Formation of Fine Oil-in-Water Emulsions by the Gel Emulsification Method with Saccharide and Protein

An emulsification method using a gel-like phase of a saccharide and protein mixture has been developed. In the method, which is called a gel emulsification method, an oil is added to the highly concentrated saccharide solution containing protein to form a clear gel-like phase, which followed by dilution with water to form a fine oil-in-water emulsion. This emulsion was investigated as to its emulsifying activity and emulsion stability as compared with that obtained by high-shear equipment, which was called a homomixer method. The emulsifying activity of the emulsions prepared by the gel emulsification method was much higher than that of the emulsions prepared by the homomixer method.

The emulsions prepared by both methods were highly stable in terms of the stability against coalescence. On the other hand, the stability against creaming of the emulsions prepared by the gel emulsification method was much higher than that of the emulsions prepared by the homomixer method.

The surface hydrophobicity of the protein and the unfreezable water content in the highly concentrated saccharide solution containing protein were not correlated to the emulsifying properties of the emulsions prepared by the gel emulsification method, which appeared to be dependent on the viscosity of the highly concentrated saccharide solution containing protein.     

Formation,Stability and In Vitro Digestion of β-carotene in Oil-in-Water Milk Fat Globule Membrane Protein Emulsions

The formation, stability and in vitro digestion of milk fat globule membrane (MFGM) proteins stabilized emulsions with 0.2 wt% β-carotene were investigated. The average particle size of β-carotene emulsions stabilized with various MFGM proteins levels (1%, 2%, 3%, 4%, 5% wt%) decreased with the increase of MFGM proteins levels. When MFGM proteins concentration in emulsions is above 2%, the average particle size of β-carotene emulsions is below 1.0 μm. A quite stable emulsion was formed at pH 6.0 and 7.0, but particle size increased with decrease in acidity of the β-carotene emulsion. β-carotene emulsions stabilized with MFGM proteins were stable with a certain salt concentrations (0–500 mMNaCl). β-carotene emulsions were quite stable to aggregation of the particles at elevated temperature and time (85 °C for 90 min). At the same time, β-carotene emulsions were stable against degradation under heat treatment conditions. In vitro digestion of β-carotene emulsion showed the mean particle size of β-carotene emulsions stabilized with MFGM proteins in the simulated stomach conditions and intestinal conditions is larger than that of initial emulsions and simulated mouth conditions. Confocal laser scanning microscopy of β-carotene MFGM proteins emulsions also showed the corresponding results to different vitro digestion model. There was a rapid release of free fatty acid (FFA) during the first 10 min and after this period, an almost constant 70% digestion extent was reached. Approximately 80% of β-carotene was released within 2 h of incubation under the simulated intestinal fluid. These results showed that MFGM protein can be used as a good emulsifier in emulsion stabilization, β-carotene rapid release as well as lipophilic bioactive compounds delivery.     

Evaluation of Electrostatic Interaction between Lysolecithin and Chitosan in Two-Layer Tuna Oil Emulsions by Nuclear Magnetic Resonance (NMR) Spectroscopy

The main objective of this work was to investigate the electrostatic interaction between lysolecithin and chitosan in two-layer tuna oil-in-water emulsions using nuclear magnetic resonance (NMR) spectroscopy. The influence of chitosan concentration on the stability and properties of these emulsions was also evaluated. The 5 wt% tuna oil one-layer emulsion (lysolecithin-stabilized oil droplets without chitosan) and two-layer emulsions (lysolecithin-chitosan stabilized oil droplets) containing 5 wt% tuna oil, 1 wt% lysolecithin and various chitosan concentrations (0.025–0.40 wt%) were prepared. The one-dimensional (1D) ³¹P and ¹H NMR spectra of emulsions were then recorded at 25 °C. The results showed that addition of chitosan affected the stability and properties of lysolecithin-stabilized one-layer emulsions. The ³¹P NMR peak of the choline head group on lysolecithin molecules disappeared when chitosan was added at concentrations above neutralization concentration (> 0.05 wt%). The ¹H NMR peak intensity monitoring free amino groups (?NH ₃ ⁺) of chitosan showed a strong positive linear relationship to the chitosan concentration with a high correlation coefficient (R² ≈ 0.99). This ¹H NMR peak in emulsions could not be detected for chitosan in emulsions lower than saturation concentration (< 0.15 wt%). These phenomena indicate an electrostatic interaction between lysolecithin and chitosan at droplet surface in emulsion and were consistent with the results from zeta-potential measurements. The T ₂* relaxation time of the choline head group (N-(CH ₃)₃) signal of lysolecithin also confirmed that lysolecithin-chitosan electrostatic interaction occurs at the surface of oil droplets in two-layer emulsions. The results suggest that NMR spectroscopy can be used as an alternative method for monitoring the electrostatic interaction between surfactant and oppositely charged electrolytes or biopolymers in two-layer emulsions.     

