Effects of environmental factors on the physical stability of pickering-emulsions stabilized by chitosan particles

Surface modification of particles/nanoparticles to improve the stability of Pickering emulsions; a critical review

Pickering emulsions (PEs) are dispersions stabilized by solid particles, which are derived from various materials, both organic (proteins, polysaccharides, lipids) and inorganic (metals, silica, metal oxides). These colloidal particles play a critical role in ensuring the stability and functionality of PEs, making them highly valued across multiple industries due to their enhanced stability and lower toxicity compared to conventional emulsions. The stabilization mechanisms in PEs differ from those in emulsions stabilized by surfactants or biopolymers. The stability of PEs is influenced by intrinsic particle properties, such as wettability, size, shape, deformability, and charge, as well as external conditions like pH, salinity, and temperature. Some particles, especially organic ones, alone may not be effective stabilizers. For instance, many polysaccharides inherently lack surface activity, while most proteins have significant surface activity but often become unstable under environmental stresses, potentially leading to emulsion instability. The chemical composition and morphology of the particles can lead to varying properties, particularly wettability, which plays a vital role in their ability to adsorb at interfaces. As a result, surface modification emerges as an essential approach for improving the effectiveness of particles as stabilizers in PEs. This review presents the mechanisms that stabilize PEs, identifies factors influencing the stability of PEs, and discusses physical and chemical techniques for modifying particle surfaces. There has been a significant advance in understanding surface modification, employing both physical (non-covalent bonds) and chemical (covalent bonds) approaches. These insights are invaluable for optimizing PE formulations, broadening their application potential across various fields.

High Internal Phase Oil-in-Water Emulsions Stabilised by Cost-Effective Rhamnolipid/Alginate Biocomplexes

A novel, cost-effective, partially purified biosurfactant in the form of a rhamnolipid biocomplex (RLBC) was investigated for its emulsifying properties. The RLBC was obtained through the cultivation of Pseudomonas sp. SP-17 on glycerol, followed by acidic precipitation, without the use of organic solvents for isolation or purification. Composed of rhamnolipids (RLs) and the exopolysaccharide alginate, RLBC exhibited emulsifying properties towards rapeseed oil comparable to those of purified RLs at concentrations as low as 0.15% (w/w), sufficient for the effective stabilisation of oil-in-water (o/w) high internal phase emulsions (HIPEs, 80% oil). Dynamic light scattering analysis revealed similar droplet sizes (9.54 ± 0.96 µm for RLBC vs. 8.93 ± 0.58 µm for RLs), while multiple light scattering confirmed high emulsion stability over 120 days. The emulsions displayed shear-thinning behaviour, with yield stresses of approximately 11.5 Pa and 7.7 Pa for systems prepared with RLBC and RLs, respectively, after seven days of pre-storage. Although increasing the RLBC concentration from 0.15% to 1% (w/w) slightly improved the degree of emulsion dispersion, it did not substantially impact the long-term stability observed at the lowest concentration. Biodegradation tests demonstrated that the RLBC preparations are environmentally friendly alternatives to synthetic surfactants, achieving 60% biodegradation within 2.5 days and complete biodegradation within 14 days, which outperformed synthetic emulsifiers. The RLBC offers both environmental and economic advantages over purified RLs, including reduced production costs and the elimination of organic solvents. Our findings highlight the potential of RLBC for stabilising HIPEs in applications requiring sustainable and biodegradable formulations, such as cosmetics, lubricants, and industrial fluids widely manufactured and utilised today.

Chitosan/octenyl succinic anhydride starch complex particles stabilize Pickering emulsion for astaxanthin encapsulation

The stabilizing effect of biopolymers on Pickering emulsions has attracted widespread interest in recent years. In this study, the interactions between chitosan (CS) and octenyl succinic anhydride starch (OS) were investigated and used to modulate the interfacial properties of Pickering emulsions, which are crucial for determining emulsion stability. CS/OS complex particles were prepared via electrostatic and hydrogen-bonding interactions and used to stabilize Pickering emulsions for the encapsulation of astaxanthin (AST). The three-phase contact angle and confocal laser microscopy results indicated that the CS/OS particles could reduce the oil-water interfacial tension and provide a stable interface layer. The loss rate of AST in CS/OS-stabilized Pickering emulsions (31.25 %) was significantly lower than that of Tween 80-stabilized emulsions (49.50 %) after storage at 37 °C for 60 days. The bioaccessibility of AST in the CS/OS-stabilized Pickering emulsions (61.38 %) was twice that in the Tween 80-stabilized emulsions (28.30 %). Moreover, CS/OS-stabilized Pickering emulsions effectively masked the undesirable algal odor of AST. The emulsions exhibited textural and rheological properties similar to those of salad dressings, suggesting their potential as substitutes for salad dressings. These findings provide novel insights into the utilization of efficient AST delivery systems.

Stabilizing emulsions by ultrasound-treated pea protein isolate - tannic acid complexes: Impact of ultrasonic power and concentration of complexes on emulsion characteristics

This work aimed to investigate the feasibility of stabilizing oil-in-water (O/W) emulsions by ultrasound-treated pea protein isolate-tannic acid (UPPI-TA) complex. The stability and microstructure of the O/W emulsions were evaluated at different ultrasonic powers (0-1000 W) and UPPI-TA complex concentrations (0.25-2.0 wt%). The contact angle (θ) of UPPI-TA was 59.6°, which was suitable for stabilizing O/W emulsions. At an ultrasonic power of 800 W, the droplet size and creaming index (CI) of emulsions decreased, and the apparent viscosity and interfacial protein adsorption content increased with increasing UPPI-TA concentration. In particular, emulsions with 1.5 % UPPI-TA showed the lowest CI, the highest interfacial protein adsorption content and viscoelasticity, as well as the best storage and thermal stability. These results showed that the suitable modifications of ultrasonic emulsification power and particle concentrations were a new potential approach to stabilize the O/W emulsions by ultrasound-treated pea protein isolated-tannic acid complex.

Cellulose nanocrystals-based Pickering emulsion with enhanced foliar adhesion and pH responsiveness for intelligent delivery of pesticides

Pickering emulsions stabilized by functionalized natural macromolecules have emerged with promising responsiveness for pesticide encapsulation and release. This study developed Pickering emulsions using amine-modified cellulose nanocrystals (ACNCs) as stabilizers. The resultant O/W ACNCs-Pickering emulsions (ACNCs-Pickering) exhibited long-term storage stability and showed increasing emulsion stability depending on the concentration of ACNCs. Imidacloprid (IMI) was subsequently loaded onto the ACNCs-Pickering to form the IMI@ACNCs-Pickering via the in-situ loading route. The release rate of IMI demonstrated a notable pH responsiveness. Moreover, the IMI@ACNCs-Pickering prepared with an ACNCs concentration of 3 wt% showed optimal performances. Its foliar adhesion on Chinese cabbage (Brassica rapa L.ssp.pekinensis) was significantly higher than that of the commercial IMI formulation (70 WS, Bayer®, LS200032) (DG). In detail, the pesticide residue for the IMI@ACNCs-Pickering was 3.8 folds to that for DG after spraying and washing for 10 min. Also, the green peach aphid mortality rate was 98.33 %, which was 1.1 folds higher than that of the DG group. The present work developed a Pickering emulsion-based fat-soluble pesticide formulation with excellent foliar adhesion, resistance to rainfall washout, and insecticidal effect. It provided a new option to ensure the sustainable development of green agriculture.

