Double Emulsions Relevant to Food Systems: Preparation, Stability, and Applications

Double-emulsion synthesis of reactive epoxy nanospheres for advanced lithium-ion battery binders

The rapid advancement of electric vehicles imposes significant challenges on lithium-ion battery (LIBs) technology. Polymer binders offer a promising low-cost solution. However, for anode materials, the conventional styrene butadiene latex/carboxymethyl cellulose (SBR/CMC) binders exhibit inherent issues, including binder flotation during solvent evaporation and undesired film formation on anode surfaces. Herein, ultra-small reactive epoxy nanospheres (EPS, 70 nm) were successfully synthesized using a customized double emulsion (DE) demulsification method. The structural design of the internal water phase, two consecutive emulsifications and an innovative phase inversion strategy are crucial to achieve ultra-small particle size. By eliminating the binder migration phenomenon and establishing a covalent cross-linked network within the electrode, the EPS bonded electrode achieved a peel strength of 7.03 N cm-1, surpassing the 4.53 N cm-1 observed in the SBR bonded electrode. Furthermore, EPS can optimize the electrode pore structure and increase the electrode's wettability to the electrolyte, thereby improving the electrode rate performance. At a current density of 10C, the EPS bonded electrode achieved a capacity retention of 50.4 %, which is much higher than that of the SBR bonded electrode (21.2 %). Consequently, reactive EPS presents an effective way to enhance the overall performance of LIBs through the strategic design of polymer binders.

Encapsulation and release of hydrophilic solutes in W/O/W double emulsions: The role of the primary and secondary homogenization steps

This study aims to explore the impact of the primary and secondary homogenization steps on the encapsulation and release properties of model water-in-oil-in-water (W/O/W) double emulsions (DEs). Based on scientific literature, it was hypothesized that a higher intensity in the 2nd step than in the 1st step negatively impacted encapsulation, whereas a relationship between homogenization intensities and release kinetics during storage was also expected. Hereby, L-valine encapsulated DEs were produced with homogenization at varying intensities in the 1st and 2nd steps, employing a rotor-stator high-shear mixing system (UT) and a microfluidizer (MF). The droplet size, entrapped water yield, and the released valine amount were determined after preparation and during storage. A remarkable impact of both the 1st and 2nd homogenization intensity on the droplet size of DEs was observed. Particularly, for the same 2nd step intensity, larger oil droplets formed at higher 1st step intensity. The rotor-stator system consistently achieved a high encapsulation efficiency (> 90 %) of water and valine even when the second homogenization intensity was higher than the first, whereas microfluidization led to a low encapsulation efficiency. Moreover, both homogenization steps affected the release kinetics of valine during storage, with a faster release at lower 1st UT processing intensity and higher 2nd homogenization intensity. Interestingly, a linear relationship between release rates and droplet size was noticed when the first UT processing intensity varied and the second remained constant. Our work elucidated the interrelationship between the primary and secondary homogenization intensities on the encapsulation and release properties of DEs.

Flaxseed mucilage - stabilized double emulsion for vitamin D delivery in Hazelnut milk ice cream: in vitro stability and storage

The present study aimed to fabricate a double emulsion stabilized with flaxseed mucilage containing vitamin D. The hazelnut milk ice cream was prepared with a 5 µg/100 g vitamin D double emulsion. The storage resistance and the in vitro release of vitamin D as well as the sensory characteristics were assessed. The results indicated that the highest vitamin release rate in the simulated intestinal situation for vitamin D occurs in a double emulsion structure. The observation affirmed no remarkable variations in the magnitude of vitamin D retention during 28 days of storage (p˃0.05). The content of vitamin D in fortified hazelnut ice cream samples showed that the content of released vitamin D during in vitro simulated stomach and simulated small intestinal circumstances were about 4% and 94.8% of the initial content of vitamin D, respectively. Sensory evaluation by approach using text highlighting technique implies no remarkable variations between control and fortified hazelnut ice cream samples in various properties. Still, the purchase intention of control and enriched samples showed significant differences. After reading the highlighted text, an important difference was observed between purchase intention before and after reading the highlighted text.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-06078-x.

Templating effect of monoglycerides in controlling the spatial distribution of solid fat crystals within double emulsions

The spatial distribution of fat crystals significantly impacts the stability and digestion properties of emulsions. This study investigated the templating effect of monoglycerides in controlling the spatial distribution of solid fat crystallization within double emulsions. Double emulsions were formulated with glyceryl monostearate (GMS), glyceryl monolaurate (GML), glyceryl monooleate (GMO), beeswax (BW), glyceryl distearate (GDS), and glyceryl tristearate (GTS) in the oil phase. Monoglycerides influenced the spatial distribution pattern of BW crystals, while minimally affecting GDS and GTS. Cooling at 4 °C increased interfacial crystallization without altering distribution patterns. Monoglycerides raised the onset and peak crystallization temperatures and enthalpy in BW emulsions, with GMS showing the most significant effects. Adding GMS slowed nucleation rates and extended induction times, promoting interface crystallization. The templating effect also reduced crystal lamellar thickness, facilitating the transition from β-crystalline to β' crystalline in BW. These findings provide insights into selecting crystallizing emulsifiers and enhancing double emulsion stability.

Encapsulation of Polyphenols in Double Water-in-Oil-in-Water Emulsions Stabilized by Polyglycerol Polyricinoleate and Tunisian Arabic Gum

Water-in-oil-in-water (W1/O/W2) double emulsions have been formulated using polyglycerol polyricinoleate (PGPR) to stabilize the reverse W1/O emulsions and Arabic Gum extracted from Bouhedma National Park in Sidi Bouzid in Tunisia to stabilize the direct emulsion, in order to encapsulate two polyphenols, oleuropein and green tea leaves polyphenol. These two polyphenols exhibit an antiradical activity. The Tunisian Arabic Gum allows obtaining a narrow size distribution for the double emulsions. Due to the presence of Arabic gum in W2, the deduction of the encapsulation efficiency, from UV-vis spectrometry measurements, is not straightforward, but the final obtained values are very high (>95%), making these double emulsions with a minimal list of ingredients interesting systems. Then, the kinetic stability of these capsule-type systems has been assessed at three storage temperatures. While the double emulsions are kinetically stable at 4 °C and at room temperature, destabilization occurs at 50 °C, the mechanism of which is discussed.

Pickering emulsion stabilized by protein-glutaminase modified soybean isolated proteins as a new delivery system

Plant protein-based Pickering emulsions have garnered significant attention for their natural, stable, and efficient properties. However, the aggregation and sedimentation of plant proteins have restricted their applications in the food industry. To address this challenge, the current study explored the effect of protein-glutaminase on the structural characteristics of soy protein isolate (SPI) and assessed the potential of emulsions prepared from deamidated SPI as carriers for bioactive compounds. Structural characterization of SPI at varying degrees of deamidation (DD) revealed that deamidation notably enhanced the solubility, emulsifying ability, and surface charge density of SPI, while preserving its higher-order structure. Moreover, SPI Pickering emulsions with moderate deamidation (5 % DD) demonstrated increased droplet density, a more compact microstructure, improved rheological properties, and enhanced light stability. Additionally, in vitro digestion studies showed that deamidated SPI Pickering emulsions could effectively deliver bioactive compounds. This study offers new insights into developing legume protein-based Pickering emulsions with superior performance.

