Physical Properties Of Emulsions Research Articles

Microscopy-Assisted Digital Image Analysis with Trainable Weka Segmentation (TWS) for Emulsion Droplet Size Determination

The size distribution of droplets in emulsions is very important for adjusting the effects of many indices on their quality. In addition to other methods for the determination of the size distribution of droplets, the usage of machine learning during microscopic analyses can enhance the reliability of the measurements and decrease the measurement cost at the same time. Considering its role in emulsion characteristics, in this study, the droplet size distributions of emulsions prepared with different oil/water phase ratios and homogenization times were measured with both a microscopy-assisted digital image analysis technique and a well-known laser diffraction method. The relationships between the droplet size and the physical properties of emulsions (turbidity and viscosity) were also investigated. The results showed that microscopic measurements yielded slightly higher values for the D(90), D[3,2], and D[4,3] of emulsions compared to the laser diffraction method for all oil/water phase ratios. When using this method, the droplet size had a meaningful correlation with the turbidity and viscosity values of emulsions at different oil/water phase ratios. From this point of view, the usage of the optical microscopy method with machine learning can be useful for the determination of the size distribution in emulsions.

Stability and in vitro digestion of high purity diacylglycerol oil-in-water emulsions

In this study, stability and in vitro digestion of sesame oil-based high purity diacylglycerol (DAG) oil-in-water emulsions were investigated. Firstly, the effects of DAG content and the freeze-thaw process on the physical properties of emulsions were assessed. The fresh DAG emulsions exhibited high absolute ζ-potential values (>40 mV), small d4,3 (<0.94 μm), and good stability during 14 days storage. However, DAG promoted partial coalescence of fat globules and the creaming index increased after the freeze-thaw process. Subsequently, the in vitro digestion of DAG emulsions was studied. The d4,3 of emulsions increased from 0.942 μm, 0.754 μm and 0.489 μm to 33 μm (0 g/kg DAG), 30 μm (50 g/kg DAG) and 25 μm (100 g/kg DAG) respectively after digestion in the simulated saliva and stomach, and then decreased to 8 μm, 7 μm and 5 μm respectively in the simulated small intestine. Notably, the variation tendency of ζ-potential was opposite to the d4,3 of emulsions during the simulated digestion. Finally, the free fatty acid release was monitored under simulated intestine digestion and it revealed that higher DAG content favored higher lipolysis. This work sheds light on employing DAG oil to prepare food emulsions.

THE INFLUENCE OF SURFACTANT AND PROTECTIVE COLLOID ON POLYVINYL ACETATE EMULSION SYNTHESIZED BY EMULSION POLYMERIZATION TECHNIQUE

A series of experiments have been carried out and reported. This report describes the stages of the polymerization reaction during emulsion Polyvinyl Acetate (PVAc) synthesis. PVAc was synthesized from the Vinyl Acetate Monomer (VAM) with Ammonium Peroxydisulphate (APS) as an inorganic thermal initiator in the aqueous media under reaction temperature was keep at 65 until 75oCs by agitation speed was 300 rpm respectively during 4 hours of reaction time. The protective colloid agents and several types of surfactants were added to improve the obtained emulsion PVAc performance. The polymerization reaction was carried out without the addition of a protective colloid agent. The surfactants were produced the emulsion PVAc with the properties of solid content 0.89%, density 1.02 g/ml, viscosity 0.0033 Poise, pH 2.8, conductivity 12 ms, respectively. While the polymerization reaction involved protective colloid agents by using Polyvinyl Alcohol (PVOH) was obtained properties of emulsion PVAc with Solid Content 4.36%, density 1.17 g/ml, viscosity 0.0216 Poise, pH 2.8, and conductivity 10 ms respectively. The same thing was shown when the surfactant was present in the polymerization reaction. The emulsion PVAc was synthesized with nonionic surfactant has solid content 8.20%, density 1.17 g/ml, viscosity 0.0099 Poise, pH 2.8, and conductivity 7 ms, the result is better rather than synthesized with anionic surfactant has solid content 2.65%, density 1.13 g/ml, viscosity 0.0068 Poise, pH 2.8, and conductivity 11 ms. According to the preliminary observations obtained, emulsion PVAc’s appearance is better when the protective colloid agents and the surfactant is present rather than without additional those substances. The physical properties of emulsion were depended on the addition of protective colloid agents and surfactants. In addition, the complete reaction indicated by solid content value was obtained from emulsion when the additional substances were present. All the testing parameters were observed using Viscometer Ostwald, Pycnometer, pH Meter, FTIR Spectrophotometer, Conductometer, and another supporting testing to explain the polymerization reaction stage of synthesis emulsion PVAc.

