Nanoemulsions of β-carotene using a high-energy emulsification–evaporation technique

Food grade nanoemulsions: promising delivery systems for functional ingredients

Nano-emulsions are receiving great attention in various industries, especially in the food sector. Peculiar properties of nano-sized droplets and high surface area are most suited for the development and delivery of functional ingredients. Nano-emulsions systems are suitable for encapsulation, protection, improving bioavailability, and target release of sensitive functional compounds. Nano-emulsions have promising potential for the delivery of nutraceuticals, probiotics, flavors, and colors. Nano-emulsions with active ingredients (antimicrobials) have a key part in ensuring food safety, nutrition, and quality of food. Nanoemulsions can also be used for biodegradable coating, packaging, antimicrobial coating, and quality and shelf life enhancement of different foods. The current review includes an overview of nanotechnology nano-emulsions, materials, techniques for formulation & production of nano-emulsions for food and nutrition. Furthermore, the analytical approaches used for the characterization of nano-emulsions and finally, the applications and limitations of nano-emulsions in the food industry are discussed in detail.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05387-3.

Carotenoid-Enriched Nanoemulsions and γ-Rays Synergistically Induce Cell Death in a Novel Radioresistant Osteosarcoma Cell Line

We previously demonstrated that SAOS human osteosarcoma cells, incubated with carotenoid-enriched nanoemulsions (CEN), activated a nonprotective form of autophagy and delayed cell proliferation. The present work focuses on the biological effects of CEN on a derivative of SAOS cells named SAOS400, recently described for their radiation resistance and higher expression of therapy-induced senescence (TIS) markers. SAOS400 cells, incubated with CEN, activated a “cytostatic” form of autophagy confirmed by cell cycle arrest in the G2/M phase and increased expression of autophagic proteins. Treatment of SAOS400 cells with CEN also resulted in decreased expression of the senescence marker p16INK4. However, when SAOS400 cells were γ-irradiated in combination with CEN, the threshold for cell death was reached (>60% after 96 h). We showed that this type of cell death corresponded to ‘cytotoxic’ or ‘lethal’ autophagy and that the combined treatment of CEN plus γ-rays was synergistic, with the combination index < 1. Since CEN contained β-carotene, the pure compound was used in SAOS400 cells at the same concentration present in CEN and up to 10 times higher. However, no radio-sensitizing effect of β-carotene was observed, suggesting that the biological effect of CEN was due to less abundant but more bioactive molecules, or to the synergistic activity of multiple components present in the extracts, confirming the functional pleiotropy of natural extracts enriched in bioactive molecules.

Recent progresses in the delivery of β-carotene: From nano/microencapsulation to bioaccessibility

Beta-carotene (BC) as an efficient pro-vitamin is effective in improving vision, immune system and cognitive function as well as preventing coronary diseases and cancer. However, besides its poor chemical stability, the high lipophilic nature of BC reduces its dispersibility and consequently bioavailability which limits its application into food, pharmaceutical and nutraceuticals. Different carriers with vesicular or particulate structures have been studied and utilized for promoting BC solubility, dispersibility, and protection against diverse operational or environmental stresses and also controlling BC release and subsequent bioaccessibility. The current study, therefore reviews different micro/nanocarriers reported on BC encapsulation with special focusing on its bioavailability. Liposomal structures have been successfully used for enhancing BC stability and bioavailability. Besides, emulsion-based carriers including Pickering emulsions, nanoemulsions and microemulsions have been widely evaluated for BC encapsulation and protection. In addition, lipid-based nanoparticles and nanostructural carriers have also been applied successfully for this context. Moreover, gel structures including emulgels, hydrogels and oleogels are studied in some researches. Most of these delivery systems led to higher hydro-solubility and dispersibility of BC which consequently increased its bioavailability; thereupon could promote its application into food, cosmetic and nutraceutical products. However, for remarkable incorporation of BC and other bioactive compounds into edible products, the safety and toxicological aspects of these delivery system especially those designed in nano scale should be addressed in the further researches.