Interfacial Dynamics and Environmental Responsiveness of Double Emulsions Stabilized by Zein Particles and Surfactant Using Microfluidic Techniques

Elucidating the stability dynamics of double emulsions is essential for advancing their sustainable applications in the food industry. This study utilizes microfluidic techniques to investigate the interactions between interfacial components, Tween 80 (Tw80) and zein particles (ZPs), in double emulsions. Our results indicate that the type and concentration of stabilizing agents are critical to emulsion stability with environmental factors further influencing this balance. Specifically, emulsions stabilized by Tw80 primarily exhibited instability through the expulsion of internal droplets (Pe). In contrast, emulsions with ZP concentrations below 0.5% experienced instability due to the coalescence of oil droplets (Po), while those with ZPs concentrations above 0.5% showed instability through Pe, attributed to decreased interfacial relaxation and elasticity. Environmental factors, such as pH, NaCl, and alginate, significantly modulated this stability. Interfacial rheological analyses demonstrated a strong correlation between the emulsion stability and the viscoelastic properties of interfacial films. Lissajous plots revealed that alginate enhanced the elasticity of interface films formed by Tw80 and ZPs, thereby improving the emulsion stability. Additionally, environmental modifications, such as NaCl introduction or pH adjustments, weakened the Tw80 interface strength but accelerated ZP adsorption, ultimately increasing deformation resistance and reducing Pe. This study underscores the potential of microfluidic technologies in advancing colloid and interface science, providing a foundation for the innovative design and precise manipulation of double emulsions.

Recent advances in the effect of simulated gastrointestinal digestion and encapsulation on peptide bioactivity and stability

Food-derived bioactive peptides have garnered significant attention from researchers due to their specific biological functions, including antihypertensive, antioxidant, antidiabetic, anticancer, anti-inflammatory, and anti-osteoporosis properties. Despite extensive in vitro research, the bioactivity of these peptides may be compromised in the gastrointestinal tract due to enzymatic hydrolysis before reaching the bloodstream or target cells. Therefore, understanding the fate of bioactive peptides during digestion is crucial before advancing to clinical trials and commercial applications. To exert their health-promoting effects, these peptides must maintain their bioactivity throughout digestion. Encapsulation has emerged as a promising strategy for protecting peptides in the gastrointestinal tract. This review examines the effects of in vitro simulated gastrointestinal digestion on peptide bioactivity and stability, highlighting recent research on encapsulation strategies designed to enhance their gastrointestinal stability. Furthermore, the review addresses existing research gaps and suggests future research directions to advance our understanding and the application of bioactive peptides.

Thermally Triggered Double Emulsion-Integrated Hydrogel Microparticles for Multiplexed Molecular Diagnostics

During the COVID-19 pandemic, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) has been recognized as the most reliable diagnostic tool. However, there is a need to develop multiplexed assays capable of analyzing multiple genes simultaneously to expand its application. To address this, a multiplexed RT-qPCR using a double emulsion (DE)-based carrier and a polymer microparticle reactor, termed primer-incorporated network tailored with Taqman probe (TaqPIN) is developed. The DE securely stores nucleic acid reagents like primers and probes within the polymer network until heating releases them for the reaction. The TaqPIN RT-qPCR demonstrates an amplification efficiency of 93.8% and can detect as few as 20 copies/µL. By loading the multiple microparticles into a single reaction, a multiplexed assay with only one optical channel is enabled. In practice, a nine-plex assay is designed to distinguish between variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Even subtle variations of a single nucleotide can be simultaneously detected. Testing on 75 nasopharyngeal swab samples yields 100% sensitivity and specificity for SARS-CoV-2 detection and 94% accuracy in variant discrimination.

Investigation on the structure characteristics, stability evaluation, and oral tribology of natural oleanolic acid-based water-in-oil high internal phase and multiple Pickering emulsions as realistic fat analogues

Herein, it proved that oleanolic acid (OA) could self-assemble into particles in oil, further exhibiting great potential in creating Pickering water-in-oil (W/O) high internal phase emulsions (HIPEs) with desirable fat-like attributes. W/O HIPE with a water content of 85 wt% could be stabilized by 3 wt% OA, their fat-like performance could be optimized by modulating the filling density of water droplets and interfacial coverage. The stabilization included particle-coated, particle and droplet co-coated, and droplet-coated interfaces depending on the OA amount. HIPEs with excellent tolerance to high-temperature and freeze-thaw treatment could be achieved. Moreover, dual-interface Pickering-stabilization water-in-oil-in-water (W/O/W) emulsions with a fat-like texture were fabricated via a one-step homogenization stabilized with OA particles and microgels. Importantly, OA-based W/O and W/O/W emulsion gels possessed smooth oral sensation and similar tribology behaviors to milk fat. This work is expected to provide a "clean-label" route to develop multiphase fat analogues involved in natural materials.

Characterization and Emulsifying Ability of Cassava Peels Solubilized Using Hydrothermal Treatments

Cassava peels are rich in polysaccharides but highly unexplored and underutilized, as they could be used to meet the increasing demand for clean-label foods. This study investigated the effect of temperature on the solubilization of cassava peel during hydrothermal treatment to determine the emulsifying ability of solubilized cassava peel (SCP). Subcritical water conditions were employed via hydrothermal (120-200 °C; 2 MPa) or autoclave (127 °C; 0.2 MPa) treatments to solubilize cassava peels. The composition of the SCPs was determined, and their emulsifying ability was assessed using interfacial tension and zeta potential measurements. Under the best treatment conditions (140 °C at 2 MPa [hydrothermal]; 127 °C at 0.2 MPa [autoclave]), SCPs reduced interfacial tension against soybean oil to 12.9 mN/m and 13.4 mN/m, respectively. A strengthened co-emulsifier system was developed by incorporating SCPs with Quillaja saponins (QS) or Tween 20 to enhance the performance. Dynamic interfacial tension and zeta potential measurements revealed synergistic interactions, showing a remarkable reduction in interfacial tension from 12.94 to 5.33 mN/m. This suggests that the SCP has a surfactant-like structure owing to its amphiphilic structure and hydrophobic chains (nonpolar region) attached to the -OH functional group (polar region). Combining a second surface-active compound or co-emulsifier results in an additive effect, reducing the interfacial tension. These findings provide novel insights into carbohydrate-saponin binding and elucidate the impact of peel composition, concentration, and hydrothermal treatment conditions on co-emulsifier system performance, which will assist in the development of emulsifiers, contributing to the advancement of clean-label food technologies, effectively replacing synthetic emulsifiers in food formulations, and offering both sustainability and functionality. A systematic investigation of processing conditions and co-emulsifier interactions provides a practical framework for developing high-performance natural emulsifiers from agricultural waste.

Engineering surfactant-free pickering double emulsions gels with different structures as low-calorie fat analogues: Tunable oral perception, inhibiting lipid digestion, and potent co-delivery for lycopene and epigallocatechin gallate

Structural design has been as a transformative strategy to create clean-label and well-nourished fat-based foods. Herin, surfactant-free, plant-based oil-in-water-in-oil (O/W/O) and water-in-oil-in-water (W/O/W) emulsions gels (EGs) were designed using protein microgels and fat crystals formed in situ, which achieved dual-interface Pickering stabilization. The suitability and difference of O/W/O and W/O/W EGs as fat analogues in maintaining fat texture, inhibiting lipid digestion, target release and bioactivity of co-loading epigallocatechin gallate (EGCG) and lycopene were examined. O/W/O and W/O/W EGs displayed own unique characteristics, and could be tailored to optimize their performance. O/W/O EGs provided smoother oral perception similar to butter. The multi-structure and interface modulation for double EGs achieved inhibiting lipid digestion, fat phase position mainly controlled the digestive process. Co-delivery systems exhibited synchronous release profiles, allowing a more obvious in-time sustained release of lycopene in O/W/O and EGCG in W/O/W EGs. Both co-delivery O/W/O and W/O/W showed anti-inflammatory bioactivity.

