Casein gel particles as novel soft Pickering stabilizers: The emulsifying property and packing behaviour at the oil-water interface

Thermo-responsive composite nanoparticles based on hydroxybutyl chitosan oligosaccharide: Fabrication, stimulus release and cancer therapy

Designing thermo-responsive nanocarriers based on biopolymers is fascinating and challenging for cancer therapy. In this study, thermo-responsive composite nanoparticles (CNPs) were prepared using hydroxybutyl chitosan oligosaccharide (HBCOS) and sodium caseinate (SC) via electrostatic interactions and covalent crosslinking. The temperature-responsive behaviors of CNPs were induced by the breakage of hydrogen bonds and the shrinkage of chains in nanoparticles. The CNPs exhibited concentration-independent thermo-responsive behavior, non-adsorption aggregation, and non-hemolysis, suggesting excellent stability and thermo-sensitivity. The initial release rate and final amount of DOX released from CNPs at 42 °C were higher than that at 37 °C, showing a thermo-responsive release, which was also more prominent at lower pH. The release of DOX from CNPs followed first order kinetics based on Fickian diffusion. In vitro cytotoxicity assays confirmed the thermo-responsive antitumor activity of DOX-loaded CNPs as the HT-29 cell viability incubated with DOX-loaded CNPs at 42 °C was significantly lower than that at 37 °C. Cellular uptake experiments proved that DOX-loaded CNPs accumulated in the cytoplasm after being endocytosed and promoted DOX release by increasing environment temperature. This study generated stable thermo-sensitive CNPs based on biopolymers, which can be used as potential nanocarriers for the controlled release of anticancer drugs for cancer therapy.

Multiple Pickering emulsions stabilized by food-grade particles as innovative delivery systems for bioactive compounds

The most common carrier for encapsulation of bioactive components is still simple emulsion. Recently, bio-based novel emulsion systems such as multiple emulsions (MEs) and Pickering emulsions (PEs) have been introduced as innovative colloidal delivery systems for encapsulation and controlled release of bioactive compounds. Multiple PEs (MPEs), which carries both benefit of MEs and PEs could be fabricated by relatively scalable and simple operations. In comparison with costly synthetic surfactants and inorganic particles which are widely used for stabilization of both MEs and PEs, MPEs stabilized by food-grade particles, while having health-promoting aspects, are able to host the "clean label" and "green label" attributes. Nevertheless, in achieving qualified techno-functional attributes and encapsulation properties, the selection of suitable materials is a crucial step in the construction of such complex systems. Current review takes a cue from both MEs and PEs emulsification techniques to grant a robust background for designing various MPEs. Herein, various fabrication methods of MEs and PEs are described comprehensively in a physical viewpoint in order to find key conception of successful formulation of MPEs. This review also highlights the link between the underlying aspects and exemplified specimens of evidence which grant insights into the rational design of MPEs through food-based ingredients to introduces MPEs as novel colloidal/functional materials. Their utilization for encapsulation of bioactive compounds is discussed as well. In the last part, instability behavior of MPEs under various conditions will be discussed. In sum, this review aims to gain researchers who work with food-based components, basics of innovative design of MPEs.

Genipin, a natural blue colorant precursor: Source, extraction, properties, and applications

Natural cross-linkers are extensively employed due to their low toxicity and biocompatibility benefits. Genipin acts as a precursor for producing blue colorants. The formation of these colorants involves the cross-linking reaction between genipin and primary amines present in amino acids, peptides, and proteins. Genipin is extracted from Gardenia jasminoides and Genipa americana. This article explains the cross-linking mechanism of genipin with proteins/polysaccharides to provide an overall understanding of its properties. Furthermore, it explores new sources of genipin and innovative methodologies to make the genipin recovery process efficient. Genipin increases food products' texture, gel strength, stability, and shelf life. The antibacterial, anti-inflammatory, and antioxidant properties of chitosan, gelatin, alginate, and hyaluronic acid increased after genipin cross-linking. Lastly, drawbacks, toxicity, and directions regarding the genipin cross-linking have also been addressed. The review article covers how to recover and cross-link genipin with biopolymers for industrial applications.

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.