Impact of Heat and Laccase on the pH and Freeze-Thaw Stability of Oil-in-Water Emulsions Stabilized by Adsorbed Biopolymer Nanoparticles

The enzymatic cross-linking of adsorbed biopolymer nanoparticles formed between whey protein isolate (WPI) and sugar beet pectin using the complex coacervation method was investigated. A sequential electrostatic depositioning process was used to prepare emulsions containing oil droplets stabilized by WPI – nanoparticle – membranes. Firstly, a finely dispersed primary emulsion (10 % w/w miglyol oil, 1 % w/w WPI, 10 mM acetate buffer at pH 4) was produced using a high-pressure homogenizer. Secondly, a series of biopolymer particles were formed by mixing WPI (0.5 % w/w) and pectin (0.25 % w/w) solutions with subsequent heating above the thermal denaturation temperature (85 °C, 20 min) to prepare dispersions containing particles in the submicron range. Thirdly, nanoparticle-covered emulsions were formed by diluting the primary emulsion into coacervate solutions (0–0.675 % w/w) to coat the droplets. Oil droplets of stable emulsions with different interfacial membrane compositions were subjected to enzymatic cross-linking. We used cross-linked multilayered emulsions as a comparison. The pH stability of primary emulsions, biopolymer complexes and nanoparticle-coated base emulsions, as well as multilayered emulsions, was determined before and after enzyme addition. Freeze-thaw stability (?9 °C for 22 h, 25 °C for 2 h) of nanoparticle-coated emulsions was not affected by laccase. Results indicated that cross-linking occurred exclusively in the multilamellar layers and not between adsorbed biopolymer nanoparticles. Results suggest that the accessibility of distinct structures may play a key role for biopolymer-cross-linking enzymes.     

Emulsification Capacity of Microgels Assembled from β-Lactoglobulin and Pectin

Microgels formed from beta-lactoglobulin were used to prepare oil-in-water emulsions in order to examine their emulsifying capacity. Corn oil emulsions prepared with microgels of pure beta-lactoglobulin at pH 5.8 were initially stable, but a fraction of the droplets quickly flocculated to form a creamed layer that could not be dispersed by shear, which was attributed to hydrophobic attractions between the microgels on adjoining droplets. Emulsions prepared from microgels of beta-lactoglobulin and pectin at pH 4.75 possessed greater droplet sizes at lower concentrations, yet all emulsions were relatively stable to irreversible flocculation. Increased stability of emulsions stabilized by BP-gels was attributed to the presence of pectin on the surface of microgels, which increased repulsions between adjoining droplets. Stable corn oil emulsions were still prepared from microgels that were previously dialyzed to remove non-aggregated protein, which verified that the microgels were responsible for stabilizing emulsion droplets. Equilibrium surface pressure of corn oil droplets was similar between microgels and the unheated beta-lactoglobulin and pectin, yet the dynamic surface pressure was reduced at intermediate times and indicated a slow relaxation and deformation of the microgels at the interface. Microgels formed with pectin stabilized emulsions containing 90 % limonene for up to 5 days of room temperature storage, demonstrating the capacity of such protein microgels to stabilize flavor oil emulsions.     

