High Oil Fractions Research Articles

Media-milled agar particles as a novel emulsifier for food Pickering emulsion

Pickering emulsions was successfully fabricated using ball-milled agar particles with sizes and sulfate content around 7 μm and 0.62 %, respectively. These particles were obtained through a simple media-milling process using agar powders initially sized at 120 μm. The lamellated agar is aggregated into a mass after the milling process. The surface charge and hydrophobicity of the ball-milled agar particles were characterized through zeta potential and contact angle measurements, respectively. The droplet size of Pickering emulsions was related to oil fraction and particle concentration, ranging from approximately 45 μm to 80 μm. Ball-milled agar stabilized emulsions were sensitive to pH and salt conditions. The results of confocal laser scanning microscopy and cryo-SEM showed that at low particle concentrations and oil fractions, ball-milled agar stabilized the emulsions by dispersing particles on the surface of the oil droplets through electrostatic repulsion. Conversely, ball-milled agar stabilized the emulsions under high particle concentrations and oil fractions by forming a gel network structure to bind the oil droplets. In this research, this developed method provides the basis for the high-value application of agar and a new idea for preparing stable food-grade Pickering emulsion-based functional foods using raw-food material without surface wettability.

Pomelo peel derived nanocellulose as Pickering stabilizers: Fabrication of Pickering emulsions and their potential as sustained-release delivery systems for lycopene

Two kinds of nanocellulose (cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) were synthesized from pomelo peels via a facile approach of TEMPO oxidation and sulfuric acid treatment respectively. The FTIR results illustrated that hemicelluloses and lignin were completely removed from the pomelo peel cellulose substrate. The obtained CNFs and CNCs possessed a uniform morphology and nanoscale particle size. The stability of CNF-based Pickering emulsions was higher than that of emulsions stabilized with CNCs, due to the formation of gel structure induced by the CNFs’ longer fibrils. Increased oil fractions enhanced the viscoelasticity of CNF-based Pickering emulsions. The in vitro digestion results suggested that increased oil fractions decreased the lipolysis degree, as a result of the larger droplet size and higher viscoelasticity of emulsion. The release of lycopene showed a trend similar to that of FFA release, suggesting that higher oil fractions were beneficial for controlling lycopene release during gastrointestinal digestion.

Physicochemical characteristics, rheology, and emulsifying properties of ultrasound-extracted pectin from 'saba' banana peel

Banana peel is an abundant agricultural waste in the Philippines. Valorization of the waste was done by extracting pectin from the 'saba' banana peel using ultrasound technology. The ultrasound-extracted pectin (UEP) was characterized physicochemically. UEP was also compared with commercial low-methoxy pectin (LMP) in terms of rheology and emulsification ability. Results showed that UEP has higher protein and ash content, and lower methoxyl, total pectic content, and interfacial tension. During the emulsion preparation, increasing the concentration of both UEP and LMP resulted in an increased production of stable emulsion droplets. Also, UEP-stabilized emulsion had improved stability when higher oil fraction and ionic strength were used. In terms of pH, higher volumes of stable emulsion were produced by UEP and LMP at conditions close to pectin's isoelectric pH. Lastly, UEP and LMP produced emulsions that were stable in all stages of in vitro digestion.

Enhancing the interfacial stability of O/W emulsion by adjusting interactions of chitosan and rice protein hydrolysate

The influences of chitosan and rice protein hydrolysate (CH/RH) ratio and oil-water ratio on the emulsification efficiency, as well as the impact of RH on the formation of CH/RH complex coacervates was investigated. Emulsions prepared by CH/RH at different concentrations (1–4%) were also evaluated. Higher proportion of CH led to an increase in turbidity, ζ-potential, and particle size and a decrease in surface hydrophobicity of CH/RH. The ζ-potential and droplet sizes of CH/RH stabilized emulsions increased with increasing CH proportion at different oil-water ratios. The formation of strong network due to electrostatic interaction between CH and RH, possessing amphiphilicity contributed by hydrophobicity of RH and hydrophilicity of CH, improve emulsion stability. The CH/RH complexes at ratio of 1:1 can form more stable emulsion as oil volume fraction from 20% to 80%. CH/RH 1:1 emulsion had greater viscosity and storage/loss modulus values than other CH/RH complexes, followed by CH/RH 1:2 at oil fraction ≥50%. Higher oil fraction (60% and 80%) enhanced the viscosity while decreased the emulsion storage stability. Increasing CH/RH concentration can help to form a thicker and stronger interfacial layer on the droplets and a more stable network structure, thus enhancing emulsion stability. Overall, CH/RH 1:1 is more effective in enhancing the interfacial adsorption and emulsification stability than CH or RH alone, especially at 50% oil volume fraction. This study may contribute to the potential of CH/RH complexes for stabilizing emulsion system at different oil contents applied in different food formulations.