Fabrication of Gel-Like Emulsions with Whey Protein Isolate Using Microfluidization: Rheological Properties and 3D Printing Performance

A gel-like emulsion stabilized with whey protein was prepared by microfluidization, and the effects of the oil phase fraction on the physical properties of emulsions were studied. The rheological analysis indicated that these emulsions exhibited thixotropic behavior, and their apparent viscosity and solid-like behavior increased with increasing oil fraction from 0.3 to 0.6 (v/v). The microstructures, droplet size distribution, and thermal stability of these emulsions were also characterized using a light microscope, dynamic light scattering (DLS), and differential scanning calorimetry (DSC), respectively. The viscosity of these emulsions increased in an exponential way versus increasing oil fraction and showed good correlation coefficient (R2 > 0.99). The size of droplets in the emulsion increased from 301 ± 3.6 to 597 ± 7.3 nm. The DSC results showed that the crystalline peak of these emulsions gradually decreased from − 15 to − 21 °C and started thawing at ~ 3 °C. Visually, the textures of these emulsions could be transformed from flexible to rigid by changing the oil fraction, which suggests they could have multiple potential applications. Finally, the semi-solid emulsions were fabricated into delicate shapes using extrusion-based 3D food printing. Based on the results obtained, these emulsions may have the potential to be used as a solid-like fat substitute, which could be used in various applications such as cake decoration or customized functional foods.

Enhancing the stability of oil-in-water emulsion using pectin-lactoferrin complexes

The present study investigated on the emulsifying properties of natural low-methoxyl pectin (LMP) extracted from Green Jelly Leaf (GJLP) in stabilising lactoferrin stabilised oil-in-water emulsions. The emulsion stability of GJLP was compared to commercial pectins with different degree of esterification (DE) i.e. high-methoxyl pectin (HMP) and LMP. The influence of pH, pectin types and concentration on the stability and physical properties of emulsions were evaluated by determining zeta potential value, particle size, microstructure, rheological properties and creaming stability. Different types of pectin exhibited different mechanisms in providing the emulsion stability and the pectin effective charge was strongly dependent on its DE and pH of the continuous phase. The mechanism of actions of pectin and lactoferrin in the system were pH dependent for low molecular weight pectin, however not for high molecular pectin such as GJLP. The results showed that the complexes formed by pectin and lactoferrin at the interface were not sufficient to maintain the emulsion stability. This study also showed the important of unabsorbed pectin molecules in continuous phase in providing the physical stability of emulsion. These molecules formed a thick multilayers surround oil droplets. In addition, the incorporation of 0.2% w/w of GJLP could produce a stable emulsion, suggesting the potential use of GJLP to improve the stability of lactoferrin stabilised oil-in-water emulsions.

Comparision of heteroaggregation, layer-by-layer and directly mixing techniques on the physical properties and in vitro digestion of emulsions

This paper systematically compared the effects of heteroaggregation, layer-by-layer and directly mixing techniques on the physical properties of emulsions through mechanical rheology, microrheology, LUMisizer stability analyzer, Cryo-scanning electron microscopy (Cryo-SEM) and in vitro simulated gastrointestinal model. The shear rheology results showed that the viscosity of emulsions stabilized with whey protein isolate (WPI) and flaxseed gum (FG) by different techniques was in the order of heteroaggregated emulsion > layer-by-layer emulsion > directly mixing emulsion. Furthermore, it confirmed that the heteroaggregated emulsion had a best stability and the interface moving speed was the slowest compared with those of layer-by-layer and directly mixing emulsions. Cryo-SEM microstructure results showed that the three dimensional network structure of heteroaggregate was the main reason for maintaining high stability and shear rheological properties. Microrheological properties results indicated that heteroaggregated emulsion was sensitive to the shearing force due to the liquid behavior. While, the structures of WPI-FG emulsions prepared by layer-by-layer and directly mixing were not destroyed after shearing due to their high elasticity and solid behaviors. It was found that the order of released FFA content at the beginning of 30 min was directly mixing emulsion > layer-by-layer emulsion > heteroaggregated emulsion, but the released free fatty acid of heteroaggregated emulsion was the most in the end, which indicated that heteroaggregated emulsion had a certain controlled release effect. The study could be helpful for choosing proper technique to gain good emulsion delivery system.