Effects of the Combination of Protein in the Internal Aqueous Phase and Polyglycerol Polyricinoleate on the Stability of Water-In-Oil-In-Water Emulsions Co-Encapsulating Crocin and Quercetin

This study aimed to diminish the reliance on water-in-oil-in-water (W/O/W) emulsions on the synthetic emulsifier polyglycerol polyricinoleate (PGPR). Considering the potential synergistic effects of proteins and PGPR, various protein types (whey, pea and chickpea protein isolates) were incorporated into the internal aqueous phase to formulate W/O/W emulsions. The effects of the combination of PGPR and protein at different ratios (5:0, 4:1, 3:2, 1:1 and 2:3) on the stability and encapsulation properties of W/O/W emulsions co-encapsulating crocin and quercetin were investigated. The findings indicated that the combination of PGPR and protein resulted in a slight reduction in the encapsulation efficiency of the emulsions, compared to that of PGPR (the control). Nonetheless, this combination significantly enhanced the physical stability of the emulsions. This result was primarily attributed to the smaller droplet sizes and elevated viscosity. These factors contributed to increased retentions of crocin (exceeding 70.04%) and quercetin (exceeding 80.29%) within the emulsions after 28 days of storage, as well as their improved bioavailability (increases of approximately 11.62~20.53% and 3.58~7.98%, respectively) during gastrointestinal digestion. Overall, combining PGPR and protein represented a viable and promising strategy for reducing the amount of PGPR and enhancing the stability of W/O/W emulsions. Notably, two plant proteins exhibited remarkable favorability in this regard. This work enriched the formulations of W/O/W emulsions and their application in the encapsulation of bioactive substances.

Synthetic and biopolymeric microgels: Review of similarities and difference in behaviour in bulk phases and at interfaces

This review discusses the current knowledge of interfacial and bulk interactions of biopolymeric microgels in relation to the well-established properties of synthetic microgels for applications as viscosity modifiers and Pickering stabilisers. We present a timeline showing the key milestones in designing microgels and their bulk/ interfacial performance. Poly(N-isopropylacrylamide) (pNIPAM) microgels have remained as the protagonist in the synthetic microgel domain whilst proteins or polysaccharides have been primarily used to fabricate biopolymeric microgels. Bulk properties of microgel dispersions are dominated by the volume fraction (ϕ) of the microgel particles, but ϕ is difficult to pinpoint, as addressed by many theoretical models. By evaluating recent experimental studies over the last five years, we find an increasing focus on the analysis of microgel elasticity as a key parameter in modulating their packing at the interfaces, within the provinces of both synthetic and biopolymeric systems. Production methods and physiochemical factors shown to influence microgel swelling in the aqueous phase can have a significant impact on their bulk as well as interfacial performance. Compared to synthetic microgels, biopolymer microgels show a greater tendency for polydispersity and aggregation and do not appear to have a core-corona structure. Comprehensive studies of biopolymeric microgels are still lacking, for example, to accurately determine their inter- and intra- particle interactions, whilst a wider variety of techniques need to be applied in order to allow comparisons to real systems of practical usage.

Stability of protein particle based Pickering emulsions in various environments: review on strategies to inhibit coalescence and oxidation

The emerging research interests in fabrication of protein particles as soft-particle emulsifiers show the prospective potential of using protein particles in novel poly-phase dispersing food systems. This review first provides a comprehensive summary and analysis on the dominant role of key physicochemical properties of protein particles including wettability, morphology, surface charge and protein concentration on their emulsifying abilities to construct Pickering emulsions. It was found that the constructed emulsions showed high sensitivity to changes in pH, ionic strength and temperature (thermal and freeze-thaw treatment). Moreover, oxidation remains as a challenge for protein particle based Pickering emulsions during prolonged storage, reducing their acceptance in food products. Current strategies for improving the stability of these emulsions to variable aqueous conditions and variable temperatures, and restricting oxidation event are summarized. In summary, an "ideal" protein particle-based Pickering emulsion system is proposed, encompassing aspects of interfacial property, emulsion network and texture, and antioxidant enrichment, thus promoting industrial translation into novel food and nutraceutical products.

