Interactions and emulsifying properties of ovalbumin with tannic acid

Soy protein isolate-xanthan gum complexes to stabilize Pickering emulsions for quercetin delivery

This study aimed to prepare soy protein isolate-xanthan gum complexes (SPI-XG) at pH 7.0 and as emulsifiers to prepare Pickering emulsions for delivering quercetin (Que). The results showed that SPI-XG exhibited a gel network structure in which protein particles were embedded. Fourier transform infrared spectroscopy (FTIR) and molecular docking elucidated that SPI-XG formed through hydrogen bonding, hydrophobic, and electrostatic interactions. Three-phase contact angle (θo/w) of SPI-XG approached 90° with biphasic wettability. SPI-XG adsorbed at the oil-water interface to form an interfacial layer with a gel network structure, which prevented droplet aggregation. Following in vitro simulated digestion, Que displayed higher bioaccessibility in SPI-XG stabilized Pickering emulsions (SPI-XG PEs) than SPI stabilized Pickering emulsions. In conclusion, SPI-XG PEs were a promising system for Que delivery.

Insighting the effect of ultrasound-assisted polyphenol non-covalent binding on the functional properties of myofibrillar proteins from golden threadfin (Nemipterus virgatus)

In this study, the effect of ultrasound-assisted non-covalent binding of different polyphenols (tannins, quercetin, and resveratrol) on the structure and functional properties of myofibrillar proteins (MP) from the golden threadfin (Nemipterus virgatus) was investigated. The effect of ultrasound-assisted polyphenol incorporation on the structure and properties of MP was evaluated by multispectral analysis, interfacial properties, emulsification properties and antioxidant properties et al. The results revealed that the protein-polyphenol interaction led to a conformational change in the microenvironment around the hydrophobic amino acid residues, resulting in an increase in the equilibrium of the MP molecules in terms of affinity and hydrophobicity. Ultrasound assisted polyphenols addition also led to a significant decrease of the oil/water interfacial tension (from 21.22 mN/m of MP to 8.66 mN/m of UMP-TA sample) and a significant increase of the EAI (from 21.57 m2/g of MP to 28.79 m2/g of UMP-TA sample) and ES (from 84.76 min of MP to 124.25 min of UMP-TA). In addition, ultrasound-assisted polyphenol incorporation could enhance the antioxidant properties of MP, with the DPPH and ABTS radical scavenging rate of UMP-TA increase of 47.7 % and 55.2 % in comparison with MP, respectively. The results demonstrated that the noncovalent combination with polyphenols under ultrasound-assisted conditions endowed MP with better functional properties, including solubility, emulsification, foaming, and antioxidant properties through structure change. This study can provide innovative theoretical guidance for effectively preparing aquatic protein-polyphenol non-covalent complexes with multiple functions and improving the processing and utilization value of aquatic proteins.

Effect of non-covalent binding of tannins to sodium caseinate on the stability of high-internal-phase fish oil emulsions

In this study, we designed the noncovalent binding of sodium caseinate (SC) to tannic acid (TA) to stabilize high internal phase emulsions (HIPEs) used as fish oil delivery systems. Hydrogen bonding was the dominant binding force, followed by weak hydrophobic interaction and weak van der Waals forces, as demonstrated by FTIR, fluorescence spectroscopy, and molecular docking experiments, with a binding constant of 3.25 × 106, a binding site of 1.2, and a static quenching of the binding. Increasing SC:TA from SC to 2:1 decreased the particle size from 107.37 ± 10.66 to 76.07 ± 2.77 nm and the zeta potential from -6.99 ± 2.71 to -22 ± 2.42 mV. TA increased the interfacial tension of SC, decreased the surface hydrophobicity from 1.3 × 104 to 1.6 × 103 and improved the oxidation resistance of SC. The particle size of high internal phase emulsions stabilized by complexes with different mass ratios (SC:TA from 1:0 to 2:1) increased from 4.9 ± 0.02 to 12.9 μm, the potential increased from -32.37 ± 2.7 to -35.07 ± 2.58 mV, and the instability index decreased from 0.75 to 0.02. Thicker interfacial layers could be observed by laser confocal microscopy, and an increase in the storage modulus indicated a formation of a stronger gel network. SC:TA of 1:0 showed emulsion breakage after 14 d of storage at room temperature. SC:TA of 2:1 showed the lowest degree of oil-water separation after freeze-thaw treatment. Especially, the most stable high endo-phase emulsion (at SC:TA of 2:1) prepared at each mass ratio was selected for further stability exploration. The emulsion particle size increased only from 15.63 ± 0.06 to 22.27 ± 0.35 μm at salt ion concentrations of 50-200 mM and to 249.33 ± 31.79 μm at 300 mM. The instability index and storage modulus of the high endo-phase emulsions increased gradually with increasing salt ion concentrations. At different heating temperatures (55-85 °C), the instability index of the high internal phase emulsion gradually decreased and the storage modulus gradually increased. Meanwhile, at 50 °C for 15 d of accelerated oxidation, the content of hydroperoxide decreased from 53.32 ± 0.18 to 37.48 ± 0.77 nmol/g, about 29.7 %, and the thiobarbituric acid value decreased from 1.06 × 103 to 0.8 × 103, about 24.5 %, in the high endo-phase emulsions prepared by 2:1 SC:TA compared to the fish oils, and the SC-stabilized high endo-phase only emulsion broke at the sixth day of oxidation. From the above findings, it was concluded that the high internal phase emulsion prepared with SC:TA of 2:1 can be used as a good delivery system for fish oil.

