Model Emulsions Research Articles

Enhanced coalescence stability of droplets through multi-faceted microgel adsorption behaviour

Tannic acid-crosslinking of whey protein isolate (WPI) microgels produces soft particles that can physically stabilize food emulsions. Here, these particles were used to investigate their compression at the air-water interface, and early-time stabilization of a model emulsion. Langmuir trough experiments show that the microgels have a compression behaviour similar to synthetic microgels with a core-shell structure. The dangling chains provide protein-protein interactions at low surface coverage, while the partially-flattened cores provide thicker surface patches. Microfluidic experiments showed that at low continuous phase concentration, WPI microgels suppress coalescence due to bridging, which leads to improved stability compared to emulsions stabilized by native WPI. In contrast to classic Pickering emulsions, longer adsorption times lead to higher adsorbed amounts, which is expected due to the chains on the microgel surface, and possibly flattening of these microgels at the interface. Both features together are expected to be instrumental in obtaining highly stable microgel-stabilized food emulsions. • Tannic acid-crosslinked whey protein microgels are soft and surface active particles. • For low coverage, increase of surface elasticity with pressure is similar to WPI. • Microgels stabilize emulsions more efficiently than proteins. • Emulsions are stabler when longer adsorption time is allowed for microgels. • Bridging flocculation prevents coalescence of droplets stabilized by microgels.

Electrospun Liquid-Infused Membranes for Emulsified Oil/Water Separation.

From an environmental perspective, microfiltration membranes are attractive for the separation of emulsified oils from contaminated water. However, fouling of the membrane is a major drawback of the technology. "Liquid-infused membranes" (LIMs) have the potential to eliminate membrane fouling. Here, we demonstrate the practical application of LIMs for the separation of oil from a stable oil-in-water emulsion and characterize their resistance to fouling. The base membrane is an electrospun nonwoven fibrous layer of the fluorinated copolymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP). The surface energy of the PVDF-co-HFP fibers was lowered by the covalent attachment of a fluorinated silane (PFOCTS), and then, the membrane was infused with a perfluoropolyether. The membrane was then challenged with model emulsions of dodecane in water in a cross-flow configuration. This PFOCTS-modified LIM showed better infused liquid stability, permeation selectivity, higher permeate flux than the unmodified LIM, and better anti-fouling properties than the bare membrane without infused liquid. We also examine the mechanism for transport of the dispersed oil phase through the liquid-infused membrane. We find a linear relationship between the dodecane flux and dodecane concentration in the feed and a higher dodecane flux through the PFOCTS-modified membrane than the unmodified one, which suggests that the capture of dodecane droplets from the feed plays an important role in determining the overall rate of permeation. Other factors such as lower viscosity of the infused liquid, larger pore size, and higher operating pressure also improved the permeate flux through the LIMs. Overall, this work provides some guidelines on the design of composite membranes comprising infused liquids and the choice of operating conditions for the filtration process.

Investigating the hydrolytic degradation of PLA/PCL/ZnO nanocomposites by using viscoelastic models

AbstractIn this research, the degradation of a polymer blend in the presence of nanoparticles by considering the effect of nanoparticles on the degradation was investigated using emulsion models and fractional Zener model for the first time. Poly(lactic acid)/poly(caprolactone)/zinc oxide nanocomposite blends were prepared using the melt mixing method. Interface complex shear modulus for the neat polymer blend and its nanocomposites were calculated using emulsion models in a range of frequencies. All competing factors imposing elasticity on the systems, including the solid‐like behavior and degradation catalytic activity of ZnO nanoparticles in the presence of polyesters, were considered. After comparing the interface complex shear modulus of samples, it was revealed that the negative elastic impact of ZnO (degradation role) governs the viscoelastic behavior of these systems. Accordingly, the samples containing ZnO nanoparticles exhibited low elasticity, which was attributed to overcoming the degradation role of ZnO compared with the hydrodynamic interaction of ZnO nanoparticles. Additionally, the results obtained from the fractional Zener model were in good harmony with the emulsion model analysis.