Emulsions Based on the Interactions Between Lactoferrin and Chitosans

In this work, purification of lactoferrin from whey was performed with high recovery rate. Lactoferrin was then exploited in the preparation of food emulsions. Two tertiary emulsions, formed by olive oil, lecithin, chitosan, and lactoferrin, were compared: both the emulsions showed similar turbidity and stability. In the secondary emulsion formed by oil/lecithin/chitosan, the pH was increased to 9 before addition of lactoferrin. Then, lactoferrin was added, and the pH was stabilized above pH 9. Lactoferrin was found in amounts of 1 to 2.5 mg/ml in the multiple experiments. A fraction of the added lactoferrin was also present in a milky layer above the emulsion layer. This was, to our knowledge, the first study of emulsions made exploiting the interactions between lactoferrin and chitosan. It was noted that chitosan droplets remained soluble, although the hydrocolloid solubility occurs at pH lower than 5.9. These results showed the feasibility of manufacturing lactoferrin-based emulsions as functional foods.     

Integration of Gas Enhanced Oil Recovery in Multiphase Fermentations for the Microbial Production of Fuels and Chemicals

In multiphase fermentations where the product forms a second liquid phase or where solvents are added for product extraction, turbulent conditions disperse the oil phase as droplets. Surface‐active components (SACs) present in the fermentation broth can stabilize the product droplets thus forming an emulsion. Breaking this emulsion increases process complexity and consequently the production cost. In previous works, it has been proposed to promote demulsification of oil/supernatant emulsions in an off‐line batch bubble column operating at low gas flow rate. The aim of this study is to test the performance of this recovery method integrated to a fermentation, allowing for continuous removal of the oil phase. A 500 mL bubble column is successfully integrated with a 2 L reactor during 24 h without affecting cell growth or cell viability. However, higher levels of surfactants and emulsion stability are measured in the integrated system compared to a base case, reducing its capacity for oil recovery. This is related to release of SACs due to cellular stress when circulating through the recovery column. Therefore, it is concluded that the gas bubble‐induced oil recovery method allows for oil separation and cell recycling without compromising fermentation performance; however, tuning of the column parameters considering increased levels of SACs due to cellular stress is required for improving oil recovery.     

Influence of processing factors on the stability of model mayonnaise with whole egg during long-term storage

Mayonnaise-like oil-in-water emulsions with different stabilities—evaluated from the degree of macroscopic defects, e.g., syneresis—were prepared by different formulations and processing conditions (egg yolk weight, homogenizer speed, and vegetable oil temperature). Emulsions prepared with lower egg yolk content were destabilized for shorter periods. The long-term stability of emulsions was weakly related to initial properties, e.g., oil droplet distribution and protein coverage at the interface. Protein aggregation between oil droplets was observed and would be responsible for the instability of emulsions exhibited by the appearance defects. SDS-PAGE results for adsorbed and unadsorbed proteins at the O/W interface suggested that predominant constituents adsorbed onto the interface were egg white proteins as compared with egg yolk components when the amount of added egg yolk was low. In present condition, egg white proteins adsorbed at the O/W interface could be a bridge of neighboring oil droplets thereby causing flocculation in emulsions.     

Comparing Carboxymethyl Cellulose and Starch as Thickeners in Oil/Water Emulsions. Implications on Rheological and Structural Properties

The study reported here aims to obtain information on how thickener type and concentration, and oil content influence rheology, particle size, particle charge and microstructure in o/w model emulsions. Emulsions were prepared at two oil concentrations (5 and 30 % wt/wt), each with three CMC concentrations (0.2, 0.3, and 0.4 % wt/wt), or three starch concentrations (2, 3, and 4 % wt/wt). For each oil concentration, a sample without any added thickener was prepared as reference. Both CMC and swollen starch granules showed a dominating effect on emulsion flow behavior, although the presence and concentration of fat droplets also played an important role. Viscoelasticity of CMC-based emulsions mainly depended of oil concentration whilst in starch-based emulsions the most influential ingredient was starch. A similar situation was detected in terms of particle size distribution; CMC effect was dependent on oil content and starch effect was mainly related to the volume occupied by swollen granules. Differences in microstructure and particle size distribution between CMC and starch emulsions were related to their rheological behavior. Apart from enabling the acquisition of food emulsions with different composition but with similar rheological behavior by adding different hydrocolloids, here we consider thickener effect on other properties in order to obtain food emulsions with adequate characteristics.     