Biopolymer-polyphenol conjugates: Novel multifunctional materials for active packaging

The development of natural active packaging materials and coatings presents a promising alternative to petroleum-based packaging solutions. These materials are engineered by incorporating functional ingredients with preservative capabilities. Concurrently, research has highlighted the diverse physicochemical, functional, and health-promoting properties of protein-polyphenol, polysaccharide-polyphenol, and protein-polysaccharide-polyphenol conjugates within various food formulations. However, a critical gap exists regarding the exploration of these biopolymers as active packaging materials. In contrast to conventional approaches for developing active packaging materials, this review presents a novel perspective by focusing on biopolymer-polyphenol conjugates. In this work, we delve into the realm of active packaging materials and coatings constructed from these conjugates, highlighting their potential as multifunctional active components in food packaging and preservation. This review comprehensively investigates the physicochemical properties, functionalities, and health-promoting activities associated with biopolymer-polyphenol conjugates. Their emulsification, antioxidant, and antimicrobial activities, coupled with enhancements in mechanical strength and permeability properties, contribute to their multifunctional nature. Furthermore, we explore the potential advantages and limitations of utilizing these conjugates in active packaging applications. Finally, the review concludes by proposing crucial research avenues for further exploration of biopolymer-polyphenol conjugates within the domain of active food packaging.

Emulsifying properties of egg proteins: Influencing factors, modification techniques, and applications

As an essential food ingredient with good nutritional and functional properties and health benefits, eggs are widely utilized in food formulations. In particular, egg proteins have good emulsification properties and can be commonly used in various food products, such as mayonnaise and baked goods. Egg protein particles can act as stabilizers for Pickering emulsions because they can effectively adsorb at the oil-water interface, reduce interfacial tension, and form a stable physical barrier. Due to their emulsifying properties, biocompatibility, controlled release capabilities, and ability to protect bioactive substances, egg proteins have become ideal carriers for encapsulating and delivering functional substances. The focus of this review is to summarize current advances in using egg proteins as emulsifiers. The effects of influencing factors (temperature, pH, and ionic strength) and various modification methods (physical, chemical, and biological modification) on the emulsifying properties of egg proteins are discussed. In addition, the application of egg proteins as emulsifiers in food products is presented. Through in-depth research on the emulsifying properties of egg proteins, the optimization of their applications in food, biomedical, and other fields can be achieved.

Enhancement of Pickering effect of ovalbumin with bacterial cellulose nanofibers prepared by electron beam irradiation and encapsulation of curcumin

In this study, the enhancement of Pickering effect of ovalbumin (OVA) with bacterial cellulose nanofibers (BCNFs) prepared by electron beam irradiation was investigated and the environmental stability of oil-in-water Pickering emulsions stabilized by OVA/BCNFs complexes was explored by varying ratios of OVA/BCNFS (1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1) and oil phase concentrations (10 %, 20 %, 30 %, 40 %, 50 %, 60 %). Droplet sizes of Pickering emulsions were decreased with the increase of the proportion of BCNFs, while the viscosity and storage modulus (G') of Pickering emulsions were increased. The gel strength of Pickering emulsions was positively correlated with the oil phase content. Pickering emulsions stabilized by OVA/BCNFs complexes were endowed excellent environmental stability under varying pH, ionic strength, and thermal conditions. Moreover, after encapsulating curcumin in Pickering emulsions, the retention rates of curcumin were improved significantly during room temperature, UV light, and thermal treatment. The present study would contribute to the advancement of novel protein/polysaccharide stabilizers and offer novel insight for investigating the stability of Pickering emulsions and delivering lipophilic bioactive compounds.

Multifunctional and edible egg white/amylose-tannin bilayer film for perishable fruit preservation

The substantial waste of perishable foods during transportation significantly contributes to greenhouse gas emissions, intensifying the climate crisis. To mitigate the rapid spoilage of fruits, an eco-friendly bilayer film was developed using natural egg white (EW), amylose (Am), and tannic acid (TA). The EW/Am-TA bilayer film features a primary layer of amphiphilic EW, ensuring a uniform coating on hydrophobic fruit surfaces, and a secondary layer composed of Am and TA, imparting notable tensile strength (5.3 ± 0.5 MPa) and elongation at break (28.5 ± 4.1 %). This bilayer film effectively shields fruits from UV-B and UV-C radiation (~0 % transmittance at 280 and 330 nm) and exhibits antioxidant and antibacterial properties due to the presence of TA. Fruits such as bananas, avocados, and cherry tomatoes, when dip-coated with the optimized EW/Am-TA bilayer, maintained their freshness, color, weight, and texture for up to seven days, demonstrating the effectiveness of this bilayer coating in food preservation. The natural materials in the coated film are edible and can be safely removed with tap water at room temperature in <10 s, posing no food safety risks. Thus, the proposed bilayer coating presents a significant solution to the global problem of food waste.