Construction of Pickering Double Emulsions Based on Xanthan Gum/Lysozyme Nanoparticles: Structure, Stability, and Co-Encapsulation of Epigallocatechin Gallate and β-Carotene

The low stability of water-in-oil-in-water (W1/O/W2) double emulsions greatly limits their applications. Therefore, in this study, W1/O/W2 Pickering double emulsions (PDEs) were prepared by a two-step emulsification method using polyglycerol polyricinoleate (PGPR) and xanthan gum/lysozyme nanoparticles (XG/Ly NPs) as lipophilic and hydrophilic emulsifiers, respectively. The regulation mechanism of the performance of PDEs by XG/Ly NPs was investigated, and the ability of the system to co-encapsulate epigallocatechin gallate (EGCG) and β-carotene was evaluated. The results showed that increasing the XG/Ly NPs concentration can enhance the stability of PDEs. At 60% W2 phase percentage and 2.0% XG/Ly NPs, the PDEs showed a smaller droplet size (23.47 ± 2.28 μm) and no phase separation after 21 days of storage. Additionally, the PDEs co-encapsulated system showed higher encapsulation efficiency (EGCG: 89.21%; β-carotene: 99.14%) and maintained high retention of active substances after 8 h of UV illumination (EGCG: 75.51%; β-carotene: 77.24%). As demonstrated by in vitro simulated gastrointestinal digestion assays, the bioaccessibility of EGCG and β-carotene simultaneously encapsulated was improved by 66.0% and 36.2%, respectively, compared with that of individually encapsulated EGCG and β-carotene. Overall, this study provides a new reference for the construction of highly stable PDEs and is promising as a co-encapsulation carrier for environmentally sensitive components.

Developing High-Coloring Natural Systems Using Double Emulsions with Daucus carota L. Extract to Meet High-Performance Requirements

Daucus carota L. extract is attracting interest as a natural colorant alternative. However, the presence of anthocyanins (ACNs), which are sensitive to pH changes, limits its application. To tackle this issue, water-in-oil-in-water (W1/O/W2) double emulsions are emerging as innovative solutions. Nevertheless, the problem of reaching robust colorant systems for industrial use still needs to be overcome. One important target is to reach a high coloring power, minimizing its impact on the final product. In this context, the effect of colorant concentration and the volume of the primary emulsion, two routes to increase the colorant power, on color attributes and stability, an important feature to reach a marketable product, was studied. The optimal experimental design was conducted to two optimal solutions, whether through heightened colorant concentration or primary emulsion volume: a 41/59 (W1/O)/W2 ratio with 11 wt.% colorant, and a 48/52 (W1/O)/W2 ratio with 6 wt.% colorant, respectively. A subsequent assessment of color and physical emulsion stability over 30 days pointed out the solution with the lower colorant concentration (6 wt.%) as the one with better performance (L*: 44.11 ± 0.03, a*: 25.79 ± 0.01, D4;3: 9.62 ± 0.1 µm, and CI: 14.55 ± 0.99%), also minimizing the permeability of the colorant to the outer aqueous phase. Overall, these optimized emulsions offer versatile coloring solutions suitable for various industrial applications, such as food matrices and functional cosmetics.

Properties regulation and mechanism on ferritin/chitooligosaccharide dual-compartmental emulsions and its application for co-encapsulation of curcumin and quercetin bioactive compounds

Dual-compartmental emulsions, containing multiple chambers, possess great advantages in co-encapsulation of different cargoes. Herein, we reported a stable dual-compartmental emulsion by regulating the ratio of Marsupenaeus japonicus ferritin (MF) and chitooligosaccharide (COS), enabling efficient co-encapsulation of different compounds. The adsorption behavior of MF/COS complex over droplet interface varied at different ratios, thereby exerting an influence on the emulsion properties. Remarkably, emulsions stabilized by MF/COS complex at a ratio of 2:1 exhibited superior stability, as evidenced by no significant creaming or demulsification during storage or heat treatment. The mechanism is that MF/COS2:1 complex can enhance the formation of thicker interfacial layer and dense continuous phase network structure. Additionally, curcumin and quercetin can be co-encapsulated into the emulsions and their retention rates were significantly improved than those in oils, implying the potential of the resulting dual-compartmental emulsions in co-encapsulation and delivery of bioactive compounds.

Pickering emulsions stabilized by prolamin-based proteins as innovative carriers of bioactive compounds

Pickering emulsions (PEs) can be used as efficient carriers for encapsulation and controlled release of different bioactive compounds. Recent research has revealed the potential of prolamins in development of nanoparticle- and emulsion-based carriers which can improve the stability and bioavailability of bioactive compounds. Prolamin-based particles have been effectively used as stabilizers of various PEs including single PEs, high internal phase PEs, multiple PEs, novel triphasic PEs, and PE gels due to their tunable self-assembly behaviors. Prolamin particles can be fabricated via different techniques including anti-solvent precipitation, dissolution followed by pH adjustment, heating, and ion induced aggregation. Particles fabricated from prolamins alone or in combination with other hydrocolloids or polyphenols have also been used for stabilization of different PEs which were shown to be effective carriers for food bioactives, providing improved stability and functionality. This article covers the recent advances in various PEs stabilized by prolamin particles as innovative carriers for bioactive ingredients. Strategies applied for fabrication of prolamin particles and prolamin-based carriers are discussed. Emerging techno-functional applications of prolamin-based PEs and possible challenges are also highlighted.

Long-term stable water-in-oil-in-water emulsion for effective protection and sustained release of lysine-calcium using chitosan and hydroxypropyl methyl cellulose

The poor tolerance to gastric acid and low absorption of calcium supplements in the intestinal tract remain a serious limitation in applications. Herein, lysine-calcium (Lys-Ca) has been synthesized via the chelation of Lys and high-temperature calcination scallop shell powder (HCSP), and subsequently encapsulated in a carefully designed water-in-oil-in-water (W/O/W) emulsion with a high encapsulation efficiency of 93 % using chitosan (CS) and hydroxypropyl methylcellulose (HPMC). Owing to the interfacial film formed by CS and HPMC between the droplets, the resulting emulsion demonstrates good acid and thermal stability, as well as long-term stability even after 60 d of storage at 25 °C. Meanwhile, the emulsion effectively protects the encapsulated Lys-Ca from damage in simulated gastric fluid (SGF). with only about 20 % Lys-Ca escaping into SGF (after 4 h). In simulated intestinal fluid (SIF), it sustainedly releases with a 61 % ratio at 1 h under the influence of bile salts and lipase, and near-complete release occurred after 6 h. Additionally, the emulsion presents no cytotoxicity and possesses appreciable calcium transport capacity. This work provides a well-designed double-emulsion strategy that offers a promising approach for developing efficient calcium supplements, aiming at improving the bioavailability of biomass calcium.