Correlation between interfacial layer properties and physical stability of food emulsions: current trends, challenges, strategies, and further perspectives

Emulsions are thermodynamically unstable systems that tend to separate into two immiscible phases over time. The interfacial layer formed by the emulsifiers adsorbed at the oil-water interface plays an important role in the emulsion stability. The interfacial layer properties of emulsion droplets have been considered the cutting-in points that influence emulsion stability, a traditional motif of physical chemistry and colloid chemistry of particular significance in relation to the food science and technology sector. Although many attempts have shown that high interfacial viscoelasticity may contribute to long-term emulsion stability, a universal relationship for all cases between the interfacial layer features at the microscopic scale and the bulk physical stability of the emulsion at the macroscopic scale remains to be established. Not only that, but integrating the cognition from different scales of emulsions and establishing a unified single model to fill the gap in awareness between scales also remain challenging. In this review, we present a comprehensive overview of recent progress in the general science of emulsion stability with a peculiar focus on interfacial layer characteristics in relation to the formation and stabilization of food emulsions, where the natural origin and edible safety of emulsifiers and stabilizers are highly requested. This review begins with a general overview of the construction and destruction of interfacial layers in emulsions to highlight the most important physicochemical characteristics of interfacial layers (formation kinetics, surface load, interactions among adsorbed emulsifiers, thickness and structure, and shear and dilatational rheology), and their roles in controlling emulsion stability. Subsequently, the structural effects of a series of typically dietary emulsifiers (small-molecule surfactants,proteins, polysaccharides, protein-polysaccharide complexes, and particles) on oil-water interfaces in food emulsions are emphasized. Finally, the main protocols developed for modifying the structural characteristics of adsorbed emulsifiers at multiple scales and improving the stability of emulsions are highlighted. Overall, this paper aims to comprehensively study the literature findings in the past decade and find out the commonality of multi-scale structures of emulsifiers, so as to deeply understand the common characteristics and emulsification stability behaviour of adsorption emulsifiers with different interfacial layer structures. It is difficult to say that there has been significant progress in the underlying principles and technologies in the general science of emulsion stability over the last decade or two. However, the correlation between interfacial layer properties and physical stability of food emulsions promotes revealing the role of interfacial rheological properties in emulsion stability, providing guidance on controlling the bulk properties by tuning the interfacial layer functionality.

In vitro oxidation and digestibility profiles of iron-loaded whey protein isolate/gum Arabic complexes with different morphologies

This study was designed to investigate the promotion of oxidation of lipids in oil-in-water (o/w) emulsions and digestive properties of the bionic dynamic gastrointestinal system of whey protein isolate (WPI) and gum arabic (GA) complexes loaded with iron ions, which were fabricated previously and shown as WPI/GA_Fe³⁺ nanoparticles (WGS) and WPI/GA_Fe³⁺ fibers (WGF). Compared with emulsions containing Fe³⁺ and GA-loaded complex (GA_Fe³⁺), WGS and WGF greatly improved the oxidative stability of lipids along with the reduced lipid oxidation products and volatile compounds, attributed to the encapsulation of iron ions. During the bionic dynamic gastrointestinal digestion, the iron ion release of WGF was significantly higher than that of WGS, probably due to different assembled internal structures. Accordingly, two proposed WPI/GA_Fe³⁺ complexes with different morphologies are expected to be developed as novel stable iron fortifiers with delayed lipid oxidation and controlled iron-ion release in food emulsions.

Zein/pullulan complex colloidal particle-stabilized Pickering emulsions for oral delivery of polymethoxylated flavones: protection effect and in vitro digestion

BACKGROUND

Polymethoxylated flavones (PMFs) show multiple biological functions, while their high hydrophobicity leads to a low bioaccessibility and limits their wide applications. The design of a reasonable food-grade drug delivery system is an effective strategy to improve the low bioaccessibility of PMFs. In this study, sinensetin, tangeretin and nobiletin were encapsulated in Pickering emulsions stabilized by zein/pullulan complex colloidal particles (ZPPs), and the protection effect and in vitro digestion were characterized.

RESULTS

Rheological analysis revealed that ZPP-Pickering emulsion loading with PMFs maintained a strong gel-like network structure. Moreover, the ability to scavenge free radicals of PMFs was improved by the emulsion delivery system. The antioxidant activity of PMFs encapsulated in Pickering emulsion was positively correlated with the oil volume fraction (φ). ZPP-Pickering emulsion loading with PMFs can effectively delay lipid oxidation, and the φ (70%) of Pickering emulsion showed the most pronounced effects, in which the lipid hydroperoxide content and malondialdehyde content decreased by 64.3% and 38.3% after 15 days of storage, compared with the bulk oil group, respectively. The bioaccessibility of the three PMFs has been increased by ZPP-Pickering emulsion simultaneously and it presented the highest values as its φ was 50%, in which the bioaccessibility of sinensetin, tangeretin and nobiletin increased by 2.5, 3.2 and 3.9 times, compared with the bulk oil group, respectively.

CONCLUSION

Pickering emulsion stabilized by ZPPs is an excellent nutrient delivery system for delivering three PMFs simultaneously and imparting functional properties to bioactive delivery systems. © 2022 Society of Chemical Industry.

The presence of propylene glycol alginate increased the stability and intestine-targeted delivery potential of carboxymethyl starch-stabilized emulsions

Propylene glycol alginate (PGA) was added to improve the stability and delivery performance of carboxymethyl starch (CMS)-stabilized emulsion. In the first instance, the CMS/PGA complexes were characterized, which proved that the formation of CMS/PGA complexes mainly depended on hydrogen bonding, and the CMS/PGA complexes showed porous networks. The CMS/PGA complexes were more hydrophobic than CMS, and the interaction of CMS with PGA enhanced the thermal stability of CMS. Next, the effects of CMS/PGA complexes on the properties of emulsions were investigated, and the intestine-targeted delivery potential of emulsions was evaluated through the in vitro release study as well. The droplet size of CMS/PGA complex-stabilized emulsions gradually decreased and the encapsulation efficiency (EE) improved with increasing the PGA content in CMS/PGA complexes. The addition of PGA also greatly improved the physical stability of emulsions, including anti-flocculation and anti-coalescence stabilities. All emulsions exhibited non-Newtonian pseudoplastic properties. Furthermore, the emulsions stabilized by CMS/PGA complexes showed reduced curcumin (Cur) release in the simulated gastric fluid (SGF), whereas exhibited sustained release in the α-amylase-containing simulated intestinal fluid (SIF). These results demonstrated that the emulsion stabilized by CMS/PGA complex was able to control and modulate the release of Cur in the gastrointestinal tract, and was therefore a promising intestine-targeted delivery system for Cur.

Ovalbumin/carboxymethylcellulose colloids: Particle compactness and interfacial stability

A protein/polysaccharide colloidal particle was prepared via combined complex coacervation and heat-induction. When the ratio of ovalbumin (OVA) to carboxymethylcellulose (CMC) was at 1:2, loose flexible particles (low D_f) with low surface hydrophobicity were obtained. Conversely, dense and compact particles (high D_f) were easily formed at a higher OVA/CMC ratio. Only in the appropriate OVA/CMC ratio, pH will have a greater impact on the colloidal particles. At the pH value of 4.4, the OVA/CMC ratio had a greater impact on the colloidal particles compared to pH. The emulsion stabilized by loose particles had a mean particle size of 3888 nm and was easily flocculated and creamed. On the other hand, compact particles formed a stable emulsion, which had a higher exponent of Δr² (0.867) and could resist flocculation during the 7 days storage. As such, the results showed that stable emulsion could be realized by utilizing compact particles as emulsifiers.

Effects of M/G Ratios of Sodium Alginate on Physicochemical Stability and Calcium Release Behavior of Pickering Emulsion Stabilized by Calcium Carbonate

The gel properties of sodium alginate (SA) have been revealed to be strongly correlated with its ratio of D-mannuronate to L-guluronate (M/G ratio). Herein, we focused on SA with different M/G ratios to conduct an in-depth study on the effect of the M/G ratio difference on physicochemical stability and calcium release behavior of the Pickering emulsion stabilized by calcium carbonate (CaCO₃). The oil phase was added to the aqueous phase, prepared by SA with different M/G ratios (2.23, 0.89, and 0.56) and CaCO₃, for one-step shearing to obtain the E1, E2, and E3 emulsions, respectively. The results of the particle size, microstructure, long-term stability, rheological, and microrheological properties of the emulsions showed that the E3 emulsion, prepared by SA with a smaller M/G ratio, had a smaller particle size and has remained in a flow condition during the long-term storage, while the E1 and E2 emulsions had a gelation behavior and a stronger viscoelasticity. Moreover, the emulsion, as a liquid calcium supplement, is not only convenient for oral intake while meeting the calcium needs of the body, but also controls the release of Ca²⁺. The calcium release of the emulsions in a simulated gastric environment demonstrated that the calcium release ratio increased with the decrease of SA concentration, with the increase of M/G ratio, and with the decrease of oil phase volume.

Synthesis, Stability, and Bioavailability of Nicotinamide Riboside Trioleate Chloride

Nicotinamide riboside chloride (NRCl) is an effective form of vitamin B3. However, it cannot be used in ready-to-drink (RTD) beverages or high-water activity foods because of its intrinsic instability in water. To address this issue, we synthesized nicotinamide riboside trioleate chloride (NRTOCl) as a new hydrophobic nicotinamide riboside (NR) derivative. Contrary to NRCl, NRTOCl is soluble in an oil phase. The results of stability studies showed that NRTOCl was much more stable than NRCl both in water and in oil-in-water emulsions at 25 °C and 35 °C. Finally, we evaluated the bioavailability of NRTOCl by studying its digestibility in simulated intestinal fluid. The results demonstrated that NRTOCl was partially digestible and released NR in the presence of porcine pancreatin in a simulated intestinal fluid. This study showed that NRTOCl has the potential to be used as an NR derivative in ready-to-drink (RTD) beverages and other foods and supplement applications.

Effect of ultrasonic pretreatment on the emulsification properties of Clanis Bilineata Tingtauica Mell protein

Clanis Bilineata Tingtauica Mell Protein (CBTMP) is a naturally high-quality insect protein resource, while its poor emulsification has limited its application in food industry. In order to change the present situation, in this research, the ultrasonic pretreatment (0 W, 200 W, 400 W, 600 W, and 800 W) method was used to improve the emulsification properties of CBTMP. Results indicated that ultrasound treatment especially at 400 W could significantly change the particle sizes, further increase the content of sulfhydryl group and surface hydrophobicity. The emulsification properties of emulsions were enhanced (from 4.16 ± 1.07 m²/g to 27.62 ± 2.20 m²/g) by sonicated CBTMP solution. Moreover, the physical stability of the emulsions to salt stress and centrifugation treatment was also promoted. Additionally, rheology revealed that a stronger network was formed at 400 W and all samples exhibited frequency-dependent and amplitude-dependent properties. The experiment demonstrated that ultrasound pretreatment was an effective means to improve the emulsification properties of CBTMP and it could provide a promising perspective for the application of CBTMP in food industry.

Fabrication and characterization of Pickering emulsion gels stabilized by zein/pullulan complex colloidal particles

BACKGROUND

Zein particles are unsuitable as stabilizers of Pickering emulsions because of their high hydrophobicity. However, few studies have reported on the use of a strong hydrophilic neutral polysaccharide to regulate its wettability. In this work, zein/pullulan complex particles (ZPPs) were formulated by an anti-solvent method to fabricate Pickering emulsions.

RESULTS

The presence of pullulan increased the size, decreased the zeta, and provided excellent resistance to the gravitational separation of zein. Scanning electron microscopy (SEM) revealed that the shape of zein particles changed from spherical as they became aggregated ZPP nanoparticles. Fourier transform infrared (FTIR) spectroscopy indicated that the flocculation phenomenon of ZPPs was related to the hydrogen bond between zein and pullulan. Moreover, the hydrophobicity of zein was modified by hydrophilic pullulan to endow the ZPPs with nearly neutral wettability when the mass ratio was 15:1, allowing for the preparation of stable Pickering emulsions. In contrast to zein, the ZPPs contributed to building a compact interface layer around the droplets and smaller emulsion droplets. Under a certain ZPP concentration, the size and viscosity of emulsion increased with an increase in the oil volume fraction, indicating that the Pickering emulsions stabilized by ZPPs showed better stability against coalescence. Confocal laser scanning microscopy (CLSM) revealed that the ZPPs constructed a dense filling layer on the surface of oil droplets, thus further emphasizing that ZPPs can potentially be used in fabricating Pickering emulsion gels.

CONCLUSION

Zein/pullulan complex particles are an excellent Pickering emulsion gel stabilizer that can be used in the delivery system of bioactive substances in food formulations. © 2020 Society of Chemical Industry.

Impact of Tetrapeptide-FSEY on Oxidative and Physical Stability of Hazelnut Oil-In-Water Emulsion

This study investigates the antioxidant behaviors of a hazelnut tetrapeptide, FSEY (Phe-Ser-Glu-Tyr), in an oil-in-water emulsion. The emulsion was prepared with stripped hazelnut oil at a ratio of 10%. O/W emulsions, both with and without antioxidants (FSEY and TBHQ), were incubated at 37 °C. The chemical stabilities, including those of free radicals and primary and secondary oxidation productions, along with the physical stabilities, which include particle size, zeta-potential, color, pH, and ΔBS, were analyzed. Consequently, FSEY displayed excellent antioxidant behaviors in the test system by scavenging free lipid radicals. Both primary and secondary oxidation products were significantly lower in the FSEY groups. Furthermore, FSEY assisted in stabilizing the physical structure of the emulsion. This antioxidant could inhibit the increase in particle size, prevent the formation of creaming, and stabilize the original color and pH of the emulsion. Consequently, FSEY may be an effective antioxidant additive to use in emulsion systems.

Effect of drying methods on the solubility and amphiphilicity of room temperature soluble gelatin extracted by microwave-rapid freezing-thawing coupling

The effect of three drying methods (hot air, freeze and spray drying) on the solubility and amphiphilicity of gelatin were investigated and compared. Results showed spray drying gelatin (SDG) and hot air drying gelatin (HDG) showed the lowest and best solubility, respectively. This phenomenon was attributed to the degree of subunits degradation and hydrophobicity. The HDG showed an obvious degradation during the hot air drying and displayed the strongest hydrophilicity, while SDG showed a slight degradation and strongest hydrophobicity. The results of wettability showed that SDG had a better amphiphilicity (92.48°) in comparison with HDG (57.7°) and freeze drying gelatin (VDG, 77.53°), which can effectively reduce the interfacial tension of gelatin, thus significantly improving the stability of foam and emulsion (p < 0.05). These results suggested the drying methods can adjust the amphiphilicity of gelatin, and the SDG displayed a better amphiphilicity, showing good potential applications in foam and emulsion.

Improved solubility and interface properties of pigskin gelatin by microwave irradiation

In this study, the microwave irradiation as a green approach was applied to improve the properties (mainly solubility and interface properties) of pigskin gelatin. The results showed that the solubility of pigskin gelatin was improved obviously at room temperature (25 °C) due to the destruction of polymer subunits. Furthermore, the exposure of more hydrophobic groups in microwave-irradiated gelatin increased its hydrophobicity, consequently improving the amphiphilic property and the interfacial properties of gelatin. The results of interface behavior showed that the interfacial tension of microwave-irradiated gelatin was reduced obviously with the extension of irradiation time (0-30 min), which is more beneficial to adsorption of gelatin molecules at the interface, thus resulting in a significant increase of adsorption rate (AP) from 56.13% (0 min) to 91.87% (30 min). Correspondingly, the foaming and emulsifying properties of gelatin were also improved significantly (p < 0.05). This study would promote the development of food-grade foam and emulsion based on pigskin gelatin by adjusting solubility and interface properties.

Tannic acid enhanced the physical and oxidative stability of chitin particles stabilized oil in water emulsion

In this work, the stability of CP-TA complex stabilized emulsion was first characterized. It was found that the peak thickness, Turbiscan Stability Index (TSI) and droplet size of CP-TA complex stabilized emulsion gradually decreased with increasing content of TA, indicating the gradually enhanced physical stability of emulsion, which was attributed to the gradually decreased interfacial tension, zeta potential and increased viscosity of CP-TA complex. Moreover, the oxidative stability of CP-TA complex stabilized emulsion gradually enhanced with increasing of TA content due to the antioxidant activity of TA. XRD and FTIR results suggested that the interaction between CP and TA gradually enhanced with increasing content of TA in CP-TA complex, leading to the formation of larger CP-TA clusters shown in AFM results. In conclusion, the presence of tannic acid (TA) enhanced the physical and oxidative stability of chitin particles-tannic acid (CP-TA) complex stabilized oil in water emulsion.

Ultrasound pre-fractured casein and in-situ formation of high internal phase emulsions

Traditional preparation of protein particles is usually complex and tedious, which is a major issue in the development of Pickering high internal phase emulsions (HIPEs). In this study, a facile and in-situ method for the preparation of food-grade Pickering HIPEs was developed using ultrasound pre-fractured casein flocs. The ultrasonic-treated casein protein and resulting Pickering HIPEs were characterised using particle size distribution, confocal laser scanning microscopy (CLSM), cryo-SEM, and rheological measurement. The results indicated that pH values of casein and ultrasonic power level were key parameters for casein protein dispersion into nanoparticles to form o/w Pickering HIPEs. In optimal conditions, the hexagons of emulsion droplets were close together, and the emulsions formed with ultrasonic caseins exhibited gel-like behaviour. Additionally, ultrasonic microscale-sized caseins (about 25 μm) disappeared upon the use of high speed homogenisation during the formation of HIPEs, while the chemical distribution revealed by confocal laser scanning microscopy indicated that the dispersive nanoparticles from casein proteins were evidently absorbed on the interface of HIPEs (cryo-SEM). These findings prove that ultrasound is an effective tool to loosen casein flocs to induce the in-situ formation of stabilised Pickering HIPEs. Overall, this work provides a green and facile route to convert edible oil into a soft solid, which has great potential for applications in biomedical materials, 3D printing technology, and various cosmetics.

Gelatin Hydrolysate Hybrid Nanoparticles as Soft Edible Pickering Stabilizers for Oil-In-Water Emulsions

The aim of this study was to fabricate edible gelatin enzymic digest (GED) based gel particles that can stabilize oil-in-water (O/W) microemulsions. The gel particles were generated by covalent crosslinking, with genipin, the individual protein molecules within tannic acid-induced gelatin hydrolysate (GED-TA) particles. The ability of the genipin-treated GED-TA (GP-GED-TA) to stabilize emulsions was evaluated by Turbiscan analysis and droplet-size changes. For comparison, gelatin hydrolysate (GE) and tannic acid-induced gelatin hydrolysate particles (GED-TA) were used as controls. The mean diameters of GED, GED-TA, and GP-GED-TA particles were 0.68 ± 0.1 nm, 66.2 ± 8.4 nm, and 66.9 ± 7.2 nm, respectively. Nanomechanic analysis using atomic force microscopy(AFM) indicated the average Young’s modulu of the GP-GED-TA particles was 760.8 ± 112.0 Mpa, indicating the GP-GED-TA were soft particles. The Turbiscan stability indexes (lower values indicate a more stable emulsion) of the emulsions stabilized with GED, GED-TA, and GP-GED-TA, after storage for three days, were 28.6 ± 1.5, 19.3 ± 4.8, and 4.4 ± 1.3, respectively. After one, or 60 days of storage, the volume-weighted mean diameters (D_[4,3]) of oil droplets stabilized by GP-GED-TA were 1.19 ± 0.11 μm and 1.18 ± 0.1 µm, respectively. The D_[4,3] of oil droplets stabilized by GED-TA, however, increased from 108.3 ± 5.1 μm to 164.3 ± 19.1 μm during the storage. Overall, the GP-GED-TA gel particles have considerable potential for stabilization of O/W emulsions in food products.

Food-Grade Gelatin Nanoparticles: Preparation, Characterization, and Preliminary Application for Stabilizing Pickering Emulsions

In this paper, the food-grade gelatin nanoparticles (GNPs) were prepared by a two-step desolvation method and using genipin as a cross-linker. The GNPs with narrow size distribution and good dispersion could be obtained only at pH 12. The effect of the genipin dosage (8-12 wt%) on the GNPs was systematically investigated. The results showed that the cross-linking degree of the GNPs increased with the increasing dosage of genipin, thus leading to a more obvious cross-linking morphology observed from scanning electron microscope (SEM). The obtained GNPs showed a good dispersibility with a size range of 386-438 nm. However, the GNPs cross-linked by 8 wt% genipin dosage revealed a relatively higher size because of the aggregation induced by hydrogen bond. The 10 wt% group had good thermal stability and storage stability. The optical microscopy results showed that the Pickering emulsions (30-50 vol% internal phase) stabilized by the GNPs had good uniformity and stability, even after 30 days of storage time, suggesting that the stable GNPs had great potential in food-grade Pickering emulsions.