Droplet Aggregation Research Articles

Polystyrene microplastics facilitate the biotoxicity and biomagnification of ZnO nanoparticles in the food chain from algae to daphnia

Ubiquitous microplastics (MPs) may affect the trophic transfer of nanoparticles (NPs), in turn threatening aquatic organisms and even human health. Thus, this study explored the influence of polystyrene microplastics (PS MPs) on the biotoxicity and biomagnification of ZnO nanoparticles (ZnO NPs) in the aquatic food chain from Chlorella vulgaris (C. vulgaris) to Daphnia magna (D. magna). The results showed that PS MPs facilitated the biotoxicity of ZnO NPs towards D. magna after dietary exposure. Compared to the control (single ZnO NPs), the heart rate and the level of reactive oxygen species were remarkably increased by 21.25% and 16.32% in the combined system (PS MPs + ZnO NPs), respectively. Notably, PS MPs suppressed the ZnO NPs accumulation in C. vulgaris, while remarkably facilitating the trophic transfer of ZnO NPs to D. magna. The biomagnification of ZnO NPs was evident with a maximal biomagnification factor (BMF) of 1.49 under acute dietary exposure of PS MPs (72 h), but was absent in the single ZnO NPs system (BMF <0.90). Moreover, PS MPs resulted in a larger biomagnification of ZnO NPs with a maximal BMF of 2.11 under chronic dietary exposure (21 days). Furthermore, the Zn element (including ZnO NPs and released Zn2+) was observed to accumulate in the intestine, thus causing ultrastructural damage and lipid droplet (LD) aggregate. Overall, these findings highlight the importance of considering the impact of MPs on co-existed pollutants and contribute to a better understanding of the ecological risks of MPs in aquatic ecosystems.

Experimental Study on the Effect of Wax Crystal-Water Droplet Aggregations on Wax Deposition of Water-in-Oil Emulsions

Wax deposition in waxy crude oil emulsions remains a flow assurance challenge in offshore production. Wax molecular diffusion driven by the positive temperature gradient from the liquid to the pipe wall has been widely studied and regarded as the primary wax deposition mechanism; however, a considerable wax deposit of emulsions at a zero-temperature difference was detected, in which condition molecular diffusion is not likely to occur, suggesting there were other mechanisms that contribute to wax deposition. In this work, the wax deposition mechanism of water-in-oil emulsions at a zero-temperature difference was explored by a cold finger apparatus regarding the role of wax crystals and water droplets on wax deposition. Through microscopy observation and component measurement of deposits, the wax deposition mechanism, namely, wax crystal-water droplet aggregation formation and adhesion behavior, was proposed. During wax deposition, wax crystals in the emulsion interacted with water droplets, organizing the basic structure of aggregation. The liquid oil phase was entrapped at the inner space of the aggregation and entrained by the wax crystal-water droplet structure to generate a wax deposit. The formation of wax crystal-water droplet aggregations depends on the experimental temperature, where a larger size of aggregations that formed at a lower temperature preferred to yield a thicker deposit under the same stirring speed, while for the same temperature operation conditions, the medium and low speed promoted the adhesion behavior of the aggregations to the cold finger resulting in an increase in deposits; however, the high stirring condition sloughed off the formed deposits, reducing the deposit mass. The findings denote that the presence of wax crystal-water droplet aggregations in emulsion should be considered when describing the wax deposition process at low temperatures.

Manipulation, aggregation, fusion and separation of droplets using laser-induced Marangoni force

Micro-scale control of liquid/droplet motion is crucial for chemical and biochemical analysis. There are several methods to manipulate droplet motion such as the Marangoni effect which can be triggered by introducing temperature gradients on suspended droplets in mineral oil.In this study, a focused continuous wave (CW) laser beam was used to induce the Marangoni force to separate, fuse, aggregate, and control droplets. Droplets experience a force due to an interfacial tension gradient near the locally heated area created by the laser beam. The work is done on a chamber and a microchannel platform.In order to fuse water droplets, we used an optical fiber (200-µm core and 220-µm glass cladding, which has a 0.065 numerical aperture (NA)) to direct focused laser beams into the oil medium, where the droplets were first moved to the heat source and then stopped at this point and merged a second time. Also, for the first-time droplet separation for different radii of 47 and 55 in the microchannel and droplet aggregation in the chamber was performed by the Marangoni effect. We have also examined the behavior of the droplets in relation to their size and distance from the hot spot.By controlling the incident laser power, we can manipulate the droplet to either fuse, separate or aggregate.

