Oil Droplet Size Research Articles

Modified coconut pulp particles: The potential candidate for stabilizing Pickering emulsions

Coconut pulp, a by-product of coconut milk extraction, was used to prepare Pickering emulsion–stabilizing particles by modification with citric acid (CA) through dry heat treatment. The treatment temperature (100, 120, and 140 °C) and CA concentration (0.7, 2.0, and 3.3 % w/v) were varied. Modification at 100 °C and high concentration of CA gave products with satisfactory appearance and surface characteristics. The product obtained by treatment at 3.3 % CA and 100 °C had a yellowish white color with a light and porous surface, 0.08 degree of substitution (DS), 70° water contact angle, −50 mv zeta potential, and an average particle size after homogenization of 8.4 µm. Unmodified CP powders could not stabilize the oil-in-water (O/W) emulsion, and phase separation occurred rapidly at 25 °C, while CP modified using 2.0 % and 3.3 % CA at 100 °C could stabilize the emulsion for at least 30 d. The oil droplet size decreased as the DS of the particles increased from 77.3 to 33.3 µm and 18.6 µm for the particles with DS of 0.046, 0.072, and 0.082, respectively. The higher hydrophobicity imparted by CA modification strongly affected the oil droplet size, while the negative surface charge of particles supported the uniform dispersion of free CP particles in the interspace among the oil droplets.

Structural and emulsion-stabilizing properties of the alkali-extracted arabinoxylans from corn and wheat brans

This study investigated the structural and emulsion-stabilizing capacities of alkali-extracted arabinoxylans from corn and wheat bran (CAXs and WAXs). The results demonstrated that all AXs were mainly composed of arabinose and xylose. WAXs had a higher weight-average molecular weight (Mw, 375–473 KDa) and protein content (3.09–8.68 %) but lower total phenolic acid content (TPC, 1.18–1.91 mg gallic acid equivalents/g) than CAXs; however, CAX stabilized emulsions exhibited smaller and more regular oil droplet size (524–589 nm) and higher absolute value of ζ potential (48–52 mV) compared with WAX stabilized emulsions during storage. Moreover, the increment of NaOH concentration caused a decrease in Mw, protein content, and TPC of CAXs or WAXs and the corresponding CAXs or WAXs emulsions showed bigger and more unstable oil droplets during 14 d storage. The Mw, protein, and TPC were well correlated with their emulsion stability. Furthermore, emulsions stabilized by AXs with low-concentration NaOH could resist better various temperatures, pH, and NaCl. In conclusion, the structural properties of AXs derived from different cereal sources and treated with different concentrations of NaOH varied, leading to differences in their ability to stabilize emulsions. CAXs or WAXs obtained from low-concentration NaOH treatment demonstrated significant potential as highly effective natural emulsifiers.

Dynamics of Non-Magnetic Droplets and Bubbles in Magnetic Fluids in Microfluidic Channels under the Influence of a Magnetic Field

The microfluidics of magnetic fluids is gaining popularity due to the possibility of the non-contact control of liquid composite systems using a magnetic field. The dynamics of non-magnetic droplets and gas bubbles in magnetic fluids were investigated for various configurations of magnetic fields, coatings, and channel geometries, as well as the rate of component supply and their physical properties. Optimal regimes for forming droplet and bubble flows were determined. The mechanism for non-contact control of the size of droplets and bubbles using a magnetic field is proposed in this article. The dependences of the sizes of non-magnetic inclusions in magnetic liquids on the continuous phase flow rate and the displacement of magnets were obtained. The obtained dependences of the volume of non-magnetic inclusions on the flow rate of the continuous phase follow the classic dependences. Changing the size of air bubbles can be achieved by shifting the magnet from −5 mm to +2 mm. The ratio of the maximum and minimum breakaway inclusion varies from 5 to 2 depending on the flow rates of the continuous phase. The range of changing the size of oil droplets with the displacement of magnets is from 1.1 to 1.51. These studies show how, with the help of various mechanisms of influence on microfluidic flows, it is possible to control the size of bubbles and droplets forming in microchannels. The obtained data can be applied for controlled microfluidic dosing and counting devices.