Exploring the impact of encapsulation on the stability and bioactivity of peptides extracted from botanical sources: trends and opportunities

Bioactive peptides derived from plant sources have gained significant attention for their potential use in preventing and treating chronic degenerative diseases. However, the efficacy of these peptides depends on their bioaccessibility, bioavailability, and stability. Encapsulation is a promising strategy for improving the therapeutic use of these compounds. It enhances their stability, prolongs their shelf life, protects them from degradation during digestion, and enables better release control by improving their bioaccessibility and bioavailability. This review aims to analyze the impact of various factors related to peptide encapsulation on their stability and release to enhance their biological activity. To achieve this, it is necessary to determine the composition and physicochemical properties of the capsule, which are influenced by the wall materials, encapsulation technique, and operating conditions. Furthermore, for peptide encapsulation, their charge, size, and hydrophobicity must be considered. Recent research has focused on the advancement of novel encapsulation methodologies that permit the formation of uniform capsules in terms of size and shape. In addition, it explores novel wall materials, including polysaccharides derived from unconventional sources, that allow the precise regulation of the rate at which peptides are released into the intestine.

One-Step Formation of Pickering Double Emulsion Costabilized by Hydrophobic Silica Nanoparticles and Sodium Alginate

Pickering double emulsions exhibit higher stability and biocompatibility compared with surfactant-stabilized double emulsions. However, tailored synthesis of particle stabilizers with appropriate wettability is time consuming and complicated and usually limits their large-scale adoption. Using binary stabilizers may be a simple and scalable strategy for Pickering double emulsion formation. Herein, commercially available hydrophobic silica nanoparticles (SNPs) and sodium alginate (SA) as binary stabilizers are used to prepare O/W/O Pickering double emulsions in one-step emulsification. The influence of system composition on double emulsion preparation is identified by optical microscopy, confocal laser scanning microscopy, and interfacial tension and water contact angle analyses. The formation of the O/W/O Pickering double emulsion depends critically on the aqueous phase viscosity and occurrence of emulsion inversion. Both hydrophobic SNPs and SA adsorb at the droplet surface to provide a steric barrier, while SA also reduces interfacial tension and increases aqueous phase viscosity, giving double emulsion long-term stability. Their microstructure and stability are controlled by adjusting the SA concentration, water-oil volume ratio, concentration and wettability of the particle stabilizer, and oil type. As a demonstration, the middle layer of the as-prepared O/W/O Pickering double emulsions can be cross-linked in situ with calcium ions to produce calcium alginate porous microspheres. We believe that our strategy for double emulsion formation holds great potential for practical applications in food, cosmetics, or pharmaceuticals.

Destabilization of a model O/W/O double emulsion: From bulk to interface

Oil-in-water-in-oil (O/W/O) double emulsions are considered an advanced oil-structuring technology that can accomplish multi-functions to improve food quality and nutrition. However, this special structure is thermodynamically unstable. This study formulated a model O/W/O double emulsion with standard surfactants, Tween 80 (4 %) and polyglycerol polyricinoleate (PGPR, 5 %), using a traditional two-step method with different homogenization parameters. Cryo-SEM and GC-FID results show that O/W/O emulsions were successfully formulated, and the release rate (RR) of medium-chain triglycerides (MCT) oil from the inner oil to the outer oil phase increased significantly with 2nd homogenization speed increasing, respectively. Interestingly, the RR of all samples reached about 75 % after 2 months of storage, suggesting that O/W/O emulsions were highly unstable. To explain the observed instability, dynamic interfacial tension and interfacial rheology were performed using a drop shape tensiometer. Results demonstrated that unadsorbed Tween 80 in the intermediate aqueous phase was a key factor in markedly decreasing the interfacial properties of the outer PGPR-assembled film by affecting the interfacial rearrangement. Additionally, it was found that the MCT release showed a positive correlation with the Tween 80 concentration, demonstrating that the formed Tween 80 micelles could transport oil molecules to strengthen the emulsion instability. Taken together, this study reveals the destabilization mechanism of model O/W/O surfactants-stabilized emulsions from bulk to interface, providing highly relevant insights for the design of stable O/W/O double emulsions.

Fabrication and characterization of salidroside W/O/W emulsion with sodium alginate

Salidroside (Sal), the main bioactive substance in Rhodiola rosea, is a promising functional food component with a wide range of pharmacological effects, but its biological activity is challenging to sustain due to its short half-life, low oral bioavailability, and susceptibility to environmental factors. The aim of this study was to investigate the effect of sodium alginate (SA) concentration on the construction of W/O/W emulsion in the protection of Sal. With the escalation of SA concentrations, the range of droplet size distribution was smaller and the droplets were more uniform. When the concentration of SA was 2 %, the average droplet size reached 9.1 ± 0.1 μm, and the encapsulation efficiency of Sal was 77.8 ± 1.8 %. Moreover, the double emulsion with 2 % SA was the most stable for 28 days at 4 °C since the oil droplets were embedded in the network structure of SA.

Formation of magnetic double emulsions under steady and variable magnetic fields from a 3D-printed coaxial capillary device

BACKGROUND

Double emulsions (DEs) have attracted researchers' attention to be utilized as a promising platform in biomedical and chemical applications. Several actuation mechanisms have been proposed for the generation of DEs. The conventional DE formation approaches (e.g. two-stage emulsification) suffer from low monodispersity. The electric actuation (i.e. coaxial electrospray technology) has been demonstrated as a controllable method for the DE formation, while the capability of magnetic actuation has not been studied yet.

RESULT

In the present study, the generation of ferrofluid double emulsions (FDEs), made from water-based ferrofluid as a core and oil as a shell, under the magnetic actuation of a permanent magnet with a steady magnetic field and an electromagnet with DC and pulse width modulation (PWM) magnetic fields was investigated with a simple controllable setup fabricated using 3D printing. The effect of various parameters affecting the FDE formation, such as the fluid flow rates, the magnetic field type, the magnetic flux density, and the PWM frequency and duty cycle, on the FDE formation characteristics, including the inner and outer equivalent diameters, and the formation frequency was studied. Under the steady magnetic field, two regimes of the FDE formation were identified: inertia-dominated and magnet-dominated.

SIGNIFICANCE

Wireless power-free magnetic actuation provides better control over the FDE formation, enhancing this process by increasing the FDE formation frequency with high monodispersity. The PWM magnetic field offers excellent controllability over the FDE formation with low-volume or no, in some cases, satellite droplets by tuning the PWM frequency and the duty cycle.

Multiple Pickering emulsions stabilized by food-grade particles as innovative delivery systems for bioactive compounds

The most common carrier for encapsulation of bioactive components is still simple emulsion. Recently, bio-based novel emulsion systems such as multiple emulsions (MEs) and Pickering emulsions (PEs) have been introduced as innovative colloidal delivery systems for encapsulation and controlled release of bioactive compounds. Multiple PEs (MPEs), which carries both benefit of MEs and PEs could be fabricated by relatively scalable and simple operations. In comparison with costly synthetic surfactants and inorganic particles which are widely used for stabilization of both MEs and PEs, MPEs stabilized by food-grade particles, while having health-promoting aspects, are able to host the "clean label" and "green label" attributes. Nevertheless, in achieving qualified techno-functional attributes and encapsulation properties, the selection of suitable materials is a crucial step in the construction of such complex systems. Current review takes a cue from both MEs and PEs emulsification techniques to grant a robust background for designing various MPEs. Herein, various fabrication methods of MEs and PEs are described comprehensively in a physical viewpoint in order to find key conception of successful formulation of MPEs. This review also highlights the link between the underlying aspects and exemplified specimens of evidence which grant insights into the rational design of MPEs through food-based ingredients to introduces MPEs as novel colloidal/functional materials. Their utilization for encapsulation of bioactive compounds is discussed as well. In the last part, instability behavior of MPEs under various conditions will be discussed. In sum, this review aims to gain researchers who work with food-based components, basics of innovative design of MPEs.