Transitioning from Pickering emulsions to Pickering emulsion hydrogels: A potential advancement in cosmeceuticals

Cosmeceuticals, focusing on enhancing skin health and appearance, heavily rely on emulsions as one of the common mediums. These emulsions pose a challenge due to their dependence on surfactants which are essential for stability but are causing concerns about environmental impact as well as evolving consumer preferences. This has led to research focused on Pickering emulsions (PEs), which are colloidal particle-based emulsion alternatives. Compared to conventional emulsions, PEs offer enhanced stability and functionality in addition to serving as a sustainable alternative but still pose challenges such as rheological control and requiring further improvement in long-term stability, whereby the limitations could be addressed through the introduction of a hydrogel network. In this review, we first highlight the strategies and considerations to optimize active ingredient (AI) absorption and penetration in a PE-based formulation. We then delve into a comprehensive overview of the potential of Pickering-based cosmeceutical emulsions including their attractive features, the various Pickering particles that can be employed, past studies and their limitations. Further, PE hydrogels (PEHs), which combines the features between PE and hydrogel as an innovative solution to address challenges posed by both conventional emulsions and PEs in the cosmeceutical industry is explored. Moreover, concerns related to toxicity and biocompatibility are critically examined, alongside considerations of scalability and commercial viability, providing a forward-looking perspective on potential future research directions centered on the application of PEHs in the cosmeceutical field.

Colloidal lignin particle reinforces the stability of Pickering emulsions prepared with zein nanoparticle

Zein nanoparticle (ZNP) is at the forefront of research on Pickering emulsions, valued for its self-assembling and surfactant-free nature. Nevertheless, its emulsion stability is undermined by inadequate amphiphilicity. Colloidal lignin particle (CLP), characterized by its antithetical charge and amphiphilic nature, appears the promising for augmenting the stability of ZNP-based emulsion. This study meticulously investigated the impact of CLP on the colloidal properties and emulsifying performance of ZNP. The results revealed that electrostatic interactions between ZNP and CLP significantly mitigated the charge of ZNP and improved its hydrophilic/lipophilic balance. Under optimized conditions (1.0 wt% particle concentration, pH 4.0, 50% oil content), CLP notably reduced droplet sizes (41-225 μm) and enhanced the stability of ZNP-based Pickering emulsion, particularly at ZNP/CLP ratios of 6:4 and 5:5. In nature, CLP improved the stability ZNP-based Pickering emulsions via increased interfacial adsorption, enhanced steric hindrance, and reinforced viscous structure.

Rice husk derived lignin/silica hybrid nanoparticles stabilized Pickering emulsion for phytosterol ester biosynthesis

This study investigates the production of lignin/silica hybrid nanoparticles (LSNPs) from rice husks, an abundant agricultural waste, and their capacity to stabilize Pickering emulsions for biocatalysis. Lignin extracted from rice husks under alkaline conditions was co-precipitated with silica to produce LSNPs in the presence or absence of ethanol as a co-solvent. Characterization of LSNPs revealed that ethanol played a key role in forming uniform, spherical nanoparticles and minimizing aggregation. Lignin imparted amphiphilicity to the LSNPs, which significantly improved their capacity to form stable Pickering emulsions. LSNPs were able to form stable oil-in-water Pickering emulsions while droplet size and emulsion stability were influenced by LSNPs concentration, oil/water ratio, temperature and pH. LSNPs-stabilized Pickering emulsions were evaluated for lipase-mediated biosynthesis of phytosterol esters, which are plant bioactive compounds that can reduce dietary cholesterol uptake. LSNPs-stabilized emulsions provided 1.915 × 106 times larger interfacial areas compared to conventional biphasic systems which facilitated improved mass transfer and lipase activity. Under optimal conditions, LSNPs-stabilized Pickering emulsion systems delivered 90.6% phytosterol ester conversion in 4 h, compared to 10 h in biphasic systems. This research highlights the potential of sustainable, biomass-derived nanoparticles in Pickering emulsion applications and offers an environmentally friendly approach to produce bioactive compounds.

Exploring the glycoprotein washing fluid-assisted cleanup for the restoration of oil-contaminated shorelines with environmental integrity

Spilled oil in ocean can spread to the shoreline and cause long-term impacts on the shoreline's ecological environment. Therefore, removing oil accumulated on shorelines is crucial. This study proposed an innovative ovalbumin (OVA) fluid-assisted method for the cleanup of oiled shoreline substrates. The oil removal efficiency of OVA fluids was systematically investigated. Higher concentrations of OVA fluids effectively enveloped and immobilized the oil, aiding in its separation from the sand surface. The increased temperature reduced the viscosity of emulsions, facilitating improved flow and oil removal. High salinity promoted the creation of oil particle aggregates molecules and facilitated the release of oil from the sand surface. The factorial analysis demonstrated that a high salt environment significantly enhances the combined impact of temperature and pH on oil removal performance. Different methods for the responsive separation of washing effluents were studied, and the most effective separation method was adjusting the pH of effluents to 4.54 (the isoelectric point of OVA). Separated precipitates exhibited good decomposition efficiency through thermal decomposition and biodegradation. OVA fluids boast advantages, such as low cost, easy recyclability, and non-toxicity, while ensuring high oil removal efficiency and making them a promising eco-friendly technique for the cleanup of oiled shorelines.

Water chestnut starch nanoparticle Pickering emulsion for enhanced apricot seed oil stability: A sustainable functionality approach

The usage of starch nanoparticles for Pickering emulsion stabilization has become more popular for various benefits. This work investigated the potential of nano reduced starch as stabilizer in Pickering emulsions. Two different concentrations of starch nanoparticles (2.5 % and 5 %) were used for stabilization of apricot seed oil-in-water Pickering emulsion. Emulsion stabilized by 5 % starch nanoparticles (PE (5 %)) displayed zeta potential of -46.92 mV and emulsions stabilized by 2.5 % starch nanoparticles (PE (2.5 %)) exhibited zeta potential of -15.33 mV. In PE (2.5 %) after 24 h, creaming index (CI) was 12 %. CI remained zero in PE (5 %) after 30 days of storage period.PE (2.5 %) and apricot oil (AO) showed higher peroxide value than PE (5 %). Malondialdehyde (MDA) content of AO was 156.02 mmol/kg oil after 30 day storage period at 45 °C. Comparatively, PE (5 %) possessed lower MDA content (36.02 mmol/kg oil). The findings revealed that starch nanoparticles can be used as stabilizer in Pickering emulsions for stabilization and preventing lipid oxidation in polyunsaturated fatty acid rich oils. This study introduces a sustainable approach to enhance the stability of apricot seed oil using underutilized starch nanoparticles.

Characteristics and stabilization of Pickering emulsions constructed using myosin from bighead carp (Aristichthys nobilis)

Myosin from bighead carp (Aristichthys nobilis) as a main type of fish protein possesses a good emulsifying ability. However, whether bighead carp myosin (BCM) could construct stable Pickering emulsions is still unclear. Therefore, myosin particles and Pickering emulsions stabilized by bighead carp myosin (BCMPEs) were analyzed. The surface structure of BCM particles at 0.6 mol/L NaCl treatment was uniform and compact with a contact angle of 86.4 ± 2.7°, exhibiting the potential ability to construct O/W Pickering emulsions. The size and flocculation index (FI) of BCMPEs decreased with the increase in BCM concentrations of 1%-4% (w/v). Reversely, the size of BCMPEs increased with the increase in oil-water ratios. BCM particles could uniformly distribute at the oil-water interface to stabilize BCMPEs at a BCM concentration of 4% (w/v) and an oil-water ratio of 6:4 (v/v). This study could help explore fish proteins to construct Pickering emulsions for the deep processing of fish products.