Intravenous Nanocarrier for Improved Efficacy of Quercetin and Curcumin against Breast Cancer Cells: Development and Comparison of Single and Dual Drug-Loaded Formulations Using Hemolysis, Cytotoxicity and Cellular Uptake Studies

The present work highlights the suitability of an oil-based nanocarrier to deliver quercetin (Q) and curcumin (C) through the intravenous route for treatment of breast cancer. The nanoemulsion prepared by the modified emulsification-solvent evaporation method resulted in particle size (<30 nm), polydispersity index (<0.2), zeta potential (<10 mV), optimum viscosity, high encapsulation efficiency and drug loading for both drugs. The pH and osmolarity of the nanoemulsion were about 7.0 and 280 mOsm, respectively, demonstrated its suitability for intravenous administration. In-vitro release of drugs from all the formulations demonstrated initial fast release followed by sustained release for a period of 48 h. The fabricated single and dual drug−loaded nanoemulsion (QNE, CNE, QC-NE) exhibited moderate hemolysis at a concentration of 50 μg/mL. The % hemolysis caused by all the formulations was similar to their individual components (p ˃ 0.05) and demonstrated the biocompatibility of the nanoemulsion with human blood. In vitro cytotoxic potential of single and dual drug−loaded nanoemulsions were determined against breast cancer cells (MF-7). The IC50 value for QNE and CNE were found to be 40.2 ± 2.34 µM and 28.12 ± 2.07 µM, respectively. The IC50 value for QC-NE was 21.23 ± 2.16 µM and demonstrated the synergistic effect of both the drugs. The internalization of the drug inside MF-7 cells was detected by cellular uptake study. The cellular uptake of QNE and CNE was approximately 3.9-fold higher than free quercetin and curcumin (p < 0.0001). This strategically designed nanoemulsion appears to be a promising drug delivery system for the proficient primary preclinical development of quercetin and curcumin as therapeutic modalities for the treatment of breast cancer.

Use of jackfruit leaf (Artocarpus heterophyllus L.) protein hydrolysates as a stabilizer of the nanoemulsions loaded with extract-rich in pentacyclic triterpenes obtained from Coccoloba uvifera L. leaf

This study aimed to evaluate the encapsulating potential of a jackfruit leaf protein hydrolysate, through obtaining pentacyclic triterpenes-rich extract loaded nanoemulsion. Response surface methodology (RSM) was used to optimize the conditions to obtain an optimal nanoemulsion (NE-Opt). The effect of protein hydrolysate concentration (0.5-2%), oil loaded with extract (2.5-7.5%), and ultrasound time (5-15 min) on the polydispersity index (PDI) and droplet size of the emulsion (D[3,2] and D[4,3]) was evaluated. RSM revealed that 1.25% protein hydrolysate, 2.5% oil, and ultrasound time of 15 min produced the NE-Opt with the lowest PDI (0.85), D[3,2] (330 nm), and D[4,3] (360 nm). Encapsulation efficiency and extract loading of the NE-Opt was of 40.15 ± 1.46 and 18.03 ± 2.78% respectively. The NE-Opt was relatively stable during storage (at 4 and 25 °C), pH, temperature, and ionic strength. Then, the protein hydrolysate could be used as an alternative to conventional emulsifiers.

Recovery of β-carotene from pumpkin using switchable natural deep eutectic solvents

The aim of the present research was to develop green and sustainable extraction procedure for β-carotene recovery from pumpkin. A series of hydrophobic natural deep eutectic solvents (NADESs) based onfatty acids were prepared to establish high extraction efficiency of β-carotene and to increase stability of extracted carotenoids from the pumpkin. To intensify extraction process, NADES composed of C8 and C10 fatty acids (3:1) was selected and coupled with ultrasound assisted extraction. Response surface methodology and artificial neural network model (ANN) model was adopted to analyze significance of extraction parameters demonstrating high prediction levels of the β-carotene yield, experimentally confirming the maximum β-carotene content of 151.41 µg/mL at the optimal process condition. Extracted carotenoids in the optimal NADES extract have shown high stability during the storing period of 180 days. A switchable-hydrophilicity eutectic solvent system has been introduced as a successful way to recover extracted carotenoids from the NADES solvent. It was capable of precipitating 90% of carotenoids present in the extract. The proposed procedure is simple, easily scalable and has minimal impact on operators and the environment.