Developing an adaptive catalyst for an FCC reactor using a CFD RSM, CFD DPM, and CFD DDPM–EM approach

Cyclone separators, which have an important role in the recovery of catalysts, constituted one of the aims of the study. In the work to be done, the pressure drop occurring during the fcc reaction is also calculated using the Ergun equation and it is aimed to provide the same value in a cyclone separator. In this study, which was presented for the first time in the literature, the best working conditions were determined by simulating the pressure drop in the cyclone separator modeled by using the various catalyst types namely NiMo/ASA–Al2O3, NiMo/p–Al2O3, NiMo/Y–Al2O3, Co-Mo, HZSM-5 zeolite, HY zeolite, pAl2O3, ASA-Al2O3, Y-Al2O3 determined from the literature in the Ergun equation. Among them, NiMo/ASA Al2O3, Co-Mo, HY zeolite, and ASA-Al2O3 were determined as the best catalyst for producing diesel from high oil fractions. Unlike previous studies, the condition that the cyclone separator modeled cleans the catalyst with maximum efficiency also determines the condition that provides low catalyst porosity in the determination of the catalyst type to be determined in diesel production. Due to the accuracy between the calculated and the predicted pressure drop results (about 1,8%), HY zeolite is the best catalyst for cyclone separator geometry. It is widely used to convert high molecular weight hydrocarbon fractions, the high boiling point of petroleum crude oils into olefinic gases, more valuable gasoline, and other products. The purpose of the FCC unit is to increase the refinery conversion and white product yield by converting heavy vacuum gas oil (HVGO) into light hydrocarbons at high temperatures with the aid of fluid catalysis. These two zones (reactor and regenerator) are placed as two different pressure vessels. For these two different systems to work in harmony with each other, unlike in previous studies, the “dense discreet phase-Eularian” approach was used in the modeling of the catalytic unit and the “discreet phase” approach was used in the modeling of the cyclone separator. The values required for both processes to work together have been determined approximately.

Insight into different roles of chitin nanocrystals and cellulose nanocrystals towards stabilizing Pickering emulsions

Rod-like polysaccharide particles such as chitin nanocrystals (ChNCs) and cellulose nanocrystals (CNCs) have been widely used for the preparation of Pickering emulsion. Both are believed playing good role of particle emulsifiers. However, these two kinds of nanocrystals have completely different surface properties: electronegative CNC is more hydrophilic and has higher surface charge level as compared to electropositive ChNC. To reveal their difference as emulsifiers in Pickering emulsions is therefore of interest. In this work, ChNCs and CNCs with the same structural parameters (aspect ratio = 28) were used to prepare olive oil- in -water emulsions for a comparative study. The two kinds of nanocrystals show the same mechanical state in emulsions, behaving like rigid rods, instead flexible fibers because they have 10 4 level of effective stiffness. Therefore, their roles of emulsifying oil/water system are dominated by their surface properties: ChNCs reveal higher emulsifying capacity relative to CNCs due to better ChNC-oil affinity, and can even emulsify the oil/water (7/3 w/w) system with high oil fractions. However, ChNC-stabilized emulsions are not that stable to centrifugation as compared to CNC-stabilized emulsions at low oil fractions due to the formation of the cluster structure resulted from less coating of droplets. Thus, the former reveals higher strain sensitivity and stronger thixotropy than the latter in shear flow. The correlation between viscoelasticity and morphology/phase behavior of the two kinds of Pickering systems was assessed, then. This work provides valuable information on formulating preparation of Pickering emulsions by using different types of rod-like polysaccharide nanocrystals. • CNCs and ChNCs have different roles towards emulsifying oil- in -water system. • ChNC has better emulsifying capacity and can emulsify high-oil-fraction system. • CNC-stabilized emulsions are stabler as compared to the ChNC-stabilized ones. • The morphology of emulsions can be well tuned by using different nanocrystals.

