Preparation and characterization of pH-responsive Pickering emulsion stabilized by grafted carboxymethyl starch nanoparticles

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.

Study on the stability and magnetically induced demulsification performance of Pickering emulsions based on arginine-modified lignin/Fe3O4 nanoparticles

In this study, four different arginine-modified lignin composites (Lig-Arg-x) were synthesized via the Mannich reaction, followed by the preparation of Lig-Arg-x/Fe3O4 magnetic nanoparticles (NPs) using hydrothermal reduction. The magnetic particles were characterized, and their emulsification properties were investigated. The highest grafting degree was achieved at a 1:1 M ratio of arginine to lignin. Pickering emulsions were formulated and Lig-Arg-x/Fe3O4 NPs as the emulsifier. The study examined the impact of arginine grafting degree, oil-to-water volume ratio, and nanoparticle concentration on emulsion stability and demulsification performance. Optimal emulsion stability, characterized by the smallest droplet size of 20.57 μm, was achieved with a 1:1 M ratio of lignin to arginine, a 7:3 oil-to-water volume ratio, and a nanoparticle concentration of 1.0 w/v%. Magnetic induction experiments demonstrated significant phase separation in the stable emulsion under a magnetic field, confirming the magnetic-induced demulsification capability of the composite particles. Oil displacement experiments demonstrated that Lig-Arg-x/Fe3O4 NPs modulate oil droplet diffusion via the Marangoni effect, indicating their potential for oil recovery applications. After three cycles, Lig-Arg-1/Fe3O4 NPs retained 80 % of their saturation magnetization, demonstrating strong reusability. This study showcases lignin-magnetite nanocomposites' versatility in stabilizing emulsions and exhibiting magnetic responsiveness, advancing demulsification and oil spill recovery technologies.

Synergistic effect and mechanism of stabilization of Pickering emulsion by carboxymethyl starch and xanthan gum

Pickering emulsions were prepared using different proportions of carboxymethyl starch (CMS) and xanthan gum (XG) combined systems as emulsifying stabilizers (The mass ratios of CMS and XG were 10:0, 9:1, 7:1, 5:1, 3:1 and 1:1, respectively). The synergistic mechanism between CMS and XG was also explored. The results demonstrated that CMS particles were uniformly and densely embedded in the gel-like structure formed by XG, and the electrostatic repulsion between CMS and XG led to a reduction in droplet size (from 3370 nm to 482 nm), resulting in a more compact and orderly droplet distribution. Combined systems of CMS and XG at different proportions enhanced the hardness (3.05-8.36 g), adhesiveness (3.26-8.41 g), and chewiness (4.05-8.20 g) of the emulsion. AFM observed that the emulsion particles were finer and more evenly dispersed. After heat treatment at 25 °C, 60 °C and 80 °C, the emulsion showed no significant stratification phenomenon, and CMS/XG enhanced the heat stability of the emulsion. LF-NMR confirmed that the oil and water could be evenly distributed and the emulsification of the system was complete. Especially when the ratio of CMS and XG was 3:1 and 1:1, the emulsion with a stable and long storage period could be obtained.

Construction and characterization of sesame meal-stabilized Pickering high internal phase emulsions and their application in cake production

Pickering high internal phase emulsions (HIPEs) show promise for solid fat replacement and nutrient delivery, but the availability of safe and easily accessible food-borne particulate emulsifiers is a bottleneck limiting their practical application. In this study, the feasibility of using sesame meal as an emulsifier for the construction of sunflower oil-based Pickering HIPEs was evaluated. These HIPEs were then characterized in terms of their microstructural and mechanical properties, and utilized as a substitute for butter in cake production. Results showed that sesame meal is rich in protein, and has a particle size (median diameter, 46.40 ± 0.83 μm), and wettability that makes it suitable for use as an emulsifier. It stabilized O/W type Pickering HIPEs formulated with sunflower oil with a volume fraction of up to 80 %. The mechanical properties of these Pickering HIPEs were positively correlated with the concentration of sesame meal. Sunflower oil-based HIPEs prepared from sesame meal can partially replace butter for cake preparation when φ = 80 % and c = 9.0 %, and enhance the internal pore structure of cake when butter substitution (Wb) ≤ 30 %. This provides a new way to use sesame meal and new type of food-grade Pickering HIPEs.

Physicochemical properties and antibacterial property of pickering emulsion stabilized by smart Janus nanospheres

In this study, responsive Janus nanospheres were prepared by grafting LMA and DMAEMA monomers on both sides of SiO2 nanospheres using the Pickering emulsion stencil method and RAFT polymerization. The successful synthesis was verified through infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), scanning electron microscopy (SEM) characterizations. Subsequently, Pickering emulsion was formulated using Janus nanospheres as emulsifiers. The particle size of the emulsion droplets was systematically investigated by manipulating factors such as pH, nanosphere dosage, water to oil ratio, and oil phase polarity. Notably, the Pickering emulsion exhibited responsive properties to pH, temperature, and CO2. Furthermore, Janus nanospheres exhibited excellent emulsification property for real oil phases, including canola oil, kerosene, gasoline, and diesel oil. Building upon this, a smart antibacterial Pickering emulsion was developed using Janus nanospheres, and its inhibition rate against E. coli could reach 100% within 4 h, which would be beneficial for its application in the food field.

Encapsulation of phenolic acids within food-grade carriers systems: a systematic review

Phenolic acids are natural compounds with potential therapeutic effects against various diseases. However, their incorporation into food and pharmaceutical products is limited by challenges such as instability, low solubility, and reduced bioavailability. This systematic review summarizes recent advances in phenolic acid encapsulation using food-grade carrier systems, focusing on proteins, lipids, and polysaccharides. Encapsulation efficiency, release behavior, and bioavailability are examined, as well as the potential health benefits of encapsulated phenolic acids in food products. Strategies to address limitations of current encapsulation systems are also proposed. Encapsulation has emerged as a promising method to enhance the stability and bioavailability of phenolic acids in food products, and various encapsulation technologies have been developed for this purpose. The use of proteins, lipids, and carbohydrates as carriers in food-grade encapsulation systems remains a common approach, but it is associated with certain limitations. Future research on phenolic acid encapsulation should focus on developing environmentally friendly, organic solvent-free, low-energy, scalable, and stable encapsulation systems, as well as co-encapsulation methods that combine multiple phenolic acids or phenolic acids with other bioactive substances to produce synergistic effects.

Edible chitosan-based Pickering emulsion coatings: Preparation, characteristics, and application in strawberry preservation

The long-term application of plant essential oils in food preservation coatings is limited by their poor water solubility and high volatility, despite their recognized synergistic antimicrobial effects in postharvest fruit preservation. To overcome these limitations, a Pickering emulsion loaded with thyme essential oil (TEO) was developed by utilizing hydrogen bonding and electrostatic interactions to induce cross-linking of chitosan particles. This novel emulsion was subsequently applied in the postharvest storage of strawberries. The shear-thinning behavior (flow index <1) and elastic gel-like characteristics of the emulsion made it highly suitable for spray application. Regarding TEO release, the headspace concentration of TEO increased from 0.21 g/L for pure TEO to 1.86 g/L after two instances of gas release due to the stabilizing effect of the chitosan particles at the oil-water interface. Notably, no phase separation was observed during the 10-day storage of the emulsion. Consequently, the emulsion was successfully employed for the postharvest storage of strawberries, effectively preventing undesirable phenomena such as weight loss, a decrease in firmness, an increase in pH, and microbial growth. In conclusion, the developed Pickering emulsion coating exhibits significant potential for fruit preservation applications, particularly for extending the shelf life of strawberries.

The soybean lecithin-cyclodextrin-vitamin E complex nanoparticles stabilized Pickering emulsions for the delivery of β-carotene: Physicochemical properties and in vitro digestion

In this work, soybean lecithin (LC) was used to modify β-cyclodextrin (β-CD) with hydrophobic fat chains to become amphiphilic (LC-CD), and vitamin E (VE) was encapsulated in former modified β-CD complexes (LC-CD-VE), the new Pickering emulsions stabilized by LC-CD-VE and LC-CD complexes for the delivery of β-carotene (BC) were created. The surface tension, contact angle, zeta potential, and particle size were used to assess the changes in complexes nanoparticles at various pH values. Furthermore, LC-CD-VE has more promise as Pickering emulsion stabilizer than LC-CD because of the smaller particle size (271.11 nm), proper contact angle (58.02°), and lower surface tension (42.49 mN/m). The interactions between β-cyclodextrin, soybean lecithin, and vitamin E were confirmed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA). The durability of Pickering emulsions was examined at various volume fractions of the oil phase and concentrations of nanoparticles. Compared to the emulsion stabilized by LC-CD, the one stabilized by LC-CD-VE showed superior storage stability. Moreover, for the delivery of BC, Pickering emulsions stabilized by LC-CD and LC-CD-VE can outperform bulk oil and Tween 80 stabilized emulsions in terms of UV light stability, storage stability, and bioaccessibility. This work could offer fresh perspectives on stabilizer alternatives for Pickering emulsion delivery systems.

Preparation and properties of pH-sensitive cationic starch nanoparticles

Environmentally friendly and outstanding pH responsiveness cationic starch nanoparticles (CSNP) were prepared through ethanol precipitation from pH-sensitive starch, which preparation of cationic starch (CS) by grafting copolymerization with dimethylaminoethyl methacrylate (DMAEMA). In this work, CSNP showed a nanometer size and regular sphere, highly free-flowing molecular chains, and outstanding pH responsiveness which was proved by the high stability of its stabilized emulsion through 6 emulsification/ demulsification transition. The result of the SEM and particle size distribution indicated that the size of the CSNP-0 was about 800 nm, and decreased with the DMAEMA increased. Moreover, the CSNP-stabilized emulsion was stable at pH = 7 and pH = 12. However, this emulsion exhibited breakage at pH = 2. In addition, the CSNP-stabilized Pickering emulsion achieved an emulsification/demulsification switching by cycling the pH at least 6 times, during which the average droplet size gradually increased. At pH ≥ 7, the emulsions exhibit shear thinning behavior.

Smart antibacterial nanocellulose packaging film based on pH-stimulate responsive microcapsules synthesized by Pickering emulsion template

Spoilage results in food waste and endangers consumer health, and the smart antibacterial packaging can effectively inhibit bacterial growth and reduce food spoilage. In this study, the smart antibacterial nanocellulose packaging films were developed by adding the pH-stimulated responsive microcapsules into cellulose nanofibril (CNF) film-forming. The microcapsules were synthesized by interfacial polymerization of Pickering emulsion. Carboxylated cellulose nanocrystals as solid particles stabilized the composited oil phase to prepare the oil-in-water Pickering emulsion. The emulsion with the particle concentration of 1.25 wt% and the oil phase mass fraction of 7.5 % processes excellent stability and uniform particle size, was chosen to synthesize microcapsules. The cinnamaldehyde in the film with the addition amount of microcapsules 0.6 g burst released in the first 1 h and then slowly, and the cumulative release at pH 2.0, 4.0, 5.5 and 7.2 was 28.43 μg/cm2, 18.84 μg/cm2, 16.52 μg/cm2 and 12.89 μg/cm2, respectively. The inhibitory rate of film against both E. coli and L. monocytogenes reached 99 % at pH 4.0. The shelf life of pork packed by the film prolonged to nearly 9 d at room temperature. The developed films have the potential to be used in food packaging.

Anthocyanin-Rich Butterfly Pea Petal Extract Loaded Double Pickering Emulsion Containing Nanocrystalline Cellulose: Physicochemical Properties, Stability, and Rheology

Butterfly pea petal extract (BPE)-loaded water-in-oil-in-water (W/O/W) emulsions were fabricated using nanocrystalline cellulose (NCC) as a hydrophilic stabilizer and polyglycerol polyricinoleate (PGPR) as a hydrophobic emulsifier. The impact of different concentrations of NCC and PGPR in different phase proportions on the emulsion formation, rheology, and stability of an anthocyanin-loaded (pH ≈ 7.0) emulsion was investigated. The mean droplet size of the emulsions increased as the NCC concentration increased, while color intensity (greenness) decreased as the PGPR and NCC concentrations increased. A microscopic examination confirmed that the NCC nanoparticles stabilized the inner W1/O phase, whereas the excess concentration of non-adsorbing NCC nanoparticles was suspended in the continuous aqueous phase. The rheological results showed that robust emulsion networks were formed when the NCC concentration increased. A network structure between the droplets and the development of the NCC network during the continuous phase were attributed to a gel-like behavior. Over the course of seven days, the emulsions with a higher proportion of NCC remained stable, as in samples 3%P-%N, 5%P-2%N, and 5%P@1%N, the total anthocyanin content decreased from 89.83% to 76.49%, 89.40% to 79.65, and 86.63% to 71.40%, respectively. These findings have significant implications for the accurate formulation of particle-stabilized double emulsions for anthocyanin delivery with higher stability.

A new insight into the influence of pH on the adsorption at oil-water interface and emulsion stability of egg yolk protein

This study investigated the impact of varied pH treatments on the structural, emulsification, and interfacial adsorption properties of egg yolk. The solubility of egg yolk proteins decreased and then increased in response to pH changes, with a minimum value (41.95 %) observed at pH 5.0. The alkaline condition (pH 9.0) significantly impacted the secondary/tertiary structure of egg yolk, with the yolk solution displaying the lowest surface tension value (15.98 mN/m). Emulsion stability was found to be optimal when egg yolk was used as the stabilizer at pH 9.0, which corresponded to the more flexible diastolic structure, smaller emulsion droplets, increased viscoelasticity, and enhanced resistance to creaming. At pH 9.0, proteins exhibited a maximum solubility (90.79 %) due to their unfolded conformation, yet the protein adsorption content at the oil-water interface showed relatively low (54.21 %). At this time, electrostatic repulsion between the droplets and the spatial site barrier made by proteins that were unable to efficiently adsorb at the oil-water interface kept the emulsion stable. Moreover, it was found that different pH treatments could effectively regulate the relative adsorption contents of various protein subunits at the oil-water interface, and all proteins except livetin displayed good interfacial adsorption capacity at the oil-water interface.

Influence of fatty acid-esterified waxy maize starch type and concentration on stability and properties of oil-in-water emulsions

In the current study, native and different fatty acid-esterified waxy maize starches (octanoate, myristoate, and stearoate), followed by an OSA-potato starch (as an industrial emulsifier) were used to prepare sunflower oil-in-water (O/W) emulsion. The effect of emulsifier type and concentration were evaluated on properties of emulsions in terms of mean droplet size, droplet size distribution, and creaming index. To prepare the emulsion, the emulsifier to oil ratios of 1.25 and 0.5 for octanoate and industrial emulsifier (control) were considered as the selected formulations based on the lowest creaming index (2.63 and 0 %, respectively). The influence of various pHs and ionic strengths on droplet size, span and zeta potential value was similar for both produced emulsions. Therefore, the fatty acid-esterified starch could be suggested as a promising environmentally friendly alternative to industrial emulsifiers for fabrication of emulsions with similar stability.

Effect of extrusion parameters on the interaction between rice starch and glutelin in the preparation of reconstituted rice

Reconstituted rice produced by extrusion has been attracted attention due to nutritional fortification and convenient production. Nevertheless, how to achieve desirable qualities and physicochemical properties of reconstituted rice nearly to natural rice by regulating extrusion process parameters is difficult. Herein, rice starch/glutelin mixture as raw material of reconstituted rice was extruded at varying extrusion conditions. Specific mechanical energy (SME) and sectional expansion index (SEI) dropped with rise in density (R² = 0.9117 and 0.8207). Solubility was enhanced with increase in product temperature (R² = 0.9085), color darkened and shifted to reddish and yellowish as extrusion temperature increased (R² = 0.8577). These trends were well fitted by sigmoid models. Furthermore, SME enhanced hydrophobic and electrostatic interactions between rice starch and glutelin and caused the reduction in crystallinity and thermal stability, promoting the formation of a bi-continuous matrix of protein aggregates with rice starch. The obtained results can be applied to guide the production of reconstituted rice with desirable qualities.

Enzymatically modified quinoa starch-based Pickering emulsion: Effect of enzymolysis and emulsifying conditions

Both the effects of enzymolysis condition on the microstructures and emulsifying property of enzymatic modified quinoa starch (EMQS) and the effects of emulsion formulation on the EMQS based emulsions were investigated. The emulsifying capacity (EC) and stability (ES) of EMQS were positive correlated with enzyme amount (0-2.4 % w/w_starch). The particle sizes of EMQS decreased and its hydrophobicity increased with increasing enzyme amount (0-2.4 % w/w_starch), which were the main reasons for the increasing emulsifying performance of EMQS. With the increasing starch concentration, the EC of the EMQS increased, the oil droplet size of the emulsion decreased. With the oil/water ratios ranging from 1:9 to 6:4, the emulsification index (EI) and oil droplet size of the emulsion increased. EMQS based emulsion had a relatively good stability in the pH range of 2-10. This study lays the foundation for the application of EMQS as a stable clean-label Pickering emulsifier.

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.

Synthesis, characteristics, and applications of modified starch nanoparticles: A review

Nowadays, starch nanoparticles (SNPs) are drawing attention to the scientific community due to their versatility and wide range of applications. Although several works have extensively addressed the SNP production routes, not much is discussed about the SNPs modification techniques, as well as the use of modified SNPs in typical and unconventional applications. Here, we focused on the SNP modification strategies and characteristics and performance of the resulting products, as well as their practical applications, while pointing out the main limitations and recommendations. We aim to guide researchers by identifying the next steps in this emerging line of research. SNPs esterification and oxidation are preferred chemical modifications, which result in changes in the functional groups. Moreover, additional polymers are incorporated into the SNP surface through copolymer grafting. Physical modification of starch has demonstrated similar changes in the functional groups without the need for toxic chemicals. Modified SNPs rendered differentiated properties, such as size, shape, crystallinity, hydrophobicity, and Zeta-potential. For multiple applications, tailoring the aforementioned properties is key to the performance of nanoparticle-based systems. However, the number of studies focusing on emerging applications is fairly limited, while their applications as drug delivery systems lack in vivo studies. The main challenges and prospects were discussed.

Polysaccharide-Based Nanoparticles as Pickering Emulsifiers in Emulsion Formulations and Heterogenous Polymerization Systems

Bio-based Pickering emulsifiers are a nontoxic alternative to surfactants in emulsion formulations and heterogenous polymerizations. Recent demand for biocompatible and sustainable formulations has accelerated academic interest in polysaccharide-based nanoparticles as Pickering emulsifiers. Despite the environmental advantages, the inherent hydrophilicity of polysaccharides and their nanoparticles limits efficiency and application range. Modification of the polysaccharide surface is often required in the development of ultrastable, functional, and water-in-oil (W/O) systems. Complex surface modification calls into question the sustainability of polysaccharide-based nanoparticles and is identified as a significant barrier to commercialization. This review summarizes the use of nanocelluloses, -starches, and -chitins as Pickering emulsifiers, highlights trends and best practices in surface modification, and provides recommendations to expedite commercialization.

Recent Developments in the Formulation and Use of Polymers and Particles of Plant-based Origin for Emulsion Stabilizations

The main scope of this Review was the recent progress in the use of plant-based polymers and particles for the stabilization of Pickering and non-Pickering emulsion systems. Due to their availability and promising performance, it was discussed how the source, modification, and formulation of cellulose, starch, protein, and lignin-based polymers and particles would impact their emulsion stabilization. Special attention was given toward the material synthesis in two forms of polymeric surfactants and particles and the corresponding formulated emulsions. Also, the effects of particle size, degree of aggregation, wettability, degree of substitution, and electrical charge in stabilizing oil/water systems and micro- and macro-structures of oil droplets were discussed. The wide range of applications using such plant-based stabilizers in different technologies as well as their challenge and future perspectives were described.

Preparation and characterization of hyacinth bean starch film incorporated with TiO2 nanoparticles and Mesona chinensis Benth polysaccharide

Hyacinth bean starch (HBS) was used to prepare nanocomposite films with the reinforcement agent of nanotitanium oxide (TiO₂-N) and Mesona chinensis Benth polysaccharide (MCP). The effects of TiO₂-N and MCP on the moisture combination, rheological properties of film-forming solutions (FFS) and physiochemical properties of films were investigated. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) revealed that HBS, TiO₂-N and MCP had good compatibility, while no novel absorption peak in FTIR spectra, and characteristic peaks of TiO₂-N were found in XRD patterns of composite films. Contact angle of HBS/TiO₂-N/M3 film increased from 65.6° to 90.9°, which illustrated that TiO₂-N and MCP effectively enhanced hydrophobicity of films. TiO₂-N and MCP positively affected anti-UV light ability of HBS films by resisting most of invisible light. Furthermore, stable and compact network structures were formed by the synergistic effect of TiO₂-N and MCP, thereby elongation to break was increased from 17.123% to 28.603% significantly, and heat resistance was enhanced clearly. This study prepared a nanocomposite HBS-based films based TiO₂-N and MCP, which had guiding significance for development of functional films and combination of polysaccharides and metallic oxide.

Oil-in-water Pickering emulsion stabilization with oppositely charged polysaccharide particles: chitin nanocrystals/fucoidan complexes

BACKGROUND

Chitin nanocrystals (ChN) are insoluble particles that can be used as stabilizers for Pickering emulsions. Their unique cationic properties and antibacterial activity have generated considerable interest among researchers. However, ChN have remained largely underexplored. Furthermore, the droplets of the emulsions stabilized by ChN are as large as 10-100 μm, and their physical stability requires further improvement. Some studies have shown that the spontaneous reaction of oppositely charged particles can effectively stabilize the emulsions. Positively charged ChN and negatively charged fucoidan (F) were therefore compounded to stabilize Pickering emulsions, and the stability of these emulsions was analyzed qualitatively.

RESULTS

The results showed that the composite particles comprising two polysaccharides in a mass ratio of 1:1 and at a pH of 2 (ChN₁ -F₁ -pH 2) possessed the lowest sulfate content (20.1%) and almost zero potential (-3 mV), indicating a high degree of neutralization of the positively charged amino group in ChN and the negatively charged sulfate group in F. Meanwhile, ChN₁ -F₁ -pH 2 displayed a dense network structure that improved the dispersibility and wettability (contact angle = 9.3°). Fourier transform infrared spectroscopy results confirmed that ChN and F were effectively combined through electrostatic interaction or neutralization to produce a polyelectrolyte complex. Furthermore, the particle size of the Pickering emulsion stabilized by ChN-F was significantly reduced, and the maximum size did not exceed 10 μm; the physical and storage stability also improved. The ChN₁ -F₁ -pH 2 emulsion presented excellent storage stability; in particular, the emulsions stabilized by ChN₁ -F₁ -pH 5 and ChN₁ -F₁ -pH 6 exhibited excellent flocculation stabilities.

CONCLUSION

The size of the emulsion droplets stabilized by the oppositely charged polysaccharide particles (ChN-F complexes) reduced significantly. Furthermore, by changing the mass ratio and pH, the microstructure and binding degree of the complexes can be adjusted, thereby promoting their adsorption on the oil-water interface and improving the stability of the Pickering emulsion. © 2020 Society of Chemical Industry.

Recent trends in the application of modified starch in the adsorption of heavy metals from water: A review

The presence of polyfunctional ligands on the bio-macromolecules acts as an efficient adsorbent for heavy metal ions. Starch is one of the most abundant, easily available and cheap biopolymer of plant origin. However, native starch exhibits significantly low adsorption capacity due to the absence of some essential functional groups like carboxyl, amino or ester groups and is thus modified using various reaction routes like grafting, cross-linking, esterification, oxidation and irradiation for addition of functional groups to increase its adsorption capacity. The present review provides a comprehensive discussion on the above mentioned modification schemes of starch over the last 10-15 years highlighting their preparation methods, physico-chemical characteristics along with their adsorption capacities and mechanisms of heavy metal ions from water.

The preparation of modified nano-starch and its application in food industry

Starch, which is a carbohydrate polymer with a semicrystalline granular structure, has been the subject of academic research for decades due to its renewable and biodegradable property as well as various applications in food, pharmaceutical and other industries. Nano-starch (NS) is a novel type of starch material with unique physiochemical properties due to its small size. However, the nano-size nature of NS determines its tendency to agglomeration as a natural process to approach a thermodynamically steady state, and the single hydroxyl functional group is also not favorable to its applications in hydrophobic environments. Thus, modified-NS with improved dispersion property, hydrophobicity, and stability is emerging as a new research direction. However, information about modified-NS is sporadic in literature, and a systematic review from its preparation, application, the problem and challenge as well as related health concerns is carried out to further the understanding of modified-NS. It is expected that the theoretical basis and new insight into the development of modified-NS will be improved.

Food-Grade Pickering Emulsions: Preparation, Stabilization and Applications

In recent years, Pickering emulsions have emerged as a new method and have attracted much attention in the fields of food sciences. Unlike conventional emulsions, Pickering emulsions are stabilized by solid particles, which can irreversibly adsorb on the oil-water interface to form a dense film to prevent the aggregation of droplets. The research and development of food-grade solid particles are increasingly favored by scientific researchers. Compared with conventional emulsions, Pickering emulsions have many advantages, such as fewer using amounts of emulsifiers, biocompatibility and higher safety, which may offer feasibility to have broad application prospects in a wide range of fields. In this article, we review the preparation methods, stabilization mechanism, degradation of Pickering emulsions. We also summarize its applications in food sciences in recent years and discuss its future prospects and challenges in this work.

Modulation of interfacial phenolic antioxidant distribution in Pickering emulsions via interactions between zein nanoparticles and gallic acid

The impacts of protein nanoparticles on the interfacial distribution of antioxidants and the oxidative stability in Pickering emulsions are attracting increasing research interests. In the present work, the distribution of gallic acid (GA) in zein nanoparticles-stabilized Pickering emulsions (ZPE) was determined by employing a pseudophase kinetic model. The interfacial distribution of GA was found to be favored in ZPEs with higher zein nanoparticle concentration (C_zein). Upon increasing C_zein, the interfacial loading of nanoparticles (Γ) dominated the modulation of %GA_I via hydrogen bonding between zein nanoparticles and GA. The interfacial percentage of GA (%GA_I) increased from 28% to 39% as Γ increased from 0.48 to 1.12 mg/m²_. In the presence of GA, a direct correlation between C_zein or Γ and oxidation stability was recognized, whereas the oxidative stability showed a non-linear dependence on either C_zein or Γ in the absence of GA. By excluding antioxidant effects of zein nanoparticles, we found that the %GA_I, which was regulated by Γ, took the leading role over the physical barrier effect on the oxidative stability of emulsions. The present work extends our current knowledge on how protein based nanoparticles manipulate the interfacial distribution of antioxidant and then affect the oxidative stability of emulsions.