Evaluation of Emulsification Techniques to Optimize the Properties of Chalcone Nanoemulsions for Antifungal Applications

Background/Objectives: Nanoemulsions (NEs) possess properties that enhance the solubility, bioavailability and therapeutic efficacy of drugs. Chalcones are compounds known for their antifungal properties. In this study, we evaluated different emulsification techniques to create alginate nanoemulsions containing chalcone (1E,4E)-1,5-bis (4-methoxyphenyl) penta-1,4-dien-3-one (DB4OCH3). Our goal was to develop an antifungal formulation targeting Candida albicans strains. Methods: Ultrasound and ultrasound combined with high-speed homogenization techniques were used to prepare alginate-stabilized nanoemulsions. Particle size, zeta potential and encapsulation efficiency were evaluated. Additionally, in vitro release studies were conducted. Results: The combined emulsification technique produced stable nanoparticles with high encapsulation efficiency and antifungal activity, with a minimum inhibitory concentration of 8.75 μg/mL for the nanoemulsions compared to 312 µg/mL for free DB4OCH3. NEs' effectiveness can be attributed to their ability to form nanodroplets efficiently, facilitating the solubilization of the chalcone in the oily phase. The particle size varied between 195.70 ± 2.69 and 243.40 ± 4.49 nm, with an increase in chalcone concentration leading to larger particle sizes. The zeta potential showed values from -91.77 ± 5.58 to -76.90 ± 4.44 mV. The UHS-7 sample exhibited an encapsulation efficiency of 92.10% ± 0.77, with a controlled in vitro release of 83% after 34 h. Molecular docking simulations showed that the aromatic nature of DB4OCH3 resulted in the formation of apolar interactions with aromatic residues located in the active site of the TMK, as observed in their respective co-crystallized inhibitors, within an affinity energy range that enables optimum specificity of the ligand for these two pathways. Pharmacokinetic analyses indicated high passive cell permeability and low hepatic clearance, and phase I metabolism reduces its oral bioavailability and metabolic stability, suggesting a promising active ingredient as an oral drug with control of the daily oral dose administered. Conclusions: The combined nanoemulsification technique led to the formation of finely dispersed nanodroplets that favored the solubilization of the chalcone in the oil phase, which led to a better performance in the antifungal properties. DB4OCH3 shows promise as an oral drug with controlled dosing.

Encapsulation of β-carotene in Pickering emulsions stabilized by self-aggregated chitosan nanoparticles: Factors affecting β-carotene stability

For conventional emulsions used to encapsulate easily degradable bioactive compounds, achieving small droplet size and high encapsulation capacity is a challenging. Pickering emulsions stabilized by self-aggregated chitosan particles may offer high encapsulation efficiency due to the robust mechanical barrier formed by solid particles adsorbed at the oil-water interface. Therefore, the effects of pH, chitosan concentration, oil volume fraction, homogenization pressure, and homogenization cycle on the stability of chitosan Pickering emulsions and the degradation of β-carotene were investigated. Effective interfacial adsorption of chitosan nanoparticles and moderate homogenization intensity facilitated the formation of small emulsion droplets. Unlike conventional emulsions, chitosan Pickering emulsions with smaller droplets provided enhanced protection for β-carotene. This enhancement was primarily attributed to the improved interfacial coverage of chitosan nanoparticles with smaller droplet sizes, which was advantageous for β-carotene protection. The optimal conditions for preparing β-carotene-loaded chitosan Pickering emulsions were as follows: pH 6.5, chitosan concentration of 1.0 wt%, oil volume fraction of 20 %, homogenization pressure of 90 MPa, and 6 homogenization cycles. These findings indicate that chitosan Pickering emulsions are well-suited for encapsulating β-carotene with both small droplet size and high encapsulation efficiency.

Controlled assembly of superparamagnetic iron oxide nanoparticle into nanoliposome for Pickering emulsion preparation

There has been a surge in effort in the development of various solid nanoparticles as Pickering emulsion stabilizers in the past decades. Regardless, the exploration of stabilizers that simultaneously stabilize and deliver bioactive has been limited. For this, liposomes with amphiphilic nature have been introduced as Pickering emulsion stabilizers but these nano-sized vesicles lack targeting specificity. Therefore in this study, superparamagnetic iron oxide nanoparticles (SPION) encapsulated within liposomes (MLP) were used as Pickering emulsion stabilizers to prepare pH and magnetic-responsive Pickering emulsions. A stable MLP-stabilized Pickering emulsion formulation was established by varying the MLP pH, concentration, and oil loading during the emulsification process. The primary stabilization mechanism of the emulsion under pH variation was identified to be largely associated with the MLP phosphate group deprotonation. When subjected to sequential pH adjustment to imitate the gastrointestinal digestion pH environment, a recovery in Pickering emulsion integrity was observed as the pH changes from acidic to alkaline. By incorporating SPION, the Pickering emulsion can be guided to the targeted site under the influence of a magnetic field without compromising emulsion stability. Overall, the results demonstrated the potential of MLP-stabilized Pickering emulsion as a dual pH- and magnetic-responsive drug delivery carrier with the ability to co-encapsulate hydrophobic and hydrophilic bioactive.

Development, Stability, and In Vitro/In Vivo Studies of Volatile Oil Pickering Emulsion Stabilized by Modified Amber

Volatile oil stabilization strategies based on encapsulation with a large number of excipients limit further applications. The primary objective of this study is to improve the stability of volatile oils using Pickering emulsion (PE) stabilized by Chinese medicinal powder based on the principle of "integrating drug and excipient". Modified amber was acquired through surface modification, and a stable oil-in-water PE loaded with Acorus tatarinowii volatile oil (ATVO) was constructed from modified amber. The stability, including the peroxide value (PV), malondialdehyde (MDA) content, and the content and composition of volatile components in modified amber-PE (MAPE) under intense light exposure, was analyzed deeply. In addition, the in vitro release and pharmacokinetics of MAPE and ATVO were investigated. The results demonstrate that the PV and MDA content in MAPE were significantly lower than in free ATVO, and the content and composition of volatile components in MAPE were closer to those in untreated ATVO. The release kinetics of β-asarone and α-asarone in MAPE demonstrated rapid and higher release, and pharmacokinetic studies show that MAPE has better bioavailability. This research provides a distinctive Chinese medicine solution to address the vaporization of volatile oil in solid formulations.

Biocompatibility and Antibacterial Activity of Eugenol and Copaiba Essential Oil-Based Emulsions Loaded on Cotton Textile Materials

The present study was focused on the preparation, characterization and application onto cotton fabrics of different topical oil-in-water emulsions based on chitosan, eugenol and copaiba essential oil for potential topical applications. Different amounts of copaiba essential oil (oil phases) and eugenol were used, while the water phase consisted of hamamelis water. The designed formulations were evaluated via optical microscopy and rheological parameters assessment. The textile materials treated with the developed emulsions were analyzed in terms of antibacterial efficiency and in vitro and in vivo biocompatibility. The rheological measurements have shown that the emulsions' stability was dependent on their viscosity and structure of the colloidal systems. The emulsions remained stable at temperatures equal to or below 35 °C, but an increase in temperature led to droplet flocculation and creaming. The emulsion-treated textiles exhibited antibacterial activity against Escherichia coli and Staphylococcus aureus, and in vivo biocompatibility on the skin of guinea pigs without sensitization effects. Our study revealed that eugenol and copaiba essential oil-based emulsions loaded on cotton textile materials could be promising candidates for developing skin-friendly textiles designed for different topical applications.

Evolution Kinetics of Stabilizing Pickering Emulsion by Brush-Modified Janus Particles: DPD Simulation and Experimental Insights

In the present study, we report the evolution of stabilizing Pickering emulsions using brush-modified Janus particles (JPs), utilizing the dissipative particle dynamics (DPD) simulation technique. Our results are subsequently corroborated with experimental findings. Each JP has one-half of the hydrophobic surface, with the other half embedded with hydrophilic polymer brushes grown via atom transfer radical polymerization (ATRP). Our generic simulation model analyzes the chemical kinetics of polymer brush growth on one-half of the initiator-embedded microparticle (MP) surface, resulting in the formation of JP. This involves evaluating monomer conversion and reaction rates. Our results exhibit a substantial influence of the number of JPs, grafted brush density, and brush length on oil-in-water emulsion stability. We studied the evolution kinetics and stability of emulsion formation by analyzing the growth of average domain size and corresponding scaling functions up to a late time limit. This study aims to clarify the connection between the size, quantity, and functionality of JPs and the stability of Pickering emulsions.

Banana peel nanocellulose and soy protein hydrolysate complexed colloidal nanoparticles synthesis using ultrasonic interventions: characterization and stable pickering emulsion formation

Pickering based emulsion system are been gaining interest in active delivery of encapsulated molecules in food system. In the present study, cellulose nanoparticles (CNPs) were isolated from food waste (banana peel) using acid hydrolysis followed by high-intensity ultrasonication. The complex colloidal nanoparticles (CNPSPH) were fabricated using hydrogen bonding and electrostatic interactions between cellulose nanoparticles and soy protein hydrolysates. With 400 W power level for 30 min, size of 53.11 ± 1.45 nm with polydispersity index of 0.21 ± 0.21 and Zeta potential of - 34.33 ± 0.77 were noted for generated CNPs. The three-phase contact angle (o/w) of CNPSPH at a mass ratio of 1:1 CNPs to SPHs (CNPSPH 1:1) was approximately 89.07°, indicating as effective Pickering emulsifiers. Furthermore, the stability of the Pickering emulsion stabilised by CNPSPH complex was investigated under various pH and temperature conditions. The findings will provide solution in development of nanocellulose-soy protein complex particles for a stabilized Pickering emulsion formation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01477-w.

Recent progress on Pickering emulsion stabilized essential oil added biopolymer-based film for food packaging applications: A review

Nowadays food safety and protection are a growing concern for food producers and food industry. The stability of food-grade materials is key in food processing and shelf life. Pickering emulsions (PEs) have gained significant attention in food regimes owing to their stability enhancement of food specimens. PE can be developed by high and low-energy methods. The use of PE in the food sector is completely safe as it uses solid biodegradable particles to stabilize the oil in water and it also acts as an excellent carrier of essential oils (EOs). EOs are useful functional ingredients, the inclusion of EOs in the packaging film or coating formulation significantly helps in the improvement of the shelf life of the packed food item. The highly volatile nature, limited solubility and ease of oxidation in light of EOs restricts their direct use in packaging. In this context, the use of PEs of EOs is suitable to overcome most of the challenges, Therefore, recently there have been many papers published on PEs of EOs including active packaging film and coatings and the obtained results are promising. The current review amalgamates these studies to inform about the chemistry of PEs followed by types of stabilizers, factors affecting the stability and different high and low-energy manufacturing methods. Finally, the review summarizes the recent advancement in PEs-added packaging film and their application in the enhancement of shelf life of food.

Design, characterization and digestibility of β-carotene-loaded emulsion system stabilized by whey protein with chitosan and potato starch addition

The physicochemical properties and gastrointestinal fate of β-carotene-loaded emulsions and emulsion gels were examined. The emulsion was emulsified by whey protein isolate and incorporated with chitosan, then the emulsion gels were produced by gelatinizing potato starch in the aqueous phase. The rheology properties, water distribution, and microstructure of emulsions and emulsion gels were modulated by chitosan combination. A standardized INFOGEST method was employed to track the gastrointestinal fate of emulsion systems. Significant changes in droplet size, zeta-potential, and aggregation state were detected during in vitro digestion, including simulated oral, stomach, and small intestine phases. The presence of chitosan led to a significantly reduced free fatty acids release in emulsion, whereas a slightly increasing released amount in the emulsion gel. β-carotene bioaccessibility was significantly improved by hydrogel formation and chitosan addition. These results could be used to formulate advanced emulsion systems to improve the gastrointestinal fate of hydrophobic nutraceuticals.

A Pickering emulsion stabilized by Chitosan-g-Poly(N-vinylcaprolactam) microgels: Interface formation, stability and stimuli-responsiveness

Pickering emulsions stabilized by solid particles are more stable and environmentally friendly compared to traditional surfactants. Herein, a series of Chitosan-g-Poly(N-vinylcaprolactam) (CS-g-PNVCL) microgel particles were synthesized via a free radical surfactant-free emulsion copolymerization and the obtained particles were used to stabilize Pickering emulsions. It is found that the ratio (CS/PNVCL = 60 wt%) was optimal to produce Pickering emulsions. The microstructures of Pickering emulsions can maintain for 60 days at room temperature and this long-term stability is attributed to the CS-g-PNVCL microgel particles adsorbed at the oil-water interface. The Pickering emulsions displayed thermo-responsive characteristics when exposed to environmental stimuli. The emulsions became destabilized with an increase in pH and temperature. The droplets turned unstable and irregular due to excessive NaCl concentration, caused by electrostatic repulsion between the microgel particles. This study presents a novel way to form smart and uniform Pickering emulsions with the application potential in food, cosmetics, and drug delivery, etc.

Subcritical water-assisted fish gelatin hydrolysis for astaxanthin-loaded fish oil emulsion stability

Though gelatin emulsifying properties have been intensively studied, how low-molecular-weight (LMW) fish gelatin affects astaxanthin (AST)-loaded fish oil emulsion stability remains elusive. In this study, subcritical water hydrolysis (SWH)-modified LMW fish gelatin (SWHG) was produced from 110 °C to 180 °C and used to enhance the AST steadiness in oil/water emulsions in the presence of an emulsifier, lecithin. In the prepared emulsions, the surface charge increased while droplet size decreased with the decrease in gelatin MW due to the reduced thickness of the adsorbed gelatin membrane. LMW gelatin and lecithin could form a firm-absorbed layer on the droplet surface by electrostatic interaction between amide groups of gelatin molecules and phosphate groups of lecithin, thus stabilizing the emulsions. SWHG improved the creaming stability of the emulsions and hindered the oxygen- and light-induced AST degradation for 11 months compared to high MW gelatin. Whereas, the control emulsion showed noticeable phase separation after two weeks of storage. These findings prove the advantage of the SWH approach and propose the use of SWHG in oil-in-water emulsions for AST stabilization.

Preparation and Characterization of Fish Oil Pickering Emulsions Stabilized by Resveratrol-Loaded Gliadin/Chitin Nanocrystal Composite Nanoparticles

Unsaturated fatty acids present in fish oil offer various physiological benefits to the human body. However, their susceptibility to oxidation severely limits their potential applications. The purpose of this study was to develop Pickering emulsions stabilized from a composite of resveratrol-loaded gliadin nanoparticles and oxidized chitin nanocrystals (GR/OC) to protect fish oil from oxidation. The effects of the GR/OC composite on the characterizations of fish oil Pickering emulsions were investigated, including the microstructure, physicochemical properties (stability and rheological behavior), and digestion properties in vitro. The results revealed that an increased concentration of the GR/OC composite significantly reduced the droplet size and improved the ambient stability of the emulsions (in terms of pH, ionic strength, temperature, and storage time). Confocal laser scanning microscopy images depicted that the GR/OC nanoparticles were uniformly dispersed at the interface between water and fish oil (W-O interface). This distribution formed a protective envelope around the droplets. Remarkably, the addition of 2% GR/OC nanoparticles stabilized the Pickering emulsions and showed the most positive effect on the antioxidant capacity compared to that of the control group. These stabilized emulsions maintained lower peroxide values and acid values, which were 1.5 times less than those of the blank control during the 14 day accelerated oxidation experiment. Furthermore, the Pickering emulsions stabilized by GR/OC nanoparticles exhibited the ability to protect fish oil from contamination by gastric juices and facilitate the intestinal absorption of omega-3 polyunsaturated fatty acids. The findings suggest that these GR/OC-stabilized Pickering emulsions offer a promising alternative for delivering fish oils in various industries, including the food industry.

Production and investigation of Pickering emulsion stabilised by casein-Qodume Shirazi (Alyssum homolocarpum) seed gum complex particles: gastrointestinal digestion

Recently, there has been growing research interests in designing Pickering emulsions. In this work, Alyssum homolocarpum seed gum (AHSG) and casein protein (CP) nanoparticles (NPs) fabricated as Pickering stabilizers. AHSG (0.0, 0.05, 0.10, and 0.15% (w/w))-CP (2% (w/w)) nanoparticles were fabricated and their properties were investigated (mean diameter, morphology, zeta potential, Fourier transform infra-red, and contact angle). Formation and stability of Pickering emulsion (Pes) stabilized by AHSG-CP NPs were monitored by mean diameter, rheological properties, and in vitro digestion. AHSG-CP Nps exhibited a small size (107.75 ± 0.42-201.52 ± 0.70 nm) and had wettability between 64.94 ± 3.44° and 70.92 ± 7.64°. The stability of PEs was greatly improved by 0.05AHSG-CP NPs, even after 30 days of storage, centrifugation, and in vitro digestion, owing to the reinforcement of particle structure at the oil/water interfaces.This study demonstrates that 0.05% (w/w) AHSG-CP NP showed the highest stability during storage and against gastrointestinal digestion which showed its suitability as a fat reducer emulsion structure.

Emulsion stability of hydroxybutyl chitosan as emulsifier at low pH: Effects of the degree of substitutions of hydroxybutyl groups

Keeping the stability of emulsions at low pH is necessary for their successful applications in food and delivery systems. To achieve this goal, hydroxybutyl chitosan (HBC) with three degrees of substitution (DSs) was used as an emulsifier to investigate the effect of HBC structure on the emulsion stability. The DSs of HBC-5, HBC-10, and HBC-20 were 0.66, 1.51, and 2.19, respectively. The stability of oil-in-water emulsions against creaming/coalescence was positively correlated with the DS. As pH decreased to 2, HBC-20-stabilized emulsions were most stable without creaming or coalescence. After 30 days of storage, no changes in the droplet sizes of HBC-20-stabilized emulsions were observed, whereas the droplet sizes of HBC-5/10- stabilized emulsions significantly increased at low pH. The stability of HBC-20- stabilized emulsions at low pH was attributed to the higher surface activity and electrostatic repulsion. Our research revealed that the emulsion stability of HBC under low pH conditions can be controlled by the density of the hydroxybutyl groups in HBC. In vitro digestion further revealed the excellent stability of HBC-20-stabilized emulsions in simulated gastric fluid, which highlighted the enormous potential of HBC-20 to protect liposoluble drugs and nutrients from the extreme pH environment.

Pickering emulsions stabilized by cellulose nanocrystals extracted from hazelnut shells: Production and stability under different harsh conditions

Cellulose nanocrystals (CNCs) are biodegradable particles that have emerged as promising stabilizers for Pickering emulsions. This study investigated the effectiveness of CNCs in forming the Pickering emulsion from hazelnut shells (HS), an agricultural waste. Following the alkaline and bleaching treatments applied to HS, CNCs were obtained from treated hazelnut shell with acid hydrolysis. The physicochemical characteristics of CNCs were investigated using dynamic light scattering, XRD, FTIR, SEM, and TEM. A high crystalline (69.6 %) CNCs with a spherical shape were obtained. Contact angle and interfacial tension tests were conducted and showed that CNCs had amphiphilic nature. Pickering emulsions were investigated for their size, zeta potential, and stability under varying CNC concentrations. The results showed that when CNCs concentration increased from 0.5 to 2.0 wt%, droplet diameter decreased approximately 1.8 times and zeta potential increased. Creaming was not observed during 28 days of storage in a concentration of 2.0 wt% CNCs. The CNC stabilized emulsions exhibited high stability within a range of pH, temperatures, and salt concentrations. This study demonstrated that CNCs extracted from HS as environmentally friendly and cost-effective materials, could serve as a new stabilizer for Pickering emulsions especially for high temperature and low pH sensitive products such as mayonnaise.

Tunability of Pickering particle features of whey protein isolate via remodeling partial unfolding during ultrasonication-assisted complexation with chitosan/chitooligosaccharide

The potential of ultrasonication-driven molecular self-assembly of whey protein isolate (WPI) with chitosan (CS)/chitooligosaccharide (COS) to stabilize Pickering emulsions was examined, based on CS/COS ligands-induced partial unfolding in remodeling the Pickering particles features. Multi-spectral analysis suggested obvious changes in conformational structures of WPI due to interaction with CS/COS, with significantly higher unfolding degrees of WPI induced by COS. Non-covalent interactions were identified as the major forces for WPI-CS/COS conjugates. Ultrasonication enhanced electrostatic interaction between CS's -NH3 groups and WPI's -COO- groups which improved emulsification activity and storability of WPI-COS stabilized Pickering emulsion. This was attributed to increased surface hydrophobicity and decreased particle size compared to WPI-CS associated with differential unfolding degrees induced by different saccharide ligands. CLSM and SEM consistently observed smaller emulsion droplets in WPI-COS complexes than WPI-CS/COS particles tightly adsorbed at the oil-water interface. The electrostatic self-assembly of WPI with CS/COS greatly enhanced the encapsulation efficiency of quercetin than those stabilized by WPI alone and ultrasound further improved encapsulation efficiency. This corresponded well with the quantitative affinity parameters between quercetin and WPI-CS/COS complexes. This investigation revealed the great potential of glycan ligands-induced conformational transitions of extrinsic physical disruption in tuning Pickering particle features.

Modulating digestibility and stability of Pickering emulsions based on cellulose nanofibers

Cellulose nanofibers (CNF) have been widely studied for their biodegradability and for their unique advantages as a stabilizer in Pickering-type emulsions. However, it is challenging to produce cellulose nanofibers from agroindustry waste with good techno-functional properties, without the use of harsh process conditions. Green alternatives (eco-friendly) have been studied to obtain nanofibers, such as enzymatic hydrolysis and/or application of mechanical processes. In this work, we used acid hydrolysis (as a control and example of an efficient method), enzymatic hydrolysis and a mechanical process (ultrasound) to obtain cellulose nanofibers. We also evaluated the effect of the presence of ethyl groups in the cellulosic matrix (ethylcellulose) on the stabilizing mechanism of emulsions. All cellulose nanofibers were able to produce Pickering emulsions at concentrations of 0.01-0.05% (w/w), although showing differences in emulsion stability and digestibility. Morphology of the different cellulose nanofibers affected the viscosity of the aqueous suspensions used as continuous phase. Emulsions with nanofibers obtained from cassava peel (without the presence of ethyl groups) were stabilized only by the Pickering-type mechanism, while ethylcellulose nanofibers also showed surface activity that contributed to the stability of the emulsion. Furthermore, these latter emulsions showed greater release of free fatty acids in in vitro digestion compared to emulsions stabilized by cellulose nanofibers. Despite these differences, in vitro digestion showed the potential of applying cellulose-stabilized emulsions to control the rate of lipid digestion, due to the low amount of free fatty acids released (<20%).

pH-responsive Pickering emulsion containing citrus essential oil stabilized by zwitterionically charged chitin nanofibers: Physicochemical properties and antimicrobial activity

In this study, zwitterionic chitin nanofibers (Z-ChNFs) were used to prepare Pickering emulsions containing citrus essential oils (CEO) and their physicochemical properties and antimicrobial activity were investigated. Results show that as-prepared Pickering emulsions exert pH-reversible properties, pH can adjust the charge of Z-ChNFs to influence the stability of the emulsion. As the concentration of Z-ChNFs increase, the droplet size of the emulsion decreases. The high concentration of Z-ChNFs (1.5 wt%) can enhance the viscosity and promote forming nano-network structures within continuous phases, and their amphiphilic nature can strengthen the capacity for adsorption on the oil/water interface, resulting in enhanced physical stability of the encapsulated CEO emulsion. Additionally, Z-ChNFs have positive effects on the improvement of antimicrobial activity of CEO. This study provides valuable implications for the development and application of essential oils as biopreservation in the food field.

An overview of the potential application of chitosan in meat and meat products

Chitosan is considered the second most ubiquitous polysaccharide next to cellulose. It has gained prominence in various industries including biomedicine, textile, pharmaceutical, cosmetic, and notably, the food industry over the last few decades. The polymer's continual attention within the food industry can be attributed to the increasing popularity of greener means of packaging and demand for foods incorporated with natural alternatives instead of synthetic additives. Its antioxidant, antimicrobial, and film-forming abilities reinforced by the polymer's biocompatible, biodegradable, and nontoxic nature have fostered its usage in food packaging and preservation. Microbial activity and lipid oxidation significantly influence the shelf-life of meat, resulting in unfavorable changes in nutritional and sensory properties during storage. In this review, the scientific studies published in recent years regarding potential applications of chitosan in meat products; and their effects on shelf-life extension and sensory properties are discussed. The utilization of chitosan in the form of films, coatings, and additives in meat products has supported the extension of shelf-life while inducing a positive impact on their organoleptic properties. The nature of chitosan and its compatibility with various materials make it an ideal biopolymer to be used in novel arenas of food technology.

Modulating the properties of myofibrillar proteins-stabilized high internal phase emulsions using chitosan for enhanced 3D-printed foods

The 3D printability of myofibrillar proteins (MP)-based high internal phase emulsions (HIPEs) is a concern. This study investigated the influence of chitosan (CS) concentrations (0-1.5 wt%) on the physicochemical properties, microstructure, rheological properties, and stability of MP-based HIPEs. Results showed that the interaction between MP and CS efficiently modulated the formation of HIPEs by modifying interfacial tension and network structure. The addition of CS (≤ 0.9 wt%, especially at 0.6 wt%) acted as a spatial barrier, filling the network between droplets, which triggered electrostatic repulsion between CS and MP particles, enhancing MP's interfacial adsorption capacity. Consequently, droplet sizes decreased, emulsion stability increased, and HIPEs became more stable during freeze-thaw cycles, centrifugation, and heat treatment. The rheological analysis further demonstrated that the low energy storage modulus (G', 330.7 Pa) of MP-based HIPEs exhibited sagging and deformation during the self-supporting phase. However, adding CS (0.6 wt%) significantly increased the G' (1034 Pa) of MP-based HIPEs. Conversely, increasing viscosity and spatial resistance attributed to CS (> 0.9 wt%) noticeably caused larger droplet sizes, thereby diminishing the printability of MP-based HIPEs. These findings provide a promising strategy for developing high-performance and consumer-satisfaction 3D printing inks using MP-stabilized HIPEs.

5-Fluorouracil and Anti-EGFR antibody scaffold chitosan-stabilized Pickering emulsion: Formulations, physical characterization, in-vitro studies in NCL-H226 cells, and in-vivo investigations in Wistar rats for the augmented therapeutic effects against squamous cell carcinoma

This research seeks to optimize a chitosan-stabilized Pickering emulsion (PE) containing 5-fluorouracil (5-FU) as a potential Squamous Cell Carcinoma therapy. The 5-Fluorouracil was also thoroughly analysed using UV spectrophotometry and RP-HPLC, demonstrating exceptional linearity, sensitivity, precision, and robustness. The techniques of characterization revealed Pickering emulsion (PE) morphology, solid-like gel properties, successful encapsulation, and promising anticancer effects. FTIR was used to validate the efficacy of encapsulation, and DSC was used to confirm the post-encapsulation drug stability. The 0.6 % chitosan-stabilized PE showed exceptional stability and drug loading efficiency. Anti-EGFR-5-FU-CS-PE gel was developed for sustained drug release in the treatment of Squamous Cell Carcinoma. Anti-EGFR-5-FU-CS-PE demonstrated potent anticancer effects in vitro, with a lower IC50 than 5-FU and 5-FU-CS-PE. Anti-EGFR-5-FU-PE Pickering emulsions based on chitosan were investigated for their rheological properties, cellular interactions, and therapeutic potential. Both emulsions and gel exhibited sustained in vitro drug release after successful encapsulation. Anti-EGFR-5-FU-CS-PE induced apoptosis, decreased mitochondrial membrane potential, and inhibited the migration of cancer cells. Wistar mice were tested for safety and tumour growth inhibition. All formulations exhibited exceptional six-month stability. Anti-EGFR-5-FU-CS-PE emerges as a viable therapeutic option, necessitating additional research.

Bioderived Pickering Emulsion Based on Chitosan/Trialkyl Phosphine Oxides Applied to Selective Recovery of Rare Earth Elements

A novel biobased pickering emulsion (PE) material was prepared by the encapsulation of Cyanex 923 (Cy923) into chitosan (CS) to selectively recover rare earth elements (REEs) from the aqueous phase. The preparation of PE was optimized through sequentially applying a 23 full factorial design, followed by a 33 Box-Behnken design varying the Cy923 content, CS concentration, and pH of CS. The material was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), optical microscopy, rheological, compositional, and stability measurements. The resultant material was evaluated in the removal of yttrium by pH influence, nitrate concentration, kinetics, equilibrium isotherms, reusability, and a comparison with liquid-liquid (L-L) extraction and tested in a real scenario to extract Y from a fluorescent lamp powder waste. In addition, the selectivity of PE for REE was investigated with Y/Ca, Gd/Ca, and La/Ni systems. PE extracts REE at 1 ≤ pH ≤ 5 at nitrate concentrations up to 2 mol/L. The kinetics and equilibrium studies showed reaction times <5 min and a maximum sorption capacity of 89.98 mg/g. Compared with L-L extraction, PE consumed 48% less Cy923 without using organic diluents. PE showed a remarkable selectivity for REE in the systems evaluated, showing separation factors of 22.62, 9.35, and 504.64 for the blends Y/Ca, Gd/Ca/Mg, and La/Ni, respectively. PE showed excellent selectivity extracting Y from a real aqueous liquor from the fluorescent lamp powder. PE demonstrates to be an effective and sustainable alternative for REE recovering due to its excellent efficiency in harsh conditions, favorable green chemistry metrics, and use of a biopolymer material in its composition avoiding the use of organic solvents used in L-L extraction.

The application of chitosan as a carrier for fertilizer: A review

The smart combination of agriculture and other sciences can greatly reduce the limits of fertilizer use. Chitosan is a linear amino polysaccharide with a rigid structure which has hydrophilic and crystal properties. The formation of intermolecular hydrogen bonds the presence of reactive groups and cross-linking, the formation of salts with organic and inorganic acids with complexing and chelating properties ionic conductivity, film formation are the characteristics of chitosan. With the presence of amino groups, chitosan can form a complex with other compounds and also enter the vascular system of plants and lead to the activation of metabolic-physiological pathways of plants. This polymeric compound can bond with other natural polymers and in combination with fertilizers and nutritional elements, on the one hand, it can provide the nutritional needs of the plant and on the other hand, it also helps to improve the soil texture. Chitosan nanomaterials as a Next-generation fertilizers act as plant immune system enhancers through slow, controlled, and targeted delivery of nutrients to plants. Chitosan can assist agricultural researchers and has become an ideal and effective option with its many applications in various fields.

A comparative study of the impacts of preparation techniques on the rheological and textural characteristics of emulsion gels (emulgels)

A subtype of soft solid-like substances are emulsion gels (emulgels; EGs). These composite material's structures either consist of a network of aggregated emulsion droplets or a polymeric gel matrix that contains emulsion droplets. The product's rheological signature can be used to determine how effective it is for a specific application. The interactions between these structured system's separate components and production process, however, have a substantial impact on their rheological imprint. Therefore, rational comprehension of interdependent elements, their structural configurations, and the resulting characteristics of a system are essential for accelerating our progress techniques as well as for fine-tuning the technological and functional characteristics of the finished product. This article presents a comprehensive overview of the mechanisms and procedures of producing EGs (i.e., cold-set and heat-set) in order to determine the ensuing rheological features for various commercial applications, such as food systems. It also describes the influence of these methods on the rheological and textural characteristics of the EGs. Diverse preparation methods are the cause of the rheological-property correlations between different EGs. In many ways, EGs can be produced using various matrix polymers, processing techniques, and purposes. This may lead to various EG matrix structures and interactions between them, which in turn may affect the composition of EGs and ultimately their textural and rheological characteristics.

Preparation and characterization of Pickering emulsion with directionally embedded antimicrobial peptide MOp2 and its preservation effect on grass carp

The peptide MOp2 obtained from Moringa oleifera seeds showed good antimicrobial activity. However, the stability of its activity has not yet been studied. In the present study, MOp2-loaded thiolated chitosan-stabilized (CMOp2) Pickering emulsion was prepared and applied to prolong the shelf life of grass carp. The encapsulation rate of MOp2 was 57.7% in CMOp2. In addition, the effects of different concentrations of CMOp2 solid particles and pH on droplet size, zeta optional and storage stability of Pickering emulsions were evaluated; the best condition for preparing Pickering emulsion through experiment was 1.75% CMOp2 solid particles at pH 9.5. Moreover, morphological observations and rheological analysis indicated that Pickering emulsions were considered a water-in-oil emulsion with typical non-Newtonian fluid characteristics. Furthermore, the prepared Pickering emulsion could significantly inhibit the growth of Escherichia coli and Staphylococcus aureus. Besides, Pickering emulsion effectively prevented spoilage of grass carp, and the Pickering emulsion-treated group reduced its pH, TVB-N and color values, inhibited microbial growth, and extended shelf life to 9 day at the storage of 4 °C. Overall, the present findings provide a reference for the application of MOp2-loaded Pickering emulsions in food preservation.

Enhancement of gum Arabic/casein microencapsulation on the survival of Lactiplantibacillus plantarum in the stimulated gastrointestinal conditions

Probiotic products that contain lactobacilli have long histories of safe use as Lactobacillus strains have many physiological functions in the gastrointestinal tract (GIT). However, the viability of probiotics can be affected by food processing and the adverse environment. This study investigated the O/W (Oil-in-water emulsions) emulsions formed by coagulation of casein/GA (Gum Arabic) complexes for Lactiplantibacillus plantarum microencapsulation, and the stability of the strains during gastrointestinal environment were also determined. The results showed that the particle size of the emulsion decreased from 9.72 μm to 5.48 μm when the GA concentration increased from 0 to 2 (w/v), and the emulsion particles were found to be more uniform as observed by CLSM (Confocal Laser Scanning Microscope). The surface of this microencapsulated casein/GA composite forms smooth, dense agglomerates and has high viscoelasticity, which effectively improved casein's emulsifying activity (8.66 ± 0.17 m2/g). After the casein/GA complexes microencapsulation, a higher viable count was detected after gastrointestinal digestion in vitro, and the activity of L. plantarum is more stable (about 7.51 log CFU/mL) during 35 days of storage at 4 °C. The results of study will help to design lactic acid bacteria encapsulation systems based on the GIT environment for the oral delivery strategy.

Chitosan-induced biotic stress tolerance and crosstalk with phytohormones, antioxidants, and other signalling molecules

Several polysaccharides augment plant growth and productivity and galvanise defence against pathogens. Such elicitors have ecological superiority over traditional growth regulators, considering their amplified biocompatibility, biodegradability, bioactivity, non-toxicity, ubiquity, and inexpensiveness. Chitosan is a chitin-derived polysaccharide that has recently been spotlighted among plant scientists. Chitosan supports plant growth and development and protects against microbial entities such as fungi, bacteria, viruses, nematodes, and insects. In this review, we discuss the current knowledge of chitosan's antimicrobial and insecticidal potential with recent updates. These effects are further explored with the possibilities of chitosan's active correspondence with phytohormones such as jasmonic acid (JA), salicylic acid (SA), indole acetic acid (IAA), abscisic acid (ABA), and gibberellic acid (GA). The stress-induced redox shift in cellular organelles could be substantiated by the intricate participation of chitosan with reactive oxygen species (ROS) and antioxidant metabolism, including hydrogen peroxide (H2O2), superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Furthermore, we propose how chitosan could be intertwined with cellular signalling through Ca2+, ROS, nitric oxide (NO), transcription factors (TFs), and defensive gene activation.

The physicochemical properties and stability of myofibrillar protein oil-in-water emulsions as affected by the structure of sugar

Different sugars (glucose, GL; fructose, FR; hyaluronic acid, HA; cellulose, CE) were added to a myofibrillar protein (MP) emulsion (MP: 1.2 w/v%, sugar: 0.1% w/v) to study the effect of sugar structure on the physicochemical properties and stability of the MP emulsions. The emulsifying properties of MP-HA were significantly (P < 0.05) higher than those of the other groups. The monosaccharide (GL/FR) exerted negligible effects on the emulsifying performance of the MP emulsions. The ζ-potential and particle size implied that HA introduced stronger negative charges, significantly reducing the final particle size (190-396 nm). Rheological examinations indicated that the introduction of polysaccharides considerably increased the viscosity and network entanglement; confocal laser scanning microscopy and creaming index revealed that MP-HA was stable during storage, whereas MP-GL/FR/CE exhibited severe delamination after long-term storage. HA, a heteropolysaccharide, is most suitable for improving MP emulsion quality.

Differentiating the effects of hydrophobic interaction and disulfide bond on the myofibrillar protein emulsion gels at the high temperature and the protein interfacial properties

The study presented the effects of modulating the hydrophobic interaction and disulfide bond on the properties of myofibrillar protein (MP) emulsion gels at high temperature (95 °C) and the differentiation on the contribution of non-covalent (hydrophobic interaction) and covalent intermolecular interactions (disulfide bond) to the properties of interfacial protein films were also determined. The hydrophobic interactions among MP were modulated by the addition of octenyl succinic anhydride (OSA), and the disulfide bonds were modulated by the SH/SS exchange reactions mediated by GSH. The results showed that the MP emulsion gel properties at 95 °C were improved by modulating the hydrophobic interaction or disulfide bonds, and the dynamic interfacial adsorption of MP and dissipation quartz crystal microbalance experiments showed the interfacial adsorption pattens of protein were also changed. In addition, the hydrophobic interactions putted emphasis on improving the gel matrix, whereas the disulfide bonds focused on increasing the stiffness of interfacial protein films.

Characterization of quinoa starch nanoparticles as a stabilizer for oil in water Pickering emulsion

Quinoa starch nanoparticles (QSNPs) prepared by nanoprecipitation had a uniform particle size of 191.20 nm. QSNPs with amorphous crystalline structure had greater contact angle than QS with orthorhombic crystalline structure, which can therefore be utilized to stabilize Pickering emulsions. QSNPs-based Pickering emulsions prepared by suitable formulations (QSNPs concentration of 2.0-2.5 %, oil volume fraction of 0.33-0.67) exhibited good stability against pH of 3-9 and ionic strength of 0-200 mM. The oxidative stability of the emulsions increased with increasing starch concentration and ionic strength. Microstructural and rheological results indicated that the structure of the starch interfacial film and the thickening effect of the water phase affected the emulsion stability. The emulsion had excellent freeze-thaw stability and can be produced as a re-dispersible dry emulsion using the freeze-drying technique. These results implied that the QSNPs had great potential for application in the preparation of Pickering emulsions.

Controlled ibuprofen release from Pickering emulsions stabilized by pH-responsive cellulose-based nanofibrils

Pickering emulsions represent a promising avenue in the field of controlled drug delivery systems. Recently, cellulose nanofibers (CNFs) and chitosan nanofibers (ChNFs) have gained interest as eco-friendly stabilizers for Pickering emulsions, yet their application in pH-responsive drug delivery systems remains unexplored. However, the potential of these biopolymer complexes in formulating stable, pH-responsive emulsions for controlled drug release is of significant interest. Here, we show the development of a highly stable, pH-responsive fish oil-in-water Pickering emulsion stabilized by ChNF/CNF complexes, with optimal stability achieved at a 0.2 wt% ChNF concentration and an average emulsion particle size of approximately 4 μm. Our results demonstrate long-term stability (16 days of storage) for ChNF/CNF-stabilized emulsions, with the interfacial membrane's pH modulation facilitating controlled, sustained ibuprofen (IBU) release. Furthermore, we observed a remarkable release of approximately 95 % of the embedded IBU within the pH range of 5-9, while the drug loading and encapsulation efficiency of the drug-loaded microspheres reached their peak at a 1 % IBU dosage, with values of 1 % and 87 %, respectively. This study highlights the potential of using ChNF/CNF complexes in designing versatile, stable, and entirely renewable Pickering systems for controlled drug delivery, with potential applications in food and eco-friendly products.

Boosting hair growth through follicular delivery of Melatonin through lecithin-enhanced Pickering emulsion stabilized by chitosan-dextran nanoparticles in testosterone induced androgenic alopecia rat model

The strategy in this work was loading Melatonin (MEL), the powerful antioxidant photosensitive molecule, in novel Pickering emulsions (PEs) stabilized by chitosan-dextran sulphate nanoparticles (CS-DS NPs) and enhanced by lecithin, for treatment of androgenic alopecia (AGA). Biodegradable CS-DS NPs dispersion was prepared by polyelectrolyte complexation and optimized for PEs stabilization. PEs were characterized for droplet size, zeta potential, morphology, photostability and antioxidant activity. Ex-vivo permeation study through rat full thickness skin was conducted with optimized formula. Differential tape stripping trailed by cyanoacrylate skin surface biopsy was executed, for quantifying MEL in skin compartments and hair follicles. In-vivo evaluation of MEL PE hair growth activity was performed on testosterone induced AGA rat model. Visual inspection followed by anagen to telogen phase ratio (A/T) and histopathological examinations were conducted and compared with marketed 5% minoxidil spray "Rogaine ®". Data showed that PE improved MEL antioxidant activity and photostability. Ex-vivo results displayed MEL PE high follicular deposition. In-vivo study demonstrated that MEL PE treated testosterone induced AGA rat group, restored hair loss and produced maximum hair regeneration along with prolonged anagen phase amongst tested groups. The histopathological examination revealed that MEL PE prolonged anagen stage, increased follicular density and A/T ratio by 1.5-fold. The results suggested that lecithin-enhanced PE stabilized by CS-DS NPs was found to be an effective approach to enhance photostability, antioxidant activity and follicular delivery of MEL. Thus, MEL-loaded PE could be a promising competitor to commercially marketed Minoxidil for treatment of AGA.

Construction of spherical cellulose nanocrystals synergized with graphene oxide to stabilize Pickering emulsions

In this study, we prepared spherical cellulose nanocrystals (S-CNCs) and stabilized n-hexadecane Pickering emulsions in conjunction with graphene oxide (GO), exploring the interaction between S-CNCs and GO in the emulsions. Both S-CNCs and GO are amphiphilic and synergistically stabilize Pickering emulsions by adhering to the surface of oil droplets and within the emulsion space through hydrogen bonding. GO's two-dimensional sheets assemble into a 3D network structure, further improving the stability of Pickering emulsions. Consequently, the stability of Pickering emulsions can be adjusted by altering the S-CNCs/GO ratio, modifying the spatial distribution relationship of stabilizers in the emulsions. At an S-CNCs concentration of 1 g/L and a GO concentration of 3 g/L, the Pickering emulsion demonstrated excellent stability and exhibited no delamination after 31 days of storage. Thus, the S-CNCs/GO combination serves as an effective Pickering emulsion stabilizer, utilizing the synergistic effect between the two components.

Pea and Soy Protein Stabilized Emulsions: Formulation, Structure, and Stability Studies

During the last decades, there has been a huge consumer concern about animal proteins that has led to their replacement with plant proteins. Most of those proteins exhibit emulsifying properties; thus, the food industry begins their extensive use in various food matrices. In the present study, pea and soy protein isolates (PPI and SPI) were tested as potential candidates for stabilizing food emulsions to encapsulate α-tocopherol and squalene. More specifically, PPI and SPI particles were formulated using the pH modification method. Following, emulsions were prepared using high-shear homogenization and were observed at both a microscopic and macroscopic level. Furthermore, the adsorption of the proteins was measured using the bicinchoninic acid protein assay. The emulsions’ droplet size as well as their antioxidant capacity were also evaluated. It was found that the droplet diameter of the SPI-based emulsions was 60.0 μm, while the PPI ones had a relatively smaller diameter of approximately 57.9 μm. In the presence of the bioactives, both emulsions showed scavenging activity of the 2,20-Azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical cation (ABTS·+) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, with the ones loaded with α-tocopherol having the greatest antioxidant capacity. Overall, the proposed systems are very good candidates in different food matrices, with applications ranging from vegan milks and soups to meat alternative products.

Dual (pH and thermal) stimuli-responsive Pickering emulsion stabilized by chitosan-carrageenan composite microgels

Formulation of water-in-oil (W/O) Pickering emulsion (PE) for food applications has been largely restricted by the limited choices of food-grade Pickering emulsifiers. In this study, composite microgels made of chitosan and carrageenan were explored as a dual (pH and thermal) stimuli-responsive Pickering emulsifier for the stabilization of W/O PE. The chitosan-carrageenan (CS-CRG) composite microgels not only exhibited pH- and thermo-responsiveness, but also displayed enhanced lipophilicity as compared to the discrete polymers. The stability of the CS-CRG-stabilized W/O PE system (CS-CRG PE) was governed by CS:CRG mass ratio and oil fractions used. The CS-CRG PE remained stable at acidic pH and at temperatures below 40 °C. The instability of CS-CRG composite microgels at alkaline pH and at temperatures above 40 °C rendered the demulsification of CS-CRG PE. This stimuli-responsive W/O PE could unlock new opportunities for the development of stimuli-responsive W/O PE using food-grade materials.

Self-assembled emulsion gel based on modified chitosan and gelatin: Anti-inflammatory and improving cellular uptake of lipid-soluble actives

To obtain a green carrier for intestinal targeted delivery, an emulsion gel was designed by the self-assembly between gelatin and Pickering emulsion based on gallic acid modified-chitosan nanoparticles (GCS NPs). The emulsion gels loaded with garlic essential oil (Geo) and curcumin (Cur) were abbreviated as GOEG and GCEG, respectively. Meanwhile, the sodium alginate bead loaded with Geo (GOEGS₃) and the bead loaded with Cur (GCEGS) were prepared as controls. Results demonstrated that the emulsion gels significantly improved the bioaccessibility of Geo and Cur, showing great intestinal targeting delivery properties comparable to that of sodium alginate beads. Moreover, Caco-2 cell experiments indicated that GOEG and GCEG displayed good biocompatibility and enhanced cellular uptake of Geo and Cur. The emulsion gels also exhibited excellent anti-inflammatory properties in the lipopolysaccharide-induced cell model, exhibiting great potential for clinical application. This work provides some references for the preparation of multifunctional emulsion gels with excellent delivery performance by a green method.

Chitosan nanocarriers containing essential oils as a green strategy to improve the functional properties of chitosan: A review

Large amounts of agricultural waste, especially marine product waste, are produced annually. These wastes can be used to produce compounds with high-added value. Chitosan is one such valuable product that can be obtained from crustacean wastes. Various biological activities of chitosan and its derivatives, especially antimicrobial, antioxidant, and anticancer properties, have been confirmed by many studies. The unique characteristics of chitosan, especially chitosan nanocarriers, have led to the expansion of using chitosan in various sectors, especially in biomedical sciences and food industries. On the other hand, essential oils, known as volatile and aromatic compounds of plants, have attracted the attention of researchers in recent years. Like chitosan, essential oils have various biological activities, including antimicrobial, antioxidant, and anticancer. In recent years, one of the ways to improve the biological properties of chitosan is to use essential oils encapsulated in chitosan nanocarriers. Among the various biological activities of chitosan nanocarriers containing essential oils, most studies conducted in recent years have been in the field of antimicrobial activity. It was documented that the antimicrobial activity was increased by reducing the size of chitosan particles in the nanoscale. In addition, the antimicrobial activity was intensified when essential oils were in the structure of chitosan nanoparticles. Essential oils can increase the antimicrobial activity of chitosan nanoparticles with synergistic effects. Using essential oils in the structure of chitosan nanocarriers can also improve the other biological properties (antioxidant and anticancer activities) of chitosan and increase the application fields of chitosan. Of course, using essential oils in chitosan nanocarriers for commercial use requires more studies, including stability during storage and effectiveness in real environments. This review aims to overview recent studies on the biological effects of essential oils encapsulated in chitosan nanocarriers, with notes on their biological mechanisms.