Impact of aluminum particles on drop size distributions and phase separation in liquid multiphase systems

This work addresses the influence of partially hydrophobic aluminum particles on the interfacial properties of o/w and w/o dispersions. For this purpose, drop size distributions are determined in an agitated tank followed by batch settling experiments after stirrer stop. In presence of hydrophobized aluminum particles, the type of dispersion (o/w or w/o) has an unexpected influence on coalescence behavior. Particles accelerate the coalescence for o/w dispersions (low oil fraction) but hinder the coalescence for w/o dispersions (high oil fraction). For a deeper understanding of this effect, an in-depth characterization and comparison of the drop size distributions of the two dispersion types was performed.

Electrical conductivity: A simple and sensitive method to determine emulsifying capacity of proteins.

Emulsifying capacity (EC) of proteins is a benchmark standard widely used to evaluate the quality of protein ingredients in emulsion foods. EC (mL of oil emulsified per g of protein) is usually measured by a sudden drop in electrical resistance (phase transition) with the continuous addition of oil to a specific protein solution. However, little is known about electrochemical mechanisms behind this process because resistance, measured with an ohmmeter, is not sensitive enough to monitor changes in the concentration of protein electrolytes. Here, pea (PPI), myofibrillar (MPI), and whey (WPI) protein isolates were vigorously homogenized with oil at a series of oil/protein ratios to prepare emulsions with different final protein concentrations. The conductivity was closely monitored using a conductivity meter. A linear relationship was discovered between conductivity and the final protein concentrations. At higher oil fractions, the migration of proteins from the aqueous phase to the oil-water interface limited protein mobility, leading to a conductivity drop. EC was calculated from the regression lines; when the starting protein concentration was raised from 0.5% to 2.0%, the EC of PPI, MPI, and WPI decreased from 717, 782, 1339 to 219, 303, and 540mL oil/g protein, respectively. The dependence of EC on the initial protein concentration and the sensitivity of conductivity to the depleting protein electrolytes suggest that protein concentration is an important factor to consider when determining EC for a given protein or comparing EC among different proteins. PRACTICAL APPLICATION: The simple and sensitive electrical conductivity test described in this paper allows for the accurate determination of emulsifying capacity of proteins. It may be adopted by the food industry to compare the emulsifying properties of different protein ingredients.

Pressurized liquid extraction of radish seed oil using ethanol as solvent: Effect of pretreatment on seeds and process variables

In this study the use of pressurized ethanol to extract oil from radish seeds was investigated. The influence of the pretreatment of the seeds and the ethanol flow rate, static time, temperature and pressure applied during the extraction was evaluated to determine the effect on the yields of oil and active compounds. The application of thermal treatment after immersion promoted an increase in the oil yields. An ethanol flow rate of 3 mL min−1 and a static time of 10 min increased the oil diffusion. The extraction at 150 °C provided a high oil fraction and higher yields of phytosterols and γ-tocopherol were obtained at 135 °C. In addition, 5 MPa was sufficient to achieve an oil yield of 36.6%, as higher pressures did not influence the process. The oil obtained was rich in oleic and erucic acids, with low acidity and high oxidative induction time.

Study of an ESP's performance handling liquid-liquid flow and unstable O-W emulsions part II: Coupled CFD-PBM modelling

The internal flow behavior of an ESP handling dispersed oil-water and emulsion flows remains quite unexplored. Previous studies have focused either on the individual droplet dynamics or on a simplified and limited modelling of the ESP's global performance. Hence, this study seeks to implement and analyze the applicability of a more robust and far-reaching CFD-PBM model which maintains a reasonable computational expenditure. Good agreement with experimental data was attained by the Eulerian-PBM framework (<10% error) and acceptable mean flow predictions were achieved with a less robust and computationally demanding VOF model (15% error). The internal flow behavior was noted to be governed by droplet size and effective viscosity variations, which induce the formation adverse pressure gradients leading to the emergence of backflow currents and eddies, particularly at higher oil fractions and lower flowrates. At higher flowrates and latter stages, well adapted flow is always attained, regardless of the mixture handled.