Design of Proanthocyanidins and TiO2 Nanoparticles-Based Novel Emulsions as a Platform for UV Protection.

A white oil-in-water novel emulsion stabilized by TiO2 nanoparticles with UVB shielding properties and proanthocyanidins with antioxidant activity was prepared, where the proanthocyanidins aggregated at the oil-water interface to reduce interfacial tension while TiO2 nanoparticles were dispersed in the continuous water phase to hinder droplet coalescence. It was found that the average oil droplet size was less than 10 μm and decreased with the increase of proanthocyanidins concentration, but the increase of the content of TiO2 nanoparticles had little effect on it. The combination of TiO2 nanoparticles and proanthocyanidins was versatile for oil phases with different polarities, and the resulting emulsion exhibited high stability in the face of centrifugation, heating and prolonging storage time. After encapsulating the UVA filter avobenzone in white oil, the emulsion was endowed with the ability to resist UVB and UVA. Further, the emulsion showed great free radical scavenging ability for superoxide anion radical (⋅O2 - ), hydroxyl radical (⋅OH) with the clearance rate of over 70 %, indicating the good antioxidant activity. The ingenious combination of UVB, UVA filter and antioxidant with emulsion as carrier provides a new idea for the preparation of full-band sunscreen emulsion.

Effects of limited enzymatic hydrolysis and polysaccharide addition on the physicochemical properties of emulsions stabilized with duck myofibrillar protein under low-salt conditions

This study aimed to investigate the role of hydrolysis and guar gum (GG) participation on the emulsification of the duck myofibrillar protein (MP) and the related stability of oil-in-water emulsion in low-salt condition. Emulsions were prepared using one of each or both treatments, and that prepared with trypsin hydrolysis and GG (T-GG) exhibited the highest stability. FTIR analysis confirmed the hydrogen bond interactions between the system components. T-GG treatment improved emulsion properties and decreased oil droplet size. Moreover, CLSM indicated that aggregation of T-GG oil droplets was prevented. Physical stability was assessed such as Turbiscan stability index, creaming index, and rheological properties. The adsorbed percentage for T-GG was the lowest. However, interfacial tension, droplet size, stability, and peroxide value analyses indicated that a denser interfacial membrane structure is formed with T-GG. Thus, T-GG treatment could be applied in the food industry, such as in nutrient delivery systems and fat mimetics.

Essence into the kinetic enhanced extraction induced by Marangoni convection on the surface of freely rising oil droplets

The enhanced separation of rare earth ions depending on different kinetic extraction behaviors can be achieved by extraction on the surface of rising droplets, where exists the nonhomogeneous chemical reaction. Marangoni instability might occur dependent on nonhomogeneous chemical reaction, which is conducive to the enhancement of interfacial mass transfer. To explore the influence from a nonhomogeneous chemical reaction on the generation of Marangoni instability, influences from the flow rate of oil droplets and the oil droplet size on interfacial extraction behaviors were performed, the interfacial tension was evaluated, and MD simulations combined DFT calculations were adopted. It was revealed that the higher interface renewal rate of the large oil droplet was favorable for the interfacial chemical reaction. Whether the interfacial extraction rate is greater than the interface renewal rate decided the occurrence of Marangoni convection. The current research highlights a novel viewpoint towards understanding microscopic nature of kinetic enhanced extraction.

Measurement of a Three-Dimensional Rotating Flow Field and Analysis of the Internal Oil Droplet Migration

Investigating the motion of discrete oil droplets in a rotating flow field can provide a theoretical basis for optimizing the flow field and structural parameters of hydrocyclones and centrifugal separation equipment. In the present work, the particle image velocimetry (PIV) method was applied to study the velocity distribution of a three-dimensional axial-rotor-driven rotating flow field and the influence of the velocity distribution of different rotor speeds on the flow field. The radial migration of oil droplets with different particle sizes in the rotating flow field was visually analyzed using high-speed video (HSV). The results showed that the oil droplets with the same radial position had diameters of 2.677 and 4.391 mm, whereas the movement times to the axis were 0.902 and 0.752 s. The larger the oil droplet size, the shorter the time to move to the axial center of the rotating flow field. The radial velocities of oil droplets with diameters of 2.677 and 2.714 mm were 0.0221 and 0.02 m·s−1, respectively. In addition, a mathematical expression was established between the radial migration time and the oil droplet size in the rotating flow field. The accuracy of the proposed expression was verified using experiments.