Camellia oil-based oleogels structuring with tea polyphenol-palmitate particles and citrus pectin by emulsion-templated method: Preparation, characterization and potential application

Camellia-oil based oleogels were structured at a constant tea polyphenol-palmitate (Tp-palmitate) particles concentration of 2.5% (m/v) and varying citrus pectin concentration of 1.5, 2.5, 3.5 and 4.5% (m/v) using emulsion-templated method. Optical and laser confocal microscope were used to observe the microstructure of emulsions, dried products formed by freeze-drying the emulsions, and oleogels obtained by further shearing the dried products. Series of rheological measurements were performed to evaluate effects of citrus pectin concentration on the gel strength of emulsions and oleogels. The texture of dried products, and the oil binding capacity, oxidative stability and potential application of oleogels were characterized, respectively. Results revealed that citrus pectin concentration had significant effects on the physical properties of emulsions, dried products and oleogels due to the reinforcement from the interactions and entanglements of polymer. With the increase in the citrus pectin concentration, the stability and viscoelasticity of the emulsions increased, the hardness of the dried products with more compact structure became larger, and the oil binding capacity and gel strength of the oleogels enhanced. Oleogels displayed a high gel strength of G′ > 17,000 Pa and a good thixotropic recovery when the citrus pectin concentration was higher 1.5% (m/v). The polyphenol-rich oleogels had high anti-oxidative activity. The hedonic score in overall quality of cakes prepared with oleogels replacement of butter and that of cakes with butter were 21.49–27.58 and 32.03, respectively. This research gave a reference for preparing oleogels with food-approved polymer and provided more information for their potential application as substitution of solid fats.

Influence of Emulsifiers on Physical Properties of Oil/Water Emulsions Containing Ostrich Oil

The fabrication of oil/water (O/W) emulsions in order to prepare the spray-dried encapsulated bioactive ostrich oil emulsions can be useful for increasing stability of commercial products. In this study, O/W emulsions were stabilized with mixed emulsifiers (Span and Tween) or soy lecithin. The effects of emulsifiers on the physical properties of emulsions containing ostrich oil were investigated. Results showed that the addition of a mixture of Span and Tween emulsifiers at concentrations between 5 and 15% w/w reduced the droplet size of the emulsions but did not decrease the zeta potential in the emulsion system. The smallest droplet size of 5.01±0.43 μm was obtained from the emulsion containing 15% w/w mixture of Span 20 and Tween 80. The zeta potential values of all emulsions containing a mixture of Span and Tween emulsifiers in the concentration range of 5 to 20% w/w were between-23 and-55 mV. In addition, the viscosity of these emulsions increased with increases in the concentrations of both emulsifiers. The stable 20% w/w ostrich oil emulsion stabilized with 15% w/w Span 20/Tween 80 presented viscosity equal to 69.56±1.82 cP. For 10% w/w ostrich oil emulsions stabilized with lecithin, the droplet size and zeta potential of the emulsions tended to decrease with increasing lecithin concentrations. An emulsion containing 10% w/w lecithin exhibited the smallest droplet size (3.93±0.11 μm). The zeta potential values of all emulsions composed of 1-15% w/w lecithin were between-33 and –66 mV and the viscosity of these emulsions increased with increases in the concentrations of lecithin. The stable 10% w/w ostrich oil emulsion stabilized with 10% w/w lecithin exhibited a high viscosity of 172.50±1.01cP. In summary, 10% w/w lecithin provides better emulsion stability than 15% w/w Span 20/Tween 80. These results therefore reveal important parameters for the fabrication of stable O/W emulsions containing ostrich oil.