Stabilization of liquid water‐in‐oil emulsions by modifying the interfacial interaction of glycerol monooleate with aqueous phase ingredients

AbstractGlycerol monooleate (GMO)‐stabilized liquid water‐in‐vegetable oil emulsions are difficult to stabilize due to the desorption of GMO from the water‐vegetable oil interface toward the oil phase. This work improved the stability of GMO‐stabilized liquid 20 wt% water‐in‐canola oil (W/CO) emulsion by modifying the dispersed aqueous phase composition with hydrogen bond‐forming agents. As a control, 20 wt% water‐in‐mineral oil (W/MO) emulsion was also utilized. Different concentrations of hydrogen bond‐forming agents (citric acid (CA), ascorbic acid (AA), low methoxyl pectin (LMP)) with and without salts (sodium chloride (S) or calcium chloride (Ca)) were added to the aqueous phase before emulsification, which enhanced emulsifier binding to the water–oil interface. W/CO emulsion without any aqueous phase additive destabilized instantly, whereas W/MO emulsion stayed stable during the week‐long observation. The addition of hydrogen bond‐forming agents and salts significantly improved emulsion stability. LMP, with many hydrogen bond‐forming groups, was able to provide the highest emulsion stability after 7 days in both oils compared to AA, CA and their mixtures with S. Emulsions with both oils formed weak gels due to the formation of an extensive network of water droplet aggregates. Overall, the hydrogen bond‐forming agents interacted with GMO at the interface, thereby favoring their presence at the water droplet surface and significantly improving the stability of liquid W/CO emulsions. The knowledge developed in this research can be useful in utilizing GMO to stabilize liquid water‐in‐oil emulsions without using any fat crystal network.

Comparison of different indirect approaches to design edible oleogels based on cellulose ethers

Growing public concern about the adverse health effects of overconsumption of saturated fat has contributed to the rising research interest in the field of using healthy oils to construct edible structured oils (oloegels) as fat-based alternatives. In this study two indirect methodologies (the emulsion template approach and the foam template approach) were investigated to prepare oleogels with hydroxypropyl methylcellulose and methylcellulose as gelling agent at three different oil concentrations. Microstructure, texture, rheology, and oil retention capacity were measured to evaluate the structural and physicochemical properties of oleogels. Results showed that the emulsion-based oleogel effectively inhibited the aggregation of droplets. The dry emulsion showed independent droplets and an oil retention capacity of 100%. In foam-type oleogels the oil retention rate was negatively correlated with the oil content. The oleogels prepared by both methods have excellent mechanical properties and gel strength, with a predominance of the elastic versus the viscous behavior. Hydroxypropyl methylcellulose and methylcellulose had different degrees of influence on the structure and mechanical properties of the two oleogels. The results of this paper provide guidance for the development and application of cellulose-based oleogels as healthy alternatives to saturated fat. • Different approaches result in different microstructure and oil retention capacity. • Oil content plays an important role in textural and rheological properties. • Oleogels present high gel strength and low dependence on frequency and temperature.

Influence of Soy Lecithin and Sodium Caseinate on The Stability and in vitro Bioaccessibility of Lycopene Nanodispersion.