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

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

Novel Pickering emulsion gels stabilized solely by phenylalanine amidated pectin: Characterization, stability and curcumin bioaccessibility

Pickering emulsion gels represent a novel class of non-toxic and biocompatible emulsions, offering extensive applications in the pharmaceutical and food additive sectors. This study delineates the synthesis of Pickering emulsion gels utilizing native and amidated pectin samples. Phenylalanine amidated pectin (AP) was procured via an ultra-low temperature enzyme method, while the control group (LP) adhered to an identical procedure without papain catalysis. Experimental outcomes revealed that the AP Pickering emulsion gel manifested superior stability compared to pectin emulsion samples (PE and LP). The Pickering emulsion gel from 5 % amidated pectin (5AP) retained stability throughout a 14-day emulsion stability assessment. Furthermore, all emulsion samples were evaluated for their capacity to deliver and sustain curcumin within an in vitro digestion simulation. Rheological properties and oil droplet size results indicated that the 5AP Pickering emulsion gel exhibited optimal cream index and emulsion stability, effectively inhibiting premature water-oil stratification within the emulsion and augmenting curcumin bioaccessibility. Within the in vitro digestion simulation, the 5AP Pickering emulsion gel demonstrated the highest curcumin bioaccessibility, measured at 17.96 %.

Reducing oil droplet sizes from a subsea oil and gas release by water jetting a laboratory study performed at different scales

The main objective of subsea mechanical dispersion (SSMD) is to reduce the oil droplet sizes from a subsea oil release, thereby influencing the fate and behaviour of the released oil in the marine environment. Subsea water jetting was identified as a promising method for SSMD and imply that a water jet is used to reduce the particle size of the oil droplets initially formed from the subsea release.This paper presents the main findings from a study including small-scale testing in a pressurised tank, via laboratory basin testing, to large-scale outdoor basin testing. The effectiveness of SSMD increases with the scale of the experiments. From a five-fold reduction in droplet sizes for small-scale experiments to more than ten-fold for large-scale experiments. The technology is ready for full-scale prototyping and field testing. Large-scale experiments performed at Ohmsett indicate that SSMD could be comparable to subsea dispersant injection (SSDI) in reducing oil droplet sizes.

Assessment of Dispersed Oil Sorption in Oily Wastewater onto Hydrophobized/Oleophilized Autoclaved Aerated Concrete (AAC) Grains

The discharge of untreated oily wastewater into the environment has serious impacts on human health, living nature, and ecosystems and leads to significant economic losses. Many engineering techniques have been proposed and applied to treat oily wastewater, but limited studies have investigated low-cost and effective techniques using by-products and waste/scrap materials from the construction industry. Materials to treat oily wastewater are needed not only to mitigate environmental pollution but also to promote the reuse and recycling of industrial by-products, especially in developing countries. This study, therefore, examined the sorption capacity of dispersed oil in wastewater (dispersed soybean oil in water; initial oil concentrations, Ci = 10–1000 mg/L; oil droplet size in water &lt;2 μm) onto the hydrophobized/oleophilized autoclaved porous aerated concrete (AAC) grains made from waste scrap in Vietnam by using batch sorption tests in the laboratory. The AAC grains (sizes 0.106–0.25, 0.25–0.85, and 0.85–2.00 mm) were hydrophobized/oleophilized using oleic and stearic acids (coating concentrations of 1.0, 5.0, and 10 g/kg), and two sands (0.18–2.00 and 0.30–2.00 mm) were used as control samples. The results showed that the hydrophobized/oleophilized AAC grains had high sorption capacity for dispersed oil (i.e., high oil removal efficiency) compared to the control sands. Especially, the removal of AAC grains coated with stearic acid was &gt;80% in high oil concentration solutions (Ci = 100 and 1000 mg/L), indicating that the hydrophobized/oleophilized AAC grains have high potential as useful adsorbents to trap dispersed oil in oily wastewater. Moreover, adsorption isotherms were drawn to examine the sorption characteristics of dispersed oil onto AAC grains. For all tested samples, the sorption of dispersed oil increased linearly with increasing equilibrium concentration. The commonly used Langmuir model, on the other hand, did not capture the measured isotherms.

