Change In Droplet Size Research Articles

Enhanced stabilization of oil-in-water (O/W) emulsions by fibrillar gel particles from lentil proteins

Pulse proteins as a sustainable protein source have attracted increasing interest in food development, but pulse proteins are generally less surface active than dairy proteins. This work introduces lentil protein (LP)-based fibrillar gel particles (FGPs) fabricated from heat-induced LP fibrillar aggregates by 1, 4, 8, and 16 h of heating, followed by particle reduction using sonication. The heating time significantly impacts the FGPs particle size and surface hydrophobicity. The FGP prepared by 4 h of heating (FGP-4) showed a small size (<200 nm) and homogeneous size distribution while possessing significantly increased surface hydrophobicity compared to untreated LP. Such structural features made FGP-4 better adsorb at the O/W interface and then completely covered the oil droplet surface, leading to homogeneous emulsions of small size (22.33 μm) and superior long-term stability without creaming for 30 days. In addition, the dispersed FGP in the bulk phase could develop interactions among each other, leading to improved emulsion viscosity and texture without oil droplet size change. This finding suggests that constructing fibril-type gel particles can provide a new strategy for forming superior O/W emulsions with improved stability from plant proteins.

Development and cytotoxicity evaluation of multiple nanoemulsions for oral co-delivery of 5-fluorouracil and short chain triglycerides for colorectal cancer

Colorectal cancer (CRC) is the third most common cancer in the world, but current chemotherapy options are limited due to adverse effects and low oral bioavailability of drugs. In this study, we investigated the obtainment parameters and composition of new multiple nanoemulsions (MN) based on microemulsions for oral co-delivery of 5-fluorouracil (5FU) and short-chain triglycerides (SCT, either tributyrin or tripropionin). The area of microemulsion formation was increased from 14% to 38% when monocaprylin was mixed with tricaprylin as oil phase. Addition of SCT reduced this value to 24–26%. Using sodium alginate aqueous dispersion as internal aqueous phase (to avoid phase inversion) did not further affected the area but increased microemulsion viscosity by 1.5-fold. To obtain the MN, selected microemulsions were diluted in an external aqueous phase; droplet size was 500 nm and stability improved using polyoxyethylene oleyl ether at 1–2.5% as surfactant in the external phase and a dilution ratio of 1:1 (v/v). 5FU in vitro release could be better described by the Korsmeyer-Peppas model. No pronounced changes in droplet size were observed when selected MNs were incubated in buffers mimicking gastrointestinal fluids. The 5FU cytotoxicity in monolayer cell lines presenting various mutations was influenced by its incorporation in the nanocarrier, presence of SCT and cell mutation status. The MNs selected reduced the viability of tumor spheroids (employed as 3D tumor models) by 2.2-fold compared to 5FU solution and did not affect the survival of the G. mellonella, suggesting effectiveness and safety.

Enhanced stability, formulations, and rheological properties of nanoemulsions produced with microfludization for eco-friendly process

HypothesisEco-friendly processes that are emerging around the world require mass production of low-energy, low-cost nanoemulsions. The process involving the high-concentrated nanoemulsions and diluting them with a large amount of solvent can certainly save the cost; however, not much detailed research has been conducted on the stability mechanism and rheological characteristics of high-concentrated nanoemulsions. ExperimentsIn this study, we produced nanoemulsions via the microfluidization (MF) process, comparing their dispersion stability and rheological characteristics with macroemulsions across various oil and surfactant concentrations. Droplet mobility and dispersion stability depended on these concentrations, with Asakura-Osawa-type attractive depletion considering interparticle interaction's role in stability changes. We investigated nanoemulsions' long-term stability based on turbidity and droplet size changes over four weeks, proposing a stability diagram showing four different states depending on emulsification conditions. FindingsWe explored the microstructure of emulsions under varying mixing conditions, observing their effects on droplet mobility and rheological properties. We monitored changes in rheology, turbidity, and droplet size over 4 weeks, establishing stability diagrams for macro- and nanoemulsions. The stability diagrams revealed that the stability of emulsions are sensitively dependent on the droplet size, concentrations, surfactant cocentrations and the strcture of coexistent phases in case of macroscopic segregation are significantly different depending on the droplet sizes. We identified their respective stability mechanisms and discovered the relationship between stability and rheological properties for highly concentrated nanoemulsion.

