Addition Of Gallic Acid Research Articles

Free-radical-induced grafting of rice starch with gallic acid and evaluation of the reaction products' ability to stabilize Pickering emulsions

Pickering emulsions can be stabilized with native rice starch (NRS), but their hydrophobicity is low. Gallic acid (GA) has a simple molecular structure and a rich variety of functional groups. Pickering emulsions can be made more stable by hydrophobically modifying the esterification reaction of NRS with GA to improve its dual wetting properties. In this study, the free radical-induced grafting method was used to prepare rice starch–GA graft copolymer (NRS-g-GA). The addition of GA could improve the crystallinity and orderliness of NRS. The results of Fourier transform infrared spectroscopy and 1H NMR indicated that GA was successfully grafted onto NRS. After modification, the contact angle of NRS increased from 18.2° to 60.2° (NRS-g-GA; 1:1). The emulsion prepared from NRS-g-GA showed better stability than NRS, improving the emulsification of NRS. Its stable emulsion exhibited an emulsion system dominated by elasticity. Thus, GA could be grafted onto NRS to enhance its emulsifying properties, opening up new applications for GA and NRS and promoting the development of starch-based Pickering emulsions in the future.

Fabrication of gallic acid containing poly(vinyl alcohol)/chitosan electrospun nanofibers with antioxidant and drug delivery properties.

Chitosan-based nanofibers with excellent properties are attractive materials for specific industrial applications of contemporary interest. This work aims to fabricate functional nanofibers based on poly(vinyl alcohol)/chitosan (CS) with an antioxidant and model drug molecule, gallic acid (GA), by electrospinning, followed by cross-linking through glutaraldehyde (PVA-CS-GAs). PVA-CS-GAs were electrospun at two different concentrations by the adjustment of the CS feeding ratio. The detailed characteristics of the as-prepared electrospun nanofibers were elucidated by Fourier Transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), water contact angle (WCA) measurements, thermogravimetric and differential scanning calorimetry (TGA and DSC) analyses. SEM images indicated that the average fiber diameter distribution was in the range of 90-110nm. The results show that morphology, mean diameter, wettability, and thermal characteristics of the composite nanofibers were affected by the CS feeding ratio. Although the increase in the amount of polar -OH groups with the addition of GA caused an improvement in the hydrophilicity and thermal stability of the electrospun nanofibers, it also caused a decrease in the thermal transition temperatures. Furthermore, antioxidant tests based on DPPH radical scavenging ability and in vitro release studies demonstrated that the cross-linked PVA-CS-GA composite nanofibers have good antioxidant activity and a pH-dependent drug release rate, indicating their potential for implementation in wound healing and drug delivery applications.

Cobalt oxyhydroxide nanoflakes enable ratiometric fluorescent assay of gallic acid

Gallic acid (GA) is widely used in beverages, food, and other fields as antioxidant. However, GA is slightly toxic and the accumulation of GA is harmful to human body. Therefore, it's vital to develop simple and sensitive detection methods for GA. In this work, a novel ratiometric fluorescent nanoprobe (named CoOOH/OPD/SiNPs) for the GA detection in different foods was designed and prepared. The fluorescence of silicon nanoparticles (SiNPs) at 443 nm would be quenched by cobalt oxyhydroxide (CoOOH) nanoflakes. o-phenylenediamine (OPD) would be oxidized to 2,3-diaminophenazine (DAP) by CoOOH nanoflakes that have peroxidase-like activity, which produces a new fluorescent peak at 556 nm. Meanwhile, SiNPs' fluorescence would be quenched through DAP due to inner filter effect (IFE). With the addition of GA, the reductive decomposition of CoOOH decreased DAP level, causing IFE being restrained. The concentration of GA indicates an excellent linear relationship with fluorescence ratio (F443/F556) in range of 0.4–12 μM (R2 = 0.9937) with 0.16 μM detection limit. This nanoprobe is applied to GA detection in water, tea leaves, fruits and nut fruits, which would be expected to act as a portable device for complex substances analysis.

Preparation, characterization, and application of gallic acid-mediated photodynamic chitosan-nanocellulose-based films

In this study, an active film composed of gallic acid (GA), chitosan (CS), and cellulose nanocrystals (CNC) was prepared using a solution casting method and synergistic photodynamic inactivation (PDI) technology. Characterization of the film showed that the CS-CNC-GA composite film had high transparency and UV-blocking ability. The addition of GA (0.2 %–1.0 %) significantly enhanced the mechanical properties, water resistance, and thermal stability of the film. The tensile strength increased up to 46.30 MPa, and the lowest water vapor permeability was 1.16 × e−12 g/(cm·s·Pa). The PDI-treated CS-CNC-GA1.0 composite film exhibited significantly enhanced antibacterial activity, with inhibition zone diameters of 31.83 mm against Staphylococcus aureus and 21.82 mm against Escherichia coli. The CS-CNC-GA composite film also showed good antioxidant activity. Additionally, the CS-CNC-GA1.0 composite film generated a large amount of singlet oxygen under UV-C light irradiation. It was found that using the CS-CNC-GA1.0 composite film for packaging and storage of oysters at 4 °C effectively delayed the increase in pH, total colony count, and lipid oxidation in oysters. In conclusion, the CS-CNC-GA composite film based on PDI technology has great potential for applications in the preservation of aquatic products.