Encapsulation of D-limonene in Alyssum homolocarpum seed gum nanocapsules by emulsion electrospraying: Morphology characterization and stability assessment

The main purpose of this research was nanoencapsulation of D-limonene with Alyssum homolocarpum seed gum (AHSG) using electrospraying process. For this purpose it was necessary to identify and optimize the factors affecting the morphology of electrosprayed nanocapsules. To this aim, D-limonene emulsions with various concentrations of AHSG and Tween 20 were homogenized by ultrasound or high speed homogenizer and electrosprayed under different process conditions including applied voltage and solution flow rate. Results indicated that the physical properties of emulsions, including viscosity, surface tension and electrical conductivity were greatly influenced by the concentrations of their ingredients, and also by the homogenization method. The physical properties of emulsion along with the processing parameters (voltage and flow rate) were the key factors affecting the morphology and size of the obtained structures (p<0.05). Briefly, round, smooth and compact capsules with an average diameter of 65.68 ± 8.80 nm were obtained from electrospraying of high speed homogenized emulsion containing 0.5% gum (w/w), 20% D-limonene (w/w) and 0.1% surfactant (w/w) under the applied voltage of 20 kV and flow rate of 0.1 mL/h. These optimum nanocapsules showed 73.4% encapsulation efficiency. The stability of encapsulated D-limonene was also monitored for 90 days at 4 °C and 25 °C. Nanocapsules provided a relatively good storage stability and maintained 91.2% and 82.4% of initial mass of the loaded D-limonene during 90 days of storage at 4 °C and 25 °C, respectively.

Physical compatibility of MCT/LCT propofol emulsions with crystalloids during simulated Y-site administration

ObjectiveIn intensive care units numerous drugs have to be infused simultaneously, resulting inline incompatibility. Propofol is formulated as a lipid emulsion and it is well known that electrolytes can affect...

Physical properties and biological fate of OSA-modified-starch-stabilized emulsions containing β-carotene: Effect of calcium and pH

Understanding the roles of the calcium ion in both the physical properties of emulsions and the biological fate of the emulsion during digestion is important for the rational design of emulsion-based delivery systems that can moderate lipid digestion and the bioaccessibility of bioactive compounds. The effect of CaCl2 on the zeta-potential, the particle size, and the microstructure of emulsions, the rate and extent of lipid digestion, and the bioaccessibility of β-carotene in emulsions stabilized by octenyl succinic anhydride (OSA)-modified starches was investigated in an in vitro mouth/stomach/intestine model system. The addition of CaCl2 to starch solutions at pH 7.0 before homogenization decreased the emulsifying ability of the OSA-modified starches. When the concentration of added CaCl2 increased, the particle size of the emulsions increased and the creaming stability decreased. At pH 3.0, CaCl2 had no influence on the physical properties of OSA-modified-starch-stabilized emulsions. However, the influence of calcium on the biological fate of emulsions containing β-carotene was independent of the emulsion pH. The addition of CaCl2 promoted the digestion of lipid but decreased the bioaccessibility of β-carotene in both emulsions made at pH 7.0 and emulsions made at pH 3.0. The effect of CaCl2 on the biological fate of the emulsions was attributed mainly to the interaction of the calcium ion with lipolytic products and bile salts, which seemed to offset the effect of structure and physical properties.

Comparison of the adjuvant activity of emulsions with different physicochemical properties on the antibody response towards the venom of West African carpet viper (Echis ocellatus)