Insight into the mechanisms of combining direct current magnetic field with phosphate in promoting emulsifying properties of myofibrillar protein

This study investigated the combined effects of direct-current magnetic field (DC-MF, 9.5 mT) and tetrasodium-pyrophosphate (TSPP, 1-5 g/L) on emulsified gel properties of porcine myofibrillar protein (MP). Results showed that MP at DC-MF and 3 g/L TSPP had decreased spectrum intensity of UV and fluorescence compared to that without DC-MF, owing to the changes of MP tertiary structure caused by DC-MF, especially tryptophan and tyrosine. The emulsion treated with DC-MF behaved better emulsifying activity and stability than that without DC-MF under such condition. And emulsion had lower creaming index and better storage stability. Gels prepared by this MP emulsion had low porosity and stable structure, accompanying with smaller size and more uniform distribution of oil droplets. Microstructure images showed that gels were covered with microporous structure, which was conducive to the good WHC of the emulsified gels (97.12%). These results showed the feasibility of DC-MF and TSPP in improving MP emulsion/emulsified gel.

Physicochemical Properties, Stability, and Functionality of Non-Covalent Ternary Complexes Fabricated with Pea Protein, Hyaluronic Acid and Chlorogenic Acid

The aim of this study was to prepare and characterize stable non-covalent ternary complexes based on pea protein (PP, 0.5%), hyaluronic acid (HA, 0.125%), and chlorogenic acid (CA, 0~0.03%). The ternary complexes were comprehensively evaluated for physicochemical attributes, stability, emulsifying capacities, antioxidant properties, and antimicrobial efficacy. PP-HA binary complexes were first prepared at pH 7, and then CA was bound to the binary complexes, as verified by fluorescence quenching. Molecular docking elucidated that PP interacted with HA and CA through hydrogen bonding, hydrophobic and electrostatic interactions. The particle size of ternary complexes initially decreased, then increased with CA concentration, peaking at 0.025%. Ternary complexes demonstrated good stability against UV light and thermal treatment. Emulsifying activity of complexes initially decreased and then increased, with a turning point of 0.025%, while emulsion stability continued to increase. Complexes exhibited potent scavenging ability against free radicals and iron ions, intensifying with higher CA concentrations. Ternary complexes effectively inhibited Staphylococcus aureus and Escherichia coli, with inhibition up to 0.025%, then decreasing with CA concentration. Our study indicated that the prepared ternary complexes at pH 7 were stable and possessed good functionality, including emulsifying properties, antioxidant activity, and antibacterial properties under certain concentrations of CA. These findings may provide valuable insights for the targeted design and application of protein-polysaccharide-polyphenol complexes in beverages and dairy products.

The present state and future outlook of pectin-based nanoparticles in the stabilization of Pickering emulsions

The stabilization of Pickering emulsions using micro/nanoparticles has gained significant attention due to their wide range of potential applications in industries such as cosmetics, food, catalysis, tissue engineering, and drug delivery. There is a growing demand for the development of environmentally friendly micro/nanoparticles to create stable Pickering emulsions. Naturally occurring polysaccharides like pectin offer promising options as they can assemble at oil/water interfaces. This polysaccharide is considered a green candidate because of its biodegradability and renewable nature. The physicochemical properties of micro/nanoparticles, influenced by fabrication methods and post-modification techniques, greatly impact the characteristics and applications of the resulting Pickering emulsions. This review focuses on recent advancements in Pickering emulsions stabilized by pectin-based micro/nanoparticles, as well as the application of functional materials in delivery systems, bio-based films and 3D printing using these emulsions as templates. The effects of micro/nanoparticle properties on the characteristics of Pickering emulsions and their applications are discussed. Additionally, the obstacles that currently hinder the practical implementation of pectin-based micro/nanoparticles and Pickering emulsions, along with future prospects for their development, are addressed.

Effect of Addition of Tannin Extract from Underutilized Resources on Allergenic Proteins, Color and Textural Properties of Egg White Gels

Tannins, present in numerous plants, exhibit a binding affinity for proteins. In this study, we aimed to exploit this property to reduce the concentration of allergenic egg white proteins. Tannins were extracted, using hot water, from the lyophilized powder of underutilized resources, such as chestnut inner skin (CIS), young persimmon fruit (YPF), and bayberry leaves (BBLs). These extracts were then incorporated into an egg white solution (EWS) to generate an egg white gel (EWG). Allergen reduction efficacy was assessed using electrophoresis and ELISA. Our findings revealed a substantial reduction in allergenic proteins across all EWGs containing a 50% tannin extract. Notably, CIS and BBL exhibited exceptional efficacy in reducing low allergen levels. The addition of tannin extract resulted in an increase in the total polyphenol content of the EWG, with the order of effectiveness being CIS > YPF > BBL. Minimal color alteration was observed in the BBL-infused EWG compared to the other sources. Additionally, the introduction of tannin extract heightened the hardness stress, with BBL demonstrating the most significant effect, followed by CIS and YPF. In conclusion, incorporating tannin extract during EWG preparation was found to decrease the concentration of allergenic proteins while enhancing antioxidant properties and hardness stress, with BBL being particularly effective in preventing color changes in EWG.