Encapsulation of Carotenoids as Food Colorants via Formation of Cyclodextrin Inclusion Complexes: A Review

The use of natural carotenoids as food colorants is an important trend of innovation in the industry due to their low toxicity, their potential as bio-functional ingredients, and the increasing demand for natural and organic foods. Despite these benefits, their inclusion in food matrices presents multiple challenges related to their low stability and low water solubility. The present review covers the main concepts and background of carotenoid inclusion complex formation in cyclodextrins as a strategy for their stabilization, and subsequent inclusion in food products as color additives. The review includes the key aspects of the molecular and physicochemical properties of cyclodextrins as complexing agents, and a detailed review of the published evidence on complex formation with natural carotenoids from different sources in cyclodextrins, comparing complex formation methodologies, recovery, inclusion efficiency, and instrumental characterization techniques. Moreover, process flow diagrams (PFD), based on the most promising carotenoid-cyclodextrin complex formation methodologies reported in literature, are proposed, and discussed as a potential tool for their future scale-up. This review shows that the inclusion of carotenoids in complexes with cyclodextrins constitutes a promising technology for the stabilization of these pigments, with possible advantages in terms of their stability in food matrices.

Food-Grade Nanoemulsions for the Effective Delivery of β-Carotene

Utilization of β-carotene in functional food products is limited due to chemical instability, lower water-solubility, and higher melting point. The present research was designed to formulate a nanoemulsion system for the effective delivery of β-carotene. β-Carotene was successfully incorporated into nanoemulsions using the ultrasonication method. During 60 days of storage, the droplet size of β-carotene-containing nanoemulsions varied from 112.36 to 133.9 nm at 4 °C and from 112.36 to 147.1 nm at 25 °C. The oxidation stability of olive oil was remarkably increased when incorporated into nanoemulsions. β-Carotene nanoemulsions remained stable under varying ionic strengths (50-400 mM), pH values (2-8), and freeze-thaw cycles (four). The values of turbidity and total color difference increased over time and at a higher temperature. Degradation of β-carotene was substantially slower in nanoemulsions, and the addition of antioxidants significantly increased the retention of β-carotene in nanoemulsions. These findings suggest that the ultrasonic homogenization method has potential for the preparation of β-carotene nanoemulsions with desirable properties. These nanoemulsions can be effectively used for the incorporation of β-carotene in the food and beverage industry.

Fate of β-Carotene within Loaded Delivery Systems in Food: State of Knowledge

Nanotechnology has opened new opportunities for delivering bioactive agents. Their physiochemical characteristics, i.e., small size, high surface area, unique composition, biocompatibility and biodegradability, make these nanomaterials an attractive tool for β-carotene delivery. Delivering β-carotene through nanoparticles does not only improve its bioavailability/bioaccumulation in target tissues, but also lessens its sensitivity against environmental factors during processing. Regardless of these benefits, nanocarriers have some limitations, such as variations in sensory quality, modification of the food matrix, increasing costs, as well as limited consumer acceptance and regulatory challenges. This research area has rapidly evolved, with a plethora of innovative nanoengineered materials now being in use, including micelles, nano/microemulsions, liposomes, niosomes, solidlipid nanoparticles, nanostructured lipids and nanostructured carriers. These nanodelivery systems make conventional delivery systems appear archaic and promise better solubilization, protection during processing, improved shelf-life, higher bioavailability as well as controlled and targeted release. This review provides information on the state of knowledge on β-carotene nanodelivery systems adopted for developing functional foods, depicting their classifications, compositions, preparation methods, challenges, release and absorption of β-carotene in the gastrointestinal tract (GIT) and possible risks and future prospects.

