. Due to oxidative instability, it presents fast degradation and bioactivity loss. In this study, vitamin E-loaded Pickering emulsions (PEs) stabilized by nano-hydroxyapatite (n-HAp) were produced using a static mixer (NETmix), a technique enabling continuous production and droplet size tailoring. Thus, oil-in-water (O/W) emulsions containing vitamin E at a content of 1 mg/mL were produced with different droplet sizes (7.53, 11.56 and 17.72 μm) using an O/W ratio of 20/80 (v/v). Their stability during in vitro gastrointestinal digestion and vitamin E bioaccessibility were investigated. It was observed that n-HAp particles disrupt in the stomach and subsequently aggregate as random calcium phosphates in the small intestine, leading to low vitamin E bioaccessibility due to oil entrapment. The emulsion showing the highest vitamin E bioaccessibility (3.29 ± 0.57%, sample with the larger average droplet size) was used to produce fortified gelatine and milk, resulting in an increased bioaccessibility (10.87 ± 1.04% and 18.07 ± 2.90%, respectively). This fact was associated with the presence of macronutrients and the lower n-HAp content. Overall, n-HAp PEs offer advantages for vitamin E encapsulation directed to fortified foods development, a process able to be extended to other lipophilic vitamins.