Exploring microbial and moist-heat effects on Pu-erh tea volatiles and understanding the methoxybenzene formation mechanism using molecular sensory science

Piling fermentation (PF) is crucial for Pu-erh tea aroma, yet its microbial and moist-heat impact on aroma quality is poorly understood. Solid-phase microextraction, solvent-assisted flavor evaporation, and gas chromatography–mass spectrometry were used to detected and analyses the samples of sun-green green tea, sterile PF and spontaneous PF. Microbiological action promotes the formation of stale aromas. Moist-heat action promotes the formation of plum-fragrance and sweet aroma. 20 microbial markers and 28 moist-heat markers were screened from 184 volatile components. Combining odor activity values and gas chromatography-olfactometry, 22 aroma-active compounds were screened (1,2,3-trimethoxybenzene, linalool, 1,2,4-trimethoxybenzene …), and analyzed during PF processing. Aroma omission and addition experiments verified its importance. Gallic acid addition experiments successfully verified that microorganisms are the main contributors to the synthesis of methoxybenzenes. Finally, Blastobotrys, Rasamsonia, and Thermomyces showed positive correlation with the synthesis of 1-ethyl-4-methoxybenzene, 1,2,4-trimethoxybenzene, 1,2,3-trimethoxybenzene, and 1,2-dimethoxybenzene. The formation mechanism of Pu-erh tea's aroma was clarified.Exploring microbial and moist-heat effects on Pu-erh tea volatiles and understanding the methoxybenzene formation mechanism using molecular sensory science.

Interaction mechanism and binding mode between different polyphenols and gellan gum

To investigate the impact of different polyphenols on the gel properties of gellan gum (GG) and the interaction mechanism, experiments and virtual molecular simulations were conducted based on nine representative polyphenols. Rheological analysis revealed that all the GG/polyphenol composite hydrogels were pseudoplastic fluids with a low viscosity. The storage modulus (G′) of hydrogel containing only GG was 28.3 Pa at 0.1 Hz. The addition of gallic acid (GA), puerarin (PUE) or cyanidin cation (CC) significantly increased the G′ of the hydrogel by 4.9-fold, 3.3-fold, and 2.6-fold, respectively. The introduction of GA reduced the water holding capacity (WHC) of the hydrogel to 62.0 %, while the other eight polyphenols increased the WHC to nearly 100 %. Regular, intact and dense honeycomb mesh structures were observed in the GG/GA, GG/PUE, GG/CC and GG/catechin microstructures. The molecular docking results indicated that, among the nine polyphenols, PUE had the strongest affinity for GG with an interaction energy of −18.64 kcal/mol. According to the results of molecular dynamics simulation, the total energy of the composite system interacting with water corresponded well with the G′ of the composite hydrogels. The GG/GA system with the highest G′ had the lowest total energy of −15655.82 kJ/mol. Hydrogen bonds were the main driving force for improving the strength and maintaining the structural stability of the composite hydrogels. Therefore, this study confirmed the various effects of nine polyphenols on GG hydrogels and provided a novel basis for investigating the synthesis and gelation mechanism of polysaccharide-polyphenol composite hydrogels.

Development, characterization and Lactobacillus plantarum encapsulating ability of novel C-phycocyanin-pectin-polyphenol based hydrogels

In this study, it was found that the enhancement in the viability of Lactobacillus plantarum under gastrointestinal conditions by encapsulating them within novel C-Phycocyanin-pectin based hydrogels (from 5.7 to 7.1 log/CFU). The hardness, the strength and the stability of the hydrogels increased when the protein concentration was increased. In addition, the addition of resveratrol (RES), and tannic acid (TA) could improve the hardness (from 595.4 to 608.3 and 637.0 g) and WHC (from 93.9 to 94.2 and 94.8 %) of the hydrogels. The addition of gallic acid (GA) enhanced the hardness (675.0 g) of the hydrogels, but the WHC (86.2 %) was decreased. During simulated gastrointestinal conditions and refrigerated storage, the addition of TA enhanced the viable bacteria counts (from 6.8 and 8.0 to 7.5 and 8.5 log/CFU) of Lactobacillus plantarum. Furthermore, TA and GA are completely encased by the protein-pectin gel as an amorphous state, while RA is only partially encased.