Complex Emulsions as an Innovative Pharmaceutical Dosage form in Addressing the Issues of Multi-Drug Therapy and Polypharmacy Challenges

This review explores the intersection of microfluidic technology and complex emulsion development as a promising solution to the challenges of formulations in multi-drug therapy (MDT) and polypharmacy. The convergence of microfluidic technology and complex emulsion fabrication could herald a transformative era in multi-drug delivery systems, directly confronting the prevalent challenges of polypharmacy. Microfluidics, with its unparalleled precision in droplet formation, empowers the encapsulation of multiple drugs within singular emulsion particles. The ability to engineer emulsions with tailored properties-such as size, composition, and release kinetics-enables the creation of highly efficient drug delivery vehicles. Thus, this innovative approach not only simplifies medication regimens by significantly reducing the number of necessary doses but also minimizes the pill burden and associated treatment termination-issues associated with polypharmacy. It is important to bring forth the opportunities and challenges of this synergy between microfluidic-driven complex emulsions and multi-drug therapy poses. Together, they not only offer a sophisticated method for addressing the intricacies of delivering multiple drugs but also align with broader healthcare objectives of enhancing treatment outcomes, patient safety, and quality of life, underscoring the importance of dosage form innovations in tackling the multifaceted challenges of modern pharmacotherapy.

Fabrication and characterization of anthocyanin-loaded double Pickering emulsions stabilized by β-cyclodextrin

Anthocyanins, one of the important water-soluble pigments, are sensitive to environmental factors, which limits the application of anthocyanins in food field. In order to overcome this limitation, double Pickering emulsions stabilized by β-cyclodextrin were developed. The optimum preparation conditions of the emulsions were determined firstly and the performance and structure of emulsions were investigated. Results showed that the optimum preparation conditions of emulsions were the ratio of (W1/O): W2 = 6:4 and 4 % β-cyclodextrin concentration. Optical microscope and confocal laser scanning microscope results confirmed that β-cyclodextrin adsorbed onto the surface of droplets forming stable double Pickering emulsions structure. In vitro gastrointestinal digestion experiments proved that double Pickering emulsions played a controlled-release effect in the small intestine. Rheological analysis proved that the emulsions exhibited elastic properties and demonstrated shear thinning behavior. The emulsions showed excellent stability under centrifugation and thermal conditions. These findings will promote anthocyanins' application in daily diet.

An Updated Comprehensive Overview of Different Food Applications of W1/O/W2 and O1/W/O2 Double Emulsions

Double emulsions (DEs) present promising applications as alternatives to conventional emulsions in the pharmaceutical, cosmetic, and food industries. However, most review articles have focused on the formulation, preparation approaches, physical stability, and release profile of encapsulants based on DEs, particularly water-in-oil-in-water (W1/O/W2), with less attention paid to specific food applications. Therefore, this review offers updated detailed research advances in potential food applications of both W1/O/W2 and oil-in-water-in-oil (O1/W/O2) DEs over the past decade. To this end, various food-relevant applications of DEs in the fortification; preservation (antioxidant and antimicrobial targets); encapsulation of enzymes; delivery and protection of probiotics; color stability; the masking of unpleasant tastes and odors; the development of healthy foods with low levels of fat, sugar, and salt; and design of novel edible packaging are discussed and their functional properties and release characteristics during storage and digestion are highlighted.

Co-delivery of hydrophobic β-carotene and hydrophilic riboflavin by novel water-in-oleic acid-in-water (W/OA/W) emulsions

Hydrophobic β-carotene and hydrophilic riboflavin offer a wide range of health benefits, but their limited stability and bioaccessibility pose challenges to their use in the food industry. This study developed a water-in-oleic acid-in-water (W/OA/W) emulsion. The effects of internal/external water phase emulsifiers were investigated on their microstructure, encapsulation efficiency, and stability. Only 0.05 wt% soybean-derived phosphatidylcholine was required as a lipophilic emulsifier to produce W/OA/W emulsions that can encapsulate both hydrophobic β-carotene and hydrophilic riboflavin. Compared to the commercial pea protein isolate (PPI), the PPI-xylooligosaccharide conjugate demonstrated superior performance as hydrophilic emulsifiers in stabilizing W/OA/W emulsions. The W/OA/W emulsion co-delivery system improved the thermal stability, light stability, and bioaccessibility of β-carotene, as well as the light stability of riboflavin. Overall, the W/OA/W emulsion holds great promise for application in natural food and for co-delivering hydrophobic and hydrophilic bioactive ingredients.

Double Emulsions Stabilized by PGPR and Arabic Gum as Capsules: The Surprising Stabilizing Role of Inner Droplets

The encapsulation efficiency and stability over time of either vitamin B12, a model hydrophilic drug, or an aqueous suspension of Cydia pomonella granulovirus (CpGV), which is a biopesticide, using a water-in-sunflower oil-in-water (W1/O/W2) double emulsion, are studied. Two antagonistic stabilizers are used to prepare the double emulsion: the mainly lipophilic polyglycerol polyricinoleate (PGPR) and the mainly hydrophilic polysaccharide Arabic gum (AG). Combining ultraviolet-visible (UV-visible) titration, rheology, and oil globule size measurement allows assessing drug release, emulsion elasticity, and globule evolution as a function of time. A stability diagram is plotted as a function of two determining parameters: the nonadsorbed PGPR concentration in the oil and the inner water droplet fraction. To understand the presence of the nonstability domains, the influence of the two identified parameters on the outermost interfacial tension is examined. Surprisingly, the inner water drop volume fraction exhibits a stabilizing phenomenon that is discussed in terms of interfacial shielding to PGPR adsorption.

Effects of the Combination of Protein in the Internal Aqueous Phase and Polyglycerol Polyricinoleate on the Stability of Water-In-Oil-In-Water Emulsions Co-Encapsulating Crocin and Quercetin

This study aimed to diminish the reliance on water-in-oil-in-water (W/O/W) emulsions on the synthetic emulsifier polyglycerol polyricinoleate (PGPR). Considering the potential synergistic effects of proteins and PGPR, various protein types (whey, pea and chickpea protein isolates) were incorporated into the internal aqueous phase to formulate W/O/W emulsions. The effects of the combination of PGPR and protein at different ratios (5:0, 4:1, 3:2, 1:1 and 2:3) on the stability and encapsulation properties of W/O/W emulsions co-encapsulating crocin and quercetin were investigated. The findings indicated that the combination of PGPR and protein resulted in a slight reduction in the encapsulation efficiency of the emulsions, compared to that of PGPR (the control). Nonetheless, this combination significantly enhanced the physical stability of the emulsions. This result was primarily attributed to the smaller droplet sizes and elevated viscosity. These factors contributed to increased retentions of crocin (exceeding 70.04%) and quercetin (exceeding 80.29%) within the emulsions after 28 days of storage, as well as their improved bioavailability (increases of approximately 11.62~20.53% and 3.58~7.98%, respectively) during gastrointestinal digestion. Overall, combining PGPR and protein represented a viable and promising strategy for reducing the amount of PGPR and enhancing the stability of W/O/W emulsions. Notably, two plant proteins exhibited remarkable favorability in this regard. This work enriched the formulations of W/O/W emulsions and their application in the encapsulation of bioactive substances.

