Encapsulation of hydrophobic capsaicin within the aqueous phase of water-in-oil high internal phase emulsions: Controlled release, reduced irritation, and enhanced bioaccessibility

Enhanced bioaccessibility of interfacial delivered oleanolic acid through self-constructed Pickering emulsion: Effects of oil types

Pentacyclic triterpenes have attracted much attention because of their many bioactivities, but their bioaccessibility is low. Oleanolic acid (OA) was used in this study as a typical edible pentacyclic triterpene. In this work, we proposed an OA interfacial delivery model based on W/O Pickering emulsion, and investigated the effects of different oil types on the emulsion properties and OA bioaccessibility of the OA W/O Pickering emulsion interfacial delivery system (EIDS). Medium chain triglyceride (MCT), long chain triglycerides (LCT) and MCT/LCT (1:1, w/w) were selected as carrier oils for the preparation of emulsions, respectively. The results showed that the emulsions formed from LCT had smaller particle sizes, which increased the deformation resistance of the emulsions and exhibited good stability during the simulated in vitro digestion. The extent of free fatty acid (FFA) release during oil digestion was MCT (103.32 ± 3.74 %) > M/L (97.89 ± 2.89 %) > LCT (71.41 ± 6.64 %). Of interest, the bioaccessibility of OA was influenced by the carrier oil: LCT (59.34 ± 2.55 %) > M/L (47.35 ± 6.25 %) > MCT (13.11 ± 1.40 %) ＞ PBS (7.11 ± 1.74 %), and such a difference was mainly attributed to the greater solubilisation of OA in mixed micelles consisting of long-chain fatty acids. In summary, the size of hydrophobic domains in the mixed micelles produced a greater effect than the effect of FFA release on OA bioaccessibility. This study provides a theoretical basis for the interfacial delivery of OA and the enhancement of OA bioaccessibility based on W/O Pickering emulsions with different oil types.

Chitosan-based food-grade Pickering emulsion loading with Rosa roxburghii extract against precancerous lesions of gastric carcinoma

Precancerous lesions of gastric carcinoma (PLGC) are the most important stage in the development of gastric cancer, accompanied by significant oxidative stress and inflammatory response. Rosa roxburghii extract (RRE) has unique advantages in anti-PLGC due to its multi-component, high antioxidant and anti-inflammatory activities. However, the astringency and instability of RRE in the digestive tract seriously hinder its clinical application. Herein, we report a chitosan-based food-grade Pickering emulsion (PE) for loading RRE to block unpleasant taste, improve stability, and promote the entry of RRE into gastric epithelial cells through the gastric adhesion of chitosan, thereby enhancing preventive and therapeutic effects against PLGC. This Pickering emulsion is constructed as a water-in-oil (W/O) emulsion stabilized by the food-grade nanoparticles composed of soybean protein isolate (SPI) and chitosan (CS) through electrostatic interaction (defined as RRE@PE). The experimental results showed that RRE@PE performed better efficacy against PLGC than RRE by scavenging or inhibiting reactive oxygen species generation and reducing inflammatory cytokines. This Pickering emulsion enhances the application potential of RRE and is expected to be used for the treatment of clinical patients with PLGC.

Differences in the Chromogenic Effect of Corn Starch and Potato Starch on Paprika Red Pigment and Structural Characterisation

The present study aims to investigate the chromogenic effect and the interaction between starch-pigment complexes of corn starch (CS) and potato starch (PS) complexed with paprika red pigment. Compared to PS, CS showed 12.5 times higher adsorption capacity for paprika red pigment. Additionally, the a* value of CS-P (26.90 ± 0.23) was significantly higher than that of PS-P (22.45 ± 1.84), resulting in a corn starch-paprika red pigment complex (CS-P) with a more intense red colour. The addition of paprika red pigment significantly decreased the particle size and porosity of CS by 48.14 ± 5.29% and 17.01 ± 3.80%, respectively. Conversely, no significant impact on PS was observed. Additionally, the Fourier transform infrared (FT-IR) spectroscopy results revealed that the starch molecules and paprika red pigment were bound to each other through strong hydrogen bonds. X-diffraction (XRD) results indicated that the starch-paprika red pigment complexes have a V-shaped structure. Furthermore, the relative crystallinity of the complexes between starch and red pepper pigment showed an increasing trend, however, the relative crystallinity of CS increased significantly by 11.77 ± 0.99-49.21 ± 3.67%. Consequently, the CS-P colouring was good.

Capsaicin-loaded alginate nanoparticles embedded polycaprolactone-chitosan nanofibers as a controlled drug delivery nanoplatform for anticancer activity

Nanocarrier-based drug delivery systems have been designed into various structures that can effectively prevent cancer progression and improve the therapeutic cancer index. However, most of these delivery systems are designed to be simple nanostructures with several limitations, including low stability and burst drug release features. A nano-in-nano delivery technique is explored to address the aforementioned concerns. Accordingly, this study investigated the release behavior of a novel nanoparticles-in-nanofibers delivery system composed of capsaicin-loaded alginate nanoparticles embedded in polycaprolactone-chitosan nanofiber mats. First, alginate nanoparticles were prepared with different concentrations of cationic gemini surfactant and using nanoemulsion templates. The optimized formulation of alginate nanoparticles was utilized for loading capsaicin and exhibited a diameter of 19.42 ± 1.8 nm and encapsulation efficiency of 98.7 % ± 0.6 %. Likewise, blend polycaprolactone-chitosan nanofibers were prepared with different blend ratios of their solutions (i.e., 100:0, 80:20, 60:40) by electrospinning method. After the characterization of electrospun mats, the optimal nanofibers were employed for embedding capsaicin-loaded alginate nanoparticles. Our findings revealed that embedding capsaicin-loaded alginate nanoparticles in polycaprolactone-chitosan nanofibers, prolonged capsaicin release from 120 h to more than 500 h. Furthermore, the results of in vitro analysis demonstrated that the designed nanoplatform could effectively inhibit the proliferation of MCF-7 human breast cells while being nontoxic to human dermal fibroblasts (HDF). Collectively, the prepared nanocomposite drug delivery platform might be promising for the long-term and controlled release of capsaicin for the prevention and treatment of cancer.

Covalent Bond Interfacial Recognition of Polysaccharides/Silica Reinforced High Internal Phase Pickering Emulsions for 3D Printing

Significant challenges remain in designing sufficient viscoelasticity polysaccharide-based high internal phase Pickering emulsions (HIPPEs) as soft materials for 3D printing. Herein, taking advantage of the interfacial covalent bond interaction between modified alginate (Ugi-OA) dissolved in the aqueous phase and aminated silica nanoparticles (ASNs) dispersed in oil, HIPPEs with printability were obtained. Using multitechniques coupling a conventional rheometer with a quartz crystal microbalance with dissipation monitoring, the correlation between interfacial recognition coassembly on the molecular scale and the stability of whole bulk HIPPEs on the macroscopic scale can be clarified. The results showed that Ugi-OA/ASNs assemblies (NPSs) were strongly retargeted into the oil-water interface due to the specific Schiff base-binding between ASNs and Ugi-OA, further forming thicker and more rigid interfacial films on the microscopic scale compared with that of the Ugi-OA/SNs (bared silica nanoparticles) system. Meanwhile, flexible polysaccharides also formed a 3D network that suppressed the motion of the droplets and particles in the continuous phase, endowing the emulsion with appropriately viscoelasticity to manufacture a sophisticated "snowflake" architecture. In addition, this study opens a novel pathway for the construction of structured all-liquid systems by introducing an interfacial covalent recognition-mediated coassembly strategy, showing promising applications.

Stability, oxidizability, and topical delivery of resveratrol encapsulated in octenyl succinic anhydride starch/chitosan complex-stabilized high internal phase Pickering emulsions

High internal phase Pickering emulsions (HIPPEs) stabilized with octenyl succinic anhydride starch/chitosan complexes were examined as a topical delivery vehicle for resveratrol. All resveratrol-loaded HIPPEs showed stable gel-like network structures, with the droplet size and microrheological properties largely dependent on the complex concentrations. HIPPEs exhibited strong stability when subjected to light, high temperature, UV radiation and freeze-thaw treatment, and resveratrol retention was greatly improved with the increasing addition of complexes and resveratrol. High amounts of resveratrol facilitated the antioxidant activity of HIPPEs, whereas sustained release of resveratrol was mainly related to the existence of complex interfacial layers. Moreover, HIPPEs overcome the stratum corneum barrier, with an approximately 3-5-fold increase in resveratrol deposition in deep skin compared to bulk oil. In conclusion, the emulsion composition (especially at the particle level) was vital for the effectiveness of HIPPEs as a carrier, which may provide new opportunities to design topical delivery systems.

Physicochemical and functional properties of capsaicin loaded cricket protein isolate and alginate complexes

As people become more aware of the health benefits of foods and their nutritional benefits for preventing diseases and promoting health, the demand for functional foods rich in proteins, fiber, and bioactives like capsaicin (CAP) is constantly rising. This study hypothesized that the electrostatic complexes developed by cricket protein isolate (CPI) and alginate (AL) could be utilized to encapsulate CAP, making it more water-soluble and protecting it at acidic pHs. Quantitative analysis revealed that CAP was efficiently encapsulated into the CPI-AL complexes with a maximum encapsulation efficiency of 91%, improving its aqueous solubility 45-fold. In vitro release tests showed that CAP was retained at acidic pHs (3.0 and 5.0) in CPI-AL complexes but released steadily at neutral pH (7.4), which will protect CAP in the stomach while enabling its release in the small intestine. Moreover, the antioxidant activity of CAP-CPI-AL complexes was superior to that of their individual bare equivalents. The complexes also demonstrated enhanced emulsifying capabilities and stability at acidic pHs (2.0-5.0) as the CPI fraction in the complexes increased. Our findings thus contribute to the growing body of knowledge that validates protein-polysaccharide complexation as a promising strategy for developing edible delivery systems.

Capsaicin encapsulated in W/O/W double emulsions fabricated via ethanol-induced pectin gelling: Improvement of bioaccessibility and reduction of irritation

Capsaicin is a water-insoluble bioactive component with several beneficial physiological functions. However, the widespread application of this hydrophobic phytochemical is limited by its low water-solubility, intense irritation, and poor bioaccessibility. These challenges can be overcome by entrapping capsaicin within the internal water phase of water-in-oil-in-water (W/O/W) double emulsions via using ethanol to induce pectin gelling. In this study, ethanol was used both to dissolve capsaicin and to promote pectin gelation, thereby forming capsaicin-loaded pectin hydrogels that were used as the internal water phase of the double emulsions. Pectin addition improved the physical stability of the emulsions and led to a high encapsulation efficiency of capsaicin (>70 % after 7d storage). After simulated oral and gastric digestion, capsaicin-loaded double emulsions maintained their compartmentalized structure, avoiding capsaicin leakage in the month and stomach. The double emulsions were digested in the small intestine, thereby releasing the capsaicin. Capsaicin bioaccessibility was significantly enhanced after encapsulation, which was attributed to mixed micelle formation by the digested lipid phase. Furthermore, encapsulation of capsaicin within the double emulsions reduced the irritation in the gastrointestinal tissues of mice. This kind of double emulsion may have great potential for the development of more palatable capsaicin-loaded functional food products.

Research progress of water-in-oil emulsion gelated with internal aqueous phase: gel factors, gel mechanism, application fields, and future direction of development

The W/O emulsion is a promising system. Its special structure can keep the sensory properties of fat while reducing the fat content. Improving the stability and physical properties of W/O emulsions is generally oriented toward outer oil-phase modified oil gels and inner water-phase modified inner hydrogels. In this paper, the research progress of internal aqueous gel was reviewed, and some gel factors suitable for internal aqueous gel and the gel mechanism of main gel factors were discussed. The advantages of this internal aqueous gel emulsion system allow its use in the field of fat substitutes and encapsulating substances. Finally, some shortcomings and possible research directions in the future were proposed, which would provide a theoretical basis for the further development of internal water-phase gelled W/O emulsion in the future.

Targeting Tumor Microenvironment by Metal Peroxide Nanoparticles in Cancer Therapy

Solid tumors have a unique tumor microenvironment (TME), which includes hypoxia, low acidity, and high hydrogen peroxide and glutathione (GSH) levels, among others. These unique factors, which offer favourable microenvironments and nourishment for tumor development and spread, also serve as a gateway for specific and successful cancer therapies. A good example is metal peroxide structures which have been synthesized and utilized to enhance oxygen supply and they have shown great promise in the alleviation of hypoxia. In a hypoxic environment, certain oxygen-dependent treatments such as photodynamic therapy and radiotherapy fail to respond and therefore modulating the hypoxic tumor microenvironment has been found to enhance the antitumor impact of certain drugs. Under acidic environments, the hydrogen peroxide produced by the reaction of metal peroxides with water not only induces oxidative stress but also produces additional oxygen. This is achieved since hydrogen peroxide acts as a reactive substrate for molecules such as catalyse enzymes, alleviating tumor hypoxia observed in the tumor microenvironment. Metal ions released in the process can also offer distinct bioactivity in their own right. Metal peroxides used in anticancer therapy are a rapidly evolving field, and there is good evidence that they are a good option for regulating the tumor microenvironment in cancer therapy. In this regard, the synthesis and mechanisms behind the successful application of metal peroxides to specifically target the tumor microenvironment are highlighted in this review. Various characteristics of TME such as angiogenesis, inflammation, hypoxia, acidity levels, and metal ion homeostasis are addressed in this regard, together with certain forms of synergistic combination treatments.

Progress in the Application of Food-Grade Emulsions

The detailed investigation of food-grade emulsions, which possess considerable structural and functional advantages, remains ongoing to enhance our understanding of these dispersion systems and to expand their application scope. This work reviews the applications of food-grade emulsions on the dispersed phase, interface structure, and macroscopic scales; further, it discusses the corresponding factors of influence, the selection and design of food dispersion systems, and the expansion of their application scope. Specifically, applications on the dispersed-phase scale mainly include delivery by soft matter carriers and auxiliary extraction/separation, while applications on the scale of the interface structure involve biphasic systems for enzymatic catalysis and systems that can influence substance digestion/absorption, washing, and disinfection. Future research on these scales should therefore focus on surface-active substances, real interface structure compositions, and the design of interface layers with antioxidant properties. By contrast, applications on the macroscopic scale mainly include the design of soft materials for structured food, in addition to various material applications and other emerging uses. In this case, future research should focus on the interactions between emulsion systems and food ingredients, the effects of food process engineering, safety, nutrition, and metabolism. Considering the ongoing research in this field, we believe that this review will be useful for researchers aiming to explore the applications of food-grade emulsions.

Detection of indigenous gut bacteria related to red chilli pepper (Capsicum annuum) in murine caecum and human faecal cultures

BACKGROUND

Red chilli pepper (Capsicum annuum; RP) is a popular spice containing the active compound capsaicin. Indigenous gut bacteria and metabolism can affect host health. The functions of capsaicin, including the regulation of metabolic health and anti-oxidant properties, may be correlated with the gut microbiota.

METHODS

To identify indigenous gut bacteria that are responsive to RP, Institute of Cancer Research mice fed a diet with no fibre or with 5% (w/w) RP for 14 days. Additionally, human stool samples collected from four healthy volunteers were incubated without (control) or with 2% (w/v) RP at 37 °C for 24 h. Microbiota in murine caecal samples and human faecal cultures were analysed using 16S rRNA (V4) amplicon sequencing.

RESULTS

Compared with the microbiota in mice fed no-fibre diets, Lachnospiraceae spp.-, Muribaculaceae spp.-, and Phacaeicola vulgatus-like bacteria were defined as murine RP-responsive indigenous gut bacteria (RP-RIB). In the human faecal cultures, acetate and propionate levels were higher in RP cultures than in the control cultures. Subdoligranulum spp.-, Blautia spp.-, Faecalibacterium prausnitzii-, P. vulgatus-, and Prevotella copri-like bacteria were defined as human RP-RIB. Compared with control culture Fe-reducing power was increased in the culture with RP.

CONCLUSION

RP increases the amount of short-chain fatty acid-producing bacteria and beneficial gut bacteria in mouse and human faecal cultures. Overall, RP could have a positive effect on the host by altering the gut microbiota.

Intestinal-targeted nanotubes-in-microgels composite carriers for capsaicin delivery and their effect for alleviation of Salmonella induced enteritis

Salmonella is a word-wide food-borne pathogen, which can cause severe enteritis and intestinal microbiota imbalance. Capsaicin (Cap), a food-based bioactive ingredient, has antibacterial and anti-inflammatory properties. However, its low solubility, low bioavailability and the irritation to digestive tract greatly limit its applications. Here, an intestinal responsively "nanotubes-in-microgel" composite carrier was constructed by capturing α-lactalbumin (α-lac) nanotubes in low-methoxy pectin microgels (LMP-NT) (52 μm). Cap was loaded in such system via hydrophobic interaction with a loading capacity of 38.02 mg/g. The LMP microgels remained stable and protected NT/Cap from early releasing in the gastric condition. It showed an excellent mucoadhesive capacity, which can prolong the intestinal retention up to 12 h and control release NT/Cap in intestine. Afterward, NT/Cap could penetrate across the mucus layer deeply and enter the intestinal villi epithelial cells efficiently. LMP-NT microgels achieved a mucoadhesive-to-penetrating transition in response to intestinal pH, improving the epithelium absorption and the in vivo bioavailability of Cap. Oral administration of LMP-NT/Cap could effectively alleviate enteritis caused by Salmonella infection and maintain the homeostasis of gut microbiota. Overall, this work suggested that LMP-NT composite microgels were promising for intestine-targeted and oral delivery of hydrophobic bioactive food compounds.

Biopolymer-Based Multilayer Microparticles for Probiotic Delivery to Colon

The potential health benefits of probiotics may not be realized because of the substantial reduction in their viability during food storage and gastrointestinal transit. Microencapsulation has been successfully utilized to improve the resistance of probiotics to critical conditions. Owing to the unique properties of biopolymers, they have been prevalently used for microencapsulation of probiotics. However, majority of microencapsulated products only contain a single layer of protection around probiotics, which is likely to be inferior to more sophisticated approaches. This review discusses emerging methods for the multilayer encapsulation of probiotic using biopolymers. Correlations are drawn between fabrication techniques and the resultant microparticle properties. Subsequently, multilayer microparticles are categorized based on their layer designs. Recent reports of specific biopolymeric formulations are examined regarding their physical and biological properties. In particular, animal models of gastrointestinal transit and disease are highlighted, with respect to trials of multilayer microencapsulated probiotics. To conclude, novel materials and approaches for fabrication of multilayer structures are highlighted.

One-Step Encapsulation of Capsaicin into Chitosan-Oleic Acid Complex Particles: Evaluation of Encapsulation Ability and Stability

Capsaicin (CAP) demonstrates a potential for application in the food and pharmaceutical industries owing to its various attractive health benefits, including anti-cancer, anti-inflammatory, and antioxidant activities. However, the application of CAP is often limited by its low solubility in water, low bioavailability, and strong pungency. In this study, a simple one-step method for the stable encapsulation and dispersion of CAP in aqueous media was developed using polyelectrolyte complex particles formed by chitosan (CHI) and oleic acid (OA). Homogeneous particles with mean diameters below 1 μm were successfully prepared via spontaneous molecular complexation by mixing an aqueous solution of CHI with an ethanolic solution of OA and CAP. CAP was incorporated into the hydrophobic domains of the CHI-OA complex particles through hydrophobic interactions between the alkyl chains of OA and CAP. The factors affecting CAP encapsulation were investigated, and a maximum encapsulation yield of approximately 100% was obtained. The CHI-OA-CAP complex particles could be stored for more than 3 months at room temperature (22-26 °C) without resulting in macroscopic phase separation or degradation of CAP. We believe that our findings provide a useful alternative encapsulation technique for CAP and contribute to expanding its practical application.

Octenyl Succinic Acid Starch-Stabilized Vanilla Essential Oil Pickering Emulsion: Preparation, Characterization, Antioxidant Activity, and Storage Stability

Applications for vanilla essential oil extracted from vanilla pods have been limited since the effective components of vanilla could be easily influenced by environmental factors, such as temperature, light, and oxygen, which hinder their effectiveness. In this study, vanilla essential oil was encapsulated in a Pickering emulsion with octenyl succinic acid starch (OSA—starch). The optimal process conditions for emulsion preparation were determined as 5% vanilla essential oil phase with 2.5% OSA—starch when they were ultrusonicated for 3 min at 470 W. Under these conditions, the minimum particle size was 0.456 μm, the oil droplets were completely encased by starch, and no new chemical bonds were formed. The smallest particle size was produced at a pH of 4 and 500 mM ion concentration. The antioxidant activity of the emulsion was greater than that of the pure vanilla oil at the same oil content. After 24 h storage, the antioxidant activity of the emulsion was enhanced, and the vanilla essential oil was slowly released in the emulsion. These results indicated that the vanilla essential oil encapsulated in a Pickering emulsion with octenyl succinic acid starch showed its tremendous potential for use in the food industry.

Encapsulation of bitter peptides in water-in-oil high internal phase emulsions reduces their bitterness and improves gastrointestinal stability

Many peptides exhibit beneficial physiological functions, but their application in foods is limited because of their undesirable taste and their tendency to degrade when exposed to gastrointestinal conditions. In this study, water-in-oil high internal phase emulsions (W/O HIPEs) were used to encapsulate bitter peptides. A combination of confocal fluorescence and electron microscopy was used to confirm the formation of W/O HIPEs. The presence of high concentrations of bitter peptides increased the apparent shear viscosity, shear modulus and sedimentation stability. They also improved the oxidative stability of the HIPEs. Electronic-tongue and sensory analysis showed that encapsulated peptides within the HIPEs substantially reduced their bitterness. Moreover, a simulated gastrointestinal study showed that W/O HIPEs protected peptides from being released in the stomach. Our results show that W/O HIPEs can be used to mask the bitterness and improve the gastrointestinal stability of peptides, which may increase their utilization as bioactive ingredients in foods.

Highly Sensitive Capsaicin Electrochemical Sensor Based on Bimetallic Metal-Organic Framework Nanocage

The content of capsaicin can be used as exotic markers of kitchen recycled oil. In this study, a bimetallic MOF nanocage (Fe^III-HMOF-5) was successfully prepared by a one-step solvothermal method and used for electrode modification to prepare a highly sensitive electrochemical sensor for rapid detection of capsaicin. Capsaicin could be selectively immobilized onto the Fe^III-HMOF-5 surface during infiltrating adsorption, thus exhibiting very excellent sensing performance. The detection conditions of the sensor were optimized. Under optimum conditions, the electrochemical sensor can linearly detect capsaicin in the range between 1–60 μM with a detection limit of 0.4 μM. In addition, the proposed electrochemical sensor showed excellent stability and selectivity. The real sample tests indicated the proposed electrochemical sensor was comparable to conventional UV spectrophotometry.

Applications of capsaicin in food industry: functionality, utilization and stabilization

As a bioactive component in Capsicum species, capsaicin is a compound of hot chili peppers which is known as the main substance responsible for the spiciness of these fruits. Besides its taste and physiological effects, it exhibits good antioxidant activity in food matrix and antimicrobial activity against foodborne pathogens and viruses. Considering its low stability and bioaccessibility, and also regarding its irritation, the entrapment methods of capsaicin are fully developed. To compensate the limitations of capsaicin, various encapsulation methods have been used so far, including coacervation, emulsion, spray chilling, and liposomal delivery. Capsaicin has been widely used as a flavoring and preservative agent in food formulations and even as an active compound in packaging film and functional foods. This review provides an overview of the techno-functional properties, stabilization procedures, and burgeoning usages of capsaicin in the latest studies of the food sector. So, it may introduce new windows for the application of this compound.