Particle morphology of mineral filler and its effects on the asphalt binder-filler interfacial interaction

This paper focused on the particle morphology of mineral filler and its effects on asphalt binder-filler interfacial interaction. The limestone, basalt, and granite fillers with various particle sizes were selected to prepare asphalt mastics. The relationship between morphological characteristics of mineral filler and asphalt binder-filler interfacial interaction was established. The results show that the angularity index and fractal dimension decrease while the form factor increase with the decreasing particle size. The granite filler particles demonstrated the higher morphological index values than the limestone and basalt ones. The K-B-G* value based on Palierne emulsion model exhibits the least susceptibility but strongest stability to filler particle size among the evaluation parameters studied. Form factor is the determining influential factor for asphalt binder-filler interfacial interaction, regardless of filler lithology. Furthermore, the packing characteristics of filler particles and the associated mastic morphologies could provide insight to possible relationship between particle morphology and interfacial behavior. All the results contribute to the selection of appropriate mineral filler to improve the asphalt binder-filler interfacial interaction and then the performance of asphalt mix system.

Formulating a model emulsion replicating SAGD in-situ emulsions

Emulsions are widely produced and handled in the petroleum industry, particularly in the recovery of heavy oil and bitumen by steam flooding enhanced oil recovery (EOR) techniques. Production of emulsions has been detected from the very early stages of steam-assisted gravity drainage (SAGD) operations, and the literature suggests emulsification occurs in the reservoir. The model fluids employed in the current SAGD sand pack testing, such as sand retention test (SRT) and flow line testing, do not account for emulsions and their properties. This study introduces model emulsions formulated to mimic some essential features of the SAGD in-situ emulsion properties in terms of droplet size, viscosity, kinetic stability, and asphaltene precipitation. Moreover, a workflow is presented which can be used to synthesize model emulsions of any desired properties.

Characterization of Moringa oleifera leaf and seed protein extract functionality in emulsion model system

This study provides a comparative overview of Moringa oleifera leaf and seed protein extract (LPE and SPE, respectively) functionality in emulsions. Raw seed cake (RS) had more protein (45.8%) than raw leaf (RL) (27.4%). RL comprised higher polyphenol and flavonoid content than RS, Granny Smith apples, and Goji berries. Protein functionality data revealed that LPE had excellent solubility, and emulsifying properties than SPE at pH 7.0. In contrast, SPE had relatively strong surface hydrophobicity. At pH 7.0, leaf extract emulsions (LEE) possessed relatively small particle size distribution, strong negative charge, excellent stability, and minimum sedimentation velocity. On contrary, at pH 3.5, particle size, and velocity increased, contributing to monodisperse sedimentation. Seed extract emulsions (SEE) had an overall large particle size and demonstrated fast and extensive creaming and sedimentation at both pH conditions. Our findings indicate that M. oleifera leaf protein extracts have considerable potential for use in emulsion-based foods.

Lubrication and Sensory Properties of Emulsion Systems and Effects of Droplet Size Distribution.

The functional and sensory properties of food emulsion are thought to be complicated and influenced by many factors, such as the emulsifier, oil/fat mass fraction, and size of oil/fat droplets. In addition, the perceived texture of food emulsion during oral processing is mainly dominated by its rheological and tribological responses. This study investigated the effect of droplet size distribution as well as the content of oil droplets on the lubrication and sensory properties of o/w emulsion systems. Friction curves for reconstituted milk samples (composition: skimmed milk and milk cream) and Casein sodium salt (hereinafter referred to as CSS) stabilized model emulsions (olive oil as oil phase) were obtained using a soft texture analyzer tribometer with a three ball-on-disc setup combined with a soft surfaces (PDMS) tribology system. Sensory discrimination was conducted by 22 participants using an intensity scoring method. Stribeck curve analyses showed that, for reconstituted milk samples with similar rheological properties, increasing the volume fraction of oil/fat droplets in the size range of 1–10 µm will significantly enhance lubrication, while for CSS-stabilized emulsions, the size effect of oil/fat droplets reduced to around 1 µm. Surprisingly, once the size of oil/fat droplets of both systems reached nano size (d90 = 0.3 µm), increasing the oil/fat content gave no further enhancement, and the friction coefficient showed no significant difference (p > 0.05). Results from sensory analysis show that consumers are capable of discriminating emulsions, which vary in oil/fat droplet size and in oil/fat content (p < 0.01). However, it appeared that the discrimination capability of the panelist was significantly reduced for emulsions containing nano-sized droplets.