Long term water trapping in Pickering emulsions undergoing compositional ripening.

One approach to achieving low-calorie foods is to substitute regions of high-calorie content with water droplets, forming water-in-oil emulsions. However, in complex food systems consisting of multiple species of dispersed phases, compositional ripening may occur in which the emulsified water undergoes mass transfer to droplets filled with a species that is less soluble in the continuous phase, for example sugar. Here we present two model systems and use them to study compositional ripening for water-in-oil Pickering emulsions. Water-in-dodecane and water-in-tributyrin emulsions stabilised by PMMA particles were prepared and combined with similar emulsions that included sugar in the water. We use confocal microscopy as a function of time combined with particle tracking to explore how these systems evolve in time. For dodecane, as the system evolves, the pure water droplets appear to crumple due to the loss of water; in extreme cases, they eventually 'explode'. Simultaneously, the sugar-filled droplets expand and slowly coalesce. Evidently, our interfacial coating of particles is unable to suppress compositional ripening. In contrast, pure water droplets in tributyrin crumple into small stable structures, potentially retaining water. We show that decreasing the concentration of the sugar solution also decreases the rate of change of water droplet size for both oils. Observations of droplet 'explosions' confirm that the driving force can overcome the trapping of the particles at the interface, in contrast to the case of Ostwald ripening. However the crumpled states in the tributyrin system provide some indication that this effect can be overcome.

Demulsification of phosphoric acid/ tri-n‑butyl phosphate (W/O) emulsion by a novel rotor-stator spinning disc device

The demulsification process of phosphoric acid/tri-n‑butyl phosphate (W/O) emulsion is investigated by a novel rotor-stator spinning disc device (RSSDD). Emulsion properties varied with emulsification rotor speed and phase ratio, and operating parameters such as flow rate and disc speed have been studied for their effects on demulsification efficiency D, relative volume of separated oil phase λ, dispersed phase fraction of creamed emulsion ɸc and change in the average droplet size of emulsion Δdc. The results show that D is primarily due to emulsion stability. Low emulsification rotor speed and phase ratio reduce the emulsion stability, resulting in an increase in D. The shear and centrifugal forces from rotation and the residence time, influenced by operating parameters, play a major role in D and Δdc. Operating at higher disc speed and lower flow rate is not supposed. D decreases with increasing flow rate and decreasing disc speed, while Δdc behaves in the opposite way. λ disperses within 1.52%-2.94%, resulting in a linear relationship between D and ɸc. The optimal operating parameters are determined with D of 41.12% for one cycle in RSSDD. A model is proposed for the prediction of D and ɸc, showing an acceptable agreement with the experimental results.

Promoting fine particle agglomeration through organic agglomeration solutions with charged atomization

• The charged atomization technology of organic agglomeration solution was proposed and investigated. • Main influence factors and agglomeration mechanism were fully investigated. • The atomization and agglomeration performance of agglomeration solution before and after charged atomization were compared. • Charged atomization improved the agglomeration ability of organic agglomeration solution greatly. Chemical agglomeration is an effective method for agglomerating fine particles. Generally, an aqueous solution of an organic polymer is used as the agglomeration solution. However, these water-soluble polymers have high viscosity, resulting in a poor atomization effect of the solution, which significantly reduces the probability of collision between the agglomeration solution droplets and particles and further reduces the agglomeration efficiency of particles. To improve the agglomeration efficiency, the charged atomization technology of organic agglomeration solutions was proposed and investigated. The results showed that although the agglomeration effects of different organic agglomeration solutions on particles were different, the agglomeration performance improved after charged atomization. Among the four solutions obtained using the charged atomization technique, sodium carboxymethyl cellulose (CMC) and sodium alginate (SAA) showed the largest improvement in performance. Compared to the uncharged droplet, the agglomeration efficiency of fine particles increased by 53.4% for the 0.01% CMC solution under the charged droplet condition. With an increase in the mass concentration, the agglomeration efficiency of the particles increased but the change rate decreased, and this trend was more apparent after charged atomization. As the concentration increased from 0.03% to 0.1%, the change rates of the relative agglomeration efficiency of CMC before and after charged atomization were 11.2% and 2.4%, respectively. The change in droplet size is among the main reasons for the change in the agglomeration ability of an organic solution. Since the conductivity and viscosity of the solution affect the change in droplet size after charged atomization, it also has an effect on the agglomeration efficiency of the solution. The agglomeration performance of the organic agglomeration solution with high conductivity and low viscosity improved significantly after charged atomization. The particles exhibited characteristics of more compact chains and clusters after charged atomization.