Preparation and characterization of pickering emulsion stabilized by hordein-chitosan complex particles

Abstract In this study, hordein-chitosan complex particles (HCPs) were prepared using anti-solvent precipitation method. The addition of chitosan led to the increase in the particle diameter and zeta-potential as well as the gradual decrease in fluorescence intensity values of HCPs, indicating chitosan absorbed onto the surface of hordein particles. Fourier transform infrared spectra of HCPs showed the significant shifts of peak position for O–H stretching vibration, amide Ⅰ and Ⅱ bands after addition of chitosan, suggesting the formation of hydrogen bonds and hydrophobic interactions between hordein and chitosan. Three-phase contact angle (θo/w) of HCPs revealed the excellent wettability (θo/w = 89.3 ± 1°) of particles when the mass ratio of hordein to chitosan was 2:1 (HCPs2:1). Oil-in-water Pickering emulsions (Caprylic/Capric Triacylglyceride as oil phase) stabilized by HCPs2:1 were further prepared. Confocal laser scanning microscope images indicated that HCPs absorbed at the oil/water interface and formed a dense steric barrier on the surface of spherical oil droplets. Higher oil fractions (50% and 60%) led to the formation of stable Pickering emulsion gels, which showed long-term storage stability. This study provides a new solution to accelerate the application of hordein-based Pickering emulsions in food industry.

Study of an ESP's performance handling liquid-liquid flow and unstable O-W emulsions Part I: Experimental

This article is the first part of a study which analyzes the performance and internal flow of an ESP when handling oil-water flow, focusing on the characterization of the two-phase flow/emulsions observed and their influence on the ESP's global performance. The testing facility consisted of a four-stage ESP located in a closed-loop arrangement. W/O emulsions are formed at high oil fractions, due to the presence of surface-active compounds and small droplet sizes. At the inversion, an increase in the viscosity and shear-thinning characteristics of the emulsion is noticed. At higher water cuts, the emulsion's microscopic structure is lost, transitioning to a dispersed two-phase flow. The head rise increased noticeably at the inversion point thanks to the shear-thinning trend observed. The ESP's performance improves at higher water fractions due to lower viscosities with a shear-thinning nature. As the non-Newtonian behavior is lost, higher water cuts do not affect the pump's operation.

Computed Tomography 3D Super-Resolution with Generative Adversarial Neural Networks: Implications on Unsaturated and Two-Phase Fluid Flow.

Fluid flow characteristics are important to assess reservoir performance. Unfortunately, laboratory techniques are inadequate to know these characteristics, which is why numerical methods were developed. Such methods often use computed tomography (CT) scans as input but this technique is plagued by a resolution versus sample size trade-off. Therefore, a super-resolution method using generative adversarial neural networks (GANs) was used to artificially improve the resolution. Firstly, the influence of resolution on pore network properties and single-phase, unsaturated, and two-phase flow was analysed to verify that pores and pore throats become larger on average and surface area decreases with worsening resolution. These observations are reflected in increasingly overestimated single-phase permeability, less moisture uptake at lower capillary pressures, and high residual oil fraction after waterflooding. Therefore, the super-resolution GANs were developed which take low (12 µm) resolution input and increase the resolution to 4 µm, which is compared to the expected high-resolution output. These results better predicted pore network properties and fluid flow properties despite the overestimation of porosity. Relevant small pores and pore surfaces are better resolved thus providing better estimates of unsaturated and two-phase flow which can be heavily influenced by flow along pore boundaries and through smaller pores. This study presents the second case in which GANs were applied to a super-resolution problem on geological materials, but it is the first one to apply it directly on raw CT images and to determine the actual impact of a super-resolution method on fluid predictions.