Effects of different oil fractions and tannic acid concentrations on konjac glucomannan-stabilized emulsions

Polysaccharide-stabilized emulsions have received extensive attention, but emulsifying activity of polysaccharides is poor. In this study, konjac glucomannan (KGM) and tannic acid (TA) complex (KGM-TA) was prepared via non-covalent binding to increase the polysaccharide interfacial stability. The emulsifying stabilities of KGM-TA complex-stabilized emulsions were analyzed under different TA concentrations and oil fractions. The results indicated that hydrogen bonds and hydrophobic bonds were the main binding forces for KGM-TA complex, which were closely related to TA concentrations. The interfacial tension of KGM-TA complex decreased from 20.0 mN/m to 13.4 mN/m with TA concentration increasing from 0 % to 0.3 %, indicating that TA improved the interfacial activity of KGM. Meanwhile, the contact angle of KGM-TA complex was closer to 90° with the increasing TA concentrations. The emulsifying stability of KGM-TA complex-stabilized emulsions increased in an oil mass fraction-dependent manner, reaching the maximum at 75 % oil mass fraction. Moreover, the droplet sizes of KGM-TA complex-stabilized high-internal-phase emulsions (HIPEs) decreased from 82.7 μm to 44.7 μm with TA concentration increasing from 0 to 0.3 %. Therefore, high TA concentrations were conducive to the improvement of the emulsifying stability of KGM-TA complex-stabilized HIPEs. High oil mass fraction promoted the interfacial contact of adjacent droplets, thus enhancing the non-covalent binding of KGM molecules at the interfaces with TA as bridges. Additionally, the high TA concentrations increased the gel network density in the aqueous phase, thus enhancing the emulsifying stability of emulsions. Our findings reveal the mechanisms by which polysaccharide-polyphenol complex stabilized HIPEs. Therefore, this study provides theoretical basis and references for the developments of polysaccharide emulsifier with high emulsifying capability and high-stability emulsions.

Investigating the mechanism of antioxidants as egg white powder flavor modifiers

BACKGROUND

The uses of egg white powder (EWP) are restricted because of its odor. It is necessary to find a method to improve its flavor. In this paper, three different antioxidants - green tea extract (GTE), sodium ascorbate (SA), and glutathione (GSH) - were selected to modify the flavor. The physicochemical and structural properties of EWP were investigated to study the mechanism of the formation and release of volatile compounds.

RESULTS

Antioxidants can modify the overall flavor of EWP significantly, inhibiting the generation or release of nonanal, 3-methylbutanal, heptanal, decanal, geranyl acetone, and 2-pemtylfuran. A SA-EWP combination showed the lowest concentration of 'off' flavor compounds; GTE-EWP and GSH-EWP could reduce several 'off' flavor compounds but increased the formation of geranyl acetone and furans. The changes in the carbonyl content and the amino acid composition confirmed the inhibition of antioxidants with the oxidative degradation of proteins or characteristic amino acids. The results of fluorescence spectroscopy and Fourier transform infrared (FTIR) spectroscopy provided structural information regarding EWP, which showed the release of volatile compounds decreased due to structural changes. For example, the surface hydrophobicity increased and the protein aggregation state changed.

CONCLUSIONS

Antioxidants reduce the 'off' flavor of EWP in two ways: they inhibit protein oxidation and Maillard reactions (they inhibit formation of 3-methylbutanal and 2-pemtylfuran) and they enhance the binding ability of heat-denatured proteins (reducing the release of nonanal, decanal, and similar compounds). © 2023 Society of Chemical Industry.

Anticorrosion and Antimicrobial Tannic Acid-Functionalized Ti-Metallic Glass Ribbons for Dental Abutment

In this study, a recently reported Ti-based metallic glass (MG), without any toxic element, but with a significant amount of metalloid (Si-Ge-B, 18 atom %) and minor soft element (Sn, 2 atom %), was produced in ribbon form using conventional single-roller melt-spinning. The produced Ti60Zr20Si8Ge7B3Sn2 ribbons were investigated by differential scanning calorimetry and X-ray diffraction to confirm their amorphous structure, and their corrosion properties were further investigated by open-circuit potential and cyclic polarization tests. The ribbon's surface was functionalized by tannic acid, a natural plant-based polyphenol, to enhance its performance in terms of corrosion prevention and antimicrobial efficacy. These properties can potentially be exploited in the premucosal parts of dental implants (abutments). The Folin and Ciocalteu test was used for the quantification of tannic acid (TA) grafted on the ribbon surface and of its redox activity. Fluorescent microscopy and ζ-potential measurements were used to confirm the presence of TA on the surfaces of the ribbons. The cytocompatibility evaluation (indirect and direct) of TA-functionalized Ti60Zr20Si8Ge7B3Sn2 MG ribbons toward primary human gingival fibroblast demonstrated that no significant differences in cell viability were detected between the functionalized and as-produced (control) MG ribbons. Finally, the antibacterial investigation of TA-functionalized samples against Staphylococcus aureus demonstrated the specimens' antimicrobial properties, shown by scanning electron microscopy images after 24 h, presenting a few single colonies remaining on their surfaces. The thickness of bacterial aggregations (biofilm-like) that were formed on the surface of the as-produced samples reduced from 3.5 to 1.5 μm.