Effects of interface generation, droplet size and antioxidant partitioning on the oxidation rate and oxidative stability of water–in–oil emulsions: A comparison of coarse emulsions and nanoemulsions

In order to gain an in–depth understanding of the factors affecting the oxidation of water–in–oil (W/O) emulsions, both initial oxidation rate and long–term oxidative stability were applied to assess the degree of oxidation of W/O emulsions. The results showed that the generation of the oil–water interface exacerbated lipid oxidation in W/O emulsions and the oxidation rate was independent of the initial droplet size (8 days). The difference in oxidative stability between coarse and nanoemulsions depended on the change in droplet size during storage and the formation of reverse micelles by the excess polyglycerol polyricinoleate (PGPR). The antioxidant (AO) esters with different alkyl chain lengths were added to the W/O emulsions to assess the effects of AO partitioning on lipid oxidation. The lipid oxidation results confirmed the applicability of the non–linear hypothesis in W/O emulsions. There was a critical chain length (CCL, octyl gallate, C8). Below or above CCL, the efficiency of the AOs decreased. C8 showed a ‘dual effect’, acting at both the oil–water and oil–air interface (interfacial tensions reduced by 0.36 and 4.66 mN/m, respectively). Future research should focus on means of effectively migrating AOs from the two phases to the oil–water interface to delay lipid oxidation.

Physicochemical properties and digestibility of thermally induced ovalbumin–oil emulsion gels: Effect of interfacial film type and oil droplets size

To investigate the effect of oil droplets surface film type and droplets size on the physicochemical properties and digestibility of thermally induced ovalbumin–oil emulsion gels, Tween 80 and ovalbumin were selected as individual emulsifiers for the emulsification of sunflower oil at different homogenization speeds (6000, 8000, and 10000 rpm), and the formed emulsions were mixed with ovalbumin matrix solution and then heated to form heat-induced ovalbumin emulsion gels (OEG). The OEG with ovalbumin as emulsifier had higher hardness, water holding capacity (WHC), and surface hydrophobicity, and lower digestibility, spin−spin relaxation time ( T 2 ) and free sulfhydryl content than those of the OEG with Tween 80 as the emulsifier ( p < 0.05). As the oil droplets size decreased, the hardness increased, WHC increased, the amide A band shifted to lower wavenumbers, digestibility decreased, T 2 decreased, free sulfhydryl content decreased, and surface hydrophobicity increased for both OEG ( p < 0.05). These results collectively indicated that the physicochemical properties of the OEG are influenced by the property of the oil interfacial film and the size of the oil droplets. The oil droplets surrounded by the interfacial protein film improved the performance of the OEG greatly, and the proteins within its OEG formed a dense gel network structure through hydrophobic aggregation, disulfide bond crosslinking, and hydrogen bonding. The oil droplets with smaller sizes favored the enhancement in the physicochemical properties of the OEG. Changes in the size of oil droplets and the type of film wrapped around them regulated the digestibility of the OEG. • The OEG-O with the small size of oil droplets had the highest hardness. • Small oil droplets filled better in the gel network to improve the hardness of OEG. • IPF-encapsulated oil droplets as active filler to increase the hardness of OEG. • Effect of filler on hardness depends on the heat stability of its interfacial layer. • Changes in oil droplet size and interfacial layer type regulated OEG digestibility.

