Hydrophilic Emulsifier Research Articles

Double (W1/O/W2) emulsions prepared with natural vegetable oils and varied inner glucose concentration: Microstructure, rheology and stability

The objective was to study the microstructure, rheology and stability of double (W1/O/W2) emulsions prepared with Tween 80 as hydrophilic emulsifier and coconut, palm or sunflower oil. The effects of glucose concentration in inner aqueous phase and crystallization of lipid phase were analyzed. Aggregation of oil globules by partial coalescence was observed in emulsions prepared with coconut or palm oil because of the crystallization of the lipid phase. The increase of glucose concentration increased the amount of inner water by osmotic swelling and produced a higher partial coalescence degree due to a higher collision frequency between oil globules. Consequently, higher elastic and viscous modules were observed at higher glucose concentration. Fat crystals in lipid phase allowed a partial retention of inner water in the absence of glucose, but they also favored the release of inner water due to partial coalescence. Creaming stability was enhanced by the presence of glucose, because of the formation of a three-dimensional network of aggregated oil globules in emulsions with coconut or palm oil, and a higher packing and global density of oil globules in systems with sunflower oil. The obtained results contribute to the understanding of partial coalescence in W1/O/W2 emulsions, including its effects on inner water release and creaming stability. This work could be relevant for the design and stabilization of vegetable, lipid-reduced food emulsions prepared with natural oils.

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.

Effect on heat treatment on the physical stability, interfacial tension and in vitro digestion of whey protein-stabilized ω-6/ω-3 fatty acid balanced pumpkin seed oil complex condensate

Despite the fact that whey proteins (WP) have shown diverse functional and nutritional properties, they exhibit poor stability when exposed to temperatures above the thermal denaturation point. Therefore, in this study, a complex coacervation layer of formed by WP treated at different heating temperatures (55, 65, 75 and 85 °C) and gum arabic (GA) was used as a wall material to microencapsulate ω-6/ω-3 fatty acid balanced pumpkin seed oil (MPO) with a view to exploring the effect of heat treatment temperatures on the nature of microencapsulation stabilized by WP-GA complexes. At pH 3.6, WP and GA formed a strong electrostatic complex. When the heat treatment temperature reached 65 °C, the WP-GA complexes exhibited more excellent particle size, absolute potential, emulsification properties and structural changes, which made them more suitable as hydrophilic emulsifiers to stabilize oil/water (O/W) systems. Further research into the physical properties and interfacial characteristics of O/W emulsions formed by the WP-GA complex was conducted. When subjected to a heat treatment temperature of 65 °C, the O/W emulsions achieved a higher interfacial protein content (3.17 ± 0.08 mg/m2), along with a lower interfacial tension (15.52 mN/m). Additionally, the encapsulated MPO demonstrates superior oxidative stability compared to its unencapsulated counterpart. In-vitro simulated digestion experiments revealed that only small fraction (17.70 ± 1.13%) of the encapsulated oil was released in simulated gastric fluid, while the majority (76.70 ± 1.47%) was released in simulated intestinal fluid, which suggested that the WP-GA composite coacervates was a promising encapsulation shell material, capable of maintaining integrity in the gastric phase and effectively delivering the encapsulant to the intestinal phase.

Improving Water Resistance and Mechanical Properties of Crosslinked Waterborne Polyurethane Using Glycidyl Carbamate

Waterborne polyurethane (WPU) often suffers from poor water resistance and mechanical properties due to hydrophilic emulsifiers. To address these issues, this study introduces glycidyl carbamate (GC) as a crosslinker to improve WPU performance. Three types of GC were synthesized using aliphatic, cycloaliphatic, and aromatic isocyanates, respectively. The crosslinked network was established through a reaction between the epoxide group of GC and the carboxylic acid and amine groups of WPU. Among these, the WPU film utilizing aromatic isocyanate-based GC exhibited the highest crosslink density, modulus, hardness, and water resistance, due to the rigidity of the aromatic molecular structure. However, the film displayed excessive brittleness, resulting in reduced tensile strength, along with yellowing typically associated with aromatic compounds. The WPU crosslinked with cycloaliphatic GC demonstrated the next best mechanical properties and water resistance, with a 2.7-fold increase in tensile strength, a 1.5-fold increase in hardness, and a 66% reduction in the water swelling ratio compared to neat WPU. This study presents a novel and effective strategy to enhance the water resistance and mechanical properties of WPU films, making them suitable for advanced coating applications.

Studies on the Properties and Stability Mechanism of Double Emulsion Gels Prepared by Heat-Induced Aggregates of Egg White Protein-Oligosaccharides Glycosylation Products.

Multiple emulsions can dissolve some substances with different properties, such as hydrophilicity and lipophilicity, into different phases. They play an important role in protection, controlled release and targeted release of the encapsulated substances. However, it's poor stability has always been one of the main problems restricting its application in the food industry. For this reason, a heat-induced aggregate (HIA) of Maillard graft product of isomalto-oligosaccharides (IMO), as well as egg white protein (EWP), was used as hydrophilic emulsifier to improve the stability of W1/O/W2 emulsions. Moreover, gelatin was added into the internal aqueous phase (W1) to construct W1/O/W2 emulsion-gels system. The encapsulation efficiency of HIA-stabilized W1/O/W2 emulsions remained nearly unaltered, dropping by only 0.86%, significantly outperforming the conjugates and physical mixture of IMO and EWP in terms of encapsulation stability. The emulsion-gels system was constructed by adding 5% gelatin in the W1, and had the highest EE% and good salt and heat stability after 30 days of storage. This experiment provides guidance for improving the stability of W1/O/W2 emulsions system and its application in the package delivery of functional substances in the food field.

Effects of hydrophilic and lipophilic emulsifier concentrations on the characteristics of Germander essential oil nanoemulsions prepared using the nanoprecipitation technique

The Germanders (Teucrium polium L.) essential oil exhibits antioxidant and bactericidal activities against a wide range of microorganisms; however, its water insolubility, susceptibility to environmental stresses, and intense flavors limit its uses in food formulations. As a solution, in the present study, nanoemulsions of Germanders (Mentha pulegium) essential oil were prepared using a bottom-up nanoprecipitation technique. A central composite design based on the response surface methodology was implemented to investigate the effects of selected lipophilic and hydrophilic emulsifier concentrations. The proposed second-order polynomial models, with relatively high coefficients of determination, could efficiently predict alterations in response parameters due to emulsifier concentrations. The results revealed that both lipophilic and hydrophilic emulsifiers had significantly affected all characteristics of the synthesized essential oil nanoemulsions. Multi-goal optimization analysis suggested that 7.8% and 4.8% concentrations of Span 80 and Tween 80, respectively, could yield the most desirable Germanders essential oil nanoemulsions, with a mean particle size of 78.56 nm, PDI of 0.1722, DPPH radical scavenging of 83.69%, Staphylococcus aureus and Salmonella enterica growth inhibition zones of 10.5 mm and 12.7 mm, respectively. The validity of the models was confirmed by the absence of substantial variations between experimental data and modeling results. While the prepared Germander essential oil nanoemulsions demonstrated acceptable physical properties, they exhibited relatively limited chemical stability during storage at 5°C for 30 days.

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.

The potential role of hydrophilic and hydrophobic liquid emulsifier-tailored sunflower wax/sunflower oil oleogels on the properties of whole wheat batter and sponge cakes

Abstract Sunflower oil (SO) oleogel was initially prepared using 5 % (w/w) sunflower wax, hydrophobic (Span 80), or hydrophilic (Tween 80) emulsifiers. This study involved the physicochemical characterization of the batter and cake prepared through partial and complete replacement of butter with the oleogels. Batter and cake properties were improvised in T80, prepared with oleogel containing 0.015 % (w/w) of Tween 80. The polarized micrograph of the T80 batter displayed a large number of air bubbles stabilized by the wax crystals. Starch gelatinization was found highest in T80 batter and could be related to the ability of hydrophilic emulsifiers to form a complex with starch. The FTIR spectra in the T80 batter and cake displayed a reduced peak for gluten content. T80 cake crumb showed a homogenous distribution of smaller air cells supporting its softness. A reduction in the firmness and hardness of T80 was obtained from the texture studies.

Fabrication of natural W1/O/W2 double emulsions stabilized with gliadin colloid particles and soybean lecithin

In this study, we successfully fabricated W1/O/W2 double emulsions and high internal phase double emulsions with gliadin colloid particles (GCPs) as the hydrophilic emulsifier and soybean lecithin as the hydrophobic emulsifier, which were obtained from natural resources and avoided the use of surfactants such as PGPR. The effects of lecithin concentration, GCP concentration, W1/O volume ratio, and pH of the external aqueous phase on the physical properties and encapsulation efficiency of the double emulsions were investigated. The double emulsions presented an encapsulation efficiency (tartrazine was used as an aqueous marker) up to 91.1 ± 0.2% under the optimised conditions (GCP concentration 2% (w/v), lecithin concentration 1% (w/v), pH 6 of the W2 phase, W1/O volume ratio 1:5). After 30-days of storage at room temperature, the encapsulation efficiency of the double emulsions remained stable at 88.8 ± 0.2%, indicating good encapsulation stability. The double emulsions exhibited pH response characteristics; their appearance changed from a semi-solid to a flow state as the pH of the W2 phase increased, and the formation of the gel net structure facilitated the maintenance of the internal aqueous phase during fabrication and storage. This study provides a strategy for the fabrication of natural double emulsions with satisfactory encapsulation efficiency.

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 D4,3 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 (D4,3 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.

W/O/W emulsions stabilized with whey protein concentrate and pectin: Effects on storage, pasteurization, and gastrointestinal viability of Lacticaseibacillus rhamnosus

Probiotics have demonstrated various bioactive functions but poor storage and application stability, and encapsulation a promising method of increasing its viability. In this study, whey protein concentrate (WPC) and pectin (PEC) formed non-covalent complexes through electrostatic interaction at pH 3.0. The formed WPC-PEC complexes showed superior particle size, absolute potential, emulsification properties, and structural changes when PEC concentration was >0.8 % (w/v). This made them appropriate as a hydrophilic emulsifier to stabilize W/O/W emulsions. Then, Lacticaseibacillus rhamnosus, one representative of probiotics, was encapsulated in the internal aqueous phase of W/O/W emulsions. We obtained higher encapsulation efficiency (78.49 %) and smaller D4,3 (9.72 μm) with 0.8 % (w/v) PEC concentration. Encapsulation of Lacticaseibacillus rhamnosus in W/O/W emulsions improved its viability under harsh conditions, including 28 days storage at 4 °C, simulated pasteurization, and simulated gastrointestinal digestion. W/O/W emulsions stabilized by WPC-PEC non-covalent complexes further improved the survival of Lacticaseibacillus rhamnosus against various adverse conditions as compared to WPC. These findings suggest that the studied W/O/W emulsions systems have the potential to deliver probiotics in food substrates to enhance their viability during production processing, storage transportation, and digestion.

The influence of iron source, hydrophilic emulsifiers, and positioning of encapsulates on in vitro bioaccessibility and simultaneous delivery of iron and curcumin by water-in-oil-in-water (W1/O/W2) double emulsions

The influence of iron source, hydrophilic emulsifiers, and positioning of encapsulates on in vitro bioaccessibility and simultaneous delivery of iron and curcumin by water-in-oil-in-water (W1/O/W2) double emulsions

Phycocyanin-rich water-in-oil-in-water (W1/O/W2) double emulsion with nanosized particles: Improved color stability against light exposure

Acidic environments and light exposure have been known to have detrimental effects on phycocyanin (PC), a spirulina-derived chromoprotein popular among food and pharmaceutical manufacturers. We developed a water-in-oil-in-water (W1/O/W2) double emulsion system for mitigating the discoloration and precipitation issues of PC at pH 3.0 and under light exposure. The nanostructured (∼170 nm) W1/O/W2 emulsion droplets were obtained under the combined efficacy of multiple stabilizing components. Glycerol (40 wt%) in the internal aqueous phase acted as both the protein stabilizer and thickener. Fine droplet size, optical clearness, and thermodynamic stability were obtained using polyglycerol polyricinoleate (PGPR, 4 wt%) as the lipophilic emulsifier and Tween 20 (8 wt%) as the hydrophilic emulsifier. The mechanical robustness of droplets withstood multiple emulsification steps by high pressure homogenization, an efficient, high energy technology amenable to industrial-scale productions. Lipid oxidation was suppressed by using medium-chain triglyceride coconut oil and multiple antioxidants, which offered photoprotection on the encapsulated PC against oxidative damage induced by UV irradiation. The optimized PC-rich W1/O/W2 emulsion exhibited high PC loading capacity and long-term physical stability without leakage, phase separation, and retained the vivid blue color with only slight turbidity. Overall, our PC-rich W1/O/W2 double emulsion system demonstrated good thermodynamical, mechanical, and photooxidative stabilities against the acidic and light storage conditions that are commonly used during food processing, making PC a widely applicable natural colorant and protein source in foods.

Hybrid liposomes composed of hydrophilic emulsifiers and lecithin: Physicochemical, interaction and curcumin loading properties

In this study, the hybrid liposomes composed of lecithin and the hydrophilic emulsifiers including Tween 80 and decaglycerol monolaurate were prepared, and their curcumin loading performance were investigated. Results showed that the fusion of hydrophilic emulsifiers into lecithin membrane formed a new liposome-micelle-hybrid (LMH) structure whereby the LMH with Tween 80 had thinner film thickness and smaller particle size as demonstrated by quartz crystal microbalance and dynamic light scattering than LMH with decaglycerol monolaurate. In addition, the binary complex of lecithin and emulsifier had synergistic effect on the improvement of solubilizing curcumin in ethanol and water. Further evaluation of loading capacity of curcumin demonstrated that the LMH with low levels of emulsifiers possessed the maximum curcumin encapsulation efficiency compared to the pure liposomes or emulsifier-based micelles. Therefore, LMH could be a promising formulation for encapsulating and delivering bioactive substances.

Synthesis and preparation of vitamin A coupled butein-loaded solid lipid nanoparticles for liver fibrosis therapy in rats

The development of a therapeutic system for hepatic fibrosis has become a research hotspot to date. Butein, a simple chalcone derivative, displays anti-fibrotic effects through different pathways. However, impurities, low solubility, and low concentration in the target tissue hinder therapy with herbal ingredients. Hepatic stellate cells (HSCs), the vitamin A (VA) storage cells, as the main contributors to liver fibrogenesis, are not readily accessible to drugs owing to their anatomical location. Targeted delivery of therapeutics to the activated HSCs is therefore critical for successful treatment.For these reasons, the current study aimed at increasing butein delivery to the liver. Hence, high purity butein was synthesized in three steps. A novel VA-Myrj52 ester conjugate was also synthesized using all-trans retinoic acid and a hydrophilic emulsifier (Myrj52) as a targeting agent. Next, butein was encapsulated inside the novel VA-modified solid lipid nanoparticles (VA-SLNs) and studied in vitro and in vivo.According to our evaluations, negatively charged SLNs with a mean diameter of 150 nm and entrapment efficacy of 75 % were successful in liver fibrosis amelioration.Intraperitoneal (i.p.) injection of VA-SLNs in fibrotic rats, for four weeks long, reduced serum AST and ALT by 58% (P, 0.001) and 72% (P, 0.05), respectively, concerning the CCl4 group. Additionally, histologic damage score decline and normalization of tissue oxidative stress markers collectively confirmed the efficacy of formulations in hepatic fibrosis and kidney damage amelioration.

Fabrication and characterization of gel-in-oil-water (G/O/W) double emulsion stabilized by flaxseed gum/whey protein isolate complexes

The aim of this study was to fabricate stable water-in-oil-in-water double emulsions with gelled internal water phase (G/O/W emulsion). The polyglycerol polyricinoleate (PGPR) was used as the lipophilic emulsifier and flaxseed gum (FG) /whey protein isolate (WPI) electrostatic complexes were used as the hydrophilic emulsifier. The rheological results showed that W1 became gelled when the FG concentration reached 0.4 wt%. Increased concentrations of FG in W1 significantly enhanced the stability of W1/O/W2 emulsions, accompanied with the diminution in droplet size and increased viscosity. It could be attributed to the strong interfacial activity and thickening effect of FG. Optical and confocal microscopy confirmed the formation of W/O/W emulsion structure and supported the particle size results. The maximum complex formation between FG and WPI occurred at pH 3.8, with the mass ratio of 1:1. In comparison to WPI, the complex of FG/WPI exhibited a significant improvement in the stability of G/O/W double emulsions. The storage stability test showed that the G/O/W emulsion fabricated with 0.8 wt% FG and 0.5 wt% FG/WPI complexes showed the highest stability without phase separation or oil-off phenomenon within 28 days. Consequently, the incorporation of FG (≥0.4 wt%) in W1 and utilization of FG/WPI complexes could be considered as a new strategy for obtaining W/O/W emulsions with long-term storage stability.

Effects of Dietary Exogenous Hydrophilic Emulsifier Supplementation on Growth Performance and Carcass Traits in Broilers

The effects of dietary exogenous hydrophilic emulsifiers on the growth, nutrient digestibility, and carcass characteristics of broilers were evaluated. A total of 200 one-day-old broilers (Ross 308) were allotted to one of four treatment groups in a randomized complete block design in five replicates with 10 birds per pen during a 5-week growth experimental period. Birds were fed a corn-soybean meal-based diet with or without the addition of 0.025, 0.050, or 0.075% exogenous hydrophilic emulsifiers. The diets contained 3,025 and 3,075 metabolizable energy/kg for Phases 1 and 2, respectively. For each phase and the overall experimental period, body weight gain (linear, <i>P</i>&lt;0.05) and feed conversion ratio (linear, <i>P</i>&lt;0.05) improved in proportion to the dietary exogenous hydrophilic emulsifier level, while the average daily feed intake was not affected by dietary treatment. Improvement in growth performance by dietary treatments was observed during the last two weeks rather than the first three weeks of the growth phase. In carcass traits, abdominal fat content increased as dietary exogenous hydrophilic emulsifier level increased (linear, <i>P</i>&lt;0.05), whereas dietary emulsifier level did not affect the relative weight of the liver, breast, and leg muscles. In conclusion, addition of dietary exogenous hydrophilic emulsifiers from 0 to 0.075% in broiler diets improved the growth rate and feed efficiency of broilers without any deleterious effects on nutrient digestibility, although a corn-soybean meal-based diet had less energy content (3,025 and 3,075 metabolizable energy/kg) for 0-3 weeks and 3-5 weeks, respectively.

Encapsulation of hydrolysable tannin from pomegranate peel in W/O/W double emulsion: In-vitro digestion, release kinetics, storage and physical stabilities

The hydrolysable tannins from pomegranate peel have been known to exert several health benefits, majorly anti-diabetic properties. The study identified polyphenols present in pomegranate peel hydrolysable tannin (PPHT) and examined their physical stability at varying pH (2.0 – 8.0) and temperatures (4, 20 and 40 °C). PPHT showed stability at acidic pH, but conversely, it degraded at neutral and basic pH. Therefore, this work aimed to encapsulate hydrolysable tannins from pomegranate peel in the internal aqueous phase of W/O/W double emulsion. The study revealed that the double emulsion formulated with span 80-to-lecithin ratio of 1:1 (as lipophilic emulsifier) and gum Arabic concentration of > 2% (as hydrophilic emulsifier) increased the storage stability up to 60 days at ambient condition. In-vitro digestibility showed that PPHT was released from the double emulsion in the intestinal phase. Also, more than 3.75 times increase in the bioaccessibility was observed for encapsulated PPHT as compared to crude PPHT. Korsmeyer-Peppas model fitted best with the experimental data, indicating Fickian diffusion as the mechanism of PPHT release from the double emulsion. Furthermore, kinetic stability was observed for the double emulsion throughout the storage at pH 3.0 – 8.0 and at pasteurization temperatures (LTLT and HTST). Thus, these results facilitated the formulation of PPHT encapsulated double emulsion with enhanced bioaccessibility, storage and physical stability.

Role of aqueous phase composition and hydrophilic emulsifier type on the stability of W/O/W emulsions

Double W1/O/W2 emulsions can act as fat substitutes in food matrices, although synthetic emulsifiers are commonly used due to their inherent instability and susceptibility to coalescence. In order to guarantee the stability of the W/O interface, the synthetic emulsifier polyglycerol polyricinoleate (PGPR − 4.5% w/w) was used. However, the replacement of chemically synthesized ingredients by natural alternatives has been extensively pursued in food applications. In this sense, whey protein isolate (WPI) and sodium caseinate (SC) were used to stabilize the external aqueous phase (W2) of water-in-oil-in-water double emulsions (W1/O/W2), in addition to Tween 80 that was used as a control. The composition of the internal aqueous phase and its effects on the double emulsion were studied by the addition of sodium chloride (0.2% w/w NaCl), gallic acid (0.5% w/w GA) or a GA/NaCl mixture (0.5% / 0.2% w/w). The effect of these different hydrophilic components was evaluated from measurements of droplet size, viscosity, ζ potential, interfacial tension and kinetic stability. SC-stabilized W/O/W emulsions showed better kinetic stability than WPI- and T80-systems. These results can be attributed to the initial droplet size (SC < T80 < WPI) and viscosity of the emulsions (SC < T80 < WPI). SC is a more flexible and unfolded protein that can quickly adsorb and rearrange at the interface, favoring the formation of smaller droplets and limiting the migration of inner water droplets to the outer phase. In addition to smaller droplets, the addition of SC (8% w/w) to the external aqueous phase promoted an increase in the viscosity of bulk systems, which reduced the destabilization rates by creaming and coalescence. All W/O/W systems containing NaCl in the inner aqueous phase presented greater kinetic stability during 7 days of storage. Although the addition GA was less efficient to stabilize double emulsions compared to NaCl, this phenolic compound reduced the interfacial tension, favoring the formation of WPI- and T80-droplets with smaller diameters. However, the use of GA/NaCl blend improved the stability and functionally of W/O/W double emulsions. We concluded that the type of hydrophilic emulsifier, the properties of the inner water droplets and the viscosity of phases influenced the droplet size, viscosity and kinetic stability of double emulsions. This work provides a better understanding of how composition influences the properties of double emulsions and how it can be used to design W/O/W emulsions as fat substitutes in more complex food systems.

Encapsulation of Pomegranate Peel Extract (Punica granatum L.) by Double Emulsions: Effect of the Encapsulation Method and Oil Phase.

Pomegranate peel is an agro-industrial waste that can be used as source of punicalagin, a polyphenolic compound with several beneficial effects on health. Since, once extracted, punicalagin is prone to degradation, its encapsulation by double emulsions can be an alternative to protect the active compound and control its release. The aim of this investigation was to evaluate the feasibility of encapsulating pomegranate peel extract (PPE) in double emulsions using different types of oils (castor, soybean, sunflower, Miglyol and orange) in a ratio of 70:30 (oil:PPE) and emulsification methods (direct membrane emulsification and mechanical agitation), using polyglycerol polyricinoleate (PGPR) and Tween 80 as lipophilic and hydrophilic emulsifiers, respectively. Direct membrane emulsification (DME) led to more stable emulsions during storage. Droplet size, span values, morphology and encapsulation efficiency (EE) were better for double emulsions (DEs) prepared by DME than for mechanical agitation (MA). DEs formulated using Miglyol or sunflower oil as the oily phase could be considered as suitable food grade systems to encapsulate punicalagin with concentrations up to 11,000 mg/L of PPE.