Pickering emulsion stabilized by Haematococcus pluvialis protein particles and its application in dumpling stuffing

In this study, the oil-in-water Pickering emulsions were prepared using Haematococcus Pluvialis protein (HPP) particles as an emulsifier by a simple one-step emulsification method. The internal oil phase was as high as 70 % due to the excellent emulsifying properties of HPP, and the average size of oil droplets in the emulsion was around 20 μm. The emulsion prepared by 2.5 % HPP with the oil phase ratio of 70 % showed the best stability after 14 days of storage, and the emulsion could maintain stability at acidic condition, high ionic strength, low and high temperatures. However, all emulsion samples exhibited shear thinning phenomenon, and the higher HPP concentration and oil phase ratio led to greater G′ and G″ modulus. NMR relaxation results showed that high concentration HPP could limit the mobility of free water in the emulsion and improve the emulsion stability. The HPP-stabilized emulsion could inhibit the oxidation of oil phase during storage due to the DPPH and ABTS radical scavenging activity of astaxanthin (AST) in HPP. Finally, the nutritional microspheres based on HPP-stabilized emulsion showed good stability in traditional dumplings and could reduce the loss of AST and DHA in algae oil during the boiling of dumplings.

Verletzungen und Überlastungsschäden beim Wingfoilen

In this study, levan from Bacillus licheniformis NS032 was modified in an aqueous medium by octenyl succinic anhydride (OSA), and the properties of the obtained derivatives were studied. The maximum efficiency in the synthesis reaction was achieved at 40 °C and a polysaccharide slurry concentration of 30 %. Increasing the reagent concentration (2–10 %) led to an increase in the degree of substitution (0.016–0.048). Structures of derivatives were confirmed by FTIR and NMR. Scanning electronic microscopy, thermogravimetry, and dynamic light scattering analyses showed that the derivatives with degrees of substitution of 0.025 and 0.036 retained levan's porous structure and thermostability and showed better colloidal stability than the native polysaccharide. The intrinsic viscosity of derivatives increased upon modification, while the surface tension of the 1 % solution was lowered to 61 mN/m. Oil-in-water emulsions prepared with sunflower oil (10 % and 20 %) by mechanical homogenization and 2 and 10 % derivatives in the continuous phase showed mean oil droplet sizes of 106–195 μm, while the distribution curves exhibited bimodal character. The studied derivatives have a good capacity to stabilize emulsions, as they have a creaming index ranging from 73 % to 94 %. The OSA-modified levans could have potential applications in new formulations of emulsion-based systems.

Synthesis of octenyl succinic anhydride-modified levan and investigation of its microstructural, physicochemical, and emulsifying properties

In this study, levan from Bacillus licheniformis NS032 was modified in an aqueous medium by octenyl succinic anhydride (OSA), and the properties of the obtained derivatives were studied. The maximum efficiency in the synthesis reaction was achieved at 40 °C and a polysaccharide slurry concentration of 30 %. Increasing the reagent concentration (2–10 %) led to an increase in the degree of substitution (0.016–0.048). Structures of derivatives were confirmed by FTIR and NMR. Scanning electronic microscopy, thermogravimetry, and dynamic light scattering analyses showed that the derivatives with degrees of substitution of 0.025 and 0.036 retained levan's porous structure and thermostability and showed better colloidal stability than the native polysaccharide. The intrinsic viscosity of derivatives increased upon modification, while the surface tension of the 1 % solution was lowered to 61 mN/m. Oil-in-water emulsions prepared with sunflower oil (10 % and 20 %) by mechanical homogenization and 2 and 10 % derivatives in the continuous phase showed mean oil droplet sizes of 106–195 μm, while the distribution curves exhibited bimodal character. The studied derivatives have a good capacity to stabilize emulsions, as they have a creaming index ranging from 73 % to 94 %. The OSA-modified levans could have potential applications in new formulations of emulsion-based systems.