Iontophoresis-driven microneedle patch for the active transdermal delivery of vaccine macromolecules

COVID-19 has seriously threatened public health, and transdermal vaccination is an effective way to prevent pathogen infection. Microneedles (MNs) can damage the stratum corneum to allow passive diffusion of vaccine macromolecules, but the delivery efficiency is low, while iontophoresis can actively promote transdermal delivery but fails to transport vaccine macromolecules due to the barrier of the stratum corneum. Herein, we developed a wearable iontophoresis-driven MN patch and its iontophoresis-driven device for active and efficient transdermal vaccine macromolecule delivery. Polyacrylamide/chitosan hydrogels with good biocompatibility, excellent conductivity, high elasticity, and a large loading capacity were prepared as the key component for vaccine storage and active iontophoresis. The transdermal vaccine delivery strategy of the iontophoresis-driven MN patch is "press and poke, iontophoresis-driven delivery, and immune response". We demonstrated that the synergistic effect of MN puncture and iontophoresis significantly promoted transdermal vaccine delivery efficiency. In vitro experiments showed that the amount of ovalbumin delivered transdermally using the iontophoresis-driven MN patch could be controlled by the iontophoresis current. In vivo immunization studies in BALB/c mice demonstrated that transdermal inoculation of ovalbumin using an iontophoresis-driven MN patch induced an effective immune response that was even stronger than that of traditional intramuscular injection. Moreover, there was little concern about the biosafety of the iontophoresis-driven MN patch. This delivery system has a low cost, is user-friendly, and displays active delivery, showing great potential for vaccine self-administration at home.

Molecular insight into the modulation of ovalbumin fibrillation by allura red dye at acidic pH

The synthetic food additive dye induces amyloid fibrillation has many implications in the laboratory and industries. The effect of Allura red (AR), on the fibrillation of ovalbumin (Ova) at pH 2.0 was investigated. The influence of salt and pH was also seen on AR-induced Ova aggregation. We have used several spectroscopic and microscopy techniques to characterize the changes. The turbidity data suggest that concentrations above 0.05 mM of AR induce aggregation, and the size of aggregates increased in response to AR concentration. The kinetics data showed that the AR induces Ova aggregation quickly without lag time. The aggregates induced by AR have amyloid-like aggregates confirmed by far-UV CD and TEM. NaCl has very marginal effects in AR-induced aggregation. The turbidity results clearly state that Ova is not forming aggregates with pH above 4.0 due to electrostatic repulsion. However, Ova forms bigger aggregates in the presence of 0.5 mM AR at a pH below 4.0. These spectroscopic data suggest that the amyloid fibrillation that occurs in Ova is due to electrostatic and hydrophobic interaction. The amyloid fibrillation induced by AR dye in protein should be taken seriously for food safety purposes.

Deciphering the interactions of phytochemicals with ovalbumin, the major food allergen from egg white: spectroscopic and computational studies

Ovalbumin (OVA), the major component of egg white, has been used as a model carrier protein to study the interaction of four bioactive phytochemicals 6-hydroxyflavone, chrysin, naringin, and naringenin. A static quenching mechanism was primarily associated with the complexation of the flavonoids with OVA. Hydrophobic forces play a major part in the stability of the complexes. The structural changes within the protein in response to flavonoid binding revealed a decrease in OVA's α-helical content. The hypothesized binding site for flavonoids in OVA overlaps with one or more immunoglobulin E-binding epitopes that may have some effect in the immunoglobulin E response pathway. The flavonoids remain in the same binding site throughout the simulation time and impart protein stability by forming different noncovalent interactions. This study presents comprehensive information about the interaction of the flavonoids with OVA and the associated structural variations after the binding, which might help researchers better comprehend similar medication pharmacodynamics and provide critical information for future therapeutic development.

Stability of oil-in-water emulsions improved by ovalbumin-procyanidins mixture: A promising substrate with emulsifying and antioxidant activity

The aim of this study is to develop a dual-functional ingredient with antioxidant activity and emulsification. The emulsion stability of ovalbumin (OVA) was improved by procyanidins (PC). The interactions between OVA and PC were investigated using multi-spectroscopy and molecular docking. Furthermore, the effect of the addition of the OVA-PC mixture on emulsion stability was evaluated as well. The fluorescence results showed that the quenching mechanism of PC to OVA's endogenous fluorescence was static quenching, and the binding ratio of OVA and PC was 1:1. Circular dichroism (CD) and Fourier Transform Infrared Spectrometer (FT-IR) showed that the addition of PC promoted the unfolding of OVA, and transformed the secondary structure of OVA from α-helix to β-sheet. The main driving force of OVA and PC was hydrogen bonding, according to molecular docking analysis. Among all the samples, the stability of the emulsion of OVA-PC at a ratio of 1:30 exhibited extremely high stability and the smallest particle size. In comparison with individual OVA emulsions, the OVA-PC emulsions had excellent physical stabilities. Meanwhile, the oxidation degree of protein and oil for the OVA-PC emulsions was lower than that of the native OVA emulsion after 8-day storage. Our work provides important insights for understanding the interaction between OVA and expanding the application of OVA-PC.

Exploring the binding mechanism of ferulic acid and ovalbumin: insights from spectroscopy, molecular docking and dynamics simulation

BACKGROUND

Ferulic acid (FA), a phenolic acid widely occurring in nature, has attracted extensive attention because of its biological activity. Ovalbumin (OVA) is a commonly used carrier protein. The mechanism of FA binding with OVA was investigated by utilizing a variety of spectral analyses, accompanied by computer simulation.

RESULTS

It was discovered that the fluorescence quenching mechanism of OVA by FA was a static mode as a result of the formation of an FA-OVA complex, which was verified by the concentration distributions and pure spectrum of the constituents decomposed from the high overlap spectrum signals using multivariate curve resolution-alternate least squares algorithm. Hydrogen bonds and Van der Waals forces drove the formation of FA-OVA complex with a binding constant of 1.69 × 10⁴  L mol^-1 . The presence of FA induced the loose structure of OVA with an attenuation of α-helix content and improved the thermal stability of OVA. Computer docking indicated that FA interacted with the amino acid residues Arg84, Asn88, Leu101 and Ser103 of OVA through hydrogen bonds. Molecular dynamics simulation proved that the combination of FA with OVA boosted the conformational stability of OVA and hydrogen bonds brought a crucial part in stabilizing the structure of the complex.