Preparation of stimulus responsive multiple emulsions by membrane emulsification using con a as biochemical sensor

In this work, a novel strategy for the controlled fabrication of biomolecular stimulus responsive water-in-oil-in-water (W/O/W) multiple emulsion using the membrane emulsification process was investigated. The emulsions interface was functionalized with a biomolecule able to function as a receptor for a target compound. The interaction between the biomolecular receptor and target stimulus activated the release of bioactive molecules contained within the structured emulsion. A glucose sensitive emulsion was investigated as a model study case. Concanavalin A (Con A) was used as the biomolecular glucose sensor. Various physicochemical strategies for stimulus responsive materials formulation are available in literature, but the preparation of biomolecule-responsive emulsions has been explored for the first time in this paper. The development of novel drug delivery systems requires advanced and highly precise techniques to obtain their particular properties and targeting requirements. The present study has proven the flexibility and suitability of membrane emulsification for the preparation of stable and functional multiple emulsions containing Con A as interfacial biomolecular receptor able to activate the release of a bioactive molecule as a consequence of interaction with the glucose target molecule. The influence of emulsion interfacial composition and membrane emulsification operating conditions on droplets stability and functional properties have been investigated. The release of the bioactive molecule as a function of glucose stimulus and its concentration has been demonstrated.     

Stability of emulsions stabilised by two physiological surfactants: L-alpha-phosphatidylcholine and sodium taurocholate

The emulsion phase formed within the stomach and duodenum during digestion of a fatty meal has been modelled using two physiological surfactants, the phospholipid L-alpha-phosphatidylcholine (PC) and the bile salt sodium taurocholate (NaT). Upon dilution of the phospholipid stabilised emulsions with a solution of NaT the bile salt became incorporated into the oil/water interface imparting a negative charge to the droplet surface. The magnitude of the droplet microelectrophoretic mobility for the mixed PC and NaT system was 47% of that found for emulsion droplets stabilised by NaT alone. But the electrostatic repulsion between droplets was not sufficient to account for the observed improvement in emulsion stability to coalescence. It is suggested that a residual liquid crystalline phospholipid interface is present imparting a significant steric component to the stabilisation of the emulsions droplets.     

Encapsulation of Lipophilic Bioactive Molecules by Microchannel Emulsification

Currently, much effort is being invested in novel formulations of bioactive molecules, such as emulsions, for pharmaceutical, food, and cosmetic applications. Therefore, methods to produce emulsions with controlled-size droplets of uniform size distribution have been developed. On this concern, a microfluidic device called the microchannel (MC) was used in this work for emulsification. This is a novel method for producing monodispersed emulsion droplets with very narrow droplet size distribution and low energy input, due to the spontaneous droplet generation basically driven by the interfacial tension, unlike other conventional emulsification processes. This technology provides the formulation of oil-in-water (O/W) emulsions containing lipophilic active molecules with increased bioavailability, which may be readily absorbed by the human body. MC emulsification enables the preparation of highly monodispersed O/W emulsions, which may be applied as enhancer on active molecules delivery systems, as well as in foodstuff. In this study, formulations of O/W emulsions loaded with bioactive molecules, such as β-carotene and γ-oryzanol, were prepared by the MC emulsification process. Refined soybean oil containing the dissolved lipophilic molecule and either sugar ester or gelatin solution (1 wt.%) were used as the dispersed and continuous phases, respectively. The emulsification process conducted using the asymmetric straight-through MC plate enabled the production of monodispersed O/W emulsions, resulting in β-carotene-loaded O/W emulsions with average droplet size (d _av) of 27.6 μm and coefficient of variation (CV) of 2.3% and γ-oryzanol-loaded droplets with d _av of 28.8 μm and CV of 3.8%. The highly monodisperse β-carotene-loaded droplets were physically stable throughout the storage period observed, resulting in droplets with d _av 28.2 μm and CV of 2.9% after 4 months storage in darkness at 5 °C. Single micrometer-sized monodisperse emulsions loaded with β-carotene were successfully formulated using the grooved MC emulsification, resulting in droplets with d _av of 9.1 μm and CV of 6.2%. This work was funded by The Ministry of Agriculture, Forestry and Fisheries of Japan, through the Food Nanotechnology Project, and the Japan Society for the Promotion of Science.     