Formation and characterisation of concentrated emulsion gels stabilised by faba bean protein isolate and its applications for 3D food printing

Concentrated emulsions were prepared at a fixed oil concentration (50 wt%) using faba bean protein isolates (FPI) as an emulsifier and texturizer. Effects of FPI concentration (1, 3 and 5 wt%; at pH7), pH (pH 3, 5, 7, and 9; 3 wt%) and addition of salts (200 mM NaCl and 40 mM CaCl2; at 3 wt% FPI and pH 7) on the emulsion formation were studied. The oil droplet size and microstructural characteristics were examined by static light scattering and confocal laser scanning microscopy (CLSM), and the viscoelastic behaviours of emulsions were characterised by oscillatory rheology. At all different FPI concentrations, the emulsions formed viscoelastic gels with different gel strengths and stability due to network formation and interactions between jammed oil droplets and protein aggregates. The oil droplet size, rheological properties, and 3D printability of emulsions were not significantly changed by the presence of salts. The storage modulus G′ (1 Hz) values were higher at higher FPI concentrations, and higher pH values (i.e., pH 7 and 9) as the droplet size was smaller and the droplet packing was more compact, resulting in a better 3D printing performance. Furthermore, the heat treatment (90 °C for 30 min) remarkedly improved gel strength and the 3D printability because of protein denaturation and oil droplet aggregation. This finding demonstrated that the emulsion gel formed with FPI was tuneable for food 3D printing. Most of samples displayed high printing precision with great self-supporting capability, which may find potential applications in creating specialised diet.

Physicochemical properties of surimi gel from silver carp as affected by ultrasonically emulsified vegetable oils

ABSTRACT The objective of this study was to investigate the effects of ultrasonically emulsified palm oil (UE-PA), peanut oil (UE-PE), and sunflower oil (UE-SU) on the whiteness, textural, rheological, and microstructural properties of surimi gels from silver carp. Three ultrasonically emulsified oils had different specific fatty acids and oil droplet sizes of 300-400 nm. Compared with the control group, low addition of UE-SU (2.5 g/100 g) showed the highest water-holding capacity (WHC), storage modulus (G’), and hydrogen bond in surimi gels. The low addition of UE-PE (2.5 g/100 g) increased disulfide bond, β-sheet, and β-turn of surimi gel, so had higher hardness and chewiness values, comparing to those with other emulsified oils. As ultrasonically emulsified oil addition increased in surimi gels (2.5–7.5 g/100 g), hardness, chewiness, WHC, G’ were decreased, while whiteness was increased (p < .05). Light microscopy showed the most uniform distribution of oil droplets of UE-SU in surimi gels. Results demonstrated that lower addition of UE-PE and UE-SU (2.5 g/100 g) could potentially improve the whiteness, textural, rheological, and nutritional quality of surimi-based products.

Preparation of oil-in-water and water-in-oil emulsions with the same composition using hydrophilic nanoparticles by three-phase emulsification