INTRAVENOUS INFUSION DOSING SYSTEM FOR VOLUME CONTROL BASED ON SIGNAL PERIODIC MEASUREMENT

Intravenous fluid therapy is a commonly used treatment modality that is used in the treatment of hospitalized patients. Intravenous flow rates are often controlled by counting the number of fluid drops in a drip chamber while adjusting the intravenous line with a watch. In this research, an intravenous infusion dosing system was designed based on periodic signal measurement using a pair of light couplers consisting of a transmitter and a receiver. The transmitter is built using an infrared LED (BPV10NF), while the receiver uses an infrared photodiode detector (BPW34). The infusion droplet will pass a slit between the two coupler components and interrupt the light transmission from the transmitter to the receiver, which will affect the current through the photodiode and change the output status of the circuits. The parameters obtained from this circuit signal are droplet frequency from 1 Hz to 10 Hz and droplet sizes 0.05 ml and 0.0167 ml. The resulting output signal is in the form of pulses due to the interruption of the droplet when it passes through the optocoupler. The droplet frequency is calculated based on the period between adjacent droplets, while the droplet size can be measured based on the width of the resulting pulse. For the droplet measurement process, variations of the droplet period and the number of droplets per ml were carried out. The droplet period is regulated by manually adjusting the aperture of the infusion droplet outlet faucet. In contrast, the droplet size is controlled by two types of infusion devices with 20 drops/ml and 60 drops/ml specifications. The experimental results can be used to develop a system response that detects changes in period and droplet size.

Experimental study on droplet breakup and droplet particles diffusion of a pressure nozzle based on PIV

• The turbulence of dust fall spray field are studied for the first time. • The I in the axial direction has an exponential relationship with the distance. • Droplet breakup mainly occurs in the range of 0–4 mm area near strong turbulence. • The droplet size and turbulence intensity change linearly in the range of 300 mm. • When the I reaches 3.35 or more, the droplets are broken more completely. The x-swirl nozzles has been widely used in the field of spray technology for dust reduction. In this study, experimental studies on the droplet breakup and droplet particles diffusion of X-swirl nozzles by particle image velocimetry (PIV). Based on the experimental results, the velocity fields at five different water supply pressures were compared, and 6 MPa was chosen as the water supply pressure to study droplet breakup and droplet particles diffusion. The results show that, turbulence can change the trajectory of droplets and have an important impact on the atomization process. The variation law of turbulence intensity in axial and radial directions is revealed. The turbulence intensity ( I ) in the spray field axial direction continuously decreased as the distance increased and had an overall exponential relationship. I within 2.5 mm in the radial direction of the spray field’s center rapidly decreased, but the downward trend slightly decelerated in the area exceeding 2.5 mm. Combined with the parameters of strain rate ( S ) and vorticity ( Ω ), the comparative analysis is carried out. When the gas and liquid are fully mixed, the turbulence intensity increases rapidly. This promotes the growth, deformation and breakup of droplets, and affects the diffusion of droplets. Through the probability density function, it is revealed that droplet breakup mainly occurs in the range of 0–4 mm near strong turbulence. The droplet size at different locations was measured by Phase Doppler Interferometer (PDI), which revealed the mechanism of turbulent flow on the droplet size. In the range of 0–300 mm, the droplets with larger initial particle size and velocity gradually evolve into droplets with small particle size, small velocity and large number over time. But in the 300–450 mm range, the turbulent flow’s effect on the breakup gradually decreased with the droplet movement time. Most of the droplets have finished breaking. Due to coalescence between small droplets, the particle sizes tended to slowly increase.

Evaluation of the synergistic effect of plant-based components on the stability of curcuminoid emulsion

In this study, the effect of matrix compounds from natural curcuminoid resources on the stability of curcuminoids and emulsions thereof was evaluated. Curcuminoid emulsions were prepared curcuminoid rich sources (curcuminoid extract, an aqueous turmeric concentrate and turmeric powder) with medium-chain triglyceride oil as lipid phase, lecithin, and pectin as emulsifiers. The curcuminoid emulsions were exposed to light in the visible wavelength range (300 nm–800 nm) at the specific energy input of 0.47 kW/m2 for 7 days and to the temperature of 4 °C, 25 °C, 40 °C for 49 days. The total curcuminoid retention (TC), droplet size (DS) change, instability index (InI), and yellowness reduction (YR) was observed during the storage time. The half-life of curcuminoids in emulsions was increased to 21 h, while the half-life of free curcuminoids was 1.3 h in the light exposure test. The co-compounds from the curcuminoid sources contributed to the emulsion stability by increasing the viscosity. In the thermal exposure test, the matrix compound system retained more than 93% curcuminoids after 49 days of storage at 40 °C, whereas the phase separation increased significantly. However, the TC reduction was independent of the InI change and droplet agglomeration. The YR depended on the TC and the amount of co-components in the emulsion.