Development of (γ-Al2O3-Zeolite Y)/α-Al2O3-HPCM Catalyst based on Highly Porous α-Al2O3-HPCM Support for Decreasing Oil Viscosity

Highly porous cellular material (α-Al2O3-HPCM) support was synthesized by the template method. Highly porous support was used for the synthesis of the catalyst. A thin secondary layer with 25–30 μ thick γ-Al2O3 and zeolite Y was applied on the α-Al2O3-HPCM surface ((γ-Al2O3 (85%)-zeolite Y (15%))/α-Al2O3-HPCM). The catalyst based on the highly porous support was tested in a process of decreasing oil viscosity. The catalyst in the form of cylindrical granules and a thermal process of decreasing oil viscosity without the catalyst were used as the basis for comparison. α-Al2O3-HPCM in the catalyst provides low-quantity pores (d &lt; 10 nm) and a quantity of general acid centers compared with the granular catalyst. On the other hand, it shows a more significant oil viscosity decrease (from 2500 to 41 cPs) and a low rate of gas generation (137 mL/h) for the catalyst with highly porous support. A high oil fraction was observed in the presence of the (γ-Al2O3-zeolite Y)/α-Al2O3-HPCM compared to the granular catalyst. The presence of large transport cells (pores) 1500–2000 μ for the catalyst based on highly porous support allowed a work period four times longer than that of experiment only with temperature without catalysts.

Development of high internal phase Pickering emulsions stabilised by ovotransferrin–gum arabic particles as curcumin delivery vehicles

SummaryThis study explored feasibility of preparing high internal phase Pickering emulsions (HIPEs) as curcumin delivery vehicles. Particles assembled from ovotransferrin (OVT) and gum arabic (GA) could stabilise HIPEs successfully, and OVT–GA particle‐stabilised HIPEs with extremely high oil fraction of 0.90 were stable. Droplet size and rheological properties of OVT–GA particle‐stabilised HIPEs were dependent on both particle concentration and oil fraction. Either increasing particle concentration or decreasing oil fraction resulted in a decrease of droplet size. Increase in storage modulus and viscosity of HIPEs could be achieved by increasing particle concentration or oil fraction. Food structures with controlled shape could be constructed by OVT–GA particle‐stabilised HIPEs. When compared with bulk MCT oil, OVT–GA particle‐stabilised HIPEs improved both extent of lipolysis and curcumin bioaccessibility significantly. These findings provided novel insight into potential application of HIPEs with extremely high oil fractions in nutraceutical delivery systems.

Transport and Retention of Concentrated Oil-in-Water Emulsions in Porous Media.

Oil-in-water emulsions are routinely used in subsurface remediation. In these applications, high oil loadings present a challenge to remedial design as mechanistic insights into transport and retention of concentrated emulsions is limited. Column experiments were designed to examine emulsion transport and retention over a range of input concentrations (1.3-23% wt). Droplet breakthrough and retention data from low concentration experiments were successfully described by existing particle transport models. These models, however, failed to capture droplet transport in more concentrated systems. At high oil fraction, breakthrough curves exhibited an early fall at the end of the emulsion pulse and extending tailing. Irrespective of input concentration, all retention profiles displayed hyper-exponential behavior. Here, we extended existing model formulations to include the additional mixing processes occurring when at high oil concentrations-with focus on the influence of deposited mass and viscous instabilities. The resulting model was parametrized with low concentration data and can successfully predict concentrated emulsion transport and retention. The role of retained mass and viscous instabilities on mixing conditions can also be applied more broadly to systems with temporal or spatially variant water saturation or when viscosity contrasts exist between fluids.

Pickering emulsions formation using kaolinite and Brazil nut oil: particle hydrophobicity and oil self emulsion effect

ABSTRACTIn this work, we investigate the role of kaolinite plate-like crystals in the stabilization of emulsions containing Brazil nut oil (Bertholletia excelsa), a natural component that is highly employed in the cosmetic industry as moisturizing and emollient agent. Initially, the interaction of kaolinite with Brazil nut oil and water was investigated. The results revealed a reduced contact angle (CA) with hydrophobic solvents, displaying a low apparent CA with oil (24.8 ± 3°) and a dominant dispersive component (). The hydrophobic character of the siloxanic side of the kaolinite layers favored the ability in adsorbing onto o/w droplets, enhancing emulsion stabilization as a function of particle concentration for a period longer than 7 days. The small content of non-esterified fatty acid present in the Brazil nut oil, based on acidity index (1.24 ± 0.5 wt%), was responsible for some self-emulsion at higher oil fraction and interfere in the kind of emulsion formed due to kaolinite adsorption and due to self-emulsification. The emulsion organization was analyzed by fluorescence confocal microscopy that demonstrated kaolinite plate-like particles deposited throughout the water/oil interface. Altogether, the results confirmed the particles’ ability to irreversibly adsorb and stabilize the emulsions.

