Preparation of HIPEs with controlled droplet size containing lutein

Nanoemulsification of soybean oil using ultrasonic microreactor: Process optimization, scale-up and numbering-up in series

Ultrasonically-induced nanoemulsions have been widely investigated for the development of functional food, cosmetics, and pharmaceuticals due to ideal droplet sizes (DS), low polydispersity index (PDI), and superior physical stability. However, a series of frequently-used ultrasonic set-ups mainly suffered from a low ultrasonic energy efficiency caused by the large acoustic impedance and energy consumption, subordinately confronted with a low throughput, complicated fabrication with complex structure and weak ultrasonic cavitation. Herein, we employed a typical ultrasonic microreactor (USMR) that ensured the high-efficient energy input and generated intense cavitation behavior for efficient breakage of droplets and continuous production of unified oil-in-water (O/W) nanoemulsions in a single cycle and without any pre-emulsification treatment. The emulsification was optimized by tuning the formula indexes, technological parameters, and numerical analysis using Response Surface Methodology (RSM), followed by a comparison with the emulsification by a traditional ultrasonic probe. The USMR exhibited superior emulsification efficiency and easy scale-up with remarkable uniformity by series mode. In addition, concurrent and uniform nanoemulsions with high throughput could also be achieved by a larger USMR with high ultrasonic power. Based on RSM analysis, uniform DS and PDI of 96.4 nm and 0.195 were observed under the optimal conditions, respectively, well consistent with the predicted values. Impressively, the optimal nanoemulsions have a uniform spherical morphology and exhibited superior stability, which held well in 45 days at 4℃ and 25℃. The results in the present work may provide a typical paradigm for the preparation of functional nanomaterials based on the novel and efficient emulsification tools.

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.

Preparation of Water-in-Oil Nanoemulsions Loaded with Phenolic-Rich Olive Cake Extract Using Response Surface Methodology Approach

In this study, we aimed to prepare stable water-in-oil (W/O) nanoemulsions loaded with a phenolic-rich aqueous phase from olive cake extract by applying the response surface methodology and using two methods: rotor-stator mixing and ultrasonic homogenization. The optimal nanoemulsion formulation was 7.4% (w/w) of olive cake extract as the dispersed phase, and 11.2% (w/w) of a surfactant mixture of polyglycerol polyricinoleate (97%) and Tween 80 (3%) in Miglyol oil as the continuous phase. Optimum results were obtained by ultrasonication for 15 min at 20% amplitude, yielding W/O nanoemulsion droplets of 104.9 ± 6.7 nm in diameter and with a polydispersity index (PDI) of 0.156 ± 0.085. Furthermore, an optimal nanoemulsion with a droplet size of 105.8 ± 10.3 nm and a PDI of 0.255 ± 0.045 was prepared using a rotor-stator mixer for 10.1 min at 20,000 rpm. High levels of retention of antioxidant activity (90.2%) and phenolics (83.1-87.2%) were reached after 30 days of storage at room temperature. Both W/O nanoemulsions showed good physical stability during this storage period.

Grape seed proanthocyanidin-loaded gel-like W/O/W emulsion stabilized by genipin-crosslinked alkaline soluble polysaccharides-whey protein isolate conjugates: Fabrication, stability, and in vitro digestion

The present work aims to fabricate the genipin-crosslinked alkaline soluble polysaccharides-whey protein isolate conjugates (G-AWC) to stabilize W/O/W emulsions for encapsulation and delivery of grape seed proanthocyanidins (GSP). After crosslinking reaction, the molecular weight was increased and surface hydrophobicity was decreased. Then, the G-AWC and polyglycerol polyricinoleate (PGPR, a lipophilic emulsifier) were employed to prepare a GSP-loaded W/O/W emulsion with the addition of gelatin and sucrose in W₁ phase via a two-step procedure. Creamed emulsion could be fabricated at W₁/O volume fraction (Φ) of 10%-70% and further increased Φ to 75% or even up to 90% could obtain gel-like emulsion with notably elastic behaviors. In the W₁/O/W₂ emulsion with Φ of 80%, the encapsulation efficiency (EE) of GSP reached up to 95.86%, and decreased by ca. 10% after a week of storage. Moreover, the encapsulated GSP in the emulsion showed a remarkably higher bioaccessibility (40.72%) compared to free GSP (13.11%) in the simulated gastrointestinal digestion. These results indicated that G-AWC-stabilized W/O/W emulsions could be an effective carrier to encapsulate water-soluble bioactive compounds with enhanced stability and bioaccessibility.

Simultaneous encapsulation of trans-resveratrol and vitamin D3 in highly concentrated double emulsions

BACKGROUND

Encapsulation of biocompounds is essential to protect them from environmental factors that could enhance their oxidation or cause them to lose their beneficial properties due to extreme photosensitivity, among other factors. The main goal of this work was to study the feasibility of preparing concentrated double emulsions with a high loading capacity containing simultaneously trans-resveratrol (RSV) and vitamin D₃ (VitD₃ ). Such emulsions could be used for food fortification or pharmaceutical formulations or as vehicles for targeted controlled release.

RESULTS

In order to achieve large concentrations of the encapsulated compounds, all the double emulsions were formulated using a W₁ /O in W₂ ratio of 80/20, while the ratios tested for W₁ in O where 20/80 and 30/70. All the emulsions were characterized by droplet size, morphology, colloidal stability and encapsulation efficiency (EE) over a period of 6 weeks. VitD₃ and RSV concentration were determined by a technique based on reverse-phase high-performance liquid chromatography. The viability of preparing concentrated W₁ /O/W₂ emulsions containing both biocompounds has been demonstrated with satisfactory results. Initial RSV concentrations in the concentrated double emulsions formulated varied from 5.0 to 8.3 mg L^-1 , while for VitD₃ values of 28-32 mg L^-1 were obtained. The presence of VitD₃ retarded RSV release in the formulated emulsions. It was observed that after 1 week of storage RSV EE increased around 10-50% when VitD₃ was simultaneously encapsulated.

CONCLUSION

Simultaneous encapsulation of RSV and VitD₃ was possible in high internal phase emulsions. The emulsions presented high colloidal stability, being suitable for food fortification applications. © 2020 Society of Chemical Industry.

Resveratrol loaded Pickering emulsions stabilized by OSA modified rice starch granules

Resveratrol is a photosensitive, bioactive molecule which has received increasing research interest during the past decade for its antioxidant properties. However, it has low solubility in water or common triglyceride oils. Resveratrol solubilization in oil can only be achieved in essential oils, such as flavour oils, but the stability of emulsions produced with this type of oils is low as they are prone to creaming phenomena and Oswald ripening. In this study, resveratrol was first dissolved in orange oil which was mixed into a medium-chain triglyceride (Miglyol) at different ratios and used as the internal phase of oil-in-water emulsions (O/W). The emulsions were stabilized by octenyl succinic anhydride (OSA) modified rice starch granules using two different ratios of starch particle:oil to study the influence of interfacial coverage on the final emulsion droplet size and emulsion stability. The results of this study indicated that stable Pickering emulsions could be prepared using OSA-modified rice starch granules even at partial coverage conditions. Emulsions prepared at an oil fraction of 0.5 using 30% v/v mixture of orange oil in Miglyol as the dispersed phase seemed to be an appropriate resveratrol carrier system, obtaining encapsulation efficiency values close to 90% which results in emulsions with a resveratrol concentration of 8.45 mg/L. Hence, the emulsions prepared are suitable for food fortification applications.

Microemulsion Synthesis of Superparamagnetic Nanoparticles for Bioapplications

Superparamagnetic nanoparticles have seen increased potential in medical and environmental applications. Their preparation is traditionally made by the coprecipitation method, with limited control over the particle size distribution. Microemulsion methods could be advantageous due to the efficient control of the size, shape, and composition of the nanoparticles obtained. Water-in-oil (W/O) microemulsions consist of aqueous microdomains dispersed in a continuous oil phase, stabilized by surfactant molecules. These work as nanoreactors where the synthesis of the desired nanoparticles takes place through a co-precipitation chemical reaction. In this work, superparamagnetic magnetite nanoparticles with average diameters between 5.4 and 7.2 nm and large monodispersity have been synthesized through precipitation in a W/O microemulsion, with Cetyl Trimethyl Ammonium Bromide (CTAB) as a main surfactant, 1-butanol as a cosurfactant, and with 1-hexanol as the continuous oily phase. The optimization of the corresponding washing protocol has also been established since a strict control is required when using these materials for bioapplications. Their applicability in those has been proved by their encapsulation in liposomes, being tested as signal enhancers for lateral flow immunoassays by using the affinity neutravidin-biotin model system. Due to their magnetic behaviour, they were also tested for magnetic separation. These novel materials have been found to be useful for analytical applications requiring high sensitivity and the removal of interferences.

Enhancing trans-Resveratrol loading capacity by forcing W1/O/W2 emulsions up to its colloidal stability limit

Trans-Resveratrol (3, 5, 4'-trihydroxystilbene) is a naturally occurring polyphenol easily oxidizable and extremely photosensitive with a short biological half-life that must be encapsulated to maintain its beneficial properties on the human body. The aim of this work is to increase the amount of resveratrol encapsulated using concentrated double water-in-oil-in-water (W₁/O/W₂) emulsions, making these systems more interesting as ingredient for functional food products and/or pharmaceutical formulations. The concentration of the inner emulsion (W₁/O) for several external (W₁O/W₂) ratios was optimized in terms of encapsulation efficiency (EE), colloidal stability and rheological behaviour. W₁/O emulsions formulated with ratios of 30/70 and 40/60 were used to obtain double emulsions (with ratios of 20/80 up to 80/20 of W₁O/W₂). Trans-Resveratrol EE increased up to 90 % when the most concentrated double emulsions were prepared for both W₁/O ratios tested. The maximum resveratrol concentrations on double emulsions were 10.8 mg/L and 14.4 mg/L when 30/70 and 40/60 of W₁/O ratios were used, respectively. However, longer time stability was found for double high internal phase emulsions (W₁O/W₂) with a ratio of 30/70 of W₁/O. The double emulsion formulated with a 80/20 W₁O/W₂ volumetric ratio together with 30/70 of W₁/O seems suitable to be used as ingredient for pharmaceutical and food devices/products due to its high colloidal stability, clearly pseudoplastic and elastic behaviour, high EE and large trans-Resveratrol carrier capacity.

Methyl Methacrylate HIPE Solely Stabilized by Fluorinated Di-block Copolymer for Fabrication of Highly Porous and Interconnected Polymer Monoliths

Preparation of stable water-in-oil (W/O) high internal phase emulsion (HIPE) containing methyl methacrylate (MMA) monomer as oil phase is a difficult task due to the significant solubility of MMA in water. Here, for the first time a fluorinated di-block copolymer (FDBC) poly (2-dimethylamino)ethylmethacrylate-b-poly (trifluoroethyl methacrylate) (PDMAEMA-b-PTFEMA) is proposed to stabilize HIPEs of MMA without the use of any co-stabilizer or thickening agent. Fluorinated segments in FDBC anchored well at oil/water interface of HIPE, offering high hydrophobicity to the partially hydrophilic MMA monomer and in turn stabilization to MMA-HIPE. By using fluorinated di-block copolymer as stabilizer, highly stable HIPEs can be obtained. In addition, highly interconnected porous monoliths were obtained after free radical polymerization, which are highly desirable materials in various practical applications including tissue engineering scaffolds, separation science, bio-engineering and so on. The as-prepared MMA-HIPEs possess high thermal stability without phase separation. The textural characteristics of as-prepared composites, such as pore size and distribution, can be easily controlled by simply varying the amount of FDBC and/or dispersed phase fraction. Moreover, the influence of di-block concentration on water uptake (WU) capability of the prepared porous monoliths is explored.

Microencapsulation of lutein by spray-drying: Characterization and stability analyses to promote its use as a functional ingredient

Lutein, a xanthophyll, is associated to decreased risk of age-related macular degeneration, atherosclerosis and other diseases (Bovier et al., 2013; El-raey, Ibrahim, & Eldahshan, 2013). When lutein is extracted, it becomes highly unstable, reducing its functionality as an antioxidant. The aim of this research was to improve the stability of lutein using maltodextrin, arabic gum and a modified starch, to obtain micro-particles using spray-drying. Each of the formulations was characterized in terms of yield, encapsulation efficiency, particle size distribution, water activity and moisture content. The formulations with arabic gum (100%) and arabic gum:maltodextrin:modified starch (33.3:33.3:33.3%), with encapsulation efficiencies of 91.94 ± 6.88 and 65.72 ± 0.93%, respectively, were selected to study stability at 45 °C and 75% RH (relative humidity). Based on our results, encapsulation could be considered as an alternative for the generation of high value-added functional ingredients that can be used in different industries.

Comparative Emulsifying Properties of Octenyl Succinic Anhydride (OSA)-Modified Starch: Granular Form vs Dissolved State

The emulsifying ability of OSA-modified and native starch in the granular form, in the dissolved state and a combination of both was compared. This study aims to understand mixed systems of particles and dissolved starch with respect to what species dominates at droplet interfaces and how stability is affected by addition of one of the species to already formed emulsions. It was possible to create emulsions with OSA-modified starch isolated from Quinoa as sole emulsifier. Similar droplet sizes were obtained with emulsions prepared at 7% (w/w) oil content using OSA-modified starch in the granular form or molecularly dissolved but large differences were observed regarding stability. Pickering emulsions kept their droplet size constant after one month while emulsions formulated with OSA-modified starch dissolved exhibited coalescence. All emulsions stabilized combining OSA-modified starch in granular form and in solution showed larger mean droplet sizes with no significant differences with respect to the order of addition. These emulsions were unstable due to coalescence regarding presence of free oil. Similar results were obtained when emulsions were prepared by combining OSA-modified granules with native starch in solution. The degree of surface coverage of starch granules was much lower in presence of starch in solution which indicates that OSA-starch is more surface active in the dissolved state than in granular form, although it led to unstable systems compared to starch granule stabilized Pickering emulsions, which demonstrated to be extremely stable.

Lutein-enriched emulsion-based delivery systems: Influence of pH and temperature on physical and chemical stability

Lutein may be utilized in foods as a natural pigment or nutraceutical ingredient to improve eye health. Nevertheless, its use is limited by its poor water-solubility and chemical instability. We evaluated the effect of storage temperature and pH on the physical and chemical stability of lutein-enriched emulsions prepared using caseinate. The emulsions (initial droplet diameter=232 nm) remained physically stable at all incubation temperatures (5-70 °C); however the chemical degradation of lutein increased with increasing temperature (activation energy=38 kJ/mol). Solution pH had a major impact on the physical stability of the emulsions, causing droplet aggregation at pH 4 and 5. Conversely, the chemical stability of lutein was largely independent of the pH, with only a slight decrease in degradation at pH 8. This work provides important information for the rational design of emulsion-based delivery systems for a lipophilic natural dye and nutraceutical.

Formulation of resveratrol entrapped niosomes for topical use

A new approach to the formulation of resveratrol (RSV) entrapped niosomes for topical use is proposed in this work. Niosomes were formulated with Gelot 64 (G64) as surfactant, and two skin-compatible unsaturated fatty acids (oleic and linoleic acids), commonly used in pharmaceutical formulations, as penetration enhancers. Niosomes were prepared by two different methods: a thin film hydration method with minor modifications followed by a sonication stage (TFH-S), and an ethanol injection modified method (EIM). Niosomes prepared with the EIM method were in the range of 299-402 nm, while the TFH-S method produced larger niosomes in the range of 293-496 nm. Moreover, niosomes with higher RSV entrapment efficiency (EE) and better stability were generated by the EIM method. Ex vivo transdermal experiments, carried out in Franz diffusion cells on newborn pig skin, indicated that niosomes prepared by the EIM method were more effective for RSV penetration in epidermis and dermis (EDD), with values up to 21% for both penetration enhancers tested. The EIM method, which yielded the best RSV-entrapped niosomes, seems to be the most suitable for scaling up.