Double Emulsions Stabilized by Food Biopolymers

Chitosan-zein-icariin complexes modulate double emulsion phase transitions to potentiate absorption efficiency

This study developed a chitosan-zein-icariin ternary complex through reversed-phase precipitation to stabilize double emulsions using one-step emulsification method. Results indicated that icariin and chitosan-zein formed spherical microstructures via the rearrangement of hydrogen bonding networks and hydrophobic interactions. All complexes exhibited pale-yellow color and demonstrated single and uniform size distribution. The thermal stability and interfacial contact angle of the complexes significantly decreased with the incorporation of icariin. The prepared double emulsion microstructures displayed multi-chambered configurations due to polarity differences, solidifying during cold storage as a result of phase shifts in coconut oil, which led to an increased storage modulus. While the double emulsion microstructure showed enhanced storage stability, droplet size increased markedly when subjected to NaCl and temperature variations. Following in-vitro digestion, the double emulsion microstructure disintegrated; average particle size decreased, resulting in the release of icariin from the ternary complex during intestinal phases, thereby enhancing bioaccessibility. Furthermore, it was observed that icariin within the ternary complex influenced absorption efficacy based on its concentration levels, as evidenced by Caco-2 cell studies, though this effect was greater than that observed for the zein-icariin binary complex. The results of this study provide a theoretical foundation for efficient delivery systems involving hydrophobic multivariate complexes.

Encapsulation of Monascus pigments in gel in oil in water (G/O/W) double emulsion system based on sodium caseinate and guar gum

In this study, a gel in oil in water (G/O/W) double emulsion system was developed with the objective of effectively encapsulating Monascus pigments and enhancing its stability. To this end, various formulations were prepared using guar gum co-dissolved with Monascus pigments in the internal phase and sodium caseinate as an outer phase surfactant. Different parameters were examined, including emulsion stability, encapsulation efficiency, rheological and tribological properties, as well as the light and thermal stability of the encapsulated Monascus pigments. The results demonstrated that Monascus pigments were effectively encapsulated in the G/O/W, with an encapsulation efficiency exceeding 90 %. The formulated system exhibited a relatively small particle size, which decreased with increasing guar gum and the external emulsifier contents. This resulted in an increase in viscosity accompanied by the formation of a gel-like structure and improved tribological properties, thereby enhancing the system's stability. The system with 1-1.25 % guar gum and 2.5 % sodium caseinate exhibited the highest stability for Monascus pigments, making them more resistant to heat and light. These findings have the potential to expand applications of Monascus pigments by providing a stable and effective encapsulation and delivery system that can also be utilized in the development of healthier food products.

Protective Effect of IgY Embedded in W/O/W Emulsion on LPS Enteritis-Induced Colonic Injury in Mice

Chicken yolk immunoglobulin (IgY), an immunologically active component, is used as an alternative to antibiotics for the treatment of enteritis. In this study, IgY was embedded in a W/O/W emulsion to overcome the digestive barrier and to investigate the protective effect of IgY against LPS-induced enteritis in mice. Four different hydrophilic emulsifiers (T80, PC, SC, and WPI) were selected to prepare separate W/O/W emulsions for encapsulating IgY. The results showed that the IgY-embedded double emulsion in the WPI group was the most effective. IgY embedded in the W/O/W emulsion could reduce the damage of LPS to the mouse intestine and prevent LPS-induced intestinal mucosal damage in mice. It increased the number of cup cells, promoted the expression of Muc2, and increased the mRNA expression levels of KLF3, TFF3, Itln1, and Ang4 (p < 0.05). It also enhanced the antioxidant capacity of the colon tissue, reduced the level of inflammatory factors in the colon tissue, and protected the integrity of the colon tissue. Stable embedding of IgY could be achieved using the W/O/W emulsion. In addition, the IgY-embedded W/O/W emulsion can be used as a dietary supplement to protect against LPS-induced enteritis in mice.

Pickering emulsion co-delivery system: Stimuli-responsive biomineralized particles act as particulate emulsifiers and bioactive carriers

Pickering emulsions provide a promising platform for the efficient delivery of bioactive. However, co-delivery of fragile bioactives with different physicochemical properties for comprehensive effects still faces practical challenges due to the limited protection for bioactives and the lack of stimuli-responsive property for on-demand release. Herein, a stimuli-responsive co-delivery system is developed based on biomineralized particles stabilized Pickering emulsions. In this tailor co-delivery system, hydrophilic bioactive (pepsin) with the fragile structure is encapsulated and immobilized by biomineralization, the obtained biomineralized particles (PPS@CaCO3) are further utilized as emulsifiers to form O/W Pickering emulsions, in which the hydrophobic oxidizable bioactive (curcumin) is stably trapped into the dispersed phase. The results show that two bioactives are successfully co-encapsulated in Pickering emulsions, and benefiting from the protection capacities of biomineralization and Pickering emulsions, the activity of pepsin and curcumin shows a 7.33-fold and 144.83-fold enhancement compared to the free state, respectively. Moreover, In vitro study demonstrates that Pickering emulsions enable to co-release of two bioactives with high activity retention by the acid-induced hydrolyzation of biomineralized particles. This work provides a powerful stimuli-responsive platform for the co-delivery of multiple bioactive compounds, enabling high activity of bioactives for the comprehensive health effects.

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.

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.

O1/W/O2 double emulsion gels based on nanoemulsions and Pickering particles for co-encapsulating quercetin and cyanidin: A functional fat substitute

An O1/W/O2 double emulsion gel, as a functional fat substitute and based on nanoemulsions and hydrophobic Pickering particles, is prepared by two-step emulsification to co-encapsulate hydrophilic cyanidin and hydrophobic quercetin. Nanoemulsions loading quercetin are fabricated by Tween-80 and combining high-speed and high-pressure emulsification. Phytosterol nanoparticles stabilize the W-O2 interface of the secondary emulsion to load cyanidin in the W phase. The concentration of Tween-80 is optimized as 0.3% by the droplet size and viscosity of nanoemulsions. The structural stability of double emulsion gels will be weakened along with the increase of nanoemulsions, showing lower modulus and encapsulation efficiency (EE) and bigger droplets. In double emulsion gels, the EE of quercetin and cyanidin reaches 93% and 85.6%, respectively. Analysis of molecular interaction indicates that Tween-80 would decrease the in-situ hydrophobicity of phytosterol nanoparticles by hydrogen bonding adsorption, thereby weakening the emulsification. The pH-chromic 3D printing of double emulsion gels is designed according to the pH sensitivity of cyanidin. Texture profile analysis is performed to test the textural properties of 3D-printed objects. The simulated digestion is conducted on double emulsion gels. The double emulsion gel with fewer nanoemulsions is beneficial for protecting quercetin and improving the delivery due to the higher structural stability, while that with more nanoemulsions is conducive to the digestion of cyanidin and camellia oil due to weakened semi-solid properties. This double emulsion gel further simulates fat tissues by co-encapsulating hydrophilic and hydrophobic substances, promoting the application of fat substitutes in the food industry.

Encapsulation of lactic acid bacteria in W1/O/W2 emulsions stabilized by mucilage:pectin complexes

Opuntia silvestri mucilage obtained from dried stems was explored as an emulsifier to prepare double emulsions aiming to encapsulate Lactiplantibacillus plantarum CIDCA 83114. W1/O/W2 emulsions were prepared using a two-step emulsification method. The aqueous phase (W1) consisted of L. plantarum CIDCA 83114, and the oil phase (O) of sunflower oil. The second emulsion was prepared by mixing the internal W1/O emulsion with the W2 phase, consisting of 4 % polysaccharides, formulated with different mucilage:(citric)pectin ratios. Their stability was assessed after preparation (day 0) and during storage at 4 °C (28 days). Determinations included creaming index, color, particle size, viscosity, turbidity, and bacterial viability, along with exposure to simulated gastrointestinal conditions. Significant differences were evaluated by analysis of variance (ANOVA) and Duncan's test (P < 0.05). After 28 days storage, bacterial viability in the W1/O/W2 emulsions was above 6 log CFU/mL for all the pectin:mucilage ratios. Emulsions containing mucilage and pectins showed lower creaming indices after 15 days, remaining stable until the end of the storage period. Formulations including 1:1 pectin:mucilage ratio exhibited the highest bacterial viability under simulated gastrointestinal conditions and were more homogeneous in terms of droplet size distributions at day 0, hinting at a synergistic effect between mucilage components (e.g., proteins, Ca2+) and pectin in stabilizing the emulsions. These results showed that Opuntia silvestri mucilage enhanced the stability of emulsions during refrigerated storage, highlighting its potential for encapsulating lactic acid bacteria. This presents an economical and natural alternative to traditional encapsulating materials.

Fabrication and stability of W/O/W emulsions stabilized by gum arabic and polyglycerol polyricinoleate

BACKGROUND

In order to study the effect of adsorption of surfactant at the two interfacial layers on emulsion stability, the kinetically stable water-in-oil-in-water (W/O/W) emulsion carriers were prepared using polyglycerol polyricinoleate (PGPR) and gum arabic (GA) as emulsifiers. The relationship between the adsorption of the surfactant and the stability mechanism of the emulsions was elucidated.

RESULTS

When the contents of PGPR and GA were low, the interfaces between oil and the inner and outer water phases, respectively, could not be completely covered. However, when the concentration of PGPR was higher than 60 g kg-1 , the excess PGPR was adsorbed on the interface between the oil phase and the outer water phase. When the concentration of GA reached 80 g kg-1 , more GA was adsorbed to the oil-in-water interface. Moreover, the presence of PGPR on the interface could reduce the adsorption capacity of GA. Two types of kinetically stable emulsions were obtained by optimizing the interface composition (60 g kg-1 GA/80 g kg-1 PGPR and 60 g kg-1 PGPR/80 g kg-1 GA). The kinetically stable W/O/W emulsions prepared in this study were successfully used to encapsulate a hydrophilic vitamin (vitamin B12) with an encapsulation efficiency (EE) of 80% and release efficiency (RE) of 95%. The interfacial adsorption GA can accelerate the hydrolysis of fat.

CONCLUSION

Overall, this study provides a new strategy for the preparation of W/O/W emulsions, which might be beneficial for application in food, cosmetic, chemical, and pharmaceutical industries. © 2023 Society of Chemical Industry.

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.

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.

Encapsulation Properties of Mentha piperita Leaf Extracts Prepared Using an Ultrasound-Assisted Double Emulsion Method

Double emulsions (W1/O/W2) have long been used in the food and pharmaceutical industries to encapsulate hydrophobic and hydrophilic drugs and bioactive compounds. This study investigated the effect of different types of emulsifiers (plant- vs. animal-based proteins) on the encapsulation properties of Mentha piperita leaf extract (MLE) prepared using the double emulsion method. Using response surface methodology, the effect of ultrasound-assisted extraction conditions (amplitude 20-50%; time 10-30 min; ethanol concentration 70-90%) on the total phenolic content (TPC) and antioxidant activity (percent inhibition) of the MLE was studied. MLE under optimized conditions (ethanol concentration 76%; amplitude 39%; time 30 min) had a TPC of 62.83 mg GA equivalents/g and an antioxidant activity of 23.49%. The optimized MLE was encapsulated using soy, pea, and whey protein isolates in two emulsifying conditions: 4065× g/min and 4065× g/30 s. The droplet size, optical images, rheology, and encapsulation efficiency (EE%) of the different encapsulated MLEs were compared. The W1/O/W2 produced at 4065× g/min exhibited a smaller droplet size and higher EE% and viscosity than that prepared at 4065× g/30 s. The higher EE% of soy and pea protein isolates indicated their potential as an effective alternative for bioactive compound encapsulation.

Food nanoemulsions: how simulated gastrointestinal digestion models, nanoemulsion, and food matrix properties affect bioaccessibility of encapsulated bioactive compounds

Food nanoemulsions are known as very effective and excellent carriers for both lipophilic and hydrophilic bioactive compounds (BCs) and have been successfully used for controlled delivery and protection of BCs during gastrointestinal digestion (GID). However, due to sensitive and fragile morphology, BCs-loaded nanoemulsions have different digestion pathways depending on their properties, food matrix properties, and applied models for testing their digestibility and BCs bioaccessibility. Thus, this review gives a critical review of the behavior of encapsulated BCs into food nanoemulsions during each phase of GID in different static and dynamic in vitro digestion models, as well as of the influence of nanoemulsion and food matrix properties on BCs bioaccessibility. In the last section, the toxicity and safety of BCs-loaded nanoemulsions evaluated on in vitro and in vivo GID models have also been discussed. Better knowledge of food nanoemulsions' behavior in different models of simulated GI conditions and within different nanoemulsion and food matrix types can help to standardize the protocol for their testing aiming for researchers to compare results and design BCs-loaded nanoemulsions with better performance and higher targeted BCs bioaccessibility.

Fabrication of grape seed proanthocyanidin-loaded W/O/W emulsion gels stabilized by polyglycerol polyricinoleate and whey protein isolate with konjac glucomannan: Structure, stability, and in vitro digestion

In this work, the effects of konjac glucomannan (KGM) concentrations on microstructure, gel properties, stability and digestibility of water-in-oil-in-water emulsion gels stabilized by polyglycerol polyricinoleate and whey protein isolate were investigated. Visual appearance indicated that a non-layered double emulsion gel was formed when KGM increased to 0.75%. Emulsion gels with 1.5% KGM showed the highest encapsulation, freeze-thaw and photochemical stability due to the formation of the smallest droplets, which were supported by microscopic observations. Moreover, the addition of KGM improved water holding capacity, rheological and texture properties of emulsion gels. Particularly, at 1.5% or 1.75% KGM, color and potential of hydrogen showed the most stable level after 14 days of storage. During in vitro digestion, KGM delayed the hydrolysis of protein and oil droplets, and then improved the bioavailability of grape seed proanthocyanidin. These results promoted the application of KGM in emulsion gels and the encapsulation of nutraceuticals.

Capsaicin encapsulated in W/O/W double emulsions fabricated via ethanol-induced pectin gelling: Improvement of bioaccessibility and reduction of irritation

Capsaicin is a water-insoluble bioactive component with several beneficial physiological functions. However, the widespread application of this hydrophobic phytochemical is limited by its low water-solubility, intense irritation, and poor bioaccessibility. These challenges can be overcome by entrapping capsaicin within the internal water phase of water-in-oil-in-water (W/O/W) double emulsions via using ethanol to induce pectin gelling. In this study, ethanol was used both to dissolve capsaicin and to promote pectin gelation, thereby forming capsaicin-loaded pectin hydrogels that were used as the internal water phase of the double emulsions. Pectin addition improved the physical stability of the emulsions and led to a high encapsulation efficiency of capsaicin (>70 % after 7d storage). After simulated oral and gastric digestion, capsaicin-loaded double emulsions maintained their compartmentalized structure, avoiding capsaicin leakage in the month and stomach. The double emulsions were digested in the small intestine, thereby releasing the capsaicin. Capsaicin bioaccessibility was significantly enhanced after encapsulation, which was attributed to mixed micelle formation by the digested lipid phase. Furthermore, encapsulation of capsaicin within the double emulsions reduced the irritation in the gastrointestinal tissues of mice. This kind of double emulsion may have great potential for the development of more palatable capsaicin-loaded functional food products.

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.

Determination of the Dominating Coalescence Pathways in Double Emulsion Formulations by Use of Microfluidic Emulsions

In water-in-oil-in-water (W1/O/W2) double emulsions several irreversible instability phenomena lead to changes. Besides diffusive processes, coalescence of droplets is the main cause of structural changes. In double emulsions, inner droplets can coalesce with each other (W1–W1 coalescence), inner droplets can be released via coalescence (W1–W2 coalescence) and oil droplets can coalesce with each other (O–O coalescence). Which of the coalescence pathways contributes most to the failure of the double emulsion structure cannot be determined by common measurement techniques. With monodisperse double emulsions produced with microfluidic techniques, each coalescence path can be observed and quantified simultaneously. By comparing the occurrence of all possible coalescence events, different hydrophilic surfactants in combination with PGPR are evaluated and discussed with regard to their applicability in double emulsion formulations. When variating the hydrophilic surfactant, the stability against all three coalescence mechanisms changes. This shows that measuring only one of the coalescence mechanisms is not sufficient to describe the stability of a double emulsion. While some surfactants are able to stabilize against all three possible coalescence mechanisms, some display mainly one of the coalescence mechanisms or in some cases all three mechanisms are observed simultaneously.

Preparation and characterization of W1 /O/W2 emulsions stabilized by glycated and heat-modified egg white proteins

BACKGROUND

Water-in-oil-in-water (W₁ /O/W₂ ) emulsions stabilized by protein-carbohydrate complexes were prepared from an inner water phase (W₁ ), an oil phase (O) and an outer water phase (W₂ ). The complexes consisted of heat-induced aggregates (HIAs) of isomalto-oligosaccharide/egg white protein Maillard conjugates. The effects of polyglycerol ester of polyricinoleic acid (PGPR) concentration, HIA concentration, W₁ -to-O volume ratio and W₁ /O-to-W₂ volume ratio on the properties of the W₁ /O/W₂ emulsions were systematically investigated.

RESULTS

At sufficiently high PGPR concentrations (>2%), the emulsions possess a high negative charge (≈-44 mV). The encapsulation efficiency of the emulsions, which was determined by incorporating a hydrophilic yellow dye in the inner water phase prior to homogenization, was relatively high (up to 93%) and did not change significantly during 14-day storage at 4 °C. All emulsions were fluids that exhibited shear thinning behavior.

CONCLUSION

Overall, this study shows that nature-derived emulsifiers can be used to create W₁ /O/W₂ emulsions suitable for application in the food industry. In addition, we provided a viable strategy to encapsulate water-soluble nutrients. © 2022 Society of Chemical Industry.

The Potential Application of Pickering Multiple Emulsions in Food

Emulsions stabilized by adsorbed particles—Pickering particles (PPs) instead of surfactants and emulsifiers are called Pickering emulsions. Here, we review the possible uses of Pickering multiple emulsions (PMEs) in the food industry. Food-grade PMEs are very complex systems with high potential for application in food technology. They can be prepared by traditional two-step emulsification processes but also using complex techniques, e.g., microfluidic devices. Compared to those stabilized with an emulsifier, PMEs provide more benefits such as lower susceptibility to coalescence, possible encapsulation of functional compounds in PMEs or even PPs with controlled release, etc. Additionally, the PPs can be made from food-grade by-products. Naturally, w/o/w emulsions in the Pickering form can also provide benefits such as fat reduction by partial replacement of fat phase with internal water phase and encapsulation of sensitive compounds in the internal water phase. A possible advanced type of PMEs may be stabilized by Janus particles, which can change their physicochemical properties and control properties of the whole emulsion systems. These emulsions have big potential as biosensors. In this paper, recent advances in the application of PPs in food emulsions are highlighted with emphasis on the potential application in food-grade PMEs.

Double emulsions as delivery systems for iron: Stability kinetics and improved bioaccessibility in infants and adults

Iron deficiency is one of the main causes of anemia in the world, especially in children and women, so food fortification through microencapsulation is a viable alternative to combat this deficiency. The present work aimed to encapsulate iron in a water-in-oil-in-water double emulsion (W₁/O/W₂), which was formed with whey protein isolate and polyglycerol polyricinoleate as the emulsifying agents, tara gum as a thickening agent, and sucrose as an osmotic active substance. The double emulsion formed with 12% whey protein isolate, 0.8% tara gum, and 2% sucrose presented high encapsulation efficiency (96.95 ± 1.00%) and good stability (up to 7 days). Additionally, after the in vitro gastrointestinal simulations, the bioaccessibility was high for adults (49.54 ± 5.50%) and infants (39.71 ± 2.33%). Finally, the study show that double emulsions can form stable systems with high iron bioaccessibility even in infant gastric systems, which indicates the possibility of using double emulsions to fortify food with iron.

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Stable double emulsions were obtained using WPI and PGPR as emulsifiers.

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Tara gum ensured an increase in the general stability of the emulsion.

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High bioaccessibility of iron were obtained for adults and infants.

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Emulsions are presented as a potential alternative to be used in iron-fortified food.

Contribution of Nanoscience Research in Antioxidants Delivery Used in Nutricosmetic Sector

Nanoscience applications in the food and cosmetic industry offer many potential benefits for consumers and society. Nanotechnologies permit the manipulation of matter at the nanoscale level, resulting in new properties and characteristics useful in food and cosmetic production, processing, packaging, and storage. Nanotechnology protects sensitive bioactive compounds, improves their bioavailability and water solubility, guarantees their release at a site of action, avoids contact with other constituents, and masks unpleasant taste. Biopolymeric nanoparticles, nanofibers, nanoemulsions, nanocapsules, and colloids are delivery systems used to produce food supplements and cosmetics. There are no barriers to nanoscience applications in food supplements and cosmetic industries, although the toxicity of nano-sized delivery systems is not clear. The physicochemical and toxicological characterization of nanoscale delivery systems used by the nutricosmeceutic industry is reviewed in this work.

The creation of raspberry-like droplets and their coalescence dynamics: An ideal model for certain biological processes

HYPOTHESIS

Although a raspberry-like configuration has been long observed in biological processes (e.g., the intimate association between Cajal bodies and B-snurposomes), studies on this morphology are very limited. Raspberry-like droplets created with multiple immiscible liquids are expected to provides an ideal model for such structures in biological systems, including their possible formation mechanism, phase behaviors, and coalescence dynamics.

EXPERIMENTS & SIMULATIONS

Using three liquid phases, one surfactant and some colloidal particles, raspberry-like droplets containing one large central droplet and multiple protrusions embedded on its surface were successfully created. Confocal microscopy studies were carried out to track their formation and coalescence dynamics. A 2D phase-field model was applied to test the influence of the protrusions in the system.

FINDINGS

The formation of this raspberry-like morphology involves a partial inversion process, which was predicted by Friberg et al. with numerical simulations but has never been demonstrated experimentally. A two-step coalescence was revealed, where the protrusions merge first and create a capillary bridge, which drives the droplets to coalesce. Increasing the viscosity of the continuous phase can help to prevent the destabilization. These fundamental features of raspberry-like droplets represent an important step toward producing multi-liquid materials with unique functionality, and can potentially illuminate some biological systems and processes.

Oil Droplet Coalescence in W/O/W Double Emulsions Examined in Models from Micrometer- to Millimeter-Sized Droplets

Water-in-oil-in-water (W1/O/W2) double emulsions must resist W1–W1, O–O and W1–W2 coalescence to be suitable for applications. This work isolates the stability of the oil droplets in a double emulsion, focusing on the impact of the concentration of the hydrophilic surfactant. The stability against coalescence was measured on droplets ranging in size from millimeters to micrometers, evaluating three different measurement methods. The time between the contact and coalescence of millimeter-sized droplets at a planar interface was compared to the number of coalescence events in a microfluidic emulsion and to the change in the droplet size distributions of micrometer-sized single and double emulsions. For the examined formulations, the same stability trends were found in all three droplet sizes. When the concentration of the hydrophilic surfactant is reduced drastically, lipophilic surfactants can help to increase the oil droplets’ stability against coalescence. This article also provides recommendations as to which purpose each of the model experiments is suited and discusses advantages and limitations compared to previous research carried out directly on double emulsions.