Formation Mechanism of Starch-Based Double Emulsions from the Interfacial Perspective

Double emulsions are of significant practical value in protecting the core material owing to their multicomponent structure and have thus been applied in various fields, such as food, cosmetics, and drugs. However, the mechanism of double emulsion formation by native starch is not well established. Herein, we demonstrate a facile route to develop type-A, type-B, and type-C double emulsions using native starch and develop an innovative design for a carrier. Interfacial interaction, enthalpy changes of starch, and interfacial properties are key factors governing the formation of double emulsions and controlling the type of double emulsions formed. Therefore, the results of this study provide a better understanding of how and what type of starch-based double emulsions are formed.

Double Emulsion Droplets as a Plausible Step to Fatty Acid Protocells

It is assumed that life originated on the Earth from vesicles made of fatty acids. These amphiphiles are the simplest chemicals, which can be present in the prebiotic soup, capable of self-assembling into compartments mimicking modern cells. Production of fatty acid vesicles is widely studied, as their growing and division. However, how prebiotic chemicals require to further yield living cells encapsulated within protocells remains unclear. Here, one suggests a scenario based on recent studies, which shows that phospholipid vesicles can form from double emulsions affording facile encapsulation of cargos. In these works, water-in-oil-in-water droplets are produced by microfluidics, having dispersed lipids in the oil. Dewetting of the oil droplet leaves the internal aqueous droplet covered by a lipid bilayer, entrapping cargos. In this review, formation of fatty acid protocells is briefly reviewed, together with the procedure for preparing double emulsions and vesicles from double emulsion and finally, it is proposed that double emulsion droplets formed in the deep ocean where undersea volcano expulsed materials, with fatty acids (under their carboxylic form) and alkanols as the oily phase, entrapping hydrosoluble prebiotic chemicals in a double emulsion droplet core. Once formed, double emulsion droplets can move up to the surface, where an increase of pH, variation of pressure and/or temperature may have allowed dewetting of the oily droplet, leaving a fatty acid vesicular protocell with encapsulated prebiotic materials.

Impact of the lipid phase composition and state on the in vitro digestibility and chlorophyllin bioaccessibility of W1/O/W2 emulsions into whole milk

Water-in-oil-in-water (W1/O/W2) emulsions offer the potential to deliver hydrophilic bioactive compounds into foods, yet their application remains limited due to their instability. Thus, the impact of lipid phase composition and state on the colloidal stability, in vitro lipid digestibility and chlorophyllin (CHL) bioaccessibility of W1/O/W2 emulsions before and after incorporation into whole milk was studied. Medium-chain triglyceride oil (MCT) was used as a liquid lipid phase and MCT with glyceryl stearate (GS) or pure hydrogenated palm oil (HPO) as gelled lipid phases. The lipid phase composition was crucial to forming W1/O/W2 emulsions. MCT or MCT+GS allowed the successful formation of W1/O/W2 emulsions, being more stable upon gastric conditions those formulated with MCT+GS than pure MCT. In contrast, the use of HPO led to phase separation, which was maintained after the gastric conditions. Regarding their lipid digestibility, W1/O/W2 emulsions formulated with MCT or MCT+GS were fully digested, whereas only 40% of the lipid was digested using HPO. In accordance, the CHL bioaccessibility was higher using MCT or MCT+GS than HPO. When co-digested with whole milk, the colloidal stability and lipid digestibility of the W1/O/W2 emulsions with MCT or MCT+GS were not altered, whereas the W1/O/W2 emulsion-HPO showed enhanced colloidal stability and lipid digestibility (57.71 ± 3.06%), due to the surface-active properties of milk protein. The present study provides useful information to develop stable functional foods enriched with hydrophilic bioactive compounds by using W1/O/W2 emulsions.

One step generation of single-core double emulsions from polymer-osmose-induced aqueous phase separation in polar oil droplets

Water-in-oil-in-water emulsions (W/O/W) are aqueous droplet(s) embedded within oil droplets dispersed in a continuous water phase. They are attracting interest due to their possible applications from cosmetic to food science since both hydrosoluble and liposoluble cargos can be encapsulated within. They are generally prepared using a one-step or a two-step method, phase inversion and also via spontaneous emulsification. Here, we describe a general and simple one-step method based on hydrophilic polymers dispersed in polar oils to generate osmose-induced diffusion of water into oil droplets, forming polymer-rich aqueous droplets inside the oil droplets. Polyethylene glycol, but also other hydrophilic polymers (branched polyethylene imine or polyvinyl pyrrolidone) were successfully dispersed in 1-octanol or other polar oils (oleic acid or tributyrin) to produce an O/W emulsion that spontaneously transformed into a W1/O/W2 emulsion, with the inner aqueous droplet (W1) only containing the hydrophilic polymer initially dispersed in oil. By combining single drop experiments, with macroscopic viscosity measurements, we demonstrated that the double emulsion resulted of water diffusion, which amplitude could be adjusted by the polymer concentration. The production of high internal phase emulsions was also achieved, together with a pH-induced transition from multiple to single core double emulsion. We expect this new method for producing double emulsions to find applications in domains of microencapsulation and materials chemistry.

Influence of different electrolytes and oils on the stability of W1/O/W2 double emulsion during storage and in vitro digestion

The aim of this study is to formulate a stable water-in-oil-in-water (W1/O/W2) double emulsion using different types of oils and electrolytes. W1/O was formulated with different electrolyte solutions (W1) dispersed in various oils (O) using polyglycerol polyricinoleate as a stabilizer. External aqueous phase was Tween-80 (W2), and W1/O dispersed in W2 was used. The emulsion containing NaCl or MgCl2 exhibited high encapsulation efficiency (EE) and maintained particle size. Regarding the oil type, the emulsion with MCT oil showed a small droplet size and a high viscosity and EE, presenting a stable droplet distribution in optical observation. The stability of emulsion containing NaCl was maintained during the in vitro digestion experiments. MCT oil, NaCl and MgCl2 have the potential to produce stable double emulsions for storage stability and in vitro digestion studies. The findings would be useful for preparing stable double emulsions used in the food and cosmetic industries.

Microfluidics potential for developing food-grade microstructures through emulsification processes and their application

The food sector continues to face challenges in developing techniques to increase the bioavailability of bioactive chemicals. Utilising microstructures capable of encapsulating diverse compounds has been proposed as a technological solution for their transport both in food and into the gastrointestinal tract. The present review discusses the primary elements that influence the emulsification process in microfluidic systems to form different microstructures for food applications. In microfluidic systems, reactions occur within small reaction channels (1-1000 μm), using small amounts of samples and reactants, ca. 102-103 times less than conventional assays. This geometry provides several advantages for emulsion and encapsulating structure production, like less waste generation, lower cost and gentle assays. Also, from a food application perspective, it allows the decrease in particle dispersion, resulting in a highly repeatable and efficient synthesis method that also improves the palatability of the food products into which the encapsulates are incorporated. However, it also entails some particular requirements. It is important to obtain a low Reynolds number (Re < approx. 250) for greater precision in droplet formation. Also, microfluidics requires fluid viscosity typically between 0.3 and 1400 mPa s at 20 °C. So, it is a challenge to find food-grade fluids that can operate at the micro-scale of these systems. Microfluidic systems can be used to synthesise different food-grade microstructures: microemulsions, solid lipid microparticles, microgels, or self-assembled structures like liposomes, niosomes, or polymersomes. Besides, microfluidics is particularly useful for accurately encapsulating bacterial cells to control their delivery and release on the action site. However, despite the significant advancement in these systems' development over the past several years, developing and implementing these systems on an industrial scale remains challenging for the food industry.