Adjuvant emulsions are widely used to enhance the antibody response of the animals used as immunoglobulin source for producing antivenoms. Usually, the adjuvant activity of emulsions is attributed both to their ability to trigger “danger” signals from cells in which they induce death, and to form depots from which immunogens are slowly released. However, there is contradictory evidence suggesting that adjuvant activity of emulsions is independent of the dispersion type and the rate of immunogen release. In order to test how physical properties of emulsions, composed of mineral oil and water, affect their ability to enhance the antibody response towards snake venoms, we compared water-in-oil (W/O) emulsions prepared at volume ratios of 70/30, 50/50 or 30/70, a 50/50 oil-in-water (O/W) emulsion, and a water-in-oil-in-water (W/O/W) multiple emulsion. Comparison included their droplet-size, viscosity, rate of immunogen release and ability to enhance the antibody response of mice immunized with the venom of the African viperid snake Echis ocellatus. It was found that all emulsions released a low amount of venom, and that the 50/50 (W/O) and the multiple emulsion (W/O/W) were those that induced the higher anti-venom antibody response. Our results suggest that the ability of emulsions to enhance the anti-venom response is not associated to their ability to form depots from which the venom is slowly released.

The Influence of Viscosity on the Static and Dynamic Properties of PS-PEO Covered Emulsion Drops

Polymer stabilized emulsions are commonplace in industries ranging from cosmetics and foods to pharmaceuticals. Understanding the physical properties of emulsions is of critical importance to the rapid advancement of industrial applications. In this work, we use a sessile drop geometry to examine the effects of viscosity changes of the surrounding glycerine/water solution on polystyrene-b-polyethylene oxide (PS-PEO) covered toluene droplets. In the experiment, emulsion drops are driven by the buoyant force into a smooth mica surface. The drops buckle as they approach the mica, trapping some of the outer fluid which slowly drains out over time. The characteristic time of the drainage process as well as the surface tension was measured as a function of glycerine/water concentration. The surface tension is found to have a minimum at a glycerine concentration of approximately 50% (by weight to water) and the drainage rate is shown to be well described by a recent model. The simple experiment not only shows how critical features of emulsion stability can be easily and reliably measured, but also identifies important new features of the drainage process.

Role of olive oil phenolics in physical properties and stability of mayonnaise-like emulsions

The effect of olive oil phenolic content and pattern on the physical properties and stability of olive oil mayonnaise-like emulsions has been investigated. Mayonnaises were formulated with either naturally phenolic-rich extra virgin olive oils or purified olive oil artificially enriched with a phenolic-rich olive extract and pure oleuropein. Mayonnaises were characterized by droplet size distribution, microstructure, textural properties and flow behaviour. The addition of phenolic extracts significantly affected the dispersion degree of the corresponding mayonnaise-like emulsions, their microstructure and physical stability especially in the systems prepared with purified olive oil treated with pure oleuropein and the highest olive phenolic extract concentration. The viscosity and back-extrusion analyses evidenced that the systems characterized by a relatively high content of phenolics, either natural or by addition, presented lower yield stress and viscosity indices and were easier to deform and to break. This study confirms the main role of olive phenolic compounds, and in particular that of oleuropein, in the dispersion state, and physical properties of emulsions with main effects on their quality and stability.

Fat Crystals and Physical Properties of Emulsion

Fat Crystals and Physical Properties of Emulsion

Entrapment of Palm-Based Medium- and Long-Chain Triacylglycerol via Maillard Reaction Products

Maillard reaction products (MRPs) are believed to possess antioxidant property besides producing emulsion which is stable and smaller in size. In our work, utilization of MRP as encapsulating agent for structured lipid palm-based medium- and long-chain triacylglycerol (MLCT) was investigated. The MRP prepared from heated aqueous mixture of sodium caseinate (SC), soy protein (SP) and maltodextrin (M) was emulsified with MLCT prior spray drying. The effect of temperature (20, 40, 60, 80, 100 °C), incubation time (2, 6, 8 h), mixture of SC: SP: M (1:0:1, 2:1:3, 1:1:2, 1:2:3, 0:1:1) and carbohydrate + protein:water ratio (1:5 and 1:8) on glycation was investigated. Degree of glycation (Dg) was determined via amount of block amino acid and L*a*b* value. As expected, increasing heat treatment (20, 40, 60, 80, 100 °C) and incubation time (2, 6 and 8 h) significantly (P < 0.05) increase the Dg. Dg was also higher (P < 0.05) at high water to solid content. Subsequently, the influence of Dg on physical properties of emulsion and spray-dried powder was also evaluated. It was found that glycation has the ability to reduce the emulsion size besides lowering moisture and surface oil content and creating larger microparticle size of the spray-dried powder. Nonetheless, whitening ability and solubility of the powder are slightly reduced especially when 100 °C MRP was used for encapsulation. SEM showed that glycation resulted in particle with smoother surface. MRP can be utilized as natural emulsifier besides improving certain functional properties of spray-dried powder oil.

