Thermal Degradation and Isomerization of β-Carotene in Oil-in-Water Nanoemulsions Supplemented with Natural Antioxidants

The construction of Moringa oleifera seed protein emulsion: in vitro digestibility and delivery of β-carotene

BACKGROUND

β-Carotene (BC) is difficult to apply effectively in the food industry due to its low solubility and bioavailability. This work aimed to fabricate Moringa oleifera seed protein (MOSP) stabilized emulsions as delivery vehicles for BC and investigate the effect of aqueous phase conditions including pH and ionic strength on this system.

RESULTS

All MOSP samples were positively charged and the particle size of MOSP increased with the increase of pH. At pH 5.0 and 0.2 mol L-1 sodium chloride (NaCl), the MOSP emulsion demonstrated the highest stability coefficient and minimal creaming index, while exhibiting a lower release rate in vitro digestion. The rheological behavior of all MOSP emulsions within the frequency range of 0.1-10 Hz was dominated by viscoelasticity, forming an elastic network structure through dispersed droplets. Additionally, the MOSP emulsion loaded with BC prepared at pH 5.0 and 0.2 mol L-1 NaCl displayed enhanced ultraviolet light stability (52.31 ± 0.03% and 51.86 ± 0.05%) as well as thermal stability (72.39 ± 8.67% and 86.78 ± 10.69%). Furthermore, the BC in the emulsion at pH 7.0 exhibited favorable stability (65.14 ± 0.02%) and optimal bioaccessibility (40.30 ± 0.04%) in vitro digestion.

CONCLUSION

The results provided reference data for utilizing MOSP as a novel emulsifier and broadening the application of BC in the food industry. © 2024 Society of Chemical Industry.

Pickering emulsions stabilized by ternary complexes involving curcumin-modified zein and polysaccharides with different charge amounts for encapsulating β-carotene

In this research, zein was modified with curcumin to obtain covalent and non-covalent complexes. They were further covered with polysaccharides (gum arabic or gum karaya) possessing different surface charge amounts to obtain ternary nanoparticles for preparing novel antioxidant Pickering emulsions. The addition of curcumin to the zein-polysaccharide system significantly retarded the UV degradation of the encapsulated β-carotene (maximum retention ∼ 97%) and effectively inhibited the lipid oxidation of the emulsions. In vitro gastrointestinal digestion assays showed that gum karaya significantly delayed the release of free fatty acids, thereby improving the bioaccessibility of β-carotene (the highest bioavailability ∼ 38%). By comparing the performance of the complex particles, the weakly charged polysaccharides were superior to the highly charged ones, while zein-curcumin covalent binding was superior to non-covalent binding in the above experiments. This study provides innovative perspectives on the use of novel Pickering emulsions to provide ideal protection and bioavailability of lipophilic nutraceuticals.

Enhancement of lycopene bioaccessibility in tomatoes using excipient emulsions: Effect of dark tea polysaccharides

This study fabricated a novel excipient emulsion by adding dark tea polysaccharides to improve the bioaccessibility of lycopene from tomatoes. Results indicated that addition of tea polysaccharides greatly increased the antioxidant activity of excipient emulsions. Additionally, tea polysaccharides markedly improved the physical stability of excipient emulsion when being mixed with tomato puree and passing through a simulated gastrointestinal tract, contributing to an increase in electrostatic and steric repulsion between the droplets. Besides, certain amount of tea polysaccharides (0.05 - 0.2 wt%) could increase the rate and extent of lipid digestion in tomato-emulsion mixtures. Finally, lycopene bioaccessibility was significantly increased (from 16.95 % to 26.21 %) when 0.1 wt% tea polysaccharides were included, which was mainly ascribed to the ability of tea polysaccharides to increase lipid digestion and reduce carotenoid oxidation within the gastrointestinal tract. These results suggest that well-designed excipient emulsions may increase carotenoids bioavailability in the complex food matrices.

Bibliometric analysis of articles on nanoemulsion and/or in-situ gel for ocular drug delivery system published during the 2011–2021 period

The bibliometric data were extracted from the Scopus database to investigate the conceptual framework of ocular nanoemulsion and/or in-situ gel drug delivery system using “ocular” AND “nanoemulsion” OR “in-situ gel” keywords. The data were evaluated with RStudio and VOSviewer program.

The results reveal that the publication trends tend to increase continually. India is the most impactful country, and the most constructive institution is Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Cairo University. International Journal of Pharmaceutics is the top influential source. Ali A is the most prolific author. The title of the most impactful article was In-situ gelling systems based on Pluronic F127/Pluronic F68 formulations for ocular drug delivery”. “Controlled release” is the most popular keyword.

These results provide insights for stimulating research collaborations and revealing open issues of controlled-release ocular preparation to overcome an ocular barrier and enhance patient compliance.

Fucoxanthin Loaded in Palm Stearin- and Cholesterol-Based Solid Lipid Nanoparticle-Microcapsules, with Improved Stability and Bioavailability In Vivo

Fucoxanthin (FX) is a marine carotenoid that has proven to be a promising marine drug due to the multiple bioactivities it possesses. However, the instability and poor bioavailability of FX greatly limit its application in pharmaceuticals or functional foods. In this study, the creative construction of a solid lipid nanoparticle-microcapsule delivery system using mixed lipids of palm stearin and cholesterol wrapped with gelatin/Arabic gum to load lipophilic FX was fabricated, aiming to improve the stability and bioavailability of FX. The results showed that the encapsulated efficiency (EE) and drug loading capacity (LC) of optimized FX microcapsules (FX-MCs) obtained were as high as 96.24 ± 4.60% and 0.85 ± 0.04%, respectively, after single-factor experiments. The average particle size was 1154 ± 54 nm with negative Zeta potential (−20.71 ± 0.93 mV) as depicted with size-zeta potential spectrometer. The differential scanning calorimeter (DSC) and thermogravimetric analyzer (TG) results indicated that FX-MC has a higher Tg and slower weight loss than FX monomers (FX crystal) and blank MCs. Besides, The Fourier transform infrared spectrometer (FTIR) confirmed the good double encapsulation of FX into the solid lipid and composite coacervate. Moreover, the encapsulated FX showed higher storage stability, sustained release (55.02 ± 2.80% release in 8 h), and significantly improved bioavailability (712.33%) when compared to free FX. The research results can provide a principle theoretical basis for the development and application of FX in pharmaceuticals or functional foods.

Structural modification of whey protein isolate by cinnamaldehyde and stabilization effect on β-carotene-loaded emulsions and emulsion gels

The effect of cinnamaldehyde (CA) on the structure and properties of whey protein isolate (WPI) was investigated. The resultant WPI/CA complex was used as stabilizer to form emulsions and emulsion gels, which were used for the delivery and protection of β-carotene. The particle size and hydrophobicity of WPI solution increased and then decreased with the addition of CA. Circular dichroism showed that CA mainly changed the secondary structure of WPI, with increasing β-fold content from 47.2% to 72.9%. The fluorescence spectra showed that both tryptophan and tyrosine in WPI were involved in the interaction with CA. WPI/CA complex as the stabilizer could form the stable emulsions and emulsion gels, which showed better protection effect on β-carotene, and helped enhance its bioaccessibility. The knowledge provides insights into the development of new multifunctional food ingredients and the enhancement of protein modification in food system.

Fabrication of chitosan-gallic acid conjugate for improvement of physicochemical stability of β-carotene nanoemulsion: Impact of Mw of chitosan

In this research, three various Mw of chitosan (CS)-gallic acid (GA) conjugates were synthesized, characterized, and used for improvement of physicochemical stability of β-carotene (BC) nanoemulsion (NE) by layer-by-layer technique. GA conjugation degrees were in the following order: HCS (125.6 mg/g) > MCS (102.3 mg/g) > LCS (74.6 mg/g) at GA:CS mass ratio of 0.5:1. Three varying Mw of CS-GA conjugates exhibited pronouncedly higher antioxidant abilities than native CS. For native CS, antioxidant abilities increased with the decrease of Mw. However, HCS-GA conjugate showed the highest antioxidant activity, due to the higher GA conjugation degrees and decreased intramolecular hydrogen bonds and crystallinity in HCS-GA conjugate. CS-GA conjugates substantially improved BC chemical stability in NE than CS and BC retentions were in the following order: HCS-GA (76.8%) > MCS-GA (68.3%) > LCS-GA (53.4%) after 30 days storage. The results obtained may provide some useful information for the applications of CS-GA conjugates for nutraceuticals stabilization in food systems.

Polysaccharide conjugates from Chin brick tea (Camellia sinensis) improve the physicochemical stability and bioaccessibility of β-carotene in oil-in-water nanoemulsions

A natural antioxidant emulsifier, tea polysaccharide conjugate (TPC), was isolated from Chin brick tea. The impact of TPC on β-carotene stability and bioaccessibility in oil-in-water nanoemulsions was assessed. TPC exhibited strong antioxidant activity and could be used to fabricate stable nanoemulsions (d < 140 nm). The extent of lipid digestion was considerably lower for lipid droplets coated by TPC (68%) than Tween 80 (94%) or whey protein isolate (WPI) (89%), probably because TPC formed interfacial layers that hindered the access of lipases to lipids. The chemical stability of β-carotene in TPC-nanoemulsions was markedly higher than in those formulated with Tween 80 or WPI due to the high antioxidant activity of TPC. The bioaccessibility of β-carotene (20-30%) was independent of emulsifier type. TPC from Chin brick tea can therefore be used as a dual-purpose functional ingredient in emulsified foods.

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.

Physicochemical stability and gastrointestinal fate of β-carotene-loaded oil-in-water emulsions stabilized by whey protein isolate-low acyl gellan gum conjugates

This study aimed to examine the effect of whey protein isolate-low acyl gellan gum (WPI-GG) conjugate on the physicochemical properties and digestibility of β-carotene-loaded oil-in-water emulsions. The WPI-GG conjugate-stabilized emulsions had lower droplet sizes with more homogenous distribution, more negative surface charge, and higher interfacial protein concentration and viscosity, compared to those stabilized by WPI-GG mixture and WPI. The emulsion droplets coated by the conjugate were also generally more stable to environmental stresses (i.e., storage, pH changes, ionic strength, freeze-thaw cycles, and thermal treatment) along with higher β-carotene retention than other systems. The stability to droplet aggregation during in vitro digestion was remarkably increased for the conjugate-stabilized emulsion. However, the β-carotene bioaccessibility was significantly affected when the conjugate was used to stabilize the emulsions, likely due to the thick interfacial layer, high viscosity, and negative charge of the corresponding emulsions that could inhibit droplet digestion and mixed micelle formation.

Preparation of 9Z-β-Carotene and 9Z-β-Carotene High-Loaded Nanostructured Lipid Carriers: Characterization and Storage Stability

Cis (Z)-β-carotenes with 25.3% 9Z-β-carotene were prepared for nanostructured lipid carriers (NLCs). The optimal conditions for NLC preparation using an orthogonal experimental method were as follows: the total lipid concentration was 9% (w/v), the surfactant concentration was 1.4% (w/v), the solid to liquid lipid ratio was 3:1 (w/w), and the homogenization pressure was set at 500 bar for three cycles. Under these conditions, the encapsulation efficiency (%) of the NLC was 95.64%, and the total β-carotene in NLCs was 2.9 mg/mL, which was significantly higher than those reported by others. The proportion of total Z-β-carotenes was as high as 53.3%, the particle size was 191 ± 6.46 nm, and the polydispersity index was 0.2 ± 0.03. Storage stability results indicated that the β-carotene-loaded NLC stabilizes both 9Z-β-carotene and total β-carotene from leakage and degradation during 21 days of storage at pH 3.5-7.5 at low temperatures (4 °C), especially for the more bioactive 9Z-β-carotene. The technique with an improved ratio of 9Z-β-carotene, loading capacity, water solubility, and bioaccessibility of the β-carotene NLC provides an effective strategy for β-carotene applications in functional foods or beverages and in nutraceutical preparations.

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.

The role of β-carotene and vitamin A in atherogenesis: Evidences from preclinical and clinical studies

Atherosclerotic cardiovascular disease (ASCVD) is the principal contributor to myocardial infarction, the leading cause of death worldwide. Epidemiological and mechanistic studies indicate that β-carotene and its vitamin A derivatives stimulate lipid catabolism in several tissues to reduce the incidence of obesity, but their roles within ASCVD are elusive. Herein, we review the mechanisms by which β-carotene and vitamin A modulate ASCVD. First, we summarize the current knowledge linking these nutrients with epidemiological studies and lipoprotein metabolism as one of the initiating factors of ASCVD. Next, we focus on different aspects of vitamin A metabolism in immune cells such as the mechanisms of carotenoid uptake and conversion to the vitamin A metabolite, retinoic acid. Lastly, we review the effects of retinoic acid on immuno-metabolism, differentiation, and function of macrophages and T cells, the two pillars of the innate and adaptive immune response in ASCVD, respectively. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.

A heat-stable microparticle platform for oral micronutrient delivery

Micronutrient deficiencies affect up to 2 billion people and are the leading cause of cognitive and physical disorders in the developing world. Food fortification is effective in treating micronutrient deficiencies; however, its global implementation has been limited by technical challenges in maintaining micronutrient stability during cooking and storage. We hypothesized that polymer-based encapsulation could address this and facilitate micronutrient absorption. We identified poly(butylmethacrylate-co-(2-dimethylaminoethyl)methacrylate-co-methylmethacrylate) (1:2:1) (BMC) as a material with proven safety, offering stability in boiling water, rapid dissolution in gastric acid, and the ability to encapsulate distinct micronutrients. We encapsulated 11 micronutrients (iron; iodine; zinc; and vitamins A, B2, niacin, biotin, folic acid, B12, C, and D) and co-encapsulated up to 4 micronutrients. Encapsulation improved micronutrient stability against heat, light, moisture, and oxidation. Rodent studies confirmed rapid micronutrient release in the stomach and intestinal absorption. Bioavailability of iron from microparticles, compared to free iron, was lower in an initial human study. An organotypic human intestinal model revealed that increased iron loading and decreased polymer content would improve absorption. Using process development approaches capable of kilogram-scale synthesis, we increased iron loading more than 30-fold. Scaled batches tested in a follow-up human study exhibited up to 89% relative iron bioavailability compared to free iron. Collectively, these studies describe a broad approach for clinical translation of a heat-stable ingestible micronutrient delivery platform with the potential to improve micronutrient deficiency in the developing world. These approaches could potentially be applied toward clinical translation of other materials, such as natural polymers, for encapsulation and oral delivery of micronutrients.

Lotus seedpod proanthocyanidin-whey protein complexes: Impact on physical and chemical stability of β-carotene-nanoemulsions

The impact of lotus seedpod proanthocyanidin (LSPC) on the functional properties of β-carotene-loaded whey-protein stabilized nanoemulsions was investigated. LSPC was selected because it is known to exhibit strong antioxidant activity, as well as having various health benefits. Physically stable nanoemulsions containing small anionic droplets (d < 0.15 μm; ζ = -27 mV) could be formed at pH 6.5 using whey protein-LSPC complexes as natural emulsifiers. The physical and chemical stabilities of the nanoemulsions were then measured when they were incubated at different pH values. LSPC addition promoted droplet aggregation at pH 4, but not at pH 3, 6.5, or 8, which was mainly attributed to its ability to reduce the electrostatic repulsion between the lipid droplets at pH 4. LSPC was shown to have stronger antioxidant activity than catechin and epicatechin. Our results show that the chemical stability of β-carotene nanoemulsions could be considerably improved by adding LSPC. We believe that LSPC-whey protein complexes can be used as effective emulsifiers and antioxidants in nutraceutical-loaded nanoemulsions, which may be useful for developing more efficacious functional foods and beverages.

Insights into Micellization of Octenylsuccinated Oat β-Glucan and Uptake and Controlled Release of β-Carotene by the Resultant Micelles

The core-shell structured micelles from octenylsuccinated oat β-glucan (OSβG) are able to solubilize β-carotene (βC). This study reveals molecular interactions governing the formation, stabilization, and βC uptake of OSβG micelles (OSβG-Ms) by means such as water contact angle, ¹H nuclear magnetic resonance, dynamic light scattering, and confocal laser scanning microscopy. The results indicated that the micellization of OSβG molecules is triggered by hydrophobic interactions between octenylsuccinate (OSA) moieties, while OSβG-Ms are stabilized via both hydrophobic interactions and hydrogen bonds. For their uptake of βC, βC molecules are first adsorbed onto OSβG-Ms by interacting with OSA moieties scattered on micelle surface. By further interacting with OSA moieties located in micelle shell, βC molecules travel across the shell and finally are trapped in the hydrophobic core. In simulated gastrointestinal fluids, βC is controlled released from OSβG-Ms as an integrated consequence of its diffusion as well as the swelling and erosion of OSβG-Ms. As a result, this study first uncovered the mechanism underlying the uptake of βC by OSβG-Ms, which will certainly facilitate the effective loading of hydrophobic ingredients by OSβG-Ms.

β-carotene in Obesity Research: Technical Considerations and Current Status of the Field

Over the past decades, obesity has become a rising health problem as the accessibility to high calorie, low nutritional value food has increased. Research shows that some bioactive components in fruits and vegetables, such as carotenoids, could contribute to the prevention and treatment of obesity. Some of these carotenoids are responsible for vitamin A production, a hormone-like vitamin with pleiotropic effects in mammals. Among these effects, vitamin A is a potent regulator of adipose tissue development, and is therefore important for obesity. This review focuses on the role of the provitamin A carotenoid β-carotene in human health, emphasizing the mechanisms by which this compound and its derivatives regulate adipocyte biology. It also discusses the physiological relevance of carotenoid accumulation, the implication of the carotenoid-cleaving enzymes, and the technical difficulties and considerations researchers must take when working with these bioactive molecules. Thanks to the broad spectrum of functions carotenoids have in modern nutrition and health, it is necessary to understand their benefits regarding to metabolic diseases such as obesity in order to evaluate their applicability to the medical and pharmaceutical fields.

Nutraceuticals' Novel Formulations: The Good, the Bad, the Unknown and Patents Involved

Traditional nutraceuticals and cosmeceuticals hold pragmatic nature with respect to their definitions, claims, purposes and marketing strategies. Their definitions are not well established worldwide. They also have different regulatory definitions and registration regulatory processes in different parts of the world. Global prevalence of nutraceuticals and cosmeceuticals is noticeably high with large market share with minimal regulation compared to traditional drugs. The global market is flooded with nutraceuticals and cosmeceuticals claiming to be of natural origin and sold with a therapeutic claim by major online retail stores such as Amazon and eBay. Apart from the traditional formulations, many manufacturers and researchers use novel formulation technologies in nutraceutical and cosmeceutical formulations for different reasons and objectives. Manufacturers tend to differentiate their products with novel formulations to increase market appeal and sales. On the other hand, researchers use novel strategies to enhance nutraceuticals and cosmeceuticals activity and safety. The objective of this review is to assess the current patents and research adopting novel formulation strategies in nutraceuticals and cosmeceuticals. Patents and research papers investigating nutraceutical and cosmeceutical novel formulations were surveyed for the past 15 years. Various nanosystems and advanced biotechnology systems have been introduced to improve the therapeutic efficacy, safety and market appeal of nutraceuticals and cosmeceuticals, including liposomes, polymeric micelles, quantum dots, nanoparticles, and dendrimers. This review provides an overview of nutraceuticals and cosmeceuticals current technologies, highlighting their pros, cons, misconceptions, regulatory definitions and market. This review also aims in separating the science from fiction in the nutraceuticals and cosmeceuticals development, research and marketing.

Stability and in vitro digestibility of beta-carotene in nanoemulsions fabricated with different carrier oils

Beta-carotene, the main dietary source of provitamin A, is required for maintaining optimum human health. The bioaccessibility of beta-carotene can be greatly improved when ingested with fat. Therefore, the aim of the current study was to select proper oils (palm oil, coconut oil, fish oil, and corn oil) as a carrier to form stable nanoemulsion that can effectively enhance the bioaccessibility of beta-carotene. The nanoemulsion was formulated with 90% (v/v) aqueous solution (2% whey protein isolate, WPI, w/v) and 10% (v/v) dispersed oil. The in vitro digestion experiment of nanoemulsions showed that the bioaccessibility of beta-carotene was as followed in order: palm oil = corn oil > fish oil > coconut oil (p < 0.05). The particle size of the nanoemulsion (initial particle size = 168-185 nm) was below 200 nm during 42 days' storage at 25°C. The retention rates of beta-carotene in nanoemulsions were 69.36%, 63.81%, 49.58%, and 54.91% with palm oil, coconut oil, fish oil, and corn oil, respectively. However, the particle size of the nanoemulsion increased significantly in the accelerated experiment at 55°C (p < 0.05), in which the retention rates of beta-carotene were 48.56%, 43.41%, 29.35%, and 33.60% with palm oil, coconut oil, fish oil, and corn oil, respectively. From above, we conclude that WPI-stabilized beta-carotene nanoemulsion with palm oil as the carrier is the most suitable system to increase bioaccessibility and stability of lipid-soluble bioactive compounds such as beta-carotene.

Fabrication of Resveratrol-Loaded Whey Protein-Dextran Colloidal Complex for the Stabilization and Delivery of β-Carotene Emulsions

The effects of resveratrol (RES)-loaded whey protein isolate (WPI)-dextran nanocomplex on the physicochemical stability of β-carotene (BC) emulsions were evaluated. WPI-dextran was prepared by Maillard-based glycation and confirmed with gel electrophoresis and OPA assay. WPI-RES and WPI-dextran-RES nanoparticles were prepared with a simple nanocomplexation protocol. Fluorescence spectra indicated that hydrophobic interaction was the main driving force for the WPI-dextran-RES nanocomplex. Spherical and uniformly dispersed structures as well as nanoscale Z-average size (<100 nm) were confirmed for WPI-RES and WPI-dextran-RES nanocomplex with DLS and TEM. The Z-average diameter of emulsions with WPI-dextran conjugate was remarkably lower than that with WPI. Environmental stress (ionic strength, heat, and pH) and storage stability were pronouncedly improved. The chemical stability of BC with WPI-dextran-RES and WPI-RES was also remarkably enhanced when exposed to UV light and thermal treatment. The advantages of the WPI-dextran-RES colloidal complex may provide a better alternative to effectively protect and deliver hydrophobic nutraceuticals.

Endocytosis of Corn Oil-Caseinate Emulsions In Vitro: Impacts of Droplet Sizes

The relative uptake and mechanisms of lipid-based emulsions of three different particle diameters by Caco-2 cells were studied. The corn oil-sodium caseinate emulsions showed little or no cytotoxicity even at 2 mg/mL protein concentration for any of the three droplet size emulsions. Confocal laser scanning microscopy (CLSM) of Nile red containing emulsions showed that the lipid-based emulsions were absorbed by Caco-2 cells. A negative correlation between the mean droplet size and cellular uptake was observed. There was a time-dependent and energy-dependent uptake as shown by incubation at different times and treatment with sodium azide a general inhibitor of active transport. The endocytosis of lipid-based emulsions was size-dependent. The internalization of nanoemulsion droplets into Caco-2 cells mainly occurred through clathrin- and caveolae/lipid raft-related pathways, while macropinocytosis route played the most important role for 556 nm emulsion endocytosis as shown by the use of specific pathway inhibitors. Permeability of the emulsion through the apical or basal routes also suggested that active transport may be the main route for lipid-based nanoemulsions. The results may assist in the design and application of lipid-based nanoemulsions in nutraceuticals and pharmaceuticals delivery.

Emulsion design for the delivery of β-carotene in complex food systems

β-Carotene has been widely investigated both in the industry and academia, due to its unique bioactive attributes as an antioxidant and pro-vitamin A. Many attempts were made to design delivery systems for β-carotene to improve its dispersant state and chemical stability, and finally to enhance the functionality. Different types of oil-in-water emulsions were proved to be effective delivery systems for lipophilic bioactive ingredients, and intensive studies were performed on β-carotene emulsions in the last decade. Emulsions are thermodynamically unstable, and emulsions with intact structures are preferable in delivering β-carotene during processing and storage. β-Carotene in emulsions with smaller particle size has poor stability, and protein-type emulsifiers and additional antioxidants are effective in protecting β-carotene from degradation. Recent development in the design of protein-polyphenol conjugates has provided a novel approach to improve the stability of β-carotene emulsions. When β-carotene is consumed, its bioaccessibility is highly influenced by the digestion of lipids, and β-carotene in smaller oil droplets containing long-chain fatty acids has a higher bioaccessibility. In order to better deliver β-carotene in complex food products, some novel emulsions with tailor-made structures have been developed, e.g., multilayer emulsions, solid lipid particles, Pickering emulsions. This review summarizes the updated understanding of emulsion-based delivery systems for β-carotene, and how emulsions can be better designed to fulfill the benefits of β-carotene in functional foods.

Antimicrobial Properties of 6-Bromoeugenol and Eugenol

We have studied the antimicrobial properties of 6-bromoeugenol and eugenol by three strains:Pseudomonas aeruginosa(S1),Escherichia coli(S2) andStaphylococcus aureus(S3). We have determined the minimum inhibitory concentration (MIC) for a range of concentrations using the disc diffusion method. We note that all samples present an antimicrobial activity toward the tested bacterial strains at different concentrations (1, 0.5 and 0.25 mg/ml). The 6-bromoeugenol gives modest activity with (S1) and (S3). Eugenol reacts positively with thePseudomonas aeruginosa(S1) at all concentrations and with theEscherichiacoli(S2) at 0.5 mg/ml. We remark that thePseudomonas aeruginosa(S1) is the more sensitive strain thanEscherichiacoli(S2) andStaphylococcus aureus(S3). We have estimated the activity coefficient which has confirmed the antimicrobial activity of the different samples. So, 6-bromoeugenol has shown his efficiency as antimicrobial agent.