This study was conducted to investigate whether oil-in-water (O/W) and water-in-oil (W/O) emulsions could be simultaneously obtained from the same raw materials via three-phase emulsification. The formation of both emulsion types was examined experimentally using the same hydrophilic nanoparticles and emulsion composition. Two different cases were considered. In the first case, only an O/W emulsion was formed, and in the other case, both O/W and W/O emulsions were produced depending on the interaction between nanoparticles and oil-water interface. These results were attributed to the location of hydrophilic nanoparticles at the oil-water interface. Only the O/W emulsion was obtained when nanoparticles were attached to the oil-water interface. Meanwhile, both types of emulsions were stably formed when nanoparticles partially penetrated the oil phase. Furthermore, even when the type of nanoparticles and emulsion composition were fully identical, the formation of both O/W and W/O emulsions could be independently controlled by varying the related non-thermodynamic parameters during preparation. For example, to produce the O/W emulsion, oil was added to the aqueous nanoparticle phase, and to prepare the W/O emulsion, the aqueous nanoparticle phase was poured into the oil phase. The findings of this work revealed that unlike conventional surfactant emulsification, the three-phase emulsification process mainly depended not on intensive parameters but on extensive parameters such as the masses and sizes of oil droplets and nanoparticles.

Combined effects of chemical dispersant and suspended minerals on the dispersion process of spilled oil

The dispersion process of spilled oil is an important concern for the effective disposal of oil spills. The dispersed oil concentration and oil droplets size distribution were studied through a wave tank test under the application of chemical dispersant and suspended minerals. The results indicated that dispersant and minerals increased the dispersed oil concentration and the effect of dispersant was more significant, and they had a synergistic effect on oil dispersion. When dispersant and minerals were applied together, the volume mean diameter of oil droplets decreased in the first 30 min, then increased and reached a maximum value at 90–120 min, and decreased again. Moreover, suspended minerals could inhibit the coalescence of oil droplets. This study can afford data support for oil spill emergency response that occurs in inshore or estuaries.

Spontaneous Emulsification of Citronella Oil: Effect of Processing Conditions and Production Scale

Nanoemulsions are gaining considerable interest for use in delivery of essential oil-based pesticides. Evaluation in the laboratory have shown promising efficacy of nanobiopesticides, and further development in nanoemulsion production at larger scale is needed for a wider application in the field. This study aimed to evaluate the changes in droplet size characteristics of citronella oil nanoemulsions produced using spontaneous emulsification at increased scales. The preparation of nanoemulsion was carried out in two stages of scale-up, namely the laboratory scale (200–1000 mL) and the larger scale (10–50 L). The process variables included stirring speed and time. Characterization was done on the oil droplet size, polydispersity index (PDI), zeta potential and microscopic structure. The oil droplet size, PDi and zeta potential varied with the emulsification process conditions and the production scale. In general, increasing mixing speed and time tended to decrease droplet size and PDI, and increase zeta potential. The changes in characteristics of nanoemulsion were minor at the higher production scales. Relatively small droplet sizes were found in the whole experiment (90–160 nm) with PDI of 0.2 – 0.4 and zeta potential of -28 to -8.8 mV. These results are useful for the design of nanoemulsion production at practical application scale.

Identification of peptides from defatted wheat germ proteins with dual functionality: Emulsifying activity and anti-adhesive activity against Helicobacter pylori

The objective of this study was to identify peptides derived from defatted wheat germ proteins with both emulsifying property and anti-adhesive activity against H. pylori. The emulsifying property was predicted by calculating the amphiphilic scores and secondary structures in silico. Six top-ranking peptides were synthesized for validation of their emulsifying and anti-adhesive activities. Three peptides (HLNLDFQLQEGGR, VNQAIYLLTTGAR, and ESLLNALTEHVK) showed high emulsifying activity by forming smaller oil droplet sizes of 1.396 ± 0.015 μm, 1.163 ± 0.010 μm, and 1.159 ± 0.257 μm, respectively. Compared to Tween 80, only VNQAIYLLTTGAR maintained good emulsifying stability at different pHs, ionic strengths, and heating. The anti-adhesive activity ranged from 36.3 ± 2.0% (VNQAIYLLTTGAR) to 5.5 ± 7.0% (AINDIRDQLER) at 10 mg/mL, which is attributable to binding of the peptides and H. pylori adhesins through hydrogen bonding and hydrophobic interactions. In conclusion, VNQAIYLLTTGAR showed both biological and techno-functional properties, thus making it a strong candidate for further development as a dual functional food ingredient.