CONCLUSIONS

The study may supply the theoretical basis for the design of FA transport system using OVA as carrier protein to improve the instability and low bioavailability of FA. © 2021 Society of Chemical Industry.

Understanding of physicochemical properties and antioxidant activity of ovalbumin-sodium alginate composite nanoparticle-encapsulated kaempferol/tannin acid

In this research, ovalbumin (OVA) and sodium alginate (SA) were used as the materials to prepare an OVA–SA composite carrier, which protected and encapsulated the hydrophobic kaempferol (KAE) and the hydrophilic tannic acid (TA) (OVA–SA, OVA–TA–SA, OVA–KAE–SA, and OVA–TA–KAE–SA). Results showed that the observation of small diffraction peaks in carriers proved the successful encapsulation of KAE/TA. The protein conformation of the composite nanoparticles changed. OVA–TA–SA composite nanoparticles had the highest α-helix content and the fewest random coils, so the protein structure of it had the strongest stability. OVA–TA–KAE–SA composite nanoparticles had the strongest system stability and thermal stability, which might be due to the synergistic effect of the two polyphenols, suggesting the encapsulation of KAE/TA increased the system stability and the thermal stability of OVA–SA composite nanoparticles. Additionally, the composite nanoparticles were endowed with antioxidant ability and antibacterial ability (against Staphylococcus aureus and Escherichia coli) in the order OVA–TA–SA > OVA–TA–KAE–SA > OVA–KAE–SA based on the difference in antibacterial diameter (D, mm) and square (S, mm²), indicating that polyphenols enhanced the antibacterial and antioxidant ability of OVA–SA composite nanoparticles, and the enhancement effect of TA was stronger than that of KAE. These results provide a theoretical basis for the application of OVA–SA composite nanoparticles in the delivery of bioactive compounds.

Ovalbumin (OVA) and sodium alginate (SA) were used as materials to prepare an OVA–SA composite carrier, which encapsulated the hydrophobic kaempferol (KAE) and the hydrophilic tannic acid (TA) (OVA–SA, OVA–TA–SA, OVA–KAE–SA, and OVA–TA–KAE–SA).

Influence of polyphenol-metal ion-coated ovalbumin/sodium alginate composite nanoparticles on the encapsulation of kaempferol/tannin acid

In this research, ovalbumin (OVA) and sodium alginate (SA) were used as the materials to prepare OVA-SA composite carriers, which protected and encapsulated the hydrophobic kaempferol (KAE) and the hydrophilic tannic acid (TA). To achieve the purpose of targeted delivery, the TA-Fe³⁺ coating film was prepared. Results showed that the observation of small diffraction peaks in carriers proved the formation of TA/Fe³⁺ coating film on the surface of four composite nanoparticles (pOVA, pOVA-SA, pOVA-KAE-SA, and pOVA-KAE-TA-SA). The protein structure of the composite nanoparticles coated with TA/Fe³⁺ changed, and the order of the changes was pOVA-KAE > pOVA > pOVA-KAE-SA > pOVA-KAE-TA-SA > pOVA-SA. This phenomenon is due to the fact that the chromophore -C=O and the auxo-chromophore -OH are in the opposite position in the benzene ring of TA, and the two substituents have opposite effects and synergize, resulting in the different degrees of redshift of the composite nanoparticle λ_max. Additionally, pOVA-SA had the highest α-helix content and the lowest random coils, conferring the protein structure the strongest stability. The coating of TA/Fe³⁺ increased the system stability and the thermal stability of the composite nanoparticles. Additionally, the carriers were endowed with antioxidant activity, and their antibacterial ability against Staphylococcus aureus and Escherichia coli was pOVA-KAE-TA-SA > pOVA-KAE-SA > pOVA-KAE > pOVA-SA > pOVA based on the difference in antibacterial diameter (D, mm) and square (S, mm²). pOVA-KAE-TA-SA had the strongest antioxidant activity and antibacterial ability, which improved the bioavailability of TA/KAE. These results provide a theoretical basis for the application of OVA-SA composite nanoparticles in the delivery of bioactive compounds.

Fabrication and digestive characteristics of high internal phase Pickering emulsions stabilized by ovalbumin-pectin complexes for improving the stability and bioaccessibility of curcumin

In this study, ovalbumin (OVA) interacted with pectin (PE) to form soluble electrostatic complexes to improve the functional properties of high internal phase Pickering emulsions (HIPEs) under extreme conditions. The results showed that the stability of the OVA-PE soluble complexes-stabilized HIPEs was significantly better than that of the free OVA-stabilized HIPEs and was modulated by the biopolymer ratio. In particular, the complexes at an OVA:PE ratio of 1:1 (C-1:1) may form particulates with a core-shell structure by a flocculation mechanism. The C-1:1-stabilized HIPEs had the smallest oil droplet size (11.34 ± 1.14 μm) and the best resistance to extreme environmental stresses due to their strong, rigid structure and dense interfacial architecture. The in vitro digestion results showed that the bioaccessibility (from 18.3% ± 0.5% to 38.8% ± 4.8%) of curcumin improved with increasing PE content. Our work is helpful in understanding OVA-PE complexes as stabilizers for HIPEs and their potential applications in food delivery systems.

Co-Application with Tannic Acid Prevents Transdermal Sensitization to Ovalbumin in Mice

Transdermal sensitization to allergens is of great concern as a sensitization route for food allergies. This skin-mediated invasion and sensitization to allergens is involved in skin barrier breakdown and inflammation, followed by the production of several kinds of cytokines. Cytokines such as thymic stromal lymphopoietin and thymus and activation-regulated chemokine are also involved. In this study, we investigated the suppressive effect of tannic acid (TA) on transdermal sensitization using ovalbumin (OVA), a major egg-white allergen. We also analyzed the mechanisms associated with the inhibitory effects of TA. The results showed that the co-application with TA prevents transdermal sensitization to OVA. As possible mechanisms, its anti-inflammatory and astringent effect on the skin and binding ability with the protein were considered. These results indicate that TA could be applied to cosmetics and lotions, which could suppress the transdermal sensitization to allergens.

Review on the Regulation of Plant Polyphenols on the Stability of Polyunsaturated-Fatty-Acid-Enriched Emulsions: Partitioning Kinetic and Interfacial Engineering

The plant polyphenols are normally presented as natural functional antioxidants, which also possess the potential ability to improve the physicochemical stability of polyunsaturated fatty acid (PUFA)-enriched emulsions by interface engineering. This review discussed the potential effects of polyphenols on the stability of PUFA-enriched emulsions from the perspective of the molecular thermodynamic antioxidative analysis, the kinetic of interfacial partitioning, and the covalent and non-covalent interactions with emulsifiers. Recently, research studies have proven that the interfacial structure of emulsions can be concurrently optimized via promoting interfacial partitioning of polyphenols and further increasing interfacial thickness and strength. Moreover, the applied limitations of polyphenols in PUFA-enriched emulsions were summarized, and then some valuable and constructive viewpoints were put forward in this review to provide guidance for the use of polyphenols in constructing PUFA-enriched emulsions.

Interfacial Properties and Antioxidant Activity of Whey Protein-Phenolic Complexes: Effect of Phenolic Type and Concentration

Whey protein is a common food additive for enhancing product stability and texture, while phenolics are considered food antioxidants. As a consequence, combining whey protein with phenolics is an effective way to improve protein functionality while also maintaining polyphenol bioactivity. Herein, the functional properties and antioxidant activity of whey protein modified with various types and concentrations of oxidized phenolic compounds, including gallic acid (OGA), ferulic acid (OFA), and tannic acid (OTA), were studied. In general, the modified whey protein had a decrease in free amino content, but an increase in total phenolic content. Whey protein modified with 5% OTA showed the highest total phenolic content and the lowest free amino content. Modification of whey protein with OTA and OGA resulted in a loss of surface hydrophobicity in contrast to whey protein modified with OFA. However, no significant difference in surface activity including foam and emulsion properties in the whey protein with/without modification was observed. The modified whey protein had an increase in antioxidant activity when compared with that of the control.

Bioactive compounds: Application of albumin nanocarriers as delivery systems

Enriched products with bioactive compounds (BCs) show the capacity to produce a wide range of possible health effects. Most BCs are essentially hydrophobic and sensitive to environmental factors; so, encapsulation becomes a strategy to solve these problems. Many globular proteins have the intrinsic ability to bind, protect, encapsulate, and introduce BCs into nutraceutical or pharmaceutical matrices. Among them, albumins as human serum albumin (HSA), bovine serum albumin (BSA), ovalbumin (OVA) and α-lactalbumin (ALA) are widely abundant, available, and applied in many industrial sectors, becoming promissory materials to encapsulate BCs. Therefore, this review focuses on researches about the main groups of natural origin BCs (namely phenolic compounds, lipids, vitamins, and carotenoids), the different types of nanostructures based on albumins to encapsulate them and the main fields of application for BCs-loaded albumin systems. In this context, phenolic compounds (catechins, quercetin, and chrysin) are the most extensively BCs studied and encapsulated in albumin-based nanocarriers. Other extensively studied subgroups are stilbenes and curcuminoids. Regarding lipids and vitamins; terpenes, carotenoids (β-carotene), and xanthophylls (astaxanthin) are the most considered. The main application areas of BCs are related to their antitumor, anti-inflammatory, and antioxidant properties. Finally, BSA is the most used albumin to produced BCs-loaded nanocarriers.

Surface characteristics and emulsifying properties of whey protein/nanoliposome complexes

The surface characteristics and emulsifying properties of whey proteins (WP) after complexation with nanoliposomes (NL) were investigated. WP surface hydrophobicity enhanced after complexation with NL, and it indicated the exposure increase of WP hydrophobic groups. WPNL interfacial tension significantly decreased compared with that of WP. The interfacial protein content of WPNL-stabilized emulsions was slightly different from that of WP-stabilized emulsions. WP emulsifying properties were significantly improved after complexation with NL. The mean sizes and polydispersity indexes of WPNL-stabilized emulsion droplets were smaller than those of WP-stabilized emulsion droplets. The absolute zeta-potential values of WPNL-stabilized emulsions were greater than those of WP-stabilized emulsions. Electrostatic repulsion played a vital role in WPNL-stabilized emulsion stability. Moreover, surface and emulsifying properties of WPNL were changed by exterior factor-induced alteration of protein advanced structures. The emulsifying properties of WP after complexation with NL were improved due to the modification of WP surface characteristics.

Self-Assembled Micellar Nanoparticles by Enzymatic Hydrolysis of High-Density Lipoprotein for the Formation and Stability of High Internal Phase Emulsions

In this study, the influence of pH on the conformational state of EHT, which was obtained from the enzymatic hydrolysis of trypsin, and the stabilizing properties of high internal phase emulsions have been demonstrated. Critical micelle concentration and transmission electron microscopy results exhibited the formation of micellar nanoparticles with mean diameters ranging from 108 to 1359.5 nm. The results of solubility, surface hydrophobicity, and conformations indicated that EHT tended to act as particulate emulsifiers at pH 3, 5, and 7, while at alkaline pH, it was more like a polymeric emulsifier, which could be proven by confocal laser scanning microscopy. The EHT at pH 7 exhibited better stabilizing properties than those at pH 9 and 11 as influenced by storage, temperature, and ionic strength. These findings might be of great importance for broadening the range of sustainable applications of amphiphilic peptides in foods and pharmaceuticals.

Tannic acid-fortified zein-pectin nanoparticles: Stability, properties, antioxidant activity, and in vitro digestion

Tannic acid was loaded into zein nanoparticles using antisolvent precipitation and then these particles were coated by anionic pectin using electrostatic deposition. The resulting core-shell nanoparticles were near spherical and had an average diameter of 166 nm, a particle yield of 95%, a tannic acid content of 5.4%, and a tannic acid loading efficiency of 89%. Circular dichroism revealed that the presence of tannic acid caused little change in the secondary structure of the zein within the nanoparticles. Fluorescence spectroscopy suggested the formation of a molecular complex between the zein and tannic acid molecules. Fourier transform infrared spectroscopy indicated that hydrogen bonding was the main force holding these complexes together. The core-shell nanoparticles remained resistant to flocculation from pH 2 to 8, when heated at 80 °C for 2 h, and when the NaCl concentration was below 30 mM. The encapsulated tannic acid preserved its high antioxidant capacity. The tannic acid was progressively released from the core-shell nanoparticles under simulated gastrointestinal conditions, with the majority of release occurring within the small intestine. Overall, this research suggests that pectin-coated zein nanoparticles may be effective encapsulation and delivery systems for hydrophilic polyphenols in nutraceutical, supplements, or pharmaceutical formulations.

Emulsion, hydrogel and emulgel systems and novel applications in cannabinoid delivery: a review

Emulsions, hydrogels and emulgels have attracted a high interest as tools for the delivery of poorly soluble hydrophobic nutraceuticals by enhancing their stability and bioavailability. This review provides an overview of these delivery systems, their unique qualities and their interactions with the human gastrointestinal system. The modulation of the various delivery systems to enhance the bioavailability and modify the release profile of bioactive encapsulates is highlighted. The application of the delivery systems in the delivery of cannabinoids is also discussed. With the recent increase of cannabis legalization across North America, there is much interest in developing cannabis edibles which can provide a consistent dose of cannabinoids per portion with a rapid time of onset. Indeed, the long time of onset of psychoactive effects and varied metabolic responses to these products result in a high risk of severe intoxication due to overconsumption. Sophisticated emulsion or hydrogel-based delivery systems are one potential tool to achieve this goal. To date, there is a lack of evidence linking specific classes of delivery systems with their pharmacokinetic profiles in humans. More research is needed to directly compare different classes of delivery systems for the gastrointestinal delivery of cannabinoids.

Egg White Protein Carrier-Assisted Development of Solid Dispersion for Improved Aqueous Solubility and Permeability of Poorly Water Soluble Hydrochlorothiazide

Hydrochlorothiazide (HTZ) is a first-line drug used in the treatment of hypertension suffered from low oral bioavailability due to poor aqueous solubility and permeability. Hence, lyophilized egg white protein-based solid dispersion (HTZ-EWP SD) was developed to explore its feasibility as a solid dispersion carrier for enhanced aqueous solubility and permeability of HTZ. The HTZ-EWP SD was prepared using the kneading method. HTZ-EWP SD was characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transforms infrared spectroscopy (FT-IR), powder X-ray diffractometer (PXRD), solubility, in vitro dissolution, and ex vivo permeation studies. The physico-chemical evaluation suggested the formation of the solid dispersion. Optimized HTZ-EWP SD4 drastically enhanced (~32-fold) aqueous solubility (~16.12 ± 0.08 mg/mL) over to pure HTZ (~ 0.51 ± 0.03 mg/mL). The dissolution study in phosphate buffer media (pH 6.8) revealed that HTZ-EWP SD4 significantly enhanced the release rate of HTZ (~ 87 %) over to HTZ (~ 25 %). The permeation rate of HTZ from optimized HTZ-EWP SD4 was enhanced significantly (~ 84 %) compared to pure HTZ (~ 24 %). Optimized HTZ-EWP-SD4 enhanced the rate of HTZ dissolution (~ 86 %) in FeSSIF (fed state simulated intestinal fluid), compared to a low dissolution rate (~ 72 %) in FaSSIF (fasted state simulated intestinal fluid) state after 2-h study. Obtained results conclude that lyophilized egg white protein can be utilized as an alternative solid dispersion carrier for enhancing the solubility and permeability of HTZ.