Nature Of Emulsifier Research Articles

Films Based on Biopolymers Incorporated with Active Compounds Encapsulated in Emulsions: Properties and Potential Applications-A Review.

The rising consumer demand for safer, healthier, and fresher-like food has led to the emergence of new concepts in food packaging. In addition, the growing concern about environmental issues has increased the search for materials derived from non-petroleum sources and biodegradable options. Thus, active films based on biopolymers loaded with natural active compounds have great potential to be used as food packaging. However, several lipophilic active compounds are difficult to incorporate into aqueous film-forming solutions based on polysaccharides or proteins, and the hydrophilic active compounds require protection against oxidation. One way to incorporate these active compounds into film matrices is to encapsulate them in emulsions, such as microemulsions, nanoemulsions, Pickering emulsions, or double emulsions. However, emulsion characteristics can influence the properties of active films, such as mechanical, barrier, and optical properties. This review addresses the advantages of using emulsions to encapsulate active compounds before their incorporation into biopolymeric matrices, the main characteristics of these emulsions (emulsion type, droplet size, and emulsifier nature), and their influence on active film properties. Furthermore, we review the recent applications of the emulsion-charged active films in food systems.

Properties of non-conventional direct O/W Pickering emulsions stabilized by partially hydrophobic silica particles controlled by rotor-stator or ultrasonic emulsification

There has been a significant increase in interest in Pickering emulsions over the last two decades due to their high stability. As the nature of emulsions is crucial for applications, Bancroft’s rule has been proposed to help in the formulation. However, several studies show that this law is far from being generic and that hydrophilic particles can also stabilize water-in-oil (W/O) emulsions. In the frame of this idea, we suggest in this study to evaluate the wetting history of particles and the emulsification process by considering the structural and the rheological properties of the emulsions. In this study, non-conventional or anti-bancroft O/W Pickering emulsions stabilized by partially hydrophobic silica particles are addressed. The latter are based on water and paraffin oil at 20 and 50 vol%. Stabilization is ensured by partially hydrophobic silica particles initially dispersed at 1 or 4 wt% in the aqueous phase. Emulsification is achieved using two mixers: a high-energy sonicator (∼109 W/m3) and a less energetic rotor-stator (∼107 W/m3). Regardless of the mixing device, silica particles adsorb at the O/W interfaces and generate stable emulsions over 2 months with a drop size that slightly decreases with increasing particle concentration. However, the sonicator leads to a finer disaggregation of the silica particles and to drops around 10 times smaller than with the rotor-stator but, surprisingly, an interface 3 orders of magnitude more concentrated in silica particles. The viscosity of the emulsions seems to be little dependent on the oil volume fraction contrary to particle content. In all cases, the emulsion produced by the sonicator are more viscous than those obtained by the rotor-stator. These results clearly indicate the importance of emulsification procedure on the characteristics of the final emulsions.

Enhancing in vivo retinol bioavailability by incorporating β-carotene from alga Dunaliella salina into nanoemulsions containing natural-based emulsifiers

The use of microalgae as a source of bioactive compounds has gained interest since they present advantages vs higher plants. Among them, Dunaliella salina is one of the best sources of natural β-carotene, which is the precursor of vitamin A. However, β-carotene shows reduced oral bioavailability due to its chemical degradation and poor absorption. The work aimed to evaluate the influence of the emulsifier and oil concentration on the digestive stability of Dunaliella Salina-based nanoemulsions and study their influence on the digestibility and the β-carotene bioaccessibility. In addition, the effect of the emulsifier nature on the absorption of β-carotene and its conversion to retinol in vivo was also investigated. Results showed that the coalescence observed in soybean lecithin nanoemulsion during the gastrointestinal digestion reduced the digestibility and β-carotene bioaccessibility. In contrast, whey protein nanoemulsion that showed aggregation in the gastric phase could be redispersed in the intestinal phase facilitating the digestibility and bioaccessibility of the compound. In vivo results confirmed that whey protein nanoemulsion increased the bioavailability of retinol to a higher extent (Cmax 685 ng/mL) than soybean lecithin nanoemulsion (Cmax 394 ng/mL), because of an enhanced β-carotene absorption.

A new methodology to assess the solubility of fatty acids: Impact of food emulsifiers

In food formulations, lipids are normally incorporated as emulsions stabilized by different types of emulsifiers. The emulsifiers can affect fatty acid (FA) solubilization as they can interact with FA. The main purpose of the present work is the development of a methodology to evaluate the FA solubilization in an aqueous medium in the absence and presence of exogenous emulsifiers. To this end, a combination of turbidimetry, oiling off and dynamic light scattering (DLS) was used. The FA solubility, as well as its supramolecular assemblies, were determined by analyzing the changes in the turbidity profile and the corresponding size of particles obtained by DLS. Oleic acid (OA) was used as a model FA and a simulated intestinal fluid (SIF) as the aqueous phase. Emulsifiers of low (Tween 80) and high (protein and polysaccharide) molecular weight were tested. Tween 80 was the only emulsifier that improved OA solubilization, whereas the macromolecules only affected the supramolecular structure that OA adopted, being the structure of these assemblies governed by the emulsifier nature.

Water in Oil W/O Pickering Emulsion Encapsulated in Oil in Water O/W Emulsion: A Double Emulsion for Poorly Soluble Drugs

There are two problems that hinder the use of double emulsions in pharmacies: large-scale equipment not available for one-step emulsification and obtaining a double emulsion and ingredients available to replace the tension-active agents as primary emulsifier because these surfactants are toxic. To overcome these difficulties, a two-stage emulsification strategy has been developed, first generating a water-in-oil Pickering emulsion stabilized by magnesium oxide particles and then the double W/O/W emulsion, thereby reducing significantly the amount of voltage-active. Pickering emulsions are surfactant-free emulsions, stabilized by colloidal particles. These systems are experiencing renewed interest on the one hand, because it is preferable to limit the use of synthetic surfactants for ecological reasons, and on the other hand, because the functionalization of particles has undergone recent advances. It is possible to make very simple calibrated emulsions of controlled size, exploiting a phenomenon called limited coalescence. The Bancroft rule served as a model for the formulation. The emulsification was carried out using a rotor stator mixer. The stability of these emulsions has been studied using several parameters (pH, conductivity, droplet size, dye test). The dye test and the conductivity measurement confirmed the W/O nature of the emulsion and W/O/W nature of the double emulsion. This study showed that we were able to develop a saturated double W/O/W emulsion.

Design, rheology and microstructure of food-grade emulsion-based systems for delivery of vitamin D

The fortification of food with vitamin D has several limitations because this group of fat-soluble compounds may degrade or undergo undesirable changes during technologic processing and storage of food. The purpose of this study was to investigate emulsions for vitamin D3 delivery in commercial foods. Oil-in-water (o/w) emulsions stabilized by mixture of various proteins (whey protein isolate (WPI), skimmed milk powder (SMP) and vegan protein isolate (VPI)) as emulsifiers and carboxymethylcellulose as thickening agent were used. The shear stress and effective dynamic viscosity of the emulsions in the wide range of shear rates were experimentally determined. By approximating experimental flow curves using the power-law model, the values of the consistency coefficient and flow behavior index were obtained, which made it possible to classify the emulsions as systems with pseudoplastic flow. Within the framework of the structural approach, the rheological data were analyzed on the basis of the generalized rheological model of Casson. The contributions to the process of viscous flow calculated from the experimental data from the integral characteristics of associates of droplets and individual particles during their hydrodynamic interaction made it possible to explain the effect of changing the viscosity of emulsions from the nature of the emulsifier used. The zeta potential values determined by the dynamic light scattering method indicate the existence of a strong repulsive force as a factor for the stability of emulsions. The sign of the potential and its magnitude indicate the process of adsorption on the surface of fat droplets molecule of protein. The presence of a peak of flocculated particles in the histograms of the particle size distribution is explained by the presence of non-adsorbing polysaccharides, which are capable of the generation of aggregated emulsion structures through depletion flocculation. Regardless of the choice of the type and nature of the protein emulsifier - animal or plant origin, all studied systems were stable and can be considered for use as emulsion-based delivery systems of vitamin D. From an economic point of view, it is advisable to use dry milk as an emulsifier. The resulting emulsions can be used as a basis for the production of vitamin D3-fortified foods, in particular for dairy products.

Impact of emulsifier nature and concentration on the stability of β-carotene enriched nanoemulsions during in vitro digestion.

The presence of emulsifiers facilitates the formation of nanoemulsions and assists in their stabilisation. Moreover, behaviour of nanoemulsions along the gastrointestinal tract primarily depends on their composition, affecting the bioaccessibility of the encapsulated compound. The goal of this work was to study how β-carotene-enriched nanoemulsions prepared with different emulsifiers (Tween 20, lecithin, sodium caseinate, sucrose palmitate) at various concentrations (2%-8%) would affect their stability (particle size and zeta potential) during an in vitro gastrointestinal tract (GIT) digestion. In addition, the lipid digestibility and β-carotene's bioaccessibility of nanoemulsions was determined. Nanoemulsions stabilised with Tween 20, lecithin and sodium caseinate did not present any variation in particle size under stomach phase. After the intestinal GIT phase, all nanoemulsions experienced physical changes, i.e. either increase or decrease in their particle size depending on the nature and concentration of the emulsifier used. The zeta potential of all nanoemulsions was maintained negative throughout the GIT digestion; moreover, it was less negative after the stomach GIT phase (between -24.2 and -1.4 mV). Lecithin-stabilised nanoemulsions presented the highest number of free fatty acids when the emulsifier concentration increased from 2% to 8%. In this sense, nanoemulsions containing 8% of lecithin exhibited the highest β-carotene bioaccessibility (23.5%), suggesting that lecithin can enhance lipid digestion and bioaccessibility of β-carotene encapsulated within nanoemulsions. This study elucidates the importance of not only the emulsifier's nature but also the concentration used when designing nanoemulsions as delivery systems for lipophilic compounds.

Влияние химической природы эмульгаторов ряда производных жирных кислот и этаноламинов на свойства гидрофобно-эмульсионных буровых растворов

Влияние химической природы эмульгаторов ряда производных жирных кислот и этаноламинов на свойства гидрофобно-эмульсионных буровых растворов

Storage modulus’ variation in aging and its application in assessing the stability of emulsion explosive matrix

ABSTRACTAn investigation was performed into the stability of bulk emulsion explosive matrix (BEEM) via studying on the variation of storage modulus in aging. The experimental results show that there is a tight relationship between storage modulus (G′) and the stability of BEEM. The increase of the amount of ammonium nitrate (AN) crystals in aging leads to the increase of G′. When the amount of AN crystals reaches a certain extent, the vastly destroyed microstructure results in the disappear of viscoelastic property of BEEM. The results demonstrated that the less growth ratio of G′ causes a better stability of BEEM. The G′ was used to investigate the effect of the nature of emulsifier and continuous phase on the stability of BEEM. It is found that the chemical structure of head group, the length of hydrophobic chain and the content of emulsifier affect the stability of BEEM. Besides that, the viscosity and polarity of continuous phase also have important effect on the stability of BEEM.

Study of emulsifier nature effect on the process of hydrocarbon fraction cooligomerization in the emulsion

The process of emulsion cooligomerization of C9 fraction unsaturated hydrocarbons of cooligomers production (synthetic low-molecular petroleum resins), which are obtained from cheap petrochemical raw materials - hydrocarbon fractions of liquid pyrolysis products (LPP) or cracking of oil, refined products and gas was investigated in the paper. Since the emulsifier and initiator nature, as well as the emulsification process have the greatest effect on the cooligomerization process in the emulsion, the research is aimed at studying the influence of the main factors - the nature and concentration of emulsifiers and initiators on the yield and physicochemical properties of cooligomers obtained, namely bromine number, softening temperature, color and molecular weight. For that, surface-active properties of emulsifiers used were thoroughly studied, the surface tension isotherm for the given emulsifiers (sodium stearate and oleate, emulsifier E-30) was obtained. To determine the optimal emulsifier concentration, the critical micelle concentration (CMC) and surface tension at the point corresponding to the CMC was defined. It was found that the emulsifier amount increase to the CMC point promotes the yield enhancement (up to 17.8 wt%) and improves the physicochemical properties of the product. Based on the studies, optimal concentrations of cooligomerization components: potassium persulfate initiator - 0.1 wt%, emulsifier E-30 - 0.7 wt% were selected.

Impact of various emulsifiers on ALA bioavailability and chylomicron synthesis through changes in gastrointestinal lipolysis.

Formulating healthy food rich in omega 3 fatty acids requires prior knowledge of the parameters influencing their bioavailability and their metabolic fate. In this context, we studied the effects of various emulsifiers widely used in the food industry, on the gastrointestinal lipolysis of flaxseed oil emulsions in an in vitro model and on the intestinal absorption and lymphatic secretion of alpha-linolenic acid (ALA) in rats. In vitro data showed that the emulsification of flaxseed oil with soya lecithin improved the gastric lipolysis of the oil (+30%), while the presence of Tween 80 or of sodium caseinate decreased it (-80% and -40%, respectively). The in vivo data demonstrated that the intestinal absorption and the lymphatic secretion of ALA were improved with soya lecithin (Cmax = 24 mg mL(-1)) and reduced in the presence of sodium caseinate (Cmax = 7 mg mL(-1)) compared to unemulsified flaxseed oil (Cmax = 16 mg mL(-1)); Tween 80 had no effect. In addition, the synthesized chylomicrons were notably larger and more numerous with soya lecithin whereas they were smaller in the presence of sodium caseinate (p < 0.05). This study shows that the intestinal bioavailability of ALA was increased by the emulsification of flaxseed oil with soya lecithin via an improved lipolysis, favouring the intestinal absorption of ALA and the secretion of many large chylomicrons in lymph.

Rheological Properties and Stability of Highly Concentrated Water-In-Oil Emulsions with Different Emulsifiers

An investigation was performed into the effect of emulsifiers on the rheological properties and stability of highly concentrated water-in-oil emulsions (HCEs). The emulsifiers were oligomers of the polyisobutylene succinic anhydride (PIBSA) based on different head-group and relatively low molecular weight sorbitan monooleate (SMO). The viscosity and storage modulus of HCE depend on the nature of head-groups of PIBSA-based emulsifiers and the ratio of SMO. It was shown that an increase in the SMO concentration results in the increase of viscosity and storage modulus. The stability of HCE with aging is also influenced by the nature of emulsifiers. The results of the precipitation of ammonium nitrate and the change of storage modulus with time show that the increase in the ratio of SMO decreases the stability of HCE. It was found that the phase transition of ammonium nitrate is important for the stability of HCE.

Analysis of soluble proteins/aggregates derived from gluten-emulsifiers systems

According to their amphiphilic nature, emulsifiers as Sodium Stearoyl Lactylate (SSL) and Diacetyl Tartaric Acid Esters of Monoglycerides (DATEM) favor interactions between dough components, although the mechanisms of action are not fully elucidated. There is quite information about the nature of emulsifier–gluten protein interaction and its consequence in breadmaking quality, but no reports were found about structural changes in gluten proteins produced by SSL and DATEM and their influence in aggregation–disaggregation gluten protein phenomena. For this reason the aim of this work was to investigate changes on gluten protein structure induced by SSL and DATEM; through the analysis of the nature of soluble aggregates by different SDS-PAGE techniques, and gliadins and glutenins extracted from gluten samples by RP-HPLC. At 1% level, SSL allowed the solubilization of a large proportion of high molecular mass aggregates, suggesting that at this high level, this emulsifier cause changes in native gluten protein network. Nevertheless, no significant differences in the protein quantity extracted of the distinct gliadins and glutenins were observed. On the other hand, the emulsifier SSL at 0.5% (w/w) level also allowed the extraction of a high percentage of γ-gliadins and low molecular weight glutenins in comparison with gluten and gluten-DATEM samples. In conclusion distinct quantity and quality of gliadins and glutenins were extracted from gluten samples, depending on the level and the chemical structure of each emulsifier.

Effect of the concentration factor and emulsifier nature on the type, stability, and structural-rheological properties of emulsion based on an epoxy oligomer

Formation conditions and structural-rheological properties of emulsions produced on the basis of ED-20 epoxy oligomer in the presence of OS-20 (B and V brands) and LCN-287 nonionogenic emulsifiers were studied.

Optimization of Oil-in-Water Emulsion Stability: Experimental Design, Multiple Light Scattering, and Acoustic Attenuation Spectroscopy

To find an optimal formulation of oil-in-water (O/W) emulsions (φo = 0.05), the effect of emulsifier nature and concentration, agitation speed, emulsifying time, storage temperature and their mutual interactions on the properties and behavior of these dispersions is evaluated by means of an experimental design (Nemrodw software). Long-term emulsion stability is monitored by multiple light scattering (Turbiscan ags) and acoustic attenuation spectroscopy (Ultrasizer). After matching surfactant HLB and oil required HLB, a model giving the Sauter diameter as a function of emulsifier concentration, agitation speed and emulsification time is proposed. The highest stability of C12E4-stabilized O/W emulsions is observed with 1% emulsifier.

Variation in emulsion stabilization behavior of hybrid silicone polymers with change in molecular structure: Phase diagram study

Silicone oils are widely used in cosmetics and personal care applications to improve softness and condition skin and hair. Being insoluble in water and most hydrocarbons, a common mode of delivering them is in the form of emulsions. Currently most applications use polyoxyethylene (non-ionic) modified siloxanes as emulsifiers to stabilize silicone oil emulsions. However, ionically grafted silicone polymers have not received much attention. Ionic silicones have significantly different properties than the non-ionic counterpart. Thus considerable potential exists to formulate emulsions of silicones with different water/silicone oil ratios for novel applications. In order to understand the mechanisms underlying the effects of hydrophilic modifications on the ability of hybrid silicone polymers to stabilize various emulsions, this article focuses on the phase diagram studies for silicone emulsions. The emulsifying ability of functional silicones was seen to depend on a number of factors including hydrophilicity of the polymer, nature of the functional groups, the extent of modification, and the method of emulsification. It was observed that the region of stable emulsion in a phase diagram expanded with increase in shear rate. At a given shear rate, the region of stable emulsion and the nature of emulsion (water-in-oil or oil-in-water) was observed to depend on hydrophilic–hydrophobic balance of the hybrid silicone emulsifier. At a fixed amount of modification, the non-ionically modified silicone stabilized an oil-in-water emulsion, whereas the ionic silicones stabilized inverse water-in-oil emulsions. This was attributed to the greater hydrophilicity of the polyoxyethylene modified silicones than the ionic counterparts. In general, it is postulated that with progressive increase in hydrophilicity of hybrid silicone emulsifiers, their tendency to stabilize water-in-oil emulsion decreases with corresponding increase in oil-in-water emulsion. Further, this behavior is hypothesized to depend on the nature of modifying functional groups. Thus a hybrid silicone polymer can be tailored by selecting the nature and degree of hydrophilicity to obtain a desired silicone emulsion.

Study of the electrical properties of cationic bitumen emulsions by microelectrophoresis

We investigate in the present work, the effects of the emulsifier nature and content on the aqueous phase viscosity and on the zeta potential of cationic bitumen emulsions, in the pH range 2–13. The bitumen in water emulsions was prepared at pH values in the range 2–2.4 and in the presence of complementary emulsifiers’ pair made of protonated amine 70 wt.% and a quaternary ammonium salt 30 wt.%. The final bitumen and emulsifier content in the emulsion were, respectively, 60 vol.% and 0.4–1.0 wt.%. For emulsions having emulsifier content in the range 0.4–0.7 wt.%, the magnitude of the zeta potential decreases as the pH increases and reaches a plateau value at pH 10, which corresponds to the pKa of the protonated amine. In the same pH range 2–13, the aqueous phase viscosity remains constant up to pH of approximately 10, increases slightly thereafter and levels out. However, for emulsions having 1 wt.% emulsifier content, the magnitude of the zeta potential decreases as the pH increases, reaches a minimum value at pH of approximately 11, and increases up to pH of approximately 13. For these systems the aqueous phase viscosity–pH curve remains constant up to pH of approximately 9, shows a pick having maximum at pH 11, and decreases thereafter. Thus, evidence of synergistic effects is observed when the protonated amine surfactant loses its functionality at pH values approximately 10, leading to high the aqueous phase viscosity and low surface electrical charge of the bitumen droplet. Further, the pH values at which the weakly flocculated bitumen emulsions are obtained coincide with the pH at which high aqueous phase viscosities and low droplet electrical surface charges are observed. This study shows that by adjusting the nature and the composition of the emulsifiers, we can control both the rheology and the surface electrical charge of bitumen emulsions. The rheology and the electrical properties determine in turn the stability of the system.

Vehicle-controlled effect of urea on normal and SLS-irritated skin

It is known that, depending on the concentration, treatment with urea could improve skin barrier function, despite its penetration-enhancing properties. This controversial skin effect of urea has been explored systematically in this study in terms of the effect of vehicle on the performance of urea. In the first part, a series of four semi-solid emulsions with 5% (w/w) urea, varying in the type of emulsion, nature of emulsifier and polarity of oil ingredients, have been evaluated with regard to their skin hydrating and transepidermal water loss (TEWL)-modifying properties. Placebo samples were tested alongside the urea-containing ones. Two best performing moisturisers from the above were chosen for the second part of the study, in which sodium lauryl sulphate (SLS)-irritated skin was treated with both placebo and urea-containing samples. In addition to TEWL and skin hydration level, the erythema index (EI) was measured before, during and after the treatment. The results have shown that barrier-improving and hydrating abilities of urea are bi-directional and dependent on both the type of vehicle used for its delivery and the state of skin.

Study of the electrical properties of cationic bitumen emulsions by microelectrophoresis

We investigate in the present work, the effects of the emulsifier nature and content on the aqueous phase viscosity and on the zeta potential of cationic bitumen emulsions, in the pH range 2–13. The bitumen in water emulsions was prepared at pH values in the range 2–2.4 and in the presence of complementary emulsifiers’ pair made of protonated amine 70 wt.% and a quaternary ammonium salt 30 wt.%. The final bitumen and emulsifier content in the emulsion were, respectively, 60 vol.% and 0.4–1.0 wt.%. For emulsions having emulsifier content in the range 0.4–0.7 wt.%, the magnitude of the zeta potential decreases as the pH increases and reaches a plateau value at pH 10, which corresponds to the p K a of the protonated amine. In the same pH range 2–13, the aqueous phase viscosity remains constant up to pH of approximately 10, increases slightly thereafter and levels out. However, for emulsions having 1 wt.% emulsifier content, the magnitude of the zeta potential decreases as the pH increases, reaches a minimum value at pH of approximately 11, and increases up to pH of approximately 13. For these systems the aqueous phase viscosity–pH curve remains constant up to pH of approximately 9, shows a pick having maximum at pH 11, and decreases thereafter. Thus, evidence of synergistic effects is observed when the protonated amine surfactant loses its functionality at pH values approximately 10, leading to high the aqueous phase viscosity and low surface electrical charge of the bitumen droplet. Further, the pH values at which the weakly flocculated bitumen emulsions are obtained coincide with the pH at which high aqueous phase viscosities and low droplet electrical surface charges are observed. This study shows that by adjusting the nature and the composition of the emulsifiers, we can control both the rheology and the surface electrical charge of bitumen emulsions. The rheology and the electrical properties determine in turn the stability of the system.

Physicochemical characteristics of food lipids and proteins at fluid-fluid interfaces

In this paper we are concerned with adsorption, structure, morphology, and dynamic properties of food dairy proteins (β-casein, caseinate, and whey protein isolate (WPI)) and water-insoluble lipids (monopalmitin and monoolein) at the air-water and oil-water interfaces. Combined surface chemistry (surface film balance and dynamic tensiometry) and microscopy (Brewster angle microscopy (BAM)) techniques have been used to determine the adsorption, structure, morphology, relative film thickness, relaxation phenomena, and dilatational rheological characteristics of emulsifiers (proteins and lipids) at fluid-fluid interfaces, including the effect of temperature. The derived information shows that protein and lipid type and temperature affect the interfacial characteristics. The nature of emulsifier (protein or lipid) interactions at the interface has an important role in their physicochemical characteristics. Important functional differences have been established between proteins and lipids, and between globular (WPI) and disordered (β-casein and caseinate) proteins.