Encapsulation properties, release behavior and physicochemical characteristics of water-in-oil-in-water (W/O/W) emulsion stabilized with pectin–pea protein isolate conjugate and Tween 80

Encapsulation of Lactobacillus plantarum in W1/O/W2 double emulsions stabilized with the high-intensity ultrasound-treated pea protein and pectin

This study focuses on developing a water-in-oil-in-water (W1/O/W2) double emulsion system using high-intensity ultrasound (HIU)-treated pea protein isolate (HIU-PPI) and pectin to encapsulate Lactobacillus plantarum (L. plantarum). The effects of ultrasound treatment on pea protein isolate (PPI) characteristics such as solubility, particle size, emulsification, surface hydrophobicity, and surface free sulfhydryl group were examined, determining optimal HIU processing conditions was 400 W for 10 min. The developed W1/O/W2 double emulsion system based on HIU-PPI demonstrated effective encapsulation and protection of L. plantarum, especially at the HIU-PPI concentration of 4 %, achieving an encapsulation efficiency of 52.65 %. Incorporating both HIU-PPI and pectin as emulsifiers increased the particle size and significantly enhanced the emulsion's viscosity. The highest bacterial encapsulation efficiency of the emulsion, 59.94 %, was attained at a HIU to pectin concentration ratio of 3:1. These emulsions effectively encapsulate and protect L. plantarum, with the concentration of HIU-PPI being a critical factor in enhancing probiotic survival under simulated gastrointestinal digestion. However, the concurrent utilization of pectin and HIU-PPI as emulsifiers did not provide a notable advantage compared to the exclusive use of HIU-PPI in enhancing probiotic viability during in vitro simulated digestion. This research offers valuable perspectives for the food industry on harnessing environmentally friendly, plant-based proteins as emulsifiers in probiotic delivery systems. It underscores the potential of HIU-modified pea protein and pectin in developing functional food products that promote the health benefits of probiotics.

Preparation of protein-stabilized Litsea cubeba essential oil nano-emulsion by ultrasonication: Bioactivity, stability, in vitro digestion, and safety evaluation

Litsea cubeba essential oil (LCEO) has garnered widespread attention due to its robust biological activity. However, challenges such as high volatility, limited water solubility, and low bioavailability impede its application. Nano-emulsion encapsulation technology offers an effective solution to these issues. In this study, we prepared litsea cubeba essential oil nano-emulsion (LCEO-NE) for the first time using whey protein (WP) as the emulsifier through an ultrasonic-assisted method, achieving high efficiency with minimal energy consumption. Transmission electron microscopy and dynamic light scattering analyses revealed that the nanoparticles were uniformly spherical, with a particle size of 183.5 ± 1.19 nm and a zeta potential of -35.5 ± 0.95 mV. Stability studies revealed that LCEO-NE exhibited excellent thermal and salt stability, maintaining its integrity for up to four weeks when stored at 4 °C and 25 °C. In vitro digestion assays confirmed the digestibility of LCEO-NE. Furthermore, evaluation of the DPPH, ABTS, and antimicrobial activities revealed that LCEO-NE displayed superior bacteriostatic and antioxidant properties compared to LCEO. Scanning electron microscopy elucidated that its bacteriostatic effect involved the disruption of bacterial microstructure. Hemocompatibility and cytotoxicity assays demonstrated the safety of LCEO-NE within the effective concentration range. This research supports the utilization of nanoparticles for encapsulating LCEO, thereby enhancing its stability and bioactivity, and consequently expanding its applications in the food and pharmaceutical industries.

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.

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.

Fabrication of double nano-emulsions loaded with hyssop (Hyssopus officinalis L.) extract stabilized with soy protein isolate alone and combined with chia seed gum in controlling the oxidative stability of canola oil

The aim of this study was to encapsulate hyssop (Hyssopus officinalis L.) extract obtained through ultrasound-assisted cold plasma pretreatment extraction within a double emulsion stabilized by soy protein isolate alone (SPI) and combined with chia seed gum (CSG) in the external aqueous phase on the stabilization of canola oil. FTIR analysis verified that there were electrostatic interactions between CSG and SPI. The SPI/CSG-stabilized emulsion demonstrated lower viscosity, smaller droplets, higher ζ-potential, and encapsulation efficiency compared to the SPI-stabilized emulsion. Non-Newtonian, pseudoplastic behaviors were shown by emulsions. Also, according to the dynamic rheological parameters (G' and G''), the SPI/CSG-stabilized emulsion had elastic behavior with weak gel properties. The antioxidant activity of the encapsulated extract at 1500 ppm during the storage in canola oil was investigated and compared to unencapsulated extract and TBHQ. The results showed that oil containing encapsulated extract had lower oxidative alterations than the unencapsulated form.

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.

Effect of Diacylglycerol Crystallization on W/O/W Emulsion Stability, Controlled Release Properties and In Vitro Digestibility

Water-in-oil-in-water (W/O/W) emulsions with high-melting diacylglycerol (DAG) crystals incorporated in the oil droplets were fabricated and the compositions were optimized to achieve the best physical stability. The stability against osmotic pressure, encapsulation efficiency and in vitro release profiles of both water- and oil-soluble bioactives were investigated. The presence of interfacial crystallized DAG shells increased the emulsion stability by reducing the swelling and shrinkage of emulsions against osmotic pressure and heating treatment. DAG crystals located at the inner water/oil (W1/O) interface and the gelation of the inner phase by gelatin helped reduce the oil droplet size and slow down the salt release rate. The DAG and gelatin-contained double emulsion showed improved encapsulation efficiency of bioactives, especially for the epigallocatechin gallate (EGCG) during storage. The double emulsions with DAG had a lower digestion rate but higher bioaccessibility of EGCG and curcumin after in vitro digestion. DAG-stabilized double emulsions with a gelled inner phase thus can be applied as controlled delivery systems for bioactives by forming robust interfacial crystalline shells.

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.

Co-Delivery System of Vitamin B12 and Vitamin E Using a Binary W/O/W Emulsion Based on Soybean Isolate Protein-Xanthan Gum/Carrageenan: Emulsification Properties, Rheological Properties, Structure, Stability, and Digestive Characteristics

In this study, the soybean protein isolate (SPI)-xanthan gum (XG) or carrageenan (CA) W/O/W emulsions for the co-delivery of vitamin B12 and vitamin E were prepared. The effects of XG and CA concentrations on the physicochemical properties and digestive characteristics of the emulsions were also investigated. The addition of XG and CA improved the SPI aggregation and increased its electrostatic repulsion so that more SPI was adsorbed at the phase interface. The emulsifying activity index and emulsifying stability index increased to 24.09 (XG 0.4%) and 14.00 (CA 0.5%) and 151.08 (XG 0.4%) and 135.34 (CA 0.5%), respectively. The adsorbed protein content increased to 88.90% (XG 0.4%) and 88.23% (CA 0.5%), respectively. Moreover, the encapsulation efficiencies of vitamin B12 and vitamin E were increased to 86.72% (XG 0.4%) and 86.47 (CA 0.5%) and 86.31% (XG 0.4%) and 85.78% (CA 0.5%), respectively. The bioaccessibility of vitamin B12 and vitamin E increased to 73.53% (XG 0.4%) and 71.32% (CA 0.5%) and 68.86% (XG 0.4%) and 68.74% (CA 0.5%). The best properties of the emulsions were obtained at a 0.4% concentration of XG and 0.5% of CA. This study offers a novel system for delivering bioactive substances, which is favorable for the advancement of food with delivery capability in food processing.

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.

Encapsulation of sesamol and retinol using alginate and chitosan-coated W/O/W multiple emulsions containing Tween 80 and Span 80

The conditions of production of multiple W/O/W nanoemulsions containing sesamol and retinol were optimized using response surface methodology (RSM). Span 80 (5, 10, and 15 % w/v), Tween 80 (1, 5.5, and 10 % w/v), and water in oil ratio (W/O) (20, 30, and 40 %) were considered as independent variables while encapsulation efficiency (EE%) and particle size were taken as dependent variables. Alginate (Alg) and chitosan (CS) were also applied to form a deposit layer. An optimum sample with an EE of 92.93 % and particle size of 381.94 nm was produced when Tween 80, Span 80, and W/O were 6.24 %, 10.84 %, and 37.70 %, respectively. Based on the Fourier transform infrared spectroscopy (FTIR), detection of hydrophobic band (2899 cm^-1) approved the physical entrapment of biomolecules. Differential scanning calorimetry (DSC) indicated an endothermic peak at 236.48 °C associated with the ionic interactions of Alg-CS. Confocal laser scanning microscopy (CLSM) indicated Alg-CS complex deposit layer formed by electrostatic attraction surrounding the W/O/W multiple layers. The in vitro release of sesamol and retinol was 39 % of sesamol and 22 % of retinol in simulated gastric fluid (SGF) and 56 % and 22 % in simulated intestinal fluid (SIF), respectively.

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.

Production of nanostructured systems: Main and innovative techniques

In the constant search for the development of more-specific and more-selective drugs, especially with regard to the challenge of encapsulating hydrophilic molecules, polymer nanotechnologies are remarkable for their biocompatible and biodegradable properties. The most-used nanoencapsulation methods consist of emulsification procedures, where emulsified droplets of a given polymer and drug solidify into nanoparticles after solvent extraction from the polymeric phase. This review introduces conventional emulsification methods but also highlights new emulsification technologies such as microfluidics, membrane emulsification and other techniques, including spray drying, inkjet printing and electrospraying.

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 Current Situation of Pea Protein and Its Application in the Food Industry

Pea (Pisum sativum) is an important source of nutritional components and is rich in protein, starch, and fiber. Pea protein is considered a high-quality protein and a functional ingredient in the global industry due to its low allergenicity, high protein content, availability, affordability, and deriving from a sustainable crop. Moreover, pea protein has excellent functional properties such as solubility, water, and oil holding capacity, emulsion ability, gelation, and viscosity. Therefore, these functional properties make pea protein a promising ingredient in the food industry. Furthermore, several extraction techniques are used to obtain pea protein isolate and concentrate, including dry fractionation, wet fractionation, salt extraction, and mild fractionation methods. Dry fractionation is chemical-free, has no loss of native functionality, no water use, and is cost-effective, but the protein purity is comparatively low compared to wet extraction. Pea protein can be used as a food emulsifier, encapsulating material, a biodegradable natural polymer, and also in cereals, bakery, dairy, and meat products. Therefore, in this review, we detail the key properties related to extraction techniques, chemistry, and structure, functional properties, and modification techniques, along with their suitable application and health attributes.

Preparation, characterization, and biological activity of Cinnamomum cassia essential oil nano-emulsion

To solve the problems of low bioavailability and unstable properties of Cinnamomum cassia Essential oil (CCEO), encapsulation technology was introduced as an effective means to improve its shortcomings. In this study, Cinnamomum cassia Essential oil nano-emulsion (CCEO-NE) was successfully synthesized by the oil-in-water method and characterized by standard analytical methods, including dynamic light scattering (DLS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The results show that the synthesized CCEO is spherical, smooth in surface, and uniform in shape, with an average particle size of 221.8 ± 1.95 nm, which is amorphous. In this experiment, by simulating the digestion of CCEO-NE in the gastrointestinal tract, it was found that CCEO-NE was undigested in the oral cavity, mainly in the stomach, followed by the small intestine. By understanding the digestion of CCEO-NE, we can improve the potential of CCEO bioavailability in food and drug applications. In addition, through the study of ABTS and DPPH free radicals by CCEO and CCEO-NE, it was found that the antioxidant activity of CCEO-NE was more potent than that of CCEO. When the concentration of CCEO-NE and CCEO is 400 μg/mL, the DPPH free radical scavenging rate is 92.03 ± 0.548% and 80.46 ± 5.811%, respectively. In comparison, ABTS free radical scavenging rate is 90.35 ± 0.480% and 98.44 ± 0.170% when the concentration of CCEO- NE, and CCEO is 75 μg/mL, respectively. The antibacterial test shows that CCEO-NE can inhibit both Gram-positive and Gram-negative bacteria. Among them, CCEO-NE has a stronger antibacterial ability than CCEO, and the maximum inhibition zone diameter of CCEO can reach 15 mm, while that of CCEO-NE can reach 18 mm. Meanwhile, SEM and TEM showed that CCEO-NE treatment destroyed the ultrastructure of bacteria. Generally speaking, we know the situation of CCEO in the gastrointestinal tract. CCEO-NE has more potent antioxidant and antibacterial ability than CCEO. Our research results show that whey protein is an effective packaging strategy that can improve the effectiveness, stability, and even bioavailability of CCEO in various applications, including food and health care industries.

Pea protein composition, functionality, modification, and food applications: A review

The demand for proteins continues to increase due to their nutritional benefits, the growing world population, and rising protein deficiency. Plant-based proteins represent a sustainable source to supplement costly animal proteins. Pea (Pisum sativum L.) is one of the most produced plant legume crops in the world and contributes to 26% of the total pulse production. The average protein content of pea is about 20%-25%. The commercial utilization of pea proteins is limited, partially due to its less desirable functionalities and beany off-flavor. Protein modification may change these properties and broaden the application of pea proteins in the food industry. Functional properties such as protein solubility, water and oil holding capacity, emulsifying/foaming capacity and stability, and gelation can be altered and improved by enzymatic, chemical, and physical modifications. These modifications work by affecting protein chemical structures, hydrophobicity/hydrophilicity balance, and interactions with other food constituents. Modifiers, reaction conditions, and degree of modifications are critical variables for protein modifications and can be controlled to achieve desirable functional attributes that may meet applications in meat analogs, baking products, dressings, beverages, dairy mimics, encapsulation, and emulsions. Understanding pea protein characteristics will allow us to design better functional ingredients for food applications.

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.

Oil Phase Solubility Rather Than Diffusivity Determines the Release of Entrapped Amino Acids and Di-Peptides from Water-in-Oil-in-Water Emulsions

The permeation of amino acids and di-peptides with different hydrophobicities across the oil phase in W/O/W double emulsions was investigated at different concentrations, considering the pH of the aqueous phase. Moreover, the particle size, yield of entrapped water and release kinetics of the double emulsions was evaluated as a function of time. Regarding the release of the entrapped amino acids and di-peptides, their hydrophobicity and the pH had a significant effect, whereas the concentration of the dissolved compound did not lead to different release kinetics. The release of the amino acids and di-peptides was faster at neutral pH as compared to acidic pH values due to the increased solute solubility in the oil phase for more hydrophobic molecules at neutral pH. Regarding the effect of the type of oil, much faster amino acid transport was observed through MCT oil as compared to LCT oil, which might be due to its higher solubility and/or higher diffusivity. As di-peptides released faster than amino acids, it follows that the increased solubility overruled the effect from the decreased diffusion coefficient of the dissolved compound in the oil phase.

Co-delivery of EGCG and Lycopene via a Pickering Double Emulsion induced Synergistic Hypolipidemic Effect

The concept of “synergy” and its applications has rapidly increased in the food industry as a practical strategy to preserve and improve health-promoting effects of the functional ingredients. In this...

Stability and release mechanisms of double emulsions loaded with bioactive compounds; a critical review

Double emulsions (DEs), known as emulsions of emulsions, are dispersion systems in which the droplets of one dispersed liquid are further dispersed in another liquid, producing double-layered liquid droplets. These systems are widely used in the food and pharmaceutical industries due to their ability to co-encapsulate both hydrophilic and hydrophobic bioactive compounds. However, they are sensitive and unstable and their controlled release is challenging. In this study, first, the stability of DEs and their release mechanisms are reviewed. Then, the factors affecting their stability, and the release of bioactive compounds are studied. Finally, modeling of the release in DEs is discussed. This information can be useful to optimize the formulation of DEs in order to utilize them in different industries.

Influence of Aqueous Phase Composition on Double Emulsion Stability and Colour Retention of Encapsulated Anthocyanins

Water-in-oil-in-water (W₁/O/W₂) emulsions (double emulsions) have often been used for the encapsulation of bioactive compounds such as anthocyanins. Instability of both anthocyanins and double emulsions creates a need for a tailored composition of the aqueous phase. In this work, double emulsions with a gelled internal water phase were produced and monitored over a 20-day storage period. The effect of the electrolyte phase composition (varying electrolyte components, including adipic acid, citric acid, and varying concentration of potassium chloride (KCl)) on anthocyanin and double emulsion stability was analysed using colour analysis, droplet sizing, and emulsion rheology. The effect of electrolytes on colour retention was shown to differ between the primary W₁/O emulsion and the secondary W₁/O/W₂ emulsion. Furthermore, droplet size analysis and emulsion rheology highlighted significant differences in the stability and structural behaviour of the emulsions as a function of electrolyte composition. In terms of colour retention and emulsion stability, a citrate-buffered system performed best. The results of this study highlight the importance of strict control of aqueous phase constituents to prevent anthocyanin degradation and maximise double emulsion stability. Additional experiments analysed the effect of pectin chemistry on the anthocyanin colour retention and leakage, finding no conclusive difference between the unmodified and amidated pectin.

Polyphenol Loaded W1/O/W2 Emulsions Stabilized with Lesser Mealworm (Alphitobius diaperinus) Protein Concentrate Produced by Membrane Emulsification: Stability under Simulated Storage, Process, and Digestion Conditions

Water-in-oil-in-water (W1/O/W2) emulsions are complex delivery systems for polyphenols amongst other bio-actives. To stabilize the oil-water interphase, dairy proteins are commonly employed, which are ideally replaced by other, more sustainable sources, such as insect proteins. In this study, lesser mealworm (Alphitobius diaperinus) protein concentrate (LMPC) is assessed and compared to whey protein (WPI) and pea protein (PPI), to stabilize W1/O/W2 emulsions and encapsulate a commercial polyphenol. The results show that LMPC is able to stabilize W1/O/W2 emulsions comparably to whey protein and pea protein when using a low-energy membrane emulsification system. The final droplet size (d4,3) is 7.4 μm and encapsulation efficiency is between 72 and 74%, regardless of the protein used. Under acidic conditions, the LMPC shows a similar performance to whey protein and outperforms pea protein. Under alkaline conditions, the three proteins perform similarly, while the LMPC-stabilized emulsions are less able to withstand osmotic pressure differences. The LMPC stabilized emulsions are also more prone to droplet coalescence after a freeze-thaw cycle than the WPI-stabilized ones, but they are the most stable when exposed to the highest temperatures tested (90 °C). The results show LMPC's ability to stabilize multiple emulsions and encapsulate a polyphenol, which opens the door for application in foods.

Nanoencapsulation of lutein within lipid-based delivery systems: Characterization and comparison of zein peptide stabilized nano-emulsion, solid lipid nanoparticle, and nano-structured lipid carrier

Three lipid-based carriers encapsulating lutein, nano-emulsion (NE), solid lipid nanoparticle (SLN), and nano-structured lipid carrier (NLC), were developed from zein peptides hydrolyzed by trypsin (TZP) and flavourzyme (FZP) as stabilizers. The physiochemical properties of FZP and TZP were evaluated. The particle size, potential, microstructure, environmental stability, rheological properties, in vitro digestion stability, and bioavailability of the lutein-loaded NE, SLN, and NLC were compared. The results showed that the surface hydrophobicity of TZP was higher than that of FZP. Except for the SLN, most samples were stable against droplet aggregation during storage, and carriers stabilized by TZP exhibited more favorable storage stabilities than those prepared from FZP. All the samples presented characteristics of fluid with good fluidity. The bioavailability of lutein was between 42.61% and 62.81%. In summary, these results provide valuable insights into the design of lipid-based delivery systems for fat-soluble biologically active compounds using zein peptides as stabilizers.

Influence of Hydrophilic Surfactants on the W1–W2 Coalescence in Double Emulsion Systems Investigated by Single Droplet Experiments

Double emulsions are a promising formulation for encapsulation and targeted release in pharmaceutics, cosmetics and food. An inner water phase is dispersed in an oil phase, which is again emulsified in a second water phase. The encapsulated inner water phase can be released via diffusion or via coalescence, neither of which is desired during storage but might be intended during application. The two interfaces in a double emulsion are stabilized by a hydrophilic and a lipophilic surfactant, to prevent the coalescence of the outer and the inner emulsion, respectively. This study focuses on the influence of the hydrophilic surfactant on the release of inner water or actives encapsulated therein via coalescence of the inner water droplet with the outer O–W2 interface. Since coalescence and diffusion are difficult to distinguish in double emulsions, single-droplet experiments were used to quantify differences in the stability of inner droplets. Different lipophilic (PGPH and PEG-30 dipolyhydroxylstearate) and hydrophilic surfactants (ethoxylates, SDS and polymeric) were used and resulted in huge differences in stability. A drastic decrease in stability was found for some combinations, while other combinations resulted in inner droplets that could withstand coalescence longer. The destabilization effect of some hydrophilic surfactants depended on their concentration, but was still present at very low concentrations. A huge spread of the coalescence time for multiple determinations was observed for all formulations and the necessary statistical analysis is discussed in this work. The measured stabilities of single droplets are in good accordance with the stability of double emulsions for similar surfactant combinations found in literature. Therefore, single droplet experiments are suggested for a fast evaluation of potentially suitable surfactant combinations for future studies on double-emulsion stability.

The Stability, Microstructure, and Microrheological Properties of Monascus Pigment Double Emulsions Stabilized by Polyglycerol Polyricinoleate and Soybean Protein Isolate

Monascus pigment is a natural food pigment and is commonly used for coloring and as antiseptic of cured meat products, confectionery, cakes, and beverages. However, Monascus pigment is sensitive to environmental conditions. The main aim of this study was to investigate the effect of polyglycerol polyricinoleate (PGPR) and soy protein isolate (SPI) on the particle size, zeta potential, physical stability, microstructure, and microrheological properties of Monascus pigment double emulsions. The effects of ionic strength, heating, and freeze thawing treatment on the stabilities of Monascus pigment double emulsions were also characterized. It was found that the optimum PGPR and SPI concentrations for fabricating Monascus pigment double emulsion were 3.6 and 3.0 wt%, respectively. The fabricated Monascus pigment double emulsion was composed of fine particles with narrow and uniform size distributions. Microrheological property results suggested that the elastic characteristic of the Monascus pigment double emulsion was dominated with increasing PGPR and SPI contents. It was mainly due to the increased collision and interaction between the droplets during the movement resulting in force increasing. Monascus pigment double emulsions with <5 mM CaCl2 prevented calcium to destroy the physical stability of emulsions, while Monascus pigment double emulsions with more than 10 mM CaCl2 formed creaming. After freeze thawing treatment, creaming occurred in Monascus pigment double emulsion. However, it was stable against heating treatment due to heating leading to a dense network structure. It could be contributed to the practical applications of Monascus pigment double emulsions in food products.

Release of amino acids encapsulated in PGPR-stabilized W/O/W emulsions is affected by temperature and hydrophobicity

Double or multiple emulsions have been under study for several decades, due to the possibility of encapsulation and controlled release of various bioactive compounds. This contribution focuses on the decisive parameters for encapsulation and release in double emulsions by considering different amino acids at different environmental conditions. Laser diffraction analysis showed that the double emulsion average droplet size increased from 50 up to 90 µm after 32 days of storage. The emulsions at 4 °C showed a higher increase compared to 37 °C. Dilution in SDS solution revealed that this droplet size increase was due to aggregation rather than coalescence. The results showed that there was no significant change in the entrapped water volume fraction of the double emulsions during 2 weeks of storage. Amino acids were encapsulated within the internal aqueous phase with an efficiency of at least 80%. Regarding the release of the entrapped amino acids, it was found that both the temperature and the hydrophobicity of the amino acid had a significant effect. Fastest release was found at the highest temperature studied (i.e. 37 °C), which was thought to be due to the higher solubility and faster diffusion rate of the amino acid in the oil phase. As hydrophobicity increased, the released amino acid concentration also increased. The pH, on the other hand, did not have a significant effect on the release within the pH range considered (i.e. 7-10). The constant internal water volume fraction, together with the significant effect of temperature and hydrophobicity, indicated that the main release mechanism of amino acids in double emulsions is by direct diffusion from the internal to the external aqueous phase.

Pseudosciaena crocea roe protein-stabilized emulsions for oral delivery systems: In vitro digestion and in situ intestinal perfusion study

Benzyl isothiocyanate (BITC) was encapsulated in oil-in-water emulsions stabilized by Pseudosciaena crocea roe protein isolate (PRPI). The stability, lipid digestion, BITC bioavailability, and retention rate of the emulsions were characterized using a simulated gastrointestinal tract model. Tween-corn and PRPI-medium-chain triglycerides (MCT) emulsions were used as controls. The membrane permeability and BITC absorption from these emulsions were investigated by in situ single-pass intestinal perfusion. The results showed that the PRPI-stabilized emulsions were stable under nonacidic environment conditions. Moreover, the PRPI-corn emulsion had more obvious protective effects than PRPI-MCT and Tween-corn emulsions. Atomic force and confocal laser scanning microscopy images showed that the protein hydrolyzed and oil droplets aggregated during simulated gastric phase digestion. Following the exposure of oil droplets in the small intestine phase, the PRPI-corn emulsion had a high rate of free fatty acid release (99.13 ± 2.49%), and the retention rate and bioavailability of BITC from the PRPI-corn emulsion were 75.93 ± 7.17% and 77.32 ± 5.36%, respectively, which were significantly higher than those measured for the other emulsions (P < 0.05). Moreover, the K_a and P_eff of the PRPI-corn emulsion reached the maximum value at 45 min and then decreased slowly. These results suggest that the PRPI-corn emulsion delivery system is effective in encapsulating, delivering, and protecting BITC. PRACTICAL APPLICATION: This study provides some useful information for the food industry to develop a Pseudosciaena crocea roe protein isolate (PRPI) emulsion that could be successfully used to construct a BITC delivery system and improve benzyl isothiocyanate (BITC) bioavailability. The protective effect on BITC assessed in vitro simulated gastrointestinal tract and in situ single-pass intestinal perfusion are discussed.

The health benefits, functional properties, modifications, and applications of pea (Pisum sativum L.) protein: Current status, challenges, and perspectives

In recent years, the development and application of plant proteins have drawn increasing scientific and industrial interests. Pea (Pisum sativum L.) is an important source of high-quality vegetable protein in the human diet. Its protein components are generally considered hypoallergenic, and many studies have highlighted the health benefits associated with the consumption of pea protein. Pea protein and its hydrolysates (pea protein hydrolysates [PPH]) possess health benefits such as antioxidant, antihypertensive, and modulating intestinal bacteria activities, as well as various functional properties, including solubility, water- and oil-holding capacities, and emulsifying, foaming, and gelling properties. However, the application of pea protein in the food system is limited due to its poor functional performances. Several frequently applied modification methods, including physical, chemical, enzymatic, and combined treatments, have been used for pea protein to improve its functional properties and expand its food applications. To date, different applications of pea protein in the food system have been extensively studied, for example, encapsulation for bioactive ingredients, edible films, extruded products and substitution for cereal flours, fats, and animal proteins. This article reviews the current status of the knowledge regarding pea protein, focusing on its health benefits, functional properties, and structural modifications, and comprehensively summarizes its potential applications in the food industry.

Designing multiple bioactives loaded emulsions for the formulations for diets of elderly

In this study, a stable double emulsion loaded with essential bioactives for the elderly was prepared using a two-step mechanical emulsification process.

Fabrication of Novel Hierarchical Multicompartment Highly Stable Triple Emulsions for the Segregation and Protection of Multiple Cargos by Spatial Co-encapsulation

High-order multiple emulsions are of great interest in both fundamental research and industrial applications as vehicles for their encapsulation capability of actives. In this work, we report a hierarchically multicompartmental highly stable triple emulsion by emulsifying and assembling of natural Quillaja saponin. Water-in-oil-in-(oil-in-water) (W₂/O₂/(O₁/W₁)) triple emulsion indicates that the compartmented system consisted of surfaced saponin-coated nanodroplets (SNDs) and dispersed oil globules, which in turn contained smaller aqueous droplets. The effects of formulation parameters, including lipophilic emulsifier content, oil fraction, and SND concentration, on the formation of multiple emulsions were systematically investigated. The assembly into fibrillar network of SNDs at the outer oil-water interface effectively protected the triple emulsion droplets against flocculation and coalescence, and strongly prevented the osmotic-driven water diffusion between the internal water droplets and the external water phase, thus contributing to superior stability during 180 days storage. All of these characteristics make the multicompartmentalized emulsions suitable to co-encapsulate a hydrophilic bioactive (gardenia blue) and two hydrophobic bioactives (eapsanthin and curcumin) in a single emulsion droplet hierarchically for the segregation and protection of multiple cargos. This approach offers a promising route toward accessing the next generation of functional deliveries and encapsulation strategies.