Droplet behavior in overexpanded supersonic two-phase jets

The interaction of liquid droplets generated by spray atomization with high-speed co-flowing gas is of interest in various applications including fuel injection, spray cooling, and surface coating. The underlying processes involve interactions between the droplets themselves, and with the carrier gas. Additionally, they are influenced by shock and expansion waves present in high-speed flows, accompanied by resulting velocity and pressure fluctuations. Non-intrusive diagnostics including Shadowgraphy and Phase Doppler Particle Anemometry, along with flow simulations, are used to study droplet behavior, characterized by size and velocity changes, as a finely atomized spray is propelled by a carrier gas through a supersonic, overexpanded jet structure. Measurements of droplet size and velocity are correlated to the shock train structure of the overexpanded jet and further to gas velocity as obtained from simulation results. While the shock structure is observed to be unaffected by spray injection, periodic increases and decreases are observed in average droplet size. Analysis using gas flow field obtained from simulations, estimated critical Weber numbers for droplet breakup and timescales for droplet dynamics, compared to residence time in the flow, suggests that droplet size changes can be attributed to alternating coalescence and breakup. The two-dimensional flow structure involving converging and diverging sections as well as a spread in droplet sizes likely promote coalescence and breakup processes leading to periodic variation in droplet SMD. The streamwise variations of gas velocity along the centerline caused by the shock train are not noticed in the droplet velocity, which can be explained by the high Stokes number causing droplets at the centerline to behave as ballistic particles moving through the shock structure. Experimental measurements, simulation results, and their subsequent analyses show that droplet collision and coalescence regimes established in previous work for ambient conditions show deviations when subject to high-speed gas flow conditions.

At-line and inline prediction of droplet size in mayonnaise with near-infrared spectroscopy

A novel use of near-infrared (NIR) spectroscopy and chemometrics is presented for non-invasive prediction of droplet-size of mayonnaise. Both at-line and inline monitoring capabilities were explored. At first during the offline experimentation, two different batches of mayonnaise were prepared under pilot plant manufacturing conditions. The mayonnaise was manufactured with different fat content levels and different milling speeds to induce differences in the droplet size during the process. The reference droplet-sizes were measured using pulsed-field gradient nuclear magnetic resonance (pfg-NMR). NIR data were calibrated with reference droplet-size measurements by partial least-square (PLS) regression. The results of at-line analysis showed that the NIR models reached high performance to predict droplet-size in mayonnaise. Furthermore, separate, and global models were used for droplet size prediction for different fat content mayonnaise. For the second part of study, a diode-array NIR spectrometer was directly integrated in the process line for mayonnaise manufacturing and real-time NIR measurements were performed. The process was modulated with different milling speeds and the effect on NIR measurements was explored. The chemometric analysis performed on the NIR process data allowed following the droplet size changes due to changing milling speed. Overall, NIR provided a good correlation with droplet-size of mayonnaise and can support applications such as real-time monitoring of droplet-size during mayonnaise manufacturing process to optimize process and product properties.

Antimicrobial Formulation of Chrysopogon zizanioides Essential Oil in an Emulsified Lotion for Acne.

Acne is a skin condition arising from excess sebum production and microbial overgrowth within the pilosebaceous unit. Several commercial essential oils have shown promising activity against acne-related pathogens. Due to their volatility and thermal instability, the formulation of essential oils into commercial products remains a pharmaceutical challenge. Thus, this study aimed to develop a viable anti-acne topical treatment as an oil-in-water emulsified lotion to overcome these challenges. Chrysopogon zizanioides (vetiver) displayed noteworthy antimicrobial activity with a mean minimum inhibitory concentration of 0.14 mg/mL against Cutibacterium acnes, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes. Emulsified lotions containing C. zizanioides were developed through the hydrophilic-lipophilic balance approach. At tested hydrophilic-lipophilic balance values of 8, 9, and 10, C. zizanioides emulsified lotions displayed maximum stability at hydrophilic-lipophilic balance 9 with a minimum change in mean droplet size and polydispersity index of 20.61 and 33.33%, respectively, over 84 days. The C. zizanioides emulsified lotion at optimum hydrophilic-lipophilic balance 9 completely inhibited the growth of C. acnes and killed S. aureus, S. epidermidis, and S. pyogenes within 24 h. Additionally, the lotion retained antimicrobial activity against these test micro-organisms over the 84-day stability test period. Thus, the C. zizanioides emulsified lotion demonstrated physical stability and antimicrobial efficiency, making it an ideal natural product anti-acne treatment.

