Formation and stabilization of nanoemulsion-based vitamin E delivery systems using natural surfactants: Quillaja saponin and lecithin

Gypenosides as natural emulsifiers for oil-in-water nanoemulsions loaded with astaxanthin: Insights of formulation, stability and release properties

The formulation, physicochemical stability and bioaccessibility of astaxanthin (AST) loaded oil-in-water nanoemulsions fabricated using gypenosides (GPs) as natural emulsifiers was investigated and compared with a synthetic emulsifier (Tween 20) that is commonly applied in food industry. GPs were capable of producing nanoemulsions with a small volume mean diameter (d_4,3 = 125 ± 2 nm), which was similar to those prepared using Tween 20 (d_4,3 = 145 ± 6 nm) under the same high-pressure homogenization conditions. GPs-stabilized nanoemulsions were stable against droplet growth over a range of pH (6-8) and thermal treatments (60-120 °C). Conversely, instability occurred under acidic (pH 3-5) and high ionic strength (25-100 mM CaCl₂) conditions. In comparison with Tween 20, GPs were more effective at inhibiting AST from degradation during 30 days of storage at both 5 and 25 °C. However, GPs led to lower lipid digestion and AST bioaccessibility from nanoemulsions than did Tween 20.

Stabilization and Rheology of Concentrated Emulsions Using the Natural Emulsifiers Quillaja Saponins and Rhamnolipids

Concentrated emulsions are widely used in the cosmetic, personal-care, and food industries to reduce storage and transportation costs and to provide desirable characteristics. The current study aimed to produce concentrated emulsions (50 wt % oil) using two natural emulsifiers, quillaja saponins and rhamnolipids. The impacts of emulsifier concentrations on the particle sizes, rheological properties, and stabilities of concentrated emulsions were evaluated. Emulsion particle sizes were negatively correlated with the concentrations of both quillaja saponins and rhamnolipids, and rhamnolipids were more effective in producing smaller droplets. Both emulsifiers formed stable concentrated emulsions against a series of environmental stresses, including various temperatures (30-90 °C), salt concentrations (≤200 mM NaCl), and pHs (pH 5-8). The rheology tests suggested that concentrated emulsions stabilized by quillaja saponins or rhamnolipids presented shear-thinning behaviors and had relatively low consistency coefficients.

Characterization of physical properties and electronic sensory analyses of citrus oil-based nanoemulsions

Citrus oils and their emulsions have been widely used in food and beverage products due to their flavor, various beneficial health functions and relative high solubility for lipophilic bioactive components. However, the non-digestibility and instability has limited the application of emulsions made from a single type of citrus oil. In this study, common triacylglycerol oils (i.e. corn oil and MCT oil) and citrus oils (i.e. bergamot oil and sweet orange oil) were used in combination with different mixing ratios (triacylglycerol oil:citrus oil = 1:0, 9:1, 5:1, 3:1, 1:1 and 0:1) to produce various nanoemulsions (10% oil phase), and their physical and electronic sensory properties were systematically characterized. The results demonstrated that the mixed oil nanoemulsions were much more stable than pure citrus oil emulsions. Electronic nose, electronic eye and electronic tongue were shown to be able to provide informative evaluation of the electronic sensory of the emulsions. Data-fitting of these electronic sensory devices significantly improved the effective discrimination and accuracy of sensory evaluation of the emulsions. These results provided basis for using triacylglycerol oils and citrus oils in combination to produce nanoemulsions with superior physical and electronic sensory properties. Moreover, the electronic sensory evaluation method utilized in this study provided a useful approach for evaluation of emulsion-based food and beverage products.

Improving curcumin solubility and bioavailability by encapsulation in saponin-coated curcumin nanoparticles prepared using a simple pH-driven loading method

Curcumin is a bioactive phytochemical that can be utilized as a nutraceutical or pharmaceutical in functional foods, supplements, and medicines. However, the application of curcumin as a nutraceutical in commercial food and beverage products is currently limited by its low water-solubility, chemical instability, and poor oral bioavailability. In this study, all-natural colloidal delivery systems were developed to overcome these challenges, which consisted of saponin-coated curcumin nanoparticles formed using a pH-driven loading method. The physicochemical and structural properties of the curcumin nanoparticles formed using this process were characterized, including particle size distribution, surface potential, morphology, encapsulation efficiency, and loading capacity. Fourier transform infrared spectroscopy and X-ray diffraction indicated that curcumin was present in the nanoparticles in an amorphous form. The curcumin nanoparticles were unstable to aggregation at low pH values (<3) and high NaCl concentrations (>200 mM), which was attributed to a reduction in electrostatic repulsion between them. However, they were stable at higher pH values (3 to 8) and lower NaCl levels (0 to 200 mM), due to a stronger electrostatic repulsion between them. They also exhibited good stability during refrigerated storage (4 °C) or after conversion into a powdered form (lyophilized). A simulated gastrointestinal tract study demonstrated that the in vitro bioaccessibility was around 3.3-fold higher for curcumin nanoparticles than for free curcumin. Furthermore, oral administration to Sprague Dawley rats indicated that the in vivo bioavailability was around 8.9-fold higher for curcumin nanoparticles than for free curcumin. These results have important implications for the development of curcumin-enriched functional foods, supplements, and drugs.

Improving emulsion formation, stability and performance using mixed emulsifiers: A review

The formation, stability, and performance of oil-in-water emulsions may be improved by using combinations of two or more different emulsifiers, rather than an individual type. This article provides a review of the physicochemical basis for the ability of mixed emulsifiers to enhance emulsion properties. Initially, an overview of the most important physicochemical properties of emulsifiers is given, and then the nature of emulsifier interactions in solution and at interfaces is discussed. The impact of using mixed emulsifiers on the formation and stability of emulsions is then reviewed. Finally, the impact of using mixed emulsifiers on the functional performance of emulsifiers is given, including gastrointestinal fate, oxidative stability, antimicrobial activity, and release characteristics. This information should facilitate the selection of combinations of emulsifiers that will have improved performance in emulsion-based products.

Fabrication of Niclosamide loaded solid lipid nanoparticles: in vitro characterization and comparative in vivo evaluation

Niclosamide (NCS) is an oral anthelminthic drug having low solubility and hence low bioavailability. Current investigation shows an approach to fabricate solid lipid nanoparticles (SLNs) of NCS and evaluated for pharmaceutical, in vitro and in vivo characterization. NFM-3 showed particle size 204.2 ± 2.2 nm, polydispersity index 0.328 ± 0.02 and zeta potential -33.16 ± 2 mV. Entrapment efficiency and drug loading capacity were 84.4 ± 0.02% and 5.27 ± 0.03%, respectively. Scanning electron microscopy image indicated that particles were nanoranged. DSC and P-XRD results showed change in physicochemical properties of NCS. FT-IR spectra confirmed compatibility between NCS and excipients. The drug release profile showed sustained release (93.21%) of NCS in 12 h. Different kinetic models showed zero-order kinetics and Case-II transport mechanism. Study showed maximum stability at refrigerated temperature. In vivo pharmacokinetic study showed 2.15-fold increase in NCS peak plasma concentration as solid lipid nanoparticle formulation (NFM-3) compared to commercial product while relative bioavailability was 11.08. Results including in vitro and in vivo release studies of NCS confirmed that SLNs system is suitable to improve oral delivery of NCS with increased aqueous solubility, permeability and finally bioavailability.

Ultrafast Delivery of Aggregation-Induced Emission Nanoparticles and Pure Organic Phosphorescent Nanocrystals by Saponin Encapsulation

Saponins are a class of naturally occurring bioactive and biocompatible amphiphilic glycosides produced by plants. Some saponins, such as α-hederin, exhibit unique cell membrane interactions. At concentrations above their critical micelle concentration, they will interact and aggregate with membrane cholesterol to form transient pores in the cell membrane. In this project, we utilized the unique permeabilization and amphiphilic properties of saponins for the intracellular delivery of deep-red-emitting aggregation-induced emission nanoparticles (AIE NPs) and pure organic room-temperature phosphorescent nanocrystals (NCs). We found this method to be biocompatible, inexpensive, ultrafast, and applicable to deliver a wide variety of AIE NPs and NCs into cancer cells.

Formulation and characterization of O/W nanoemulsions encapsulating high concentration of astaxanthin

This study evaluates the effect of modified lecithin (ML) and sodium caseinate (SC) on the formulation, stability and bioaccessibility of astaxanthin (AXT) loaded oil-in-water (O/W) nanoemulsions. These nanoemulsions were formulated using high-pressure homogenization in four passes at 100MPa. The volume mean diameter (d_4,3) of nanoemulsions produced by ML and SC were 163±5 and 144±12 nm, respectively. The physiochemical stability of nanoemulsions was recorded at 25°C. The nanoemulsions prepared by ML were stable for 30 minutes against a wide range of pH and heating temperatures (60-120 °C). However, ML-stabilized nanoemulsions showed droplet growth when treated at high NaCl concentrations. In comparison, droplet growth was observed in SC-stabilized nanoemulsions at pH4 and at high temperature treatment. However, SC-stabilized nanoemulsions were stable at high NaCl concentration (500 mM). The SC-stabilized nanoemulsions showed good physical and chemical stability (>70%) after 30 days of storage. The bioaccessibility of AXT in nanoemulsions was significantly higher in ML (33%) than in SC-stabilized nanoemulsions (6%), indicating a strong influence of emulsifier on bioaccessibility. These findings provide valuable information in designing nutritional products such as aqueous based AXT fortified beverages.

Sugar Beet Extract (Beta vulgaris L.) as a New Natural Emulsifier: Emulsion Formation

The interfacial and emulsion-forming properties of sugar beet extract (Beta vulgaris L.) were examined and compared to a Quillaja extract that is widely used within the food industry. We investigated the influence of extract concentration on surface activity at oil-water and air-water interfaces and on the formation of oil-in-water emulsions (10% w/w, pH 7). Sugar beet extract reduced the interfacial tension up to 38% at the oil-water interface, and the surface tension up to 33% at the air-water surface. The generated emulsions were negatively charged (ζ ≈ -46 mV) and had the smallest particle sizes (d₄₃) of ∼1.3 μm at a low emulsifier-to-oil ratio of 0.75:10. Applying lower or higher extract concentrations increased the mean particle sizes. The smallest emulsions were formed at an optimum homogenization pressure of 69 MPa. Higher homogenization pressures led to increased particle sizes. Overall, sugar beet extract showed high surface activity. Furthermore, the formation of small emulsion droplets was successful; however, the droplets were bigger compared to those from the Quillaja extract. These results indicate sugar beet as an effective natural emulsifier that may be utilized for a variety of food and beverage applications.

Saponins - Self-assembly and behavior at aqueous interfaces

Saponins are interfacially active ingredients in plants consisting of a hydrophobic aglycone structure with hydrophilic sugar residues. Variations in aglycone structure as well as type and amount of sugar residues occur depending on the botanical origin. Saponins are a heterogeneous and broad class of natural substances and therefore the relationship between molecular structure and interfacial properties is complex and, yet, not completely understood. A wide range of research focused either on structural elucidation of saponins or interfacial properties. This review combines recent knowledge on structural features with interfacial properties and draws conclusions on how saponin structure affects interfacial properties. Fundamental understanding on interfacial configuration of individual saponin molecules at the interface distinctly increased. It was shown that interfacial configuration may differ depending on botanical origin and thus structure of the saponins. The formation of strong viscoelastic interfacial films by some saponins was attributed to hydrogen bonds between neighboring sugar residues. Few studies analyzed the relationship between botanical origin and interfacial rheology and derived main conclusions on important structural features. Saponins with a triterpenoid structure are most likely to form viscoelastic films, which result in stable foams and emulsions. The aglycone subtype may also affect interfacial properties as triterpenoid saponins of oleanane type formed most stable interfacial networks. But for more reliable conclusions more saponins from other aglycone subtypes (dammarane, ursolic) have to be analyzed. To-date only extracts from Quillaja saponaria Molina are approved for food products and many studies focused on these extracts. From experiments on interfacial rheology a reasonable model for supramolecular structure of Quillaja saponins was developed. It was further shown that Quillaja saponins may form micelles loaded with hydrophobic substances, nano-emulsions and stable foams. In combination proteins an increase in interfacial film stability may be observed but also negative phenomena like aggregation of oil droplets in emulsions may occur.

Recent Advances in the Utilization of Natural Emulsifiers to Form and Stabilize Emulsions

Consumer concern about human and environmental health is encouraging food manufacturers to use more natural and sustainable food ingredients. In particular, there is interest in replacing synthetic ingredients with natural ones, and in replacing animal-based ingredients with plant-based ones. This article provides a review of the various types of natural emulsifiers with potential application in the food industry, including phospholipids, biosurfactants, proteins, polysaccharides, and natural colloidal particles. Increased utilization of natural emulsifiers in food products may lead to a healthier and more sustainable food supply. However, more research is needed to identify, isolate, and characterize new sources of commercially viable natural emulsifiers suitable for food use.

Formulation and stability assessment of ergocalciferol loaded oil-in-water nanoemulsions: Insights of emulsifiers effect on stabilization mechanism

In the study, we investigated the effect of emulsifiers with different stabilizing mechanisms on the formulation and stability of ergocalciferol loaded oil-in-water (O/W) emulsions. O/W emulsion stabilized by modified lecithin (ML; electrostatic stabilization), sodium caseinate (SC; electrosteric stabilization) or decaglycerol monooleate (MO-7S; steric stabilization) were formulated using high-pressure homogenization. The Sauter mean diameter (d_3,2) of emulsions produced by ML, SC and MO-7S were 126±1, 127±4 and 138±3nm, respectively. The stability of resulting emulsions was evaluated when they exposed to different environmental stresses and during 30days of storage at 25 and 55°C. Results showed that the emulsions prepared by MO-7S or ML were stable against a wide range of pH (2-8), while SC-stabilized emulsions showed instability with extensive droplet aggregation at pH4 or and 5. Only ML-stabilized emulsions showed droplet growth due to coalescence when treated at high NaCl concentration (300-500mM). In the absence of glucose, SC-stabilized O/W emulsions showed better freeze-thaw stability, in comparison to those formed with ML or MO-7S emulsifiers. The emulsion produced by ML was found to be stable to droplet aggregation at heating temperatures (80-120°C) for 1h. All the O/W emulsions stored at 25°C showed good physical and chemical stability. However, the chemical stability of ergocalciferol in emulsion system decreased in order of ML>MO-7S≫SC during storage at 55°C for a period of 30days. These findings provide valuable information for the development of nanoemulsion-based delivery system applied in food and beverage products.

Saponin-Based Nanoemulsification Improves the Antioxidant Properties of Vitamin A and E in AML-12 Cells

Our work aimed to investigate the protective effects of saponin-based nanoemulsions of vitamin A and E against oxidative stress-induced cellular damage in AML-12 cells. Saponin nanoemulsions of vitamin A (SAN) and vitamin E (SEN) were prepared by high-pressure homogenization and characterized in terms of size, zeta potential, and polydispersity index. SEN and SAN protect AML-12 cells against oxidative stress-induced cellular damage more efficiently via scavenging reactive oxygen species (ROS), and reducing DNA damage, protein carbonylation, and lipid peroxidation. These results provide valuable information for the development of nanoemulsion-based delivery systems that would improve the antioxidant properties of vitamin A and E.

Natural emulsifiers - Biosurfactants, phospholipids, biopolymers, and colloidal particles: Molecular and physicochemical basis of functional performance

There is increasing consumer pressure for commercial products that are more natural, sustainable, and environmentally friendly, including foods, cosmetics, detergents, and personal care products. Industry has responded by trying to identify natural alternatives to synthetic functional ingredients within these products. The focus of this review article is on the replacement of synthetic surfactants with natural emulsifiers, such as amphiphilic proteins, polysaccharides, biosurfactants, phospholipids, and bioparticles. In particular, the physicochemical basis of emulsion formation and stabilization by natural emulsifiers is discussed, and the benefits and limitations of different natural emulsifiers are compared. Surface-active polysaccharides typically have to be used at relatively high levels to produce small droplets, but the droplets formed are highly resistant to environmental changes. Conversely, surface-active proteins are typically utilized at low levels, but the droplets formed are highly sensitive to changes in pH, ionic strength, and temperature. Certain phospholipids are capable of producing small oil droplets during homogenization, but again the droplets formed are highly sensitive to changes in environmental conditions. Biosurfactants (saponins) can be utilized at low levels to form fine oil droplets that remain stable over a range of environmental conditions. Some nature-derived nanoparticles (e.g., cellulose, chitosan, and starch) are effective at stabilizing emulsions containing relatively large oil droplets. Future research is encouraged to identify, isolate, purify, and characterize new types of natural emulsifier, and to test their efficacy in food, cosmetic, detergent, personal care, and other products.

Formation and stabilization of nanoemulsions using biosurfactants: Rhamnolipids

Nanoemulsions are used in the food, cosmetics, personal care and pharmaceutical industries to provide desirable optical, textural, stability, and delivery characteristics. In many industrial applications, it is desirable to formulate nanoemulsions using natural ingredients so as to develop label-friendly products. Rhamnolipids are biosurfactants isolated from certain microorganisms using fermentation processes. They are glycolipids that have a polar head consisting of rhamnose units and a non-polar tail consisting of a hydrocarbon chain. In this study, the interfacial characteristics of this natural surfactant at medium chain triglyceride (MCT) oil-water interfaces were characterized, and its ability to form nanoemulsions was compared to that of another natural surfactant (quillaja saponins). The influence of rhamnolipid concentration, homogenization pressure, and oil type on the mean droplet diameter of emulsions produced by microfluidization was determined. Rhamnolipids were highly effective at forming small droplets (d32<0.15μm) at low surfactant-to-oil ratios (SOR<1:10) for MCT oil. Rhamnolipids could also be used to form small droplets using long chain triglyceride oils, such as corn and fish oil. Rhamnolipid-coated droplets were stable to aggregation over a range of pH values (5-9), salt concentrations (<100mM NaCl) and temperatures (20-90°C). However, droplet aggregation was observed at highly acidic (pH 2-4) and high ionic strength (200-500mM NaCl) conditions. These effects were attributed to a reduction in electrostatic repulsion at low pH and high salt levels. Rhamnolipid-coated droplets had a high negative charge at neutral pH that decreased in magnitude with decreasing pH. These results indicate that rhamnolipids are effective natural surfactants that may be able to replace synthetic surfactants in certain commercial applications.

Plant-derived surfactants as an alternative to synthetic surfactants: surface and antioxidant activities

Biosurfactants have great advantages as an eco-friendly alternative to synthetic surfactants. Surface active properties and antioxidant activity of extracts prepared from

The influence of droplet size on the stability, in vivo digestion, and oral bioavailability of vitamin E emulsions

Vitamin E (α-tocopherol) is a nutraceutical compound, which has been shown to possess potent antioxidant and anticancer activity.

Fabrication of a nutrient delivery system of docosahexaenoic acid nanoemulsions via high energy techniques

A high energy nanoemulsification technique has been developed to encapsulate docosahexaenoic acid (DHA), with the major objective of enhancing its chemical and kinetic stability for a substantial storage period.