Modelling the Spectral Index to Detect a Baltic-Type Crude Oil Emulsion Dispersed in the Southern Baltic Sea

Information was obtained on the possibility of detecting oil-in-water emulsions located under the sea based on the modelling of the directional distribution of the radiance field above the water surface. The optical sea model used applies to the southern Baltic Sea, while the oil emulsion model is based on the optical properties of crude oil extracted in this region of the sea. The analyses were carried out while taking into account eight wavelengths in the range 412–676 nm, assuming different thicknesses of the layer contaminated with oil. The most favourable combination of two wavelengths (555/412 nm) for the determination of an index related to the polluted sea area compared to the same index for oil-free water (difference index) was identified, the value of which is indicative of the presence of the oil emulsion in water. Changes in the difference index depending on the viewing direction are shown for almost the entire upper hemisphere (zenith angles from 0° to 80°). The observation directions for which the detection of emulsions should be the most effective are shown.

Characterization, Bioactivity and Application of Chitosan-Based Nanoparticles in a Food Emulsion Model

In this study, chitosan nanoparticles (CNPs) were prepared by the ionic gelation technique with tripolyphosphate (TPP), and the effect of CNP composition and physicochemical characteristics were evaluated. After the synthesis optimization, CNPs were used as carriers for a fish protein hydrolysate (FPH) with bioactive properties (CNPH). The physicochemical characteristics, antioxidant capacity and antimicrobial, antihypertensive and emulsifier properties of unloaded and loaded CNPs in a food system model were studied. CNPH showed a uniform particle distribution, size ~200 nm, high stability (zeta potential around 30 mV), radical scavenging activity and increased antimicrobial activity against Staphylococcus aureus, Shigella sonnei and Aeromonas hydrophila. Additionally, CNPH showed an angiotensin I-converting enzyme (ACE)-inhibitory activity of 63.6% and, when added to a food emulsion model, this system containing CNPs, with or without FHP, exhibited improved food emulsion stability. Thus, CNPs were able to carry the FPH while maintaining their bioactive properties and can be an alternative to the delivery of bioactive peptides with potential as an emulsion stabilizer for food applications.

Stigmasterol Stability in Medium Chain Triacylglycerides (MCT)‐in‐Water Emulsions: Impact of Sodium Dodecyl Sulphate (SDS) Surfactant Micelles

AbstractThe stability of the health‐promoting phytosterols in emulsions can be affected by various factors such as lipid medium, storage time, and temperature. In addition to these well‐studied factors, emulsions normally contain excessive amount of surfactant that self‐assemble into micelles. However, the potential of these surfactant micelles to alter the stability of phytosterol is unclear. In this study, medium chain triacylglycerides(MCT)‐in‐water emulsion is used as a model emulsion system to report how surfactant micelles of sodium dodecyl sulphate (SDS) can affect the stability of stigmasterol. Addition of SDS micelles (0.5, 1, and 2 wt%) significantly increases the amounts of stigmasterol and stigmasterol hydroperoxides in the aqueous phase of emulsion. A large proportion of stigmasterol hydroperoxides (up to 64.14%) is solubilized into the aqueous phase although the majority of stigmasterol (&gt;90%) remains in the oil phase. Such different distributions of stigmasterol and its hydroperoxides can be responsible for the increased storage time (19, 27, and 33 d for control, 1 and 2 wt% additional SDS, respectively) of stigmasterol in emulsions stored at 60 °C.Practical Applications: Surfactant micelles have the potential to be developed into economical antioxidant strategies to extend the stability of phytosterols when developing phytosterol‐enriched food emulsions.

Bioethanol Production and Alkali Pulp Processes as Sources of Anionic Lignin Surfactants.