Wheat gluten-stabilized high internal phase emulsions as mayonnaise replacers

Plant protein-based diets (e.g., egg or meat alternatives) have emerged as a promising approach for developing healthy and sustainable food systems. Mayonnaise, a formulated sauce prepared by mixing vegetable oil, egg yolk, vinegar and salt, is probably one of the most widely used condiments in the world today. In this paper, wheat gluten (WG) as an available and low-cost plant protein ingredient was used to prepare and stabilize oil-in-water high internal phase emulsions (HIPEs) as mayonnaise replacers via emulsification–evaporation method. Firstly, WG was dissolved into aqueous acetic acid/ethanol (55/45, v/v, pH 3.0) solution to form phase-separated WG particles, and then HIPEs were prepared through homogenization of high sunflower oil fraction (75 wt%) with WG particles suspension at 80 °C after evaporating ethanol completely. Compared with egg-based mayonnaise, HIPEs (especially for 1.0 wt% WG) exhibited very similar droplet size distribution, rheological behavior, near-perfect thixotropic recovery, and tribological property. These results demonstrated that HIPEs and mayonnaise might have similar sensory property and perceived texture such as creaminess, smoothness, and sliminess. The confocal laser scanning microscopy (CLSM) indicated that close-packed oil droplets could allow them to form homogeneous oil-in-protein network microstructure in HIPEs and mayonnaise, which might contribute to high viscoelasticity, consistency, and correct texture. In addition, thermal stability of HIPEs was much better than that of the mayonnaise. Design and construction of WG-stabilized oil-in-water HIPEs may provide a potential strategy for preparing mayonnaise replacers.

Characterization of Pickering emulsion gels stabilized by zein/gum arabic complex colloidal nanoparticles

Recently, Pickering emulsions have attracted extensive interests due to their advantages of “surfactant-free” and sustained delivery for bioactives. However, developing natural, biodegradable and food grade nanoparticles as Pickering emulsion stabilizers face new challenges. In this study, zein/gum arabic (GA) complex colloidal nanoparticles (ZGAPs) were prepared with a core-shell structure through hydrogen bonding and electrostatic interactions. The mean size of ZGAPs was larger than that of zein nanoparticles, and the zeta potential reversed from positive to negative, further confirming that GA molecules adsorbed onto the surface of zein nanoparticles. The three-phase contact angle (θo/w) of zein nanoparticles was around 133.75°. After addition of GA, the θo/w of ZGAPs was adjusted to 88.95° closing to neutral wettability. This result indicated that ZGAPs could be developed as effective Pickering emulsifiers. Confocal laser scanning microscope images evidenced that ZGAPs formed a densely packed layer at the surface of oil droplets, which provided compact barriers of the droplets against coalescence and Ostwald ripening. At constant particle concentrations, the oil volume fraction significantly influenced the droplet sizes and rheological properties of Pickering emulsions. The droplet size and emulsified phase volume fraction of Pickering emulsions were increased with the rise of oil fraction. Consequently, Pickering emulsion gels were successfully fabricated at a higher oil fraction φ ≥ 0.5, which exhibited a long-term storage stability. These findings would provide a potential way of producing Pickering emulsion gels, which showed the advantages of both emulsions and gels, and could become novel and effective delivery systems of bioactives.

Gravity induced coalescence in emulsions with high volume fractions of dispersed phase in the presence of surfactants

We report studies on the effect of volume fraction and surfactant concentration on the kinetics of destabilization of emulsions under the influence of gravity. Model oil‐in‐water emulsions, designed to mimic crude oil–water emulsions, were prepared with varying volume fractions of dispersed oil but nearly identical normalized initial drop size distributions. The gravity separation process was observed by periodically withdrawing samples, and examining the droplet size distribution under the microscope. Experiments were performed for three volume fractions of dispersed phase and two surfactant concentrations (0.4 and 1.6% by weight). At higher oil fractions (20%) and a lower surfactant concentration (0.4%), it was observed that although the rate of coalescence increased, the actual oil separation was delayed. At higher surfactant concentrations (1.6%), the dominant factor in suppressing destabilization is the rate of drop to interface coalescence. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4379–4389, 2017