Preparation, optimization using a mixture design, and characterization of a novel astaxanthin-loaded rice bran oil self-microemulsifying delivery system formulation

This research aimed to develop a self-microemulsifying delivery system (SMEDS) to increase dissolution rate of astaxanthin (AST) using a design of experiment (DoE) approach for investigating the effect of components on the physicochemical properties of AST SMEDS formulation. By applying the mixture design, the optimal compositions of rice bran (RB) oil (oil; X1), Kolliphor® RH40 (surfactant; X2), and Span® 20 (cosurfactant; X3) were determined based on the preliminary screening studies. The optimization models were validated by comparing the regression coefficient (R2) of the predicted values to the experimentally measured ones. Based on the desirability function, the optimized AST SMEDS was composed of 33.67% rice bran oil, 34.70% Kolliphor® RH40, and 31.63% Span® 20 which contained AST concentration (Y1) of 0.04% in the formulation and yielded microemulsion droplet size (Y2) of 40.79 ± 3.11 nm. The experimentally measured values obtained from the optimized AST SMEDS were in accordance with its predicted values with relatively low prediction errors (< 2%). The validated models were investigated by the contour plots, three-dimensional surface plots, and main effect plots. It was found that surfactant and cosurfactant inversely affected on droplet size changes whereas all three components (oil, surfactant and cosurfactant) did not relatively impact AST solubilizing capacity. In vitro release of AST SMEDS was significantly increased more than 90% compared to the raw AST powder. The optimized AST SMEDS was successfully developed by the mixture design and could be economically effective to enhance dissolution of poorly water-soluble AST.

Experimental studies into the effect of air pressure on the atomization characteristics of coal-water slurries

The paper studies the effect of atomizing agent pressure on the spray characteristics after spraying coal-water slurry that contains small additives of liquid waste from the pyrolysis of industrial rubber goods and used engine oil. The conducted experiments used automobile tires as the indicated rubber products; spraying was carried out employing an internal mixing pneumatic atomizer. Following the atomization of considered fuels, droplet size changes were studied using the interferometric particle imaging (IPI) technique. The spray angle was determined by means of a Photron high-speed camera. In addition, coal-water slurry containing liquid waste from the pyrolysis of industrial rubber goods and used engine oil (3–12 wt%) was sprayed to study the effect of atomizing agent pressure on the spray characteristics. A decrease in air pressure was found to reduce the spray angle by less than 6%, which resulted in the formation of rather large droplets exceeding 600 µm in size. It is experimentally confirmed that more fine droplets are formed at similar fuel and air pressures when using a spraying device equipped with an internal mixing chamber for slurry and air. The number of droplets, in this case, is 2–9% higher as compared to a typical two-component coal-water slurry fuel, with the spray angle of the sprayed coal slurry having the greatest value. When using an atomizer having an internal mixing chamber for slurry and an atomizing agent, fuel droplet breakup occurs due to the aerodynamic drag forces of the environment. Thus, the use of such atomizers reduces the number of possible breakup mechanisms for sprayed fuel droplets.

Compound jetting from bubble bursting at an air-oil-water interface

Bursting of bubbles at a liquid surface is ubiquitous in a wide range of physical, biological, and geological phenomena, as a key source of aerosol droplets for mass transport across the interface. However, how a structurally complex interface, widely present in nature, mediates the bursting process remains largely unknown. Here, we document the bubble-bursting jet dynamics at an oil-covered aqueous surface, which typifies the sea surface microlayer as well as an oil spill on the ocean. The jet tip radius and velocity are altered with even a thin oil layer, and oily aerosol droplets are produced. We provide evidence that the coupling of oil spreading and cavity collapse dynamics results in a multi-phase jet and the follow-up droplet size change. The oil spreading influences the effective viscous damping, and scaling laws are proposed to quantify the jetting dynamics. Our study not only advances the fundamental understanding of bubble bursting dynamics, but also may shed light on the airborne transmission of organic matters in nature related to aerosol production.