Combination of carotenoids from Spirulina and PLA/PLGA or PHB: New options to obtain bioactive nanoparticles

The use of poly-β-hydroxybutyrate (PHB) is an alternative polymer that can be considered environment friendly and renewable to prepare nanoparticles of carotenoids. This study aimed to develop and characterize aqueous dispersion nanoparticles and lyophilized nanoparticles of carotenoid extract obtained from Spirulina sp. LEB 18 by nanoprecipitation, using poly _d,l-lactic acid (PLA)/poly _d,l-lactic-co-glycolic acid (PLGA) (75:25 w/w) or PHB as encapsulants. The samples were characterized for the particle size, polydispersity index, zeta potential, apparent viscosity, pH, color parameters, ultraviolet-visible (UV/Vis) spectrophotometry, carotenoid profile, encapsulation efficiency, morphology, and thermal analysis. Nanoparticles containing microalgae carotenoid extract showed average particle diameter on a nanoscale (<200 nm), high homogeneity and stability, high thermal stability, and encapsulation efficiency carotenoid (>80%) when compared to nanoparticles containing β-carotene synthetic. PHB or PLA/PLGA as encapsulating material in the production of nanoparticles from microalgae carotenoids can be a polymeric alternative capable of promoting greater stability and application of carotenoids.

Dissolved-oxygen feedback control fermentation for enhancing β-carotene in engineered Yarrowia lipolytica

The DO-stat fed-batch fermentation was carried out to explore the volumetric productivity of β-carotene in engineered Yarrowia lipolytica C11 strain. Using DO-stat fed-batch fermentation, we achieved 94 g/L biomass and 2.01 g/L β-carotene. Both biomass and β-carotene were about 1.28-fold higher than that in fed-batch fermentation. The ATP, NADP+/NADPH, and gene expression levels of tHMG, GGS1, carRA, and carB were promoted as compared to that in fed-batch fermentation. As for as the kinetic parameters in DO-stat fed-batch fermentation, μm', Yx/s', and Yp/s' was 0.527, 0.353, and 0.158, respectively. The μm' was elevated 4.66-fold than that in fed-batch fermentation. These data illustrate that more dissolved oxygen increased the biomass. The Yx/s' and Yp/s' were increased 1.15 and 22.57-fold, which suggest that the DO-stat fed-batch fermentation reduced the Crabtree effect and improved the utilization rate of glucose. Therefore, DO-stat fed-batch fermentation is a promising strategy in the industrialized production of β-carotene.

The role of breadfruit OSA starch and surfactant in stabilizing high-oil-load emulsions using high-pressure homogenization and low-frequency ultrasonication

This study aimed to investigate the role of modified breadfruit starch in the presence of Tween 80 for stabilizing the oil-in-water emulsions. An ultra turrax homogenizer was used to produce coarse emulsions, followed by high-pressure homogenization (HPH) or low-frequency ultrasonication (LFU) for fine emulsions. The breadfruit starch was chemically modified using octenyl succinic anhydride (OSA) to produce modified breadfruit OSA starch (BOSA). The dispersed phase was a mixture of palm and lemon oil in a 9:1 ratio. Two BOSA (1% and 2%), three oil concentrations (10%, 25%, and 40%) and Tween 80 (1% of the total amount of oil) were examined based on the emulsion stability. The Fourier transform infrared spectroscopy (FTIR) indicated that starch modification was successful (Degree of Substitution-DS, 0.0241). The most stable coarse emulsions contained 40% oil and 2% BOSA starch. The same formula produced fine emulsions that remained stable for over 42 days, regardless of the homogenization method. BOSA starch and Tween 80 exhibit a mixed stabilization effect on the oil-in-water emulsions. HPH produced more uniformly sized emulsion droplets when compared with those produced using LFU.

One-Step Preparation of Z-Isomer-Rich β-Carotene Nanosuspensions Utilizing a Natural Catalyst, Allyl Isothiocyanate, via Supercritical CO2

This study aims to improve the production efficiency of β-carotene suspensions using a naturally occurring Z-isomerization-accelerating catalyst, allyl isothiocyanate (AITC), via supercritical CO2 (SC-CO2). Namely, utilizing solubility improvement of β-carotene with the Z-isomerization by adding AITC in the SC-CO2-used dispersion process, the encapsulation efficiency of β-carotene was enhanced. The dispersion of β-carotene was conducted by ultrasonic treatment, and there was no involvement of organic solvents in the whole process. When 100 mg of AITC was added in the dispersion process, the encapsulation efficiency (β-carotene content in resulting suspension) was approximately 3.5 times higher than that without addition of the catalyst. Moreover, the Z-isomer ratio of β-carotene in the suspensions significantly improved, that is, it was approximately 12 times higher than the raw β-carotene material. Since Z-isomers of β-carotene are known to have higher antiatherosclerotic and antiatherogenic activities compared to the all-E-isomer, this one-step method not only efficiently produces β-carotene suspensions without organic solvents but also enhances the bioactivities of them.

Nanoemulsions as delivery systems for lipophilic nutraceuticals: strategies for improving their formulation, stability, functionality and bioavailability

The food and beverage industry often need to encapsulate hydrophobic functional ingredients in their products, including colors, flavors, lipids, nutraceuticals preservatives, and vitamins. Encapsulation can improve the handling, water-dispersibility, chemically stability, and efficacy of these functional ingredients. In this review article, we focus on the design of nanoemulsion-based delivery systems to encapsulate, protect, and deliver non-polar bioactive agents, such as vitamin A, D and E, β-carotene, lycopene, lutein, curcumin, resveratrol, and coenzyme Q10. Initially, the challenges associated with incorporating these different bioactives into foods are highlighted. The relative merits and drawbacks of different nanoemulsion fabrication methods are then discussed. Finally, examples of the application of nanoemulsions for improving the stability and bioavailability of various kinds of hydrophobic vitamins and nutraceuticals are provided.

Facile methodology of nanoemulsion preparation using oily polymer for the delivery of poorly soluble drugs

Aqueous solubility of an active pharmaceutical ingredient (API) is a determining factor that has a direct impact on formulation strategies and overall bioavailability. Fabrication of nanoemulsions of poorly soluble drugs is one of the widely utilized approaches to overcome this problem. However, thermodynamic instability and tedious manufacturing processes of nanoemulsions limit their clinical translation. Therefore, this study was focused on circumventing the abovementioned hurdles by utilizing the polymer as an oil phase, instead of conventional oils. The nanoemulsion was prepared via a facile low-energy nanoprecipitation method using renewable poly(δ-decalactone) (PDL), as an oil phase and Pluronic F-68 as surfactant. The prepared nanoemulsions were characterized in terms of size, drug encapsulation efficiency, stability, and toxicity. Five different hydrophobic drugs were utilized to evaluate the drug delivery capability of the PDL nanoemulsion. The prepared nanoemulsions with sizes less than 200 nm were capable to enhance the aqueous solubility of the drugs by 3 to 10 times compared with the well-established Pluronic F-68 micelles. No phase separation or significant changes in size and drug content was observed with PDL nanoemulsions after high-speed centrifugation and 3 months of storage at two different temperatures (20 °C and 50 °C). PDL nanoemulsions were found to be non-heamolytic up to concentrations of 1 mg/mL, and the cell cytotoxicity studies on MDA-MB-231 and MEF cells suggest a concentration and time-dependent toxicity, where the PDL polymer itself induced no cytotoxicity. The results from this study clearly indicate that the PDL polymer has a tremendous potential to be utilized as an oil phase to prepare stable nanoemulsions via a facile methodology, ultimately favouring clinical translations.

Graphical abstract

Optimization the formulation parameters in preparation of α-tocopherol nanodispersions using low-energy solvent displacement technique

α-Tocopherol is the main compound of vitamin E with great antioxidant activity. However, like other functional lipid bioactive compounds, it suffers from low bioavailability due to its low water solubility and liable chemical structure. A bottom-up procedure based on a solvent-displacement method was constructed for fabrication of α-tocopherol nanodispersions using response surface methodology (RSM). The effects of main formulation parameters, namely, weight ratio of emulsifier to α-tocopherol and volumetric percent of acetone to water on the average particle size (nm), polydispersity index, concentration of α-tocopherol loss (% w/w) and turbidity of the nanodispersions were evaluated and optimized to gain the most desirable nanodispersions (least particle size, polydispersity index, turbidity and highest α-tocopherol concentrations). Second order regression equations, holding quite high coefficients of determination (R² and adjusted R² > 0.882), were significantly (p-value < 0.05) fitted for predicting the α-tocopherol nanodispersion characteristics variations as functions of studied formulation parameters. A multiple optimization analysis offered 6.5 and 10% for weight ratio of Tween 20 to α-tocopherol and volume percent of acetone, respectively, as overall optimum values for studied parameters. Statistically insignificant differences between experimental and predicted values of studied responses, verified the satisfactoriness of presented models for explaining the response characteristics as a function of formulation parameters. Thus, the employed solvent-displacement technique may provide the most desired water dispersible α-tocopherol nanoparticles for several water-based foods, cosmetic nutraceutical formulations.

Ultrasound-mediated fucoxanthin rich oil nanoemulsions stabilized by κ-carrageenan: Process optimization, bio-accessibility and cytotoxicity

This work aims to produce and optimize a κ-carrageenan-based nanoemulsion (NE) to encapsulate seaweed oil, which is rich in fucoxanthin (FX), using ultrasound-assisted emulsification. κ-Carrageenan was produced using subcritical water, and seaweed oil was extracted using supercritical carbon dioxide with sunflower oil as the co-solvent. Response surface methodology (RSM) was used to understand the influence of several process parameters such as ultrasound amplitude, time, temperature, and duty cycle to produce an NE. The RSM factor was used to focus on droplet size, polydispersity index, zeta potential, viscosity, antioxidant, FX, encapsulation efficiency, and emulsion stability. Our outcomes suggested that the ultrasound process had a noteworthy influence on the NE. The best conditions to obtain an NE were an ultrasound amplitude of 87 µm, a sonication time of 394 s, a temperature of 60 °C, and a duty cycle of 50%. The resulting NE was studied by UV-Vis, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, scanning electron microscopy, atomic force microscopy, and X-ray diffraction. Moreover, the NE obtained from optimized conditions was checked for fatty acid content, color, oxidative stability, in vitro digestion, bioaccessibility of FX, and cytotoxicity. The results obtained suggest that lower droplet size of the emulsion can improve oxidative stability, in vitro digestion, bioaccessibility of FX, and good cell inhibition against a few cell lines. Therefore, a κ-carrageenan-stabilized NE can be used as a potential delivery system to endorse applications of seaweed oil, which is rich in FX, in functional foods, beverage systems, and pharmaceuticals.

Improved Carotenoid Processing with Sustainable Solvents Utilizing Z-Isomerization-Induced Alteration in Physicochemical Properties: A Review and Future Directions

Carotenoids—natural fat-soluble pigments—have attracted considerable attention because of their potential to prevent of various diseases, such as cancer and arteriosclerosis, and their strong antioxidant capacity. They have many geometric isomers due to the presence of numerous conjugated double bonds in the molecule. However, in plants, most carotenoids are present in the all-E-configuration. (all-E)-Carotenoids are characterized by high crystallinity as well as low solubility in safe and sustainable solvents, such as ethanol and supercritical CO₂ (SC-CO₂). Thus, these properties result in the decreased efficiency of carotenoid processing, such as extraction and emulsification, using such sustainable solvents. On the other hand, Z-isomerization of carotenoids induces alteration in physicochemical properties, i.e., the solubility of carotenoids dramatically improves and they change from a “crystalline state” to an “oily (amorphous) state”. For example, the solubility in ethanol of lycopene Z-isomers is more than 4000 times higher than the all-E-isomer. Recently, improvement of carotenoid processing efficiency utilizing these changes has attracted attention. Namely, it is possible to markedly improve carotenoid processing using safe and sustainable solvents, which had previously been difficult to put into practical use due to the low efficiency. The objective of this paper is to review the effect of Z-isomerization on the physicochemical properties of carotenoids and its application to carotenoid processing, such as extraction, micronization, and emulsification, using sustainable solvents. Moreover, aspects of Z-isomerization methods for carotenoids and functional difference, such as bioavailability and antioxidant capacity, between isomers are also included in this review.

Innovative functional nanodispersion: Combination of carotenoid from Spirulina and yellow passion fruit albedo

The nanoencapsulation of carotenoids is presented as a positive alternative to broaden the application of these pigments in the food industry. In this study, we investigated the use of yellow passion fruit albedo flour as an encapsulating material for the production of nanodispersions of carotenoid extract obtained from Spirulina sp. LEB 18. Nanodispersions were characterized for their physicochemical properties, antioxidant activity, stability, and retention of carotenoids after 60 days of storage (4 °C). The nanodispersions made from yellow passion fruit albedo flour and microalgae carotenoid extract presented an average particle diameter at the nanometer scale, high antioxidant activity, and carotenoid retention compared to nanodispersions containing synthetic β-carotene. Yellow passion fruit albedo flour as a polymeric material in the production of carotenoid nanodispersions is an alternative to commercial polymers and allows greater stability and broader application of these pigments.

Ostwald Ripening Rate of Orange Oil Emulsions: Effects of Molecular Structure of Emulsifiers and Their Oil Composition

Ostwald ripening, one of the frequently observed instability of flavor oil emulsions, can be easily prevented by adding triacylglycerols to the oil phase. The effect of interfacial characteristics of the emulsion droplets (particularly thickness) on the effectiveness of triacylglycerol inhibition of Ostwald ripening was evaluated in this study. The prepared emulsions were stabilized with emulsifiers with different-size hydrophilic groups, which correlate to droplet interfacial thickness. Emulsions with an oil phase of pure orange oil were unstable due to Ostwald ripening. Modifying the oil phase by adding corn oil or medium-chain triacylglycerol (MCT) effectively inhibited droplet growth. Thicker and less dense droplet surfaces in the emulsions required more triacylglycerol, regardless of its type, to resist Ostwald ripening. When the oil phase contained the same amounts of triacylglycerols, MCT was more effective at inhibiting Ostwald ripening than corn oil. Compared with corn oil, MCT more effectively inhibited Ostwald ripening of the emulsions containing micelles. PRACTICAL APPLICATIONS: When food and beverage industries produce food products containing flavor or essential oils vulnerable to Ostwald ripening as emulsion forms, the findings in this work could provide useful information on the interfacial engineering of emulsions and on how to modify the oil compositions of emulsions using triacylglycerols to improve the stability of these emulsions against Ostwald ripening.

A systematic review on nanoencapsulation of food bioactive ingredients and nutraceuticals by various nanocarriers

Today, there is an ever-growing interest on natural food ingredients both by consumers and producers in the food industry. In fact, people are looking for those products in the market which are free from artificial and synthetic additives and can promote their health. These food bioactive ingredients should be formulated in such a way that protects them against harsh process and environmental conditions and safely could be delivered to the target organs and cells. Nanoencapsulation is a perfect strategy for this situation and there have been many studies in recent years for nanoencapsulation of food components and nutraceuticals by different technologies. In this review paper, our main goal is firstly to have an overview of nanoencapsulation techniques applicable to food ingredients in a systematic classification, i.e., lipid-based nanocarriers, nature-inspired nanocarriers, special-equipment-based nanocarriers, biopolymer nanocarriers, and other miscellaneous nanocarriers. Then, application of these cutting-edge nanocarriers for different nutraceuticals including phenolic compounds and antioxidants, natural food colorants, antimicrobial agents and essential oils, vitamins, minerals, flavors, fish oils and essential fatty acids will be discussed along with presenting some examples in each field.

Preparation and characterization of nanoemulsion based β-carotene hydrogels

The aim of this study was to develop β-carotene hydrogels using nanoemulsions, with increased β-carotene aqueous solubility, bioavailability and improved physical and chemical stabilities. The nanoemulsion of β-carotene was prepared using a solvent-displacement technique and converted into hydrogels using sodium alginate as stabilizer and calcium chloride as cross-linker. The effects of formulation parameters, mainly, the effects sodium alginate and calcium chloride concentrations on the physicochemical properties of hydrogels were evaluated using a surface response methodology. The second order polynomial equations, subsequently, were suggested to predict the changes of studied physicochemical characteristics of hydrogels, with relatively high regression of coefficients values. Based on numerical multiple optimization, it was concluded that using 4.1 g/l sodium alginate and 5.7 g/l calcium chloride, resulted in a hydrogel with the most desired physicochemical characteristics. No significant differences between the measured and predicted data, reconfirmed the accuracy of the models.

Influence of Oxidants on the Stability of Tocopherol in Model Nanoemulsions: Role of Interfacial Membrane Organized by Nonionic Emulsifiers

Nanoemulsions were prepared by using emulsifiers with various sizes of hydrophilic and hydrophobic groups to determine the impact of interfacial characteristics on the stability of α-tocopherol incorporated into the nanoemulsions. The α-tocopherol concentration remaining after 3 weeks of storage at 25°C depended greatly on the type of oxidative stress, which indicated that the environment surrounding the oil droplets could determine the stability of α-tocopherol in nanoemulsions. α-Tocopherol was gradually degraded by radical-mediated oxidation over storage, and approximately 60% of its initial concentration remained after 3 weeks of storage. However, under acid- and iron-mediated oxidation, α-tocopherol concentration steeply decreases for the initial 3-day storage, but the degradation rate of α-tocopherol decreased after 3 days of storage and over 90% of the initial α-tocopherol remained after 3 weeks of storage. Interestingly, and contrary to our expectations, the thickness and/or density of the droplet interfacial membrane rarely affected the stability of α-tocopherol incorporated into nanoemulsions. Although it is difficult to generalize beyond α-tocopherol, we conclude that the properties of oil droplet surfaces had no influence on the storage stability of α-tocopherol encapsulated in the droplets.

Nanodispersions of beta-carotene: effects on antioxidant enzymes and cytotoxic properties

Beta-carotene is a carotenoid precursor of vitamin A, known for its biological activities. Due to its high hydrophobicity, nanonization processes, i.e. the transformation into nanoparticles, can improve its water affinity, and therefore the activity in aqueous systems. The objective of this study was to produce beta-carotene nanoparticles by the solid dispersion method and to evaluate their effects on the activity of glutathione-S-transferase and acetylcholinesterase enzymes using Drosophila melanogaster (DM) homogenate, the superoxide dismutase- and catalase-like activities under in vitro conditions, and their cytotoxic properties against tumor and non-tumor cells. The formed nanometric beta-carotene particles resulted in stable colloids, readily dispersed in water, able to modulate acetylcholinesterase (AChE) activity, and presenting high potential to control the cholinergic system. Beta-carotene nanoparticles, at concentrations much lower than the pure pristine beta-carotene, presented in vitro mimetic activity to superoxide dismutase and altered glutathione-S-transferase activity in DM tissue. The content of hydrogen peroxide was neither affected by the nanoparticles (in aqueous solution) nor by pristine beta-carotene (in DMSO). In the cytotoxic assays, beta-carotene nanoparticles dispersed in water showed activity against four different tumor cell lines. Overall, beta-carotene nanoparticles presented significant bioactivity in aqueous medium surpassing their high hydrophobicity constraint.