Encapsulation of Epigallocatechin-3-gallate (EGCG) Using Oil-in-Water (O/W) Submicrometer Emulsions Stabilized by ι-Carrageenan and β-Lactoglobulin

Oil-in-water (O/W) submicrometer emulsions stabilized by ι-carrageenan and β-lactoglobulin were successfully prepared by high-pressure homogenization (HPH), with the goal to develop biocompatible carriers for the active component of green tea, epigallocatechin-3-gallate (EGCG). The effects of pressure and the number of cycles on the physical properties of emulsions, such as droplet sizes, microstructure, and rheological properties were investigated. The increase in both processing pressure and the number of HPH cycles resulted in a decrease in droplet sizes and viscosities. A submicrometer O/W emulsion with a droplet size of about 400 nm was used to encapsulate EGCG. The results showed that, when EGCG concentration was up to 0.5% in the emulsion, EGCG could be successfully encapsulated in the O/W emulsions stabilized by ι-carrageenan and β-lactoglobulin. Within 14 days, emulsion droplet sizes showed negligible changes. However, when EGCG concentration was >0.5%, significant instability of the O/W emulsions due to the binding between EGCG and β-lactoglobulin was observed, as evidenced by the largely increased droplet sizes from light scattering and the appearance of large aggregates in the optical images. Moreover, EGCG encapsulated in an O/W submicrometer emulsion revealed an enhanced in vitro anticancer activity compared to the free EGCG. This study provides a novel encapsulation formulation to increase the biological efficacy of EGCG.

Rheology and phase behavior of aggregating emulsions related to droplet-droplet interactions

The present work deals with the relationship between colloidal interactions and physical properties of emulsions, in particular rheology and gel transition. Experimental data on protein-stabilized oil-in-water emulsions are considered. In this system, the excess of protein in the aqueous phase yields reversible droplet aggregation by the mechanism of depletion. Thus both phase and flow behaviors can be controlled by changing protein concentration, ionic strength and temperature. Calculations of the potential of interaction between droplets are carried out in the framework of colloid science. Particular emphasis is placed on the role that droplet-droplet interaction plays in defining the morphology of the aggregates, hence the microstructure and finally, the bulk physical properties. This understanding offers new perspectives in the study of complex food systems.

On the transport of emulsions in porous media

Emulsions appear in many subsurface applications including bioremediation, surfactant-enhanced remediation, and enhanced oil-recovery. Modeling emulsion transport in porous media is particularly challenging because the rheological and physical properties of emulsions are different from averages of the components. Current modeling approaches are based on filtration theories, which are not suited to adequately address the pore-scale permeability fluctuations and reduction of absolute permeability that are often encountered during emulsion transport. In this communication, we introduce a continuous time random walk based alternative approach that captures these unique features of emulsion transport. Calculations based on the proposed approach resulted in excellent match with experimental observations of emulsion breakthrough from the literature. Specifically, the new approach explains the slow late-time tailing behavior that could not be fitted using the standard approach. The theory presented in this paper also provides an important stepping stone toward a generalized self-consistent modeling of multiphase flow.

Use of animal fats as CI engine fuel by making stable emulsions with water and methanol

This paper presents a detailed analysis on different properties of two kind of animal fats and their suitability of using them as fuel in diesel engines. Initially, the physical and chemical properties (viscosity, low heating value (LHV) and chemical compositions) of animal fats are obtained experimentally. In the second phase of work, the animal fats are modified to form emulsions with water in different quantities. In the last phase, methanol is added to improve the physical properties of emulsions further. On the whole it is concluded that the animal fats can be transformed into a stable biofuel emulsions with improved physical and chemical properties and used as good alternative fuel in diesel engines. An optimum formulation is obtained by mixing 15% of water, 15% of methanol and 2% of surfactant.