Lignin is an abundant biopolymer with potential value-added applications that depend on biomass source and fractioning method. This work explores the use as emulsifiers of three native lignin-rich product coming from industrial bioethanol production and alkali or Kraft pulping. In addition to their distinctive characteristics, the different molecular organization induced by emulsification pH is expected to interact in various ways at the water-oil interface of the emulsion droplets. Initially, model oil-in-water (O/W) emulsions of a silicone oil will be studied as a function of lignin source, disperse phase concentration and emulsification pH. Once stablished the effect of such variables, emulsion formulations of three potential bitumen rejuvenators (waste vegetable cooking oil, recycled lubricating oil and a 160/220 penetration range soft bitumen). Droplet size distribution, Z-potential and viscous tests conducted on model emulsions have shown that emulsification pH strongly affects stabilization ability of the lignins tested. Regarding bitumen rejuvenators, lignin emulsification capability will be affected by surfactant source, pH and, additionally, by the dispersed phase characteristics. Lower Z-potential values shown by KL at pH 9 and 11 seem to facilitate emulsification of the less polar disperse phases formed by RLUB and bitumen. In any case, lower particle size and higher yield stress values were found for both bioethanol-derived lignins emulsifying RVO and RLUB at pH 13, which are expected to exhibit a longer stability.

Antimicrobial and Antioxidant Potential of Papain Liver Hydrolysate in Meat Emulsion Model at Chilling Storage Under Aerobic Packaging Condition

Antimicrobial and Antioxidant Potential of Papain Liver Hydrolysate in Meat Emulsion Model at Chilling Storage Under Aerobic Packaging Condition

Identification of the thistle milk component Silibinin(A) and Glutathione-disulphide as potential inhibitors of the pancreatic lipase: Potential implications on weight loss

• Lipase inhibition, as occurs with orlistat, is suitable for weight loss. • Natural compounds with similar activity than orlistat may help in obesity treatment. • Our data revealed silibinin(A) and glutathione-disulphide as lipase inhibitors. • At an oil–water interface, the inhibition of silibinin(A) and orlistat was similar. • More studies are needed to confirm the role of silibinin(A) for obesity treatment. Peripheral targets like pancreatic-lipase appear to be the most suitable pharmacological alternative for obesity, as with orlistat, although its adverse effects limit its use. Therefore, the aim of this work was to identify new natural compounds able to inhibit pancreatic-lipase in an in vitro model. The DrugBank database was used to perform docking calculations. The best fitting-score compounds were further evaluated in vitro . Our data revealed that glutathione-disulphide (GSSG) and silibinin(A) inhibit pancreatic-lipase. This was confirmed by measuring hydrolysis in an emulsion model, obtaining that the suppression of lipid digestion by silibinin(A) was higher than that of GSSG and close to the effect of orlistat. Combined analysis established the existence of different inhibition mechanisms for each compound. In summary, silibinin(A) and GSSG inhibited pancreatic-lipase and, therefore, may be served as promise natural compounds to face with obesity. Further studies comprise the next step to fully validate the suitability of these compounds.

Effect of different concentrations of sodium chloride and soy protein isolate with mono- and diglycerides/corn oil on physical properties and stability of w/o/w double emulsion

The successful fabrication of double emulsion is determined by the ingredients or the process. The aim of the study was to determine the effects of sodium chloride and soy protein isolate with addition of mono-and diglycerides/corn oil on physical and stability of emulsion. Model emulsions with different concentration of sodium chloride (0.5% and 1.5%) and soy protein isolate (1% and 3%) with addition of mono-and diglycerides/corn oil (ratio 1:1) were prepared. Physical properties and stability of double emulsion were characterized by viscosity, emulsion stability, pH, and color. The results showed that the stability of double emulsion was significantly affected (p < 0.05) by the interaction between sodium chloride and soy protein isolate, whereas pH and viscosity were affected only by the concentration of soy protein isolate. However, double emulsion containing 1.5% of sodium chloride and 3% of soy protein isolate (SPI) with addition of mono-and diglycerides/corn oil showed the highest stability in comparing with emulsion containing 0.5% of sodium chloride and 3% of SPI.

Stringiness of hyaluronic acid emulsions.