Formation and characterisation of high-internal-phase emulsions stabilised by high-pressure homogenised quinoa protein isolate

High pressure homogenised (HPH) quinoa protein isolates (QPI) suspensions (1, 3, and 5 wt%) were used to prepare high-internal-phase emulsions (HIPEs) (ɸ=0.8). The viscoelastic behaviours of HIPEs were characterised by oscillatory rheology, while the oil droplet size distribution and microstructural characteristics were examined by static light scattering and confocal laser scanning microscopy (CLSM). At all QPI concentrations, HIPEs behaved as viscoelastic gels due to network formation as a result of interactions between jammed oil droplets and protein aggregates. As the QPI concentration increased, the oil droplet size decreased from ~80 to~40 µm and the elastic modulus G´(1 Hz) increased from ~100 to~580 Pa. Effects of prolonged storage (30 days) and heat treatment (80 °C, 30 min) on the rheological behaviour and microstructures of HIPEs were also investigated. All emulsions showed excellent stabilities against phase separation, oil coalescence, and creaming during storage or under heat treatment. Prolonged storage induced a substantial increase in G´, while no significant change in oil droplet size was observed. CLSM revealed that the interfacial layer became thicker and large protein aggregates were formed during storage, which led to a more dense and compact packing of droplets and greater gel strength. Heat treatment induced a 3–5 folds enhancement in the gel strength due to protein denaturation and proteins and oil droplets aggregation. These findings provide useful information for the design and preparation of HIPEs stabilised by quinoa proteins.

Oil separation from oil in water emulsion by coalescence filtration using kapok fibre

ABSTRACT In this study, the stable emulsion of engine oil in water of concentration 10% was prepared using a non-ionic surfactant. Kapok fibres were used as filter beds to separate oil from the oil–water emulsion. The surface morphology of fibres was investigated using Scanning Electron Microscope (SEM) analysis and chemical bond analysis of fibres done using Fourier transform infrared (FTIR). Kapok filter beds were prepared with three different bed heights 10, 20 and 30 mm each with four different porosities 0.90, 0.92, 0.95 and 0.98 for preparing the coalescence filter. The oil–water emulsion (influent) was pumped into the filtration column and the coalesced oil droplets, water, as well as un-coalesced oil droplets, especially the finer oil droplets, were collected as effluent. Oil separation efficiency was evaluated in terms of change in droplet size (D50) and oil concentration from influent to effluent. With increasing porosity and bed height, apart from porosity of 0.92, the separation efficiency increases. Increasing the bed heights at lower porosities does not improve the efficiency of the process. A combination of 0.98 porosity and a bed height of 30 mm provided the highest filtration performance in terms of oil separation efficiency and D50 droplet ratio. At 0.98 porosity, increasing the bed height from 10 mm to 30 mm resulted in a D50 droplet ratio of 0.25–0.14, representing a significant decrease in droplet size in the effluent and therefore an increase in oil separation efficiency from 91.3% to 99.63%.

Enhancing the stability of oil-in-water emulsions by synergistic interplay between binary protein particles and starch nanocrystals

Oil in water (o/w) emulsions are ubiquitous in food systems, where the stabilization of a homogeneous biphasic texture is necessary. In this study, binary protein particles (CRPs) with hydrophilic shells (cod proteins) and hydrophobic cores (rice proteins) were fabricated as stabilizers of o/w emulsions. To circumvent their instability at the interface due to conformational changes, the CRPs were further reinforced by starch nanocrystals (SNCs) to form a secondary complex (CRP@SNCs). Results from cryo-scanning electron microscope and confocal laser scanning microscope confirmed the stable adsorption of SNC-reinforced CRPs on the biphasic interface with excessive SNCs as the spacers separating the adjacent oil droplets, leading to emulsions featuring both Pickering-type and steric-type stabilization. At the optimum SNCs/CRPs mass ratio, the emulsions showed undetectable phase-separation and negligible changes in droplet size during the tested storage for up to 28 days. Our study presents a facile strategy for innovating novel stabilization protocols for emulsions.