The internal aqueous phase gelation improves the viability of probiotic cells in a double water/oil/water emulsion system

This research studied the viability of probiotic bacterium Lactobacillus plantarum (L. plantarum) encapsulated in the internal aqueous phase (W 1) of a water-in-oil-in-water (W 1/O/W 2) emulsion system, with the help of gelation and different gelling agents. Additionally, the physicochemical, rheological, and microstructural properties of the fabricated emulsion systems were assessed over time under the effect of W 1 gelation. The average droplet size and zeta potential of the control system and the systems fabricated using gelatin, alginate, tragacanth gum, and carrageenan were 14.7, 12.0, 5.1, 6.4, and 7.3 μm and - 21.1, -34.1, -46.2, -38.3, and -34.7 mV, respectively. The results showed a significant increase in the physical stability of the system and encapsulation efficiency of L. plantarum after the W 1 gelation. The internal phase gelation significantly increased the viability of bacteria against heat and acidic pH, with tragacanth gum being the best gelling agent for increasing the viability of L. plantarum (28.05% and 16.74%, respectively). Apparent viscosity and rheological properties of emulsions were significantly increased after the W 1 gelation, particularly in those jellified with alginate. Overall, L. plantarum encapsulation in W 1/O/W 2 emulsion, followed by the W 1 gelation using tragacanth gum as the gelling agent, could increase both stability and viability of this probiotic bacteria.

One-Step Generation of O/W/O Double Pickering Emulsions Utilizing Biocompatible Gliadin/Ethyl Cellulose Complex Particles as the Exclusive Stabilizer

Double emulsions hold great potential for various applications due to their compartmentalized internal structures. However, achieving their long-term physical stability remains a challenging task. Here, we present a simple one-step method for producing stable oil-in-water-in-oil (O/W/O) double emulsions using biocompatible gliadin/ethyl cellulose complex particles as the sole stabilizer. The resulting O/W/O systems serve as effective platforms for encapsulating enzymes and as templates for synthesizing porous microspheres. We investigated the impact of particle concentration and water fraction on the properties of Pickering O/W/O emulsions. Our results demonstrate that the number and volume of inner oil droplets increased proportionally with both the water fraction and particle concentration after a 60-day storage period. Moreover, the catalytic reaction rate of the encapsulated lipase within the double emulsion exhibited a significant acceleration, achieving a substrate conversion of 80.9% within 15 min. Remarkably, the encapsulated enzyme showed excellent recyclability, enabling up to 10 cycles of reuse. Additionally, by utilizing the O/W/O systems as templates, we successfully obtained porous microspheres whose size can be controlled by the outer water droplet. These findings have significant implications for the future design of Pickering complex emulsion-based systems, opening avenues for extensive applications in pharmaceuticals, food, cosmetics, material synthesis, and (bio)catalysis.

Nanocellulose-stabilized Pickering emulsions: Fabrication, stabilization, and food applications

Pickering emulsions have been widely studied due to their good stability and potential applications. Nanocellulose including cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and bacterial cellulose nanofibrils (BCNFs) has emerged as sustainable stabilizers/emulsifiers in food-related Pickering emulsions due to their favorable properties such as renewability, low toxicity, amphiphilicity, biocompatibility, and high aspect ratio. Nanocellulose can be widely obtained from different sources and extraction methods and can effectively stabilize Pickering emulsions via the irreversible adsorption onto oil-water interface. The synergistic effects of nanocellulose and other substances can further enhance the interfacial networks. The nanocellulose-based Pickering emulsions have potential food-related applications in delivery systems, food packaging materials, and fat substitutes. Nanocellulose-based Pickering emulsions as 3D printing inks exhibit good injectable and gelling properties and are promising to print spatial architectures. In the future, the utilization of biomass waste and the development of "green" and facile extraction methods for nanocellulose production deserve more attention. The stability of nanocellulose-based Pickering emulsions in multi-component food systems and at various conditions is an utmost challenge. Moreover, the case-by-case studies on the potential safety issues of nanocellulose-based Pickering emulsions need to be carried out with the standardized assessment procedures. In this review, we highlight key fundamental work and recent reports on nanocellulose-based Pickering emulsion systems. The sources and extraction of nanocellulose and the fabrication of nanocellulose-based Pickering emulsions are briefly summarized. Furthermore, the synergistic stability and food-related applications of nanocellulose-stabilized Pickering emulsions are spotlighted.

Advances in lipo-solubility delivery vehicles for curcumin: bioavailability, precise targeting, possibilities and challenges

BACKGROUND

Curcumin (Cur) is a natural pigment containing a diketone structure, which has attracted extensive attention due to its strong functional activities. However, the low solubility and poor stability of Cur limit its low bioavailability and multi-function. It is essential to develop effective measures to improve the unfavorable nature of Cur and maximize its potential benefits in nutritional intervention.

SCOPE AND APPROACH

The focus of this review is to emphasize the construction of lipo-solubility delivery vehicles for Cur, including emulsion, nanoliposome and solid liposome. In addition, the potential benefits of vehicles-encapsulated Cur in the field of precise nutrition were summarized, including high targeting properties and multiple disease interventions. Further, the deficiencies and prospects of Cur encapsulated in vehicles for precise nutrition were discussed.

KEY FINDINGS AND CONCLUSIONS

The well-designed lipo-solubility delivery vehicles for Cur can improve its stability in food processing and the digestion in vivo. To meet the nutritional requirements of special people for Cur-based products, the improvement of the bioavailability by using delivery vehicles will provide a theoretical basis for the precise nutrition of Cur in functional food.

Ultrasound-assisted multilayer Pickering emulsion fabricated by WPI-EGCG covalent conjugates for encapsulating probiotics in colon-targeted release

This study demonstrated the influences of ultrasound-assisted multilayer Pickering double emulsion capsules on the pasteurization and gastrointestinal digestive viability of probiotic (L. plantarum) strain liquid. Firstly, the role of ultrasonic homogenization on the morphology of W₁/O/W₂ double emulsions were studied. The double emulsion formed by ultrasonic intensity at 285 W had a single and narrow distribution with smallest droplet size. The double emulsion particles were then coated with chitosan(Chi), alginate (Alg), and CaCl₂(Ca). The multilayer emulsion after pasteurization and gastrointestinal digestion both had the highest viability at 5 coating layers, but its particle size (108.65 μm) exceeded the limit of human oral sensory (80 μm). It could be noted that the deposition of 3-4 layers of coating had similar activity after pasteurization/GIT digestion. And droplets with 3 layers of coating were the minimum and most available formulation for encapsulated probiotics (L. plantarum). Hence, the results suggest that the use of ultrasound-assisted multilayer emulsions encapsulated with probiotics in granular food and pharmaceutical applications is a promising strategy.

A review of oil and water retention in emulsified meat products: The mechanisms of gelation and emulsification, the application of multi-layer hydrogels

Emulsified meat products are key deep-processing products due to unique flavor and high nutritional value. Myosin dissolves, and protein aggregation and heat-induced gelation occur after myosin unfolds and hydrophobic groups are exposed. Myosin could form interfacial protein membranes and wrap fat globules. Emulsified fat globules may be filled in heat-induced gel networks. Therefore, this review intends to discuss the influences of heat-induced gelation and interfacial adsorption behavior on oil and water retention. Firstly, the mechanism of heat-induced gelation was clarified from the perspective of protein conformation and micro-structure. Secondly, the mechanism of emulsification stability and its factors affecting interfacial adsorption were demonstrated as well as limitations and challenges. Finally, the structure characteristics and application of multi-layer hydrogels in the gelation and emulsification were clarified. It could conclude that the characteristic morphology, spatial conformation and structure adjustment affected heat-induced gelation and interfacial adsorption behavior. Spatial conformation and microstructure were adjusted to improve the oil and water retention by pH, ionic strength, amino acid, oil phase characteristic and protein interaction. Multi-layer hydrogels facilitated oil and water retention. The comprehensive review of gelation and emulsification mechanisms could promote the development of meat products and improvement of meat processing technology.

Emulsion-Based Delivery Systems to Enhance the Functionality of Bioactive Compounds: Towards the Use of Ingredients from Natural, Sustainable Sources

In recent years, the trend in the population towards consuming more natural and sustainable foods has increased significantly. This claim has led to the search for new sources of bioactive compounds and extraction methods that have less impact on the environment. Moreover, the formulation of systems to protect these compounds is also focusing on the use of ingredients of natural origin. This article reviews novel, natural alternative sources of bioactive compounds with a positive impact on sustainability. In addition, it also contains information on the most recent studies based on the use of natural (especially from plants) emulsifiers in the design of emulsion-based delivery systems to protect bioactive compounds. The properties of these natural-based emulsion-delivery systems, as well as their functionality, including in vitro and in vivo studies, are also discussed. This review provides relevant information on the latest advances in the development of emulsion delivery systems based on ingredients from sustainable natural sources.

Starch physical treatment, emulsion formation, stability, and their applications

Pickering emulsions are increasingly preferred over typical surfactant-based emulsions due to several advantages, such as lower emulsifier usage, simplicity, biocompatibility, and safety. These types of emulsions are stabilized using solid particles, which produce a thick layer at the oil-water interface preventing droplets from aggregating. Starch nano-particles (SNPs) have received considerable attention as natural alternatives to synthetic stabilizers due to their unique properties. Physical formulation processes are currently preferred for SNP production since they are environmentally friendly procedures that do not require the use of chemical reagents. This review provides a thorough overview in a critical perspective of the physical processes to produce starch nano-particles used as Pickering emulsion stabilizers, fabricated by a 2-step process. Specifically, the reviewed physical approaches for nano-starch preparation include high hydrostatic pressure, high pressure homogenization, ultrasonication, milling and antisolvent precipitation. All the essential parameters used to evaluate the effectiveness of particles in stabilizing these systems are also presented in detail, including the hydrophobicity, size, and content of starch particles. Finally, this review provides the basis for future research focusing on physical nano-starch production, to ensure the widespread use of these natural stabilizers in the ever-evolving field of food technology.

Evaluation of the Physical and Oxidative Stabilities of Fish Oil-in-Water-in-Olive Oil Double Emulsions (O1/W/O2) Stabilized with Whey Protein Hydrolysate

This work studied the physical and oxidative stabilities of fish oil-in-water-in-olive oil double emulsions (O₁/W/O₂), where whey protein hydrolysate was used as a hydrophilic emulsifier. A 20 wt.% fish oil-in-water emulsion, stabilized with whey protein hydrolysate (oil: protein ratio of 5:2 w/w) and with a zeta potential of ~-40 mV, only slightly increased its D_4,3 value during storage at 8 °C for seven days (from 0.725 to 0.897 µm), although it showed severe physical destabilization when stored at 25 °C for seven days (D_4,3 value increased from 0.706 to 9.035 µm). The oxidative stability of the 20 wt.% fish oil-in-water emulsion decreased when the storage temperature increased (25 vs. 8 °C) as indicated by peroxide and p-anisidine values, both in the presence or not of prooxidants (Fe²⁺). Confocal microscopy images confirmed the formation of 20 wt.% fish oil-in-water-in-olive oil (ratio 25:75 w/w) using Polyglycerol polyricinoleate (PGPR, 4 wt.%). Double emulsions were fairly physically stable for 7 days (both at 25 and 8 °C) (Turbiscan stability index, TSI < 4). Moreover, double emulsions had low peroxide (<7 meq O₂/kg oil) and p-anisidine (<7) values that did not increase during storage independently of the storage temperature (8 or 25 °C) and the presence or not of prooxidants (Fe²⁺), which denotes oxidative stability.

Recent Advances in Pickering Double Emulsions and Potential Applications in Functional Foods: A Perspective Paper

Double emulsions are complex emulsion systems with a wide range of applications across different fields, such as pharmaceutics, food and beverage, materials sciences, personal care, and dietary supplements. Conventionally, surfactants are required for the stabilization of double emulsions. However, due to the emerging need for more robust emulsion systems and the growing trends for biocompatible and biodegradable materials, Pickering double emulsions have attracted increasing interest. In comparison to double emulsions stabilized solely by surfactants, Pickering double emulsions possess enhanced stability due to the irreversible adsorption of colloidal particles at the oil/water interface, while adopting desired environmental-friendly properties. Such advantages have made Pickering double emulsions rigid templates for the preparation of various hierarchical structures and as potential encapsulation systems for the delivery of bioactive compounds. This article aims to provide an evaluation of the recent advances in Pickering double emulsions, with a special focus on the colloidal particles employed and the corresponding stabilization strategies. Emphasis is then devoted to the applications of Pickering double emulsions, from encapsulation and co-encapsulation of a wide range of active compounds to templates for the fabrication of hierarchical structures. The tailorable properties and the proposed applications of such hierarchical structures are also discussed. It is hoped that this perspective paper will serve as a useful reference on Pickering double emulsions and will provide insights toward future studies in the fabrication and applications of Pickering double emulsions.

Co-delivery of curcumin and epigallocatechin gallate in W/O/W emulsions stabilized by protein fibril-cellulose complexes

Hydrophobic curcumin and hydrophilic epigallocatechin gallate (EGCG) are reported to exhibit a variety of biological activities and may exhibit synergistic effects when used in combination. A co-encapsulation system was developed to improve their applicability and bioavailability. This delivery system consisted of a water-in-oil-in-water (W₁/O/W₂) double emulsion stabilized by whey protein isolate fibrils (WPIFs) and cellulose nanocrystals (CNCs). Double emulsions were fabricated using a two-step emulsification method using either WPIF-CNC complexes or WPIF alone. The physicochemical stability, encapsulation performance, and digestive properties of the delivery systems were then investigated. The double emulsions stabilized by the WPIF-CNC complexes were more resistant to heat and salt stress, exhibited greater encapsulation stability, and had a higher bioaccessibility for curcumin (67.8%) and EGCG (68.9%) than those stabilized by WPIFs. This research shows that the stability and bioaccessibility of curcumin and EGCG can be enhanced by co-encapsulating them in emulsion-based delivery systems using nanostructured protein-polysaccharide complexes.