Various approaches have been used to present functional lipids including lycopene in a palatable food form to consumers. However, being highly hydrophobic, lycopene is insoluble in aqueous systems and has a limited bioavailability in the body. Lycopene nanodispersion is expected to improve the properties of lycopene, but its stability and bioaccessibility are also affected by emulsifier type and environmental conditions such as pH, ionic strength and temperature. The influence of soy lecithin, sodium caseinate and soy lecithin/sodium caseinate at 1:1 ratio on the physicochemical properties and stability of lycopene nanodispersion prepared using the emulsification-evaporation methods before and after treatment at different pH, ionic strength and temperature were investigated. The in vitro bioaccessibility of the nanodispersions was also studied. Under neutral pH conditions, nanodispersion stabilized with soy lecithin had the highest physical stability and the smallest particle size (78 nm), the lowest polydispersity index (PDI) value (0.180) and highest zeta potential (-64 mV) but the lowest lycopene concentration (1.826 mg/100 mL). Conversely, nanodispersion stabilized with sodium caseinate had the lowest physical stability. Combining the soy lecithin with sodium caseinate at 1:1 ratio resulted in a physically stable lycopene nanodispersion with the highest lycopene concentration (2.656 mg/100 mL). The lycopene nanodispersion produced by soy lecithin also had high physical stability under different pH range (pH=2-8) where the particle size, PDI and zeta potential remained fairly consistent. The nanodispersion containing sodium caseinate was unstable and droplet aggregation occurred when the pH was reduced close to the isoelectric point of sodium caseinate (pH=4-5). The particle size and PDI value of nanodispersion stabilized with soy lecithin and sodium caseinate mixture increased sharply when the NaCl concentration increased above 100 mM, while the soy lecithin and sodium caseinate counterparts were more stable. All of the nanodispersions showed good stability with respect to temperature changes (30-100 °C) except for the one stabilized by sodium caseinate, which exhibited an increased particle size when heated to above 60 °C. The combination of soy lecithin and sodium caseinate was found to increase the bioaccessibility of the lycopene nanodispersion. The physicochemical properties, stability and extent of the lycopene nanodispersion digestion highly depend on the emulsifier type. Producing a nanodispersion is considered one of the best ways to overcome the poor water solubility, stability and bioavailability issues of lycopene. Currently, studies related to lycopene-fortified delivery systems, particularly in the form of nanodispersion, are still limited. The information obtained on the physicochemical properties, stability and bioaccessibility of lycopene nanodispersion is useful for the development of an effective delivery system for various functional lipids.

Improving the physicochemical stability of Pickering emulsion stabilized by glycosylated whey protein isolate/cyanidin-3-glucoside to deliver curcumin

Protein-polysaccharide-polyphenol delivery systems function as a promising tool to deliver bioactive ingredients aiming to improve their solubility and bioavailability. In this study, whey protein isolate (WPI), short-chain inulin (SCI), and cyanidin-3-glucoside (C3G) were first used to stabilize Pickering emulsions. The physicochemical properties and stability of curcumin encapsulated or not in Pickering emulsions were explored. Results showed that glycosylation and C3G reduced surface and interfacial tension on protein surfaces and inhibited the aggregation of emulsion droplets, thereby reducing the emulsion's particle size. WPI-SCI/C3G stabilized Pickering emulsion had the best stability. The CLSM results showed that the WPI-SCI and WPI-SCI/C3G stabilized emulsions were uniformly dispersed, suggesting that glycosylation and the interaction between protein and C3G enhanced the adsorption capacity of the interfacial protein and improved the stability of the Pickering emulsion. The retention rates of curcumin-loaded WPI-SCI- (67.34 %) and WPI-SCI/C3G- (77.07 %) stabilized Pickering emulsions on day 8 of storage were higher than those in WPI- (33.97 %) and WPI/C3G- (37.02 %) stabilized emulsions, and the degradation half-life was also extended from 7 days to >15 days. These findings provide a theoretical basis for the application of WPI Pickering emulsion and indicate a useful means for the delivery of bioactive components.

Physicochemical Properties and Oxidative Stability of an Emulsion Prepared from (-)-Epigallocatechin-3-Gallate Modified Chicken Wooden Breast Myofibrillar Protein.

The deterioration of wooden breast myofibrillar protein (WBMP) causes a decline in its processing performance, and the protein becomes easier to oxidize. Previous studies have revealed that the use of (-)-epigallocatechin-3-gallate (EGCG) may improve the physicochemical properties and oxidative stability of proteins in aqueous solutions. The effects of varying concentrations (0.01%, 0.02%, 0.03%, and 0.04% w/v) of EGCG on the physicochemical properties of a WBMP emulsion (1.2% WBMP/10% oil) and the inhibition of lipid and protein oxidation were studied. The results revealed that a moderate dose of EGCG (0.03%) could significantly (p &lt; 0.05) improve the emulsion activity index (4.66 ± 0.41 m2/g) and emulsion stability index (91.95 ± 4.23%), as well as reduce the particle size of the WBMP emulsion. According to the micrographs and cream index, 0.03% EGCG retarded the phase separation by stopping the aggregation of droplets and proteins, thus significantly improving the stability of WBMP emulsions. During storage at 50 °C for 96 h, 0.03% EGCG inhibited lipid oxidation (lipid hydroperoxide and 2-thiobarbituric acid-reactive substance formation) and protein oxidation (carbonyl formation and sulfhydryl loss). In contrast, lower and higher EGCG concentrations (0.01%, 0.02%, and 0.04%) demonstrated shortcomings (such as weak antioxidant capacity or protein over-aggregation) in improving the quality and oxidation stability of the emulsion. In conclusion, a moderate dose of EGCG (0.03%) can be used to improve the quality and shelf life of WBMP emulsions.

Fabrication and characterization of nanoemulsions for encapsulation and delivery of vitexin: antioxidant activity, storage stability and in vitro digestibility.

Nanoemulsions were prepared as an encapsulation and delivery system for vitexin, a poorly water-soluble antioxidant. This study evaluated how the type and concentration of the dispersed oil phase and vitexin loading impacted droplet characteristics and nanoemulsion stability. The influences of storage temperature on antioxidant activity and in vitro gastrointestinal digestion on nanoemulsion stability were also investigated. Nanoemulsions prepared at different dispersed oil concentrations showed diverse characteristics and stability. Highest stability against droplet aggregation and phase separation with small oil droplets (< 150 nm) was observed for nanoemulsions prepared using 300 g kg-1 medium-chain triglyceride oil. These nanoemulsions are able to entrap and deliver vitexin with high encapsulation efficiency (88-90%) with no significant effect on emulsion stability. Vitexin-loaded nanoemulsions were stable during storage when refrigerated (4 °C) and at room temperature (25 °C) for up to 45 days with no effect on their antioxidant activity. Significantly delayed lipolysis rate and decreased extent of lipid digestion were observed in vitexin-loaded nanoemulsions. Stable vitexin-loaded nanoemulsions were successfully produced by high-pressure homogenization using a mixture of Tween 80 and lecithin as emulsifiers. Vitexin-loaded nanoemulsions stabilized with a mixture of these two emulsifiers were effective in retaining antioxidant activity during storage and protecting vitexin from changes during gastrointestinal digestion. Our results suggested that nanoemulsions were effective vitexin delivery systems for food applications. © 2022 Society of Chemical Industry.

High internal phase Pickering emulsions prepared by globular protein-tannic acid complexes: A hydrogen bond-based interfacial crosslinking strategy

Native soluble globular proteins (SGPs) need to further strengthen their structural integrity to stabilize high internal phase Pickering emulsions (HIPPEs). In this study, four common SGPs in food, including ovalbumin, whey protein, bovine serum albumin (BSA), and lysozyme (LY), were used as models to form complexes with tannic acid (TA). SGPs became outstanding stabilizers for HIPPEs due to the enhanced integrity after complexing with TA. TA interacted strongly with SGPs mainly through hydrogen-bond and hydrophobic interactions. However, hydrogen-bond interaction played a key role in the SGP-TA stabilized HIPPEs. The presence of TA enhanced the wetting ability of the SGP-TA complexes at the oil–water interface, resulting in more uniform and smaller droplets of HIPPEs. These phenomena were also related to the formation of strong hydrogen bond networks among SGP-TA complexes at the interface and aqueous phase. In comparison, the BSA-TA complex had the optimal ability to stabilize HIPPEs, while LY-TA complex exhibited the lowest emulsifying activity. Notably, the gel-like network of SGP-TA stabilized HIPPEs effectively prevented droplet aggregation during storage, freeze–thaw, and heat treatment. This study developed a tangible and facile method to improve the application of SGPs in protein-based HIPPEs.

Numerical Investigation of Fine Particulate Matter Aggregation and Removal by Water Spray Using Swirling Gas Flow

In this paper, a mathematical model based on the two-fluid frame model coupled with the population balance model which considers the aggregation of particles and droplets in detail for cyclonic spray dedusting is proposed. The model is applied to study the characteristics of multiphase flow field and the effects of the gas velocity, spray volume, and particle concentration on the removal efficiency. In addition, the simulation results are verified by the experimental data. The results suggest that the turbulence kinetic energy increases near the wall as the inlet velocity increases, and the spray region increases as the spray volume increases. This is conducive to turbulent mixing of the particles and droplets, and the agglomeration efficiency of the particles is improved, so the particle size increases, and the particle removal efficiency increases to 99.7% by simulation results are within the allowable range of error (about 99-99.5% in dedusting efficiency by experimental data). As the particle concentration increases, the particle removal efficiency initially increases, then decreases and reaches the highest value at 2 g/m3, which is due to the limited adsorption efficiency of the spray droplets. The results are helpful for providing a theoretical basis for spray to promote agglomeration of particles and improving the dust removal efficiency in the swirl field.

Impact of polyelectrolyte complex layer on the stability of palm oil multiple emulsions encapsulating a water-soluble compound during heating, cooling, and storage processes

The effect of an interfacial polyelectrolyte complex layer on the stability of multiple water-in-oil-in-water (W/O/W) emulsions containing palm oil (oil phase) was investigated. Monodisperse W/O/W emulsions prepared by primary ultrasonic emulsification using polyglycerin polycondensed ricinoleic acid ester as an oil-soluble emulsifier followed by secondary microchannel emulsification contained multiple sodium caseinate-stabilized droplets with a mean diameter of 44 μm. The multiple droplets containing palm oil maintained their diameter at 60 °C for a minimum of 24 h, whereas significant aggregation of the multiple droplets, with a partially crystallized palm oil phase, was observed below its crystallization temperature (∼27 °C). The formation of a chitosan-sodium caseinate complex layer by the electrostatic interaction of positively charged chitosan with negatively charged sodium caseinate at the oil–water interface could suppress the aggregation of the multiple droplets, even below the crystallization temperature of palm oil. Calcein, a water-soluble fluorescent dye, was stably encapsulated for a month with a high entrapment yield at 25 °C with a chitosan-sodium caseinate complex layer, although without the complex layer, it leaked to the external water phase within a day. The W/O/W emulsion with the polyelectrolyte complex layer improved both the droplet dispersibility and encapsulation efficiency of the multiple droplets during heating at 80 °C, followed by cooling at 25 °C. Polarized microscopic observations indicated that the chitosan-sodium caseinate complex layer affected the crystallization of palm oil in multiple droplets: partial crystallization of palm oil in the multiple droplets may be delayed by the presence of the polyelectrolyte complex layer at the oil–water interface.

Effect of phospholipid matrix on emulsion stability, microstructure, proteolysis, and in vitro digestibility in model infant formula emulsion

The effects of adding different phospholipid (PL) matrices [milk sphingomyelin (SM) vs soy phosphatidylcholine (PC)] on emulsion stability, microstructure, and in vitro simulated lipid digestion were examined using a Model Infant Formula Emulsion (MIFE). The emulsion stability of MIFE increased significantly with PL addition (0.1 and 0.2 %). Compared to sole MIFE or MIFE + PC, the incorporation of SM resulted in increased emulsion stability (p < 0.05) and a greater amount of free fatty acid release (p < 0.05) during in vitro simulated digestion. This was mainly due to the reduction of intensive droplet aggregation, thus providing a large surface area and improved digestibility. This is further experimentally supported by the evolution of particle size distribution, zeta-potential, and microstructure analysis using confocal laser scanning microscopy. The incorporation of SM in the emulsion formation significantly delayed digestion of β-lactoglobulin during in vitro digestion. Lipid digestibility in MIFE was altered depending on the type of PL matrix, and SM displayed a superior effect to PC. Thus, the creation of a novel emulsion interface by the appropriate selection of emulsifiers can be used to improve lipid digestion in infants and obtain desirable nutritional consequences.

Supplement of Caulerpa lentillifera polysaccharide by pre-prandial gavage and free feeding demonstrates differences to prevent obesity and gut microbiota disturbance in mice.

Caulerpa lentillifera has received extensive attention regarding expansion of its farming and increasing consumption. In our previous study, the structure of C.lentillifera polysaccharide (CLP) was elucidated. However, little information is available about its health effects. In this study, the anti-obesity effect of CLP was investigated by using a high-fat diet-induced obese mice model with two different supplementation methods. In vitro simulated digestion results showed that CLP significantly decreased the lipid digestibility and induced the lipid droplets aggregation in the intestinal stage to inhibit the absorption of lipids. As revealed by 16S ribosomal RNA sequencing and non-targeted metabolomics, supplement of CLP by both pre-prandial gavage and free feeding patterns effectively prevented mice obesity via ameliorating intestinal flora disturbance and regulating bile acids circulation metabolism. Of note was that CLP administration had no effect on short-chain fatty acids production, suggesting the anti-obesity effect was uncorrelated with their production. Moreover, pre-prandial administration of CLP had a better anti-obesity effect in lowering body weight and serum lipid levels, but the free feeding resulted in a higher α-diversity of gut microbiota. The findings of this study indicate that CLP could be a potential anti-obesity nutraceutical and that pre-prandial supplement of CLP may be a better intake method to exhibit its hypolipidemic effect. © 2022 Society of Chemical Industry.

Oxidized high-amylose starch as pickering stabilizer for oil-in-water emulsion and delivery of bioactive compound

Polysaccharide based emulsions have received considerable attention due to their biodegradability, biocompatibility and food-safety. In this study, oxidized high-amylose starch (OHAS) is adopted for stabilization of oil-in-water (O/W) emulsion. Results showed that OHAS with oxidation degree of 90% (DO90-OHAS) exhibited higher wettability with three-phase contact angle of 70.6°. The obtained emulsion was stable within a wide range of different solution condition, with pH ranging from 3 to 7, salt concentration as high as 1.0 M and temperature ranging from -25 to 80 ℃. The gel-like network structure of DO90-OHAS effectively stabilized the emulsion and prevented the aggregation of oil droplets under different pH, as evidenced by confocal laser scanning microscopy (CLSM) observation. Furthermore, DO90-OHAS based emulsion prepared at different pH showed satisfactory long-term storage stability (up to 30 days). The fabricated emulsion was utilized for encapsulation of hydrophobic bioactive substances, with ∼72.5% encapsulation efficiency for β-carotene. The DO90-OHAS based emulsion enabled the controlled-release of β-carotene in vitro, with antioxidant activity maintained ∼50% of initial activity when exposed to elevated temperature (80°C). This research may provide a new avenue for OHAS based Pickering emulsions preparation and bioactive components delivery.

Improving freeze-thaw stability and 3D printing performance of soy protein isolate emulsion gel inks by guar & xanthan gums

Frozen storage of 3D printing inks could increase their shelf life. We improved freeze-thaw stability and 3D printing performance of soy protein isolate (SPI) emulsion gel inks by guar (GG) and xanthan gums (XG). Freeze-thawed inks led to higher storage modulus (G′), lower water holding capability (WHC) and poor printing performance compared to initial inks. An increase in gums content decreased oil droplet aggregation and protein flocculation in all freeze-thawed inks, hence reducing syneresis in the gel structure and preventing solid-liquid separation during 3D printing. The freeze-thaw stability of SPI-XG inks was consistently greater than that of SPI-GG inks at the same concentrations, resulting in superior 3D printing performance. The hardness of cylinders printed with SPI-XG0.5 freeze-thawed inks was lower than that of the cylinders printed by initial inks, in contrast to the results of G'. At the maximum strain amplitude (500%), Lissajous analysis indicated that the SPI-XG0.5 freeze-thawed inks retained less energy than the initial inks, resulting in a weaker gel. Overall, this study demonstrated that freeze-thaw treatment negatively affected the 3D printing performance of SPI emulsion gel inks, but that the 3D printing performance of freeze-thaw inks could be reinforced by modifying the formulation.

Static stability of partially crystalline emulsions: Impacts of carrageenan and its blends with xanthan gum and/or guar gum

In the present study, four different combinations of gums, including carrageenan (CG), its binary blends with xanthan gum (XG) or guar gum (GG) in equal ratios, and its ternary blends with XG and GG in three equal ratios, were involved into making partially crystalline emulsions (PCEs), respectively. The freshly prepared emulsions were systematically characterized by rheological property, particle size distribution, microscopic morphology, interfacial property, and intermolecular interactions, and their emulsion stabilities were further evaluated using multiple light scattering technique and storage test. All PCEs stabilized by gum blends (CG + XG, CG + GG, and CG + XG + GG) obtained decreased apparent viscosities at 0.01 s−1 (10.12–25.32 Pa·s), particle sizes (3.12–4.06 μm), as well as interfacial protein concentrations (22.60–27.01 mg/m2), which were much lower than those with single CG (35.98 Pa·s, 6.72 μm, and 47.74 mg/m2, respectively). The microscopic morphology showed that blending CG with XG and/or GG contributed to formation of firmer three-dimensional matrix, thereby preventing the aggregation of fat droplets. Inclusion of XG and/or GG also significantly reduced contribution of hydrophobic interactions from 0.72 to 0.24–0.44 mg/mL. Both multiple light scattering and storage test revealed that emulsion instabilities were mainly manifested as a clarification at the bottom and an agglomeration at the top. PCE-CG + XG + GG exhibited superior stability with low creaming index (6.20 %) and viscosity (1180.0 mPa·s) after three months of storage. The research aims to evaluate the effects of CG and its blends with XG and GG on stability of PCEs, and the results potentially provide valuable information for manufacture of stable PCE foods.

The formation mechanism of multilayer emulsions studied by isothermal titration calorimetry and dynamic light scattering

The formation of multilayer interfaces in oil-in-water (O/W) systems has many advantages in delivering lipid-soluble active compounds. In this study, isothermal titration calorimetry (ITC) and dynamic light scattering (DLS) were used to investigate the formation mechanism of multilayer emulsions by mixing low methoxyl pectin (LMP) and sodium caseinate (CAS) stabilized O/W emulsion. Thermodynamic properties and ζ-potential curves were studied as a function of polymer ratio, suggesting that ITC could provide more accurate information about the polymer concentration effect. ITC titration confirmed that LMP binds CAS-coated droplets mainly through electrostatic forces, which was a spontaneous exothermic process (ΔG < 0). Furthermore, stable multilayer emulsions were obtained by titrating CAS-stabilized droplets into LMP instead of back-titrating. Finally, the effects of mixing methods on the stability of multilayer emulsions were evaluated. The results suggest that titration rather than direct mixing can produce uniform and smaller-sized droplets and delay the onset of droplets aggregation.

The Effects of Pectin Structure on Emulsifying, Rheological, and In Vitro Digestion Properties of Emulsion.

Pectin, a complex hydrocolloid, attracts extensive attention and application stemming from its good emulsification. However, the source of emulsification remains a conundrum. In this experiment, the structures of six kinds of commercial pectin, including LM 101 AS (101), LM 104 AS (104), 121 SLOW SET (121), YM 150 H (150), LM 13 CG (13CG), and β-PECTIN (β-P) were determined, and the effects of pectin structure on emulsion emulsification, rheology and in vitro digestibility were studied. The results showed that the β-P pectin contained a higher content of protein, ferulic acid, and acetyl and had a lower interfacial tension; this pectin-stabilized emulsion exhibited a smaller droplet size and superior centrifugal and storage stability. The results showed that β-P pectin had higher contents of protein, ferulic acid, and acetyl and lower interfacial tension than other pectins, and its stabilized emulsion exhibited smaller droplet size and superior centrifugation and storage stability. Furthermore, the emulsion formed by the pectin with high molecular weight and degree of methoxylation (DM) had a higher viscosity, which can inhibit the aggregation of emulsion droplets to some extent. However, the DM of pectin affected the charge and digestion behavior of pectin emulsion to a great extent. The smaller the DM, the more negative charge the emulsion carried, and the higher the release rate of free fatty acids. The results provided a basis for the rational selection and structural design of the pectin emulsifier.

Lab-in-Syringe, a Useful Technique for the Analysis and Detection of Pollutants of Emerging Concern in Environmental and Food Samples.

Lab-in-syringe is a new approach for the integration of various analytical extraction steps inside a syringe. Fully automated dispersive liquid-liquid microextraction is carried out in-syringe using a very simple instrumental setup. Dispersion is achieved by aspiration of the organic phase and then the watery phase into the syringe as rapidly as possible. After aggregation of the solvent droplets, the organic phase is pushed towards the detector allowing a highly sensitive spectrophotometric or fluorimetric detection. This technique is very useful not only for the preconcentration of analyte, but also for the elimination of their interferences. In this work, its application is described using solvents that are lighter and denser than water. The magnetically assisted variant and its coupling to different instruments has been also described with the aim of increasing the resolution of complex samples, especially useful for the determination of emerging contaminants.