Gallic acid crosslinked peanut protein‐corn starch composite edible films produced at alkaline pH with ultrasound application

AbstractCorn starch and peanut protein blend films were prepared with and without gallic acid addition (0.25%, w/v) at pH 7, 9, and 11 by casting. The ultrasound (160 W, 20 kHz, 10 min) treatment was applied to the film‐forming solutions. This study aimed to develop biopolymer‐based films with gallic acid and to determine the interactions of components at different pHs and with ultrasound. The barrier, optical, mechanical, and thermal properties of films were examined. Moreover, structural characterization of films was conducted by Fourier transform infrared (FTIR), x‐ray diffraction, and trinitro benzenesulfonic acid assay to enlighten the crosslinking interactions of gallic acid with biopolymers at different pHs. At neutral pH, gallic acid behaved as plasticizer. By acting as a crosslinker at pH 9, gallic acid provided the lowest moisture content, darker and more opaque appearance, enhanced barrier performance and thermal stability. The crosslinking degrees of gallic acid‐enriched films were 49.1% (pH 7), 77% (pH 9), and 67.4% (pH 11). Additionally, gallic acid increased antioxidant capacity. The ultrasonication adversely affected the film properties by breaking bonds in the film structure. Peanut protein‐corn starch‐gallic acid films under mild alkaline conditions exhibited outstanding thermal stability, mechanical durability, light, and water barrier characteristics, making them appropriate for sustainable food packaging applications.

Green synthesis of carbon nanoparticle-reinforced nanocomposites with gallic acid as a crosslinking agent on poly(butylene adipate-co-terephthalate): Preparation, characterization, and performances

In this work, we performed green processing of Couroupita guianensis carbon nanoparticle (CNPs). The plants of Couroupita guianensis have been carbonized at successive temperatures at 700 °C for 2 h. Solution casting methods was performed for the fabrication of poly(butylene adipate-co-terephthalate) (PBAT) nanocomposites via addition of 0.5, 1.0, 3.0, and 5.0 wt% of CNPs to PBAT and gallic acid (GA) in a 70/30 (w/w) ratio, GA acting as a crosslinking agent. The PBAT-GA/CNPs nanocomposites have been studied with FTIR, XRD, SEM, TGA, and DSC. Barrier (O2 and H2O), and mechanical (tensile strength and elongation) tests were investigated and compared. The mechanical properties of the PBAT nanocomposites were enhanced due to the CNPs and GA addition. The nanocomposites with 3.0 wt% CNP added had a tensile strength that was greater than pure PBAT (PBAT-GA filled to 3.0 wt% at 24.19 MPa vs. PBAT filled to 11.22 MPa), which had the least tensile strength. The smallest, WVTR and OTR values have been observed in the PBAT nanocomposites with 5.0 wt% CNPs filler added. The 5.0 wt% CNPs added film exhibited the greatest barrier property. Increased antimicrobial activity has been shown by the PBAT-GA/CNPs nanocomposites against the microorganisms that are pathogenic to foods (S. aureus and E. coli). In addition, according to the results on food quality test, PBAT nanocomposites were used to exceed the performance of commercial polyethylene (PE) film in increasing the shelf-life of edible grapes from 1 to 15 days. The results of the study suggested that PBAT loaded nanocomposites with GA and CNPs could be good choices for uses in food packaging.

Effects of alkaline pH and gallic acid enrichment on the physicochemical properties of sesame protein and common vetch starch-based composite films

In this study, sesame (Sesamum indicum L.) meal protein and common vetch (Vicia sativa L.) starch were extracted and used to obtain biodegradable composite films at different pH values (7, 9, and 11). Films were plasticized with glycerol (2.5 %) and enriched with gallic acid (0.25 %). Increasing pH promoted mechanical properties of the films with the developed barrier and thermal characteristics. Gallic acid addition at pH 7 resulted in lower tensile strength and higher elongation by reducing intermolecular forces, and a shift of diffraction peaks through lower angles due to crystal lattice expansion, as compared to neutral films without gallic acid. On the other hand, gallic acid-enriched films at neutral pH exhibited superior antioxidant properties. The mild alkalinity with gallic acid provided the lowest water vapor permeability, high thermal stability, improved mechanical properties and light barrier property due to deprotonation and subsequent interactions with biopolymers. The FTIR spectrum confirmed intense interactions, such as crosslinking and covalent bonding, promoted by mild alkalinity. Therefore, sesame protein and common vetch starch-based composite film with gallic acid incorporation at pH 9 can be recommended to be used in biodegradable active food packaging applications.

Preparation and characterization of zein/gelatin electrