Synergistic stabilization of a menthol Pickering emulsion by zein nanoparticles and starch nanocrystals: Preparation, structural characterization, and functional properties

A Pickering emulsion was synergistically stabilised with zein nanoparticles (ZNPs) and starch nanocrystals (SNCs) to prepare it for menthol loading. After response surface optimisation of the emulsion preparation conditions, a Pickering emulsion prepared with a ZNPs:SNCs ratio of 1:1, a particle concentration of 2 wt% and a water:oil ratio of 1:1 provided the highest menthol encapsulation rate of the emulsions tested (83%) with good storage stability within 30 days. We examined the bilayer interface structure of the emulsion by optical microscopy, scanning electron microscopy, and confocal laser scanning microscopy. The results of simulated digestion experiments showed that the release rate of free fatty acid was 75.06 ± 1.23%, which ensured bioavailability. At the same time, the emulsions facilitated the slow release of menthol. Bacteriostatic studies revealed that the Pickering emulsion had a protective effect on menthol, with the most significant inhibitory effects on Escherichia coli and Staphylococcus aureus under the same conditions. Overall, this study proposes a novel approach for the application and development of l-menthol by combining it with Pickering emulsion.

Structural characteristics and emulsifying properties of linear dextrin/eicosapentaenoic acid composites: Effect of the degree of polymerization

This work aimed at building functional emulsions based on the linear dextrins (LDs) emulsion system. The gradient polyethylene glycol (PEG) precipitaion method was used to fractionate LDs into fractions with different degrees of polymerization (DP). A package, and co-precipitation procedure of LDs, and eicosapentaenoic acid (EPA) was used to fabricate LDs-EPA composites. The gas chromatograph, Fourier transform infrared spectroscopy, X-ray diffraction and differential scanning calorimetry analyses affirmed the formation of the LDs-EPA composites. The sizes of these composites were 38.55 nm, 59.14 nm to 80.62 nm, respectively, and they had good amphiphilicity. Compared with LDs, these LDs-EPA composites stabilized Pickering emulsion had higher stability and antioxidant capacity. Their emulsifying ability was positively correlated with the DP values of LDs. Furthermore, the oxidation stability results showed that LDsF10-EPA emulsion had the lowest lipid hydroperoxide (LHs) content, malondioxide (MDA) content and hexal concentration, which were 138.75 mmol kg-1 oil, 15.50 mmol kg-1 oil and 3.83 μmol kg-1 oil, respectively. The study provided a new idea and application values for the application of LDs in emulsion.

Starch-based particles as stabilizers for Pickering emulsions: modification, characteristics, stabilization, and applications

The potential utilization of starch as a particle-based emulsifier in the preparation of Pickering emulsions is gaining interest within the food industry. Starch is an affordable and abundant functional ingredient, which makes it an excellent candidate for the stabilization of Pickering emulsions. This review article focuses on the formation, stabilization, and properties of Pickering emulsions formulated using starch-based particles and their derivatives. First, methods of isolating and modifying starch-based particles are highlighted. The key parameters governing the properties of starch-stabilized Pickering emulsions are then discussed, including the concentration, size, morphology, charge, and wettability of the starch-based particles, as well as the type and size of the oil droplets. The physicochemical mechanisms underlying the ability of starch-based particles to form and stabilize Pickering emulsions are also discussed. Starch-based Pickering emulsions tend to be more resistant to coalescence than conventional emulsions, which is useful for some food applications. Potential applications of starch-stabilized Pickering emulsions are reviewed, as well as recent studies on their gastrointestinal fate. The information provided may stimulate the utilization of starch-based Pickering emulsions in food and other industries.

Facile solid-phase synthesis of starch-fatty acid complexes via mechanical activation for stabilizing curcumin-loaded Pickering emulsions

Starch-fatty acid complexes used as emulsifiers have caught great attention because of their renewability and excellent emulsifying property, the development of a simple and efficient synthesis method for the fabrication of starch-fatty acid complexes is still greatly challenging. Herein, the rice starch-fatty acid complexes (NRS-FA) were successfully prepared by mechanical activation method using different long chain fatty acids (myristic acid, palmitic acid, and stearic acid) and native rice starch (NRS) as the raw materials. The results showed that the prepared NRS-FA with a V-shaped crystalline structure exhibited a higher digestion resistance than NRS. Moreover, when the chain length of fatty acids increased from 14 to 18 carbons, the contact angle of the complexes was much closer to 90°, and the average particle size was smaller, deriving the better emulsifying property of NRS-FA18 complexes, which were suitable to be used as an emulsifier to stabilize curcumin-loaded Pickering emulsions. The results of storage stability and in vitro digestion showed that the curcumin retention could reach 79.4 % after 28 days of storage and 80.8 % of curcumin was retained in the system after simulated gastric digestion, showing good encapsulation and delivery performance of prepared Pickering emulsions, which attributed to the enhancement of the coverage of particles at the oil-water interface.

Enhanced Bioaccessibility of Microencapsulated Puerarin Delivered by Pickering Emulsions Stabilized with OSA-Modified Hydrolyzed Pueraria montana Starch: In Vitro Release, Storage Stability, and Physicochemical Properties

Puerarin is a bioactive flavonoid isolated from Kudzu roots that possesses numerous health benefits. However, its poor bioavailability and existing complex delivery systems with safety issues are challenging tasks for its incorporation into functional foods. Preparing modified-starch-stabilized Pickering emulsions containing microencapsulated puerarin with improved bioaccessibility was the key objective of the present research work. Acid-hydrolyzed high-amylose Pueraria montana starch (PMS) was modified with octenyl succinic anhydride (OSA) and evaluated as an emulsifier to prepare emulsions. The FTIR, SEM, and XRD results showed that PMS was successfully modified. Furthermore, the emulsification index (EI), mean droplet size, and ζ-potential values showed that modified starch with a higher degree of substitution (DS) enhanced the storage stability of emulsions. Similarly, the retention degree and encapsulation efficiency results of puerarin proved the assumption after storage of 16 d. The Pickering emulsions also helped in the controlled release of microencapsulated puerarin in vitro. The study outcomes proved that Pickering emulsions stabilized with OSA-modified PMS have promising applicability in functional foods as efficient food-grade delivery systems, enhancing oral supplementation and accessibility of puerarin.

Starch-lauric acid complex-stabilised Pickering emulsion gels enhance the thermo-oxidative resistance of flaxseed oil

Hydrophobic-modified starch complexes have the potential to form Pickering emulsions and improve the oxidative stability of flaxseed oil. Here, V-type starch-lauric acid complexes (SLACs) were fabricated via solid encapsulation within 0.5-12 h and applied in flaxseed oil Pickering emulsions. Complexing index, X-ray diffraction and differential scanning calorimetry analyses confirmed that the degree of complexation increased with the reaction time. Pickering emulsion gels stabilised by SLACs generated with reaction times of 6 h and 12 h exhibited good storage stability and high yield stress, G' values and apparent viscosity. Confocal laser scanning microscopy and cryo-scanning electron microscopy revealed a gelation mechanism involving increased interface roughness and enhanced droplet-droplet interaction. In comparison to pure flaxseed oil, higher thermo-oxidative resistance was observed at 130 °C, with a markedly longer oxidation induction for emulsions and emulsion gels stabilised by SLACs. Our findings could assist in the design of hydrophobic-modified starch and provide a new paradigm for delaying oil oxidation.

A review of recent progress in improving the bioavailability of nutraceutical-loaded emulsions after oral intake

Increasing awareness of the health benefits of specific constituents in fruits, vegetables, cereals, and other whole foods has sparked a broader interest in the potential health benefits of nutraceuticals. Many nutraceuticals are hydrophobic substances, which means they must be encapsulated in colloidal delivery systems. Oil-in-water emulsions are one of the most widely used delivery systems for improving the bioavailability and bioactivity of these nutraceuticals. The composition and structure of emulsions can be designed to improve the water dispersibility, physicochemical stability, and bioavailability of the encapsulated nutraceuticals. The nature of the emulsion used influences the interfacial area and properties of the nutraceutical-loaded oil droplets in the gastrointestinal tract, which influences their digestion, as well as the bioaccessibility, metabolism, and absorption of the nutraceuticals. In this article, we review recent in vitro and in vivo studies on the utilization of emulsions to improve the bioavailability of nutraceuticals. The findings from this review should facilitate the design of more efficacious nutraceutical-loaded emulsions with increased bioactivity.

Fabrication and characterization of Pickering high internal phase emulsions stabilized by debranched starch-capric acid complex nanoparticles

High internal phase emulsions (HIPEs) stabilized by debranched starch-capric acid (DBS-CA) complex nanoparticles were fabricated and their performance was evaluated. DBS-CA was prepared through enzymatic debranching and solid encapsulation methods, and displayed V-type crystalline structure. Contact angle measurements show enhanced hydrophobicity of DBS-CA compared to native starch. The DBS-CA nanoparticles have an average size of 463.77 nm and tended to be aggregating as analyzed by scanning electron microscope and dynamic light scattering particle size analysis. When used as a particulate emulsifier, DBS-CA could stabilize HIPEs with oil volume fraction as high as 80%. The HIPEs showed pH-dependent properties; good storage stability and mechanical strength were achieved within pH range from 3 to 11, especially under alkaline conditions. It was proposed that smaller particle size and higher surface charging were responsible for the more tightly connected gel structure and thus their performance. This study demonstrates a novel approach to fabricate food-grade Pickering HIPEs, which may have many promising potential applications in the food industry.

Formation and properties of starch-palmitic acid complex nanoparticles and their influence on Pickering emulsions

The starch-palmitic acid complex nanoparticles were prepared by Cyperus esculentus starch with enzymatic hydrolysis for different times and then complexed with palmitic acid. The FACE and ¹³C CP/MAS NMR analysis showed that there were more amylose molecules formed and complexed with palmitic acid when starch was treated by enzymatic hydrolysis for 4 h. With the enzymatic hydrolysis time increasing from 0 h to 4 h, the mean size of starch-palmitic acid complex nanoparticles increased from 500 ± 38.83 nm to 567.2 ± 22.32 nm, the size distribution became more uniform, and the crystallinity increased from 14.99% to 47.72%. The starch-palmitic acid complex nanoparticles could be used as a kind of stabilizers to stabilize Pickering emulsions. Rheological properties and storage stability of Pickering emulsions indicted that starch-palmitic acid complex nanoparticles can better stabilize. The starch-palmitic acid complex nanoparticles could be used as stabilizer of Pickering emulsion and encapsulation of bioactive compounds.

All-natural oil-in-water high internal phase Pickering emulsions featuring interfacial bilayer stabilization

HYPOTHESIS

Synergistic stabilization of high internal phase Pickering emulsions (HIPPEs) by food-grade colloidal particles are necessary for food, pharmaceuticals or cosmetics owing to their biocompatibility and multi-functionality. By tuning the interfacial structure of adsorbed binary particles, the HIPPE may exhibit extraordinary characteristics compared to conventional all-natural HIPPEs solely stabilized by single-component particle or composite particle, which should have potential applications in varies fields.

EXPERIMENTS

HIPPEs were prepared by using zein protein nanoparticles (ZNPs) and starch nanocrystals (SNCs) as stabilizers. We systematically investigated the effect of particle concentration and internal phase fraction on HIPPEs morphology, stability and rheological behaviors. Further, the stabilization mechanism as well as potential applications were demonstrated.

FINDINGS

HIPPEs were prepared with excellent stability against centrifugation and high temperature (50 °C). Our result indicates the successful construction of unique bilayer interfacial structures consisting of inner ZNPs layer and outer SNCs layer. Since SNCs could gelatinize at 50 °C, dense shells can form around droplets afterwards. Such thermally responsive interfacial structures can be used to protect hydrophobic bioactive substances at higher temperatures while still allowing controlled release at certain conditions. Furthermore, with high internal phase fraction, HIPPEs can possibly replace mayonnaise and salad dressing on the market due to comparable appearance and properties. Following the removal of inner oil, porous materials can be further fabricated, which have potential applications in environmental protection or tissue engineering.

Ultra-stable Pickering emulsion stabilized by a natural particle bilayer

An all-natural Pickering emulsion with a Janus interface of particle bilayer is prepared, which has unprecedented stability.