ObjectiveCosmetic emulsions containing hyaluronic acid are ubiquitous in the cosmetic industry. However, the addition of (different molecular weight) hyaluronic acid can affect the filament stretching properties of concentrated emulsions. This property is often related to the “stringiness” of an emulsion, which can affect the consumer's choice for a product. It is thus very important to investigate and predict the effect of hyaluronic acid on the filament stretching properties of cosmetic emulsions.MethodsModel emulsions and emulsions with low and high molecular weights are prepared and their filament stretching properties are studied by the use of an extensional rheometer. Two different stretching speeds are employed during the stretching of the emulsions, a low speed at 10 µm/s and a high speed at 10 mm/s. The shear rheology of the samples is measured by rotational rheology.ResultsWe find that filament formation only occurs at high stretching speeds when the emulsion contains high molecular weight hyaluronic acid. The formation of this filament, which happens at intermediate states of the break‐up, coincides with an exponential decay in the break‐up dynamics. The beginning and end of the break‐up of high molecular weight hyaluronic acid emulsions show a power law behaviour, where the exponent depends on the initial stretching rate. At a lower stretching speed, no filament is observed for both high molecular weight and low molecular weight hyaluronic acid emulsions and the model emulsion. The emulsions show a power law behaviour over the whole break‐up range, where the exponent also depends on the stretching rate. No significant difference is observed between the shear flow properties of the emulsions containing different molecular weights hyaluronic acid.ConclusionIn this work, we underline the importance of the molecular weight of hyaluronic acid on the elongational properties of concentrated emulsions. The filament formation properties, for example the stringiness, of an emulsion is a key determinant of a product liking and repeat purchase. Here, we find that high molecular weight hyaluronic acid and a high stretching speed are the control parameters affecting the filament formation of an emulsion.

Multifunctional Polymer Particles Containing Quaternary Ammonium for Antimicrobial Particulate Surfactants and Defoaming

The preparation of multifunctional polymer particles containing quaternary ammonium molecules by emulsion iodine transfer polymerization (emulsion ITP) via polymerization-induced self-assembly was proposed for the first time. Poly(2-methacryloyloxy ethyl trimethyl ammonium chloride-dimethylamino ethyl methacrylate 12 alkyl chain length)-iodide (P(MTMA-QAC12)12-I) was first synthesized by solution iodine transfer polymerization. It was simultaneously used as a macro-chain transfer agent and emulsifier in emulsion ITP. All conditions smoothly proceeded without coagulation, where the polymerization reached high conversion within only 4 h. When the methyl methacrylate-styrene (P(MMA-S)) copolymer was synthesized in the second block as P(MTMA-QAC12)12-b-P(MMA-S)462, the water contact angle of the obtained particles was close to 90°, which was the most appropriate to use as the particulate surfactant. The P(MTMA-QAC12)12-b-P(MMA-S)462 particles represented a good antimicrobial property based on the positive charge quaternary ammonium groups existing on surfaces. Using such P(MTMA-QAC12)12-b-P(MMA-S)462 nanoparticles (∼90 nm) at 1 wt %, the obtained cutting oil emulsion model represented high colloidal stability with approximately 50 μm oil droplet size without any coalescence. Moreover, foam formation was significantly reduced compared to the commercial cutting oil. According to their excellent properties, P(MTMA-QAC12)12-b-P(MMA-S)462 nanoparticles would be effectively used as a particulate surfactant in Pickering emulsion, including defoamers and antimicrobial agents.

Application of Capillary Polypropylene Membranes for Microfiltration of Oily Wastewaters: Experiments and Modeling

Oily wastewaters are considered as one of the most dangerous types of environmental pollution. In the present study, the microfiltration (MF) process of model emulsions and real oily wastewaters was investigated. For this purpose, capillary polypropylene (PP) membranes were used. The experiments were conducted under transmembrane pressure (TMP) and feed flow rate (VF) equal to 0.05 MPa and 0.5 m/s, respectively. It was found that the used membranes ensured a high-quality permeate with turbidity equal to about 0.4 NTU and oil concentration of 7–15 mg/L. As expected, a significant decrease in the MF process performance was noted. However, it is shown that the initial decline of permeate flux could be slightly increased by increasing the feed temperature from 25 °C to 50 °C. Furthermore, Hermia’s models were used to interpret the fouling phenomenon occurring in studied experiments. It was determined that cake formation was the dominant fouling mechanism during filtration of both synthetic and real feeds. Through detailed studies, we present different efficient methods of membrane cleaning. Results, so far, are very encouraging and may have an important impact on increasing the use of polypropylene MF membranes in oily wastewater treatments.

Reducing phosphate in low sodium and low‐cost meat emulsions: A healthier approach

This study investigated the effect of reducing sodium chloride (NaCl) and phosphate in meat emulsion models added of chloride salt substitutes (KCl and CaCl2) on the physicochemical characteristics and microstructure of meat emulsions containing high content of mechanically deboned poultry meat (MDPM). Ten treatments were performed containing NaCl, KCl, CaCl2, or blend of these salts, with the same ionic strength were used to substitute of the NaCl, and 0.25% or 0.5% sodium tripolyphosphate (STPP). The treatments containing CaCl2 contributed negatively to the formation and stability of the batter. KCl promoted physicochemical characteristics similar to NaCl. It was possible to reduce 50% of the STPP content without negatively affecting the functional properties. The results of blends containing NaCl, KCl, and CaCl2 can be useful to reduce the content of sodium and phosphate in emulsified products with a high content of MDPM resulting in a healthier and more accessible cost for consumers. Practical applications There is a growing demand for the development of healthier meat products, being the reduction of sodium and phosphate content one of the main challenges, mainly in matrices with high content of mechanically deboned meat. It was evidenced that the reduction of NaCl content maintaining the STPP content did not promote major impact on the characteristics of meat emulsions with high content of MDPM. Replacing NaCl by KCl proved to be a good option to reduce the sodium content in meat emulsions.

Effects of different molecular architectures in terms of comonomer content and composition distribution on the miscibility of cyclic olefin copolymer/polyolefin (COC/POE and COC/LLDPEB) blends

In this work, morphology and rheology of the blends of cyclic olefin copolymer (COC) with two types of crystalline polyolefins were investigated through a wide range of compositions. The used polyolefins had various plasticity, elasticity and viscoelastic behavior. Their molecular structures were similar but their molecular architectures were different in terms of comonomer content and composition distribution (i.e., a linear low-density polyethylene with 4 mol% of 1-butene comonomer (LLDPEB labeled as LLB) and nonuniform composition distribution and a polyolefin elastomer (POE) with 33 mol% of 1-butene comonomer and uniform composition distribution). Morphology of the COC/POE blends was droplet-matrix at low concentrations of the dispersed phase which was changed to co-continuous morphology at intermediate concentrations. Good compatibility and adhesion between phases were also observed. In COC/LLB blends, droplet-matrix morphology and good compatibility were observed between the two phases, except for compositions of 70/30 and 50/50, which exhibited continuous morphology and phase separation. The results of morphology and rheological data such as Cole–Cole plots and variations of viscosity versus composition revealed that these blends were immiscible. The interfacial interaction of the blend phases was investigated using rheological diagrams of variations of their complex viscosities, storage modulus versus frequency, relaxation time spectra and tan δ versus frequency. In addition, the interfacial tension was calculated using emulsion models. It was found that in the intermediate concentrations and COC-rich compounds, the interfacial interaction of the phases and form relaxation time of the dispersed particles of the COC/POE blends were higher than those of the COC/LLB blends, resulting in a further increase in elasticity. In blends with low COC content, the interfacial interaction of the phases and form relaxation time of the dispersed particles of the COC/LLB blends were higher than those of the COC/POE blends.

Modification of Chestnut Leaf Litter for Application in Water Treatment

The effect of the temperature of heat treatment of chestnut tree waste (CTW) on the turbidity of oil-containing emulsions was studied. A granulometric analysis of the dispersity of particles of heat-treated CTW was carried out. In the experiments, the influence of the heat treatment temperature of the TW on the decrease in the turbidity of the model emulsions of spindle oil was determined. Sorption and desorption isotherms are constructed. Mixing of the sorption material with the model emulsion was carried out with a laboratory mixer for 24 hours. Initial parameters: solution temperature 25 ° C, sorbent quantity 3 g / dm3 The maximum sorption capacity of CTWT relative to spindle oil, according to the results of the studies, was 370 mg / g.