Emulsifier Dependent <Emphasis Type="Italic">in vitro</Emphasis> Digestion and Bioaccessibility of β-Carotene Loaded in Oil-in-Water Emulsions

This study was performed to examine the effect of emulsifiers used to coat emulsion droplets containing β-carotene on the behavior of lipid digestion and bioaccessibility. Different emulsifiers (whey protein isolate, soy protein isolate, sodium caseinate, Tween 20, and soy lecithin) were used to prepare emulsions with similar sized droplets (200–400 nm). Protein-stabilized emulsions showed a similar behavior of digestion, and morphological change in the simulated gastrointestinal conditions. Soy lecithin-stabilized emulsions showed the lowest rate and extent of lipid digestion probably due to the low emulsifying capability of soy lecithin, showing coalesced droplets occurring after exposure to the gastric phase. Tween 20-stabilized emulsions had a lower rate and extent of lipid digestion than that of protein-stabilized emulsions, even though Tween 20-stabilized emulsions had a more stable structure to resistant to aggregation in gastric phase. Even though the difference in the digestion rate and extent, β-carotene bioaccessibility was not significantly different among emulsions stabilized by different emulsifiers at p?<?0.05.     

Flow cytometry: a promising technique for the study of silicone oil-induced particulate formation in protein formulations

Subvisible particles in formulations intended for parenteral administration are of concern in the biopharmaceutical industry. However, monitoring and control of subvisible particulates can be complicated by formulation components, such as the silicone oil used for the lubrication of prefilled syringes, and it is difficult to differentiate microdroplets of silicone oil from particles formed by aggregated protein. In this study, we demonstrate the ability of flow cytometry to resolve mixtures comprising subvisible bovine serum albumin (BSA) aggregate particles and silicone oil emulsion droplets with adsorbed BSA. Flow cytometry was also used to investigate the effects of silicone oil emulsions on the stability of BSA, lysozyme, abatacept, and trastuzumab formulations containing surfactant, sodium chloride, or sucrose. To aid in particle characterization, the fluorescence detection capabilities of flow cytometry were exploited by staining silicone oil with BODIPY 493/503 and model proteins with Alexa Fluor 647. Flow cytometric analyses revealed that silicone oil emulsions induced the loss of soluble protein via protein adsorption onto the silicone oil droplet surface. The addition of surfactant prevented protein from adsorbing onto the surface of silicone oil droplets. There was minimal formation of homogeneous protein aggregates due to exposure to silicone oil droplets, although oil droplets with surface-adsorbed trastuzumab exhibited flocculation. The results of this study demonstrate the utility of flow cytometry as an analytical tool for monitoring the effects of subvisible silicone oil droplets on the stability of protein formulations.     

The Influence of Emulsion Droplet Interactions on the Structural,Material and Functional Properties of a Model Mozzarella Cheese

We present findings on the influence of interfacial layer composition on the colloidal interactions and associated structural and material properties of oil-in-protein gel emulsions, as applied to a model Mozzarella cheese analogue. Model cheese samples were produced through thermal mixing of pre-prepared oil-in-water emulsions with a renneted casein gel. Sodium caseinate and Tween 20 were used as the emulsifiers. Microstructural analysis showed sodium caseinate stabilised droplets to be homogeneously dispersed within the cheese structure, whilst droplets stabilised by Tween 20 were phase concentrated into localised fat domains within the continuous protein network. Particle size measurements determined that, on chilled storage, the droplets in these localised regions underwent extensive partial coalescence, whilst the homogenously distributed caseinate droplets showed little change in droplet size. Small deformation rheology (4 to 80 °C) determined the sodium caseinate emulsion as providing a reinforcing effect on the protein network across the entire temperature range, while the Tween 20 emulsion was observed to mechanically strengthen the cheese structure at only at temperatures for which the fat phase was solid whilst serving to weaken the structure on transitioning to a molten state. Differences in droplet structure and stability were determined as influencing cheese melt and flow characteristics. During melting, no oiling-off observed for cheese samples comprising sodium caseinate stabilised droplets, compared to Tween 20 stabilised emulsions where extensive oiling-off was observed. Findings corroborate the hypothesis that caseinate coated droplets behave as active fillers within the protein network, whilst the Tween 20 stabilised emulsion are non-interactive.     

Effects of Lecithin Addition in Oil or Water Phase on the Stability of Emulsions Made with Whey Proteins

The effects of lecithin addition in oil or water phase on the stability of oil-in-water emulsions made with 0.1 wt% whey protein and 10 wt% n-tetradecane at neutral and acidic pH were studied by monitoring the gravitational creaming and phase separation. The effects of lecithin addition on the interfacial behavior of β-lactoglobulin were also studied to compare with the results of emulsion stability. At neutral pH, crude phosphatidylcholine (PC) from egg yolk or soybean increased the stability of the emulsion made with protein and lowered the interfacial tension of protein films more effectively than pure egg PC. A more remarkable effect on both the emulsion stability and the interfacial tension was found when crude PC was added in the oil phase rather than in the water phase. The purity of lecithins and the way to add them are suggested to be very important to make a stable emulsion with protein. On acidic pH (4.5 or 3.0), the increased creaming or phase separation in a whey protein-stabilized emulsion, but the lowered interfacial tension of β-lactoglobulin films, were found upon the addition of pure or crude PC in oil or water phase. These results suggest that in acidic pH, densely packed films may be formed on a planar oil–water interface, but not on adsorbed layers around oil droplets in an emulsion.     

银耳粗多糖对桉叶油的乳化性研究

对不同浓度、温度、pH、NaCl浓度条件下,银耳粗多糖对桉叶油的乳化能力,以及乳化体系的稳定性进行了研究。结果表明,银耳粗多糖对桉叶油的乳化性随浓度增大上升,在浓度1%时达到最大,随后呈下降趋势;在pH 4.0~8.0之间;有较好的乳化性及乳化稳定性,在此范围以外,随pH的升高、降低,银耳粗多糖的乳化和乳化性均呈下降趋势;随着温度和NaCl浓度升高,银耳粗多糖的乳化活性和乳化稳定性有所降低。     

Development and Evaluation of Emulsions from <Emphasis Type="Italic">Carapa guianensis</Emphasis> (Andiroba) Oil

Carapa guianensis, a popular medicinal plant known as “Andiroba” in Brazil, has been used in traditional medicine as an insect repellent and anti-inflammatory product. Additionally, this seed oil has been reported in the literature as a repellent against Aedes aegypti. The aim of this work is to report on the emulsification of vegetable oils such as “Andiroba” oil by using a blend of nonionic surfactants (Span 80® and Tween 20®), using the critical hydrophilic–lipophilic balance (HLB) and pseudo-ternary diagram as tools to evaluate the system’s stability. The emulsions were prepared by the inverse phase method. Several formulations were made according to a HLB spreadsheet design (from 4.3 to 16.7), and the products were stored at 25°C and 4°C. The emulsion stabilities were tested both long- and short-term, and the more stable one was used for the pseudo-ternary diagram study. The emulsions were successfully obtained by a couple of surfactants, and the HLB analysis showed that the required HLB of the oil was 16.7. To conclude, the pseudo-ternary diagram identified several characteristic regions such as emulsion, micro-emulsion, and separation of phases.     

Stability of the oil-in-water type triacylglycerol emulsions

Lipid emulsions with saturated triacylglycerols (TAGs) with 4 to 10 carbons in each acyl chain were prepared to study how the oil component alters the stability of the lipid emulsions when phosphatidylcholines were used as emulsifiers. The average droplet size of the emulsions became smaller as the chain length of the TAG increased. For a given oil, emulsion with smaller droplets was formed with an emulsifier having higher HLB value. The influence of HLB values on the droplet size was biggest for the tributyrin (C4) emulsions. For the tricaprylin (C8) emulsions, droplet size was identical at given emulsifier concentrations regardless of HLB values. The HLB value and the concentration of the emulsifiers also affect the droplet size of the emulsions. The emulsions with smaller average droplet size were more stable than with bigger size for 20 days. The oil and water (o/w) interfacial tension is inversely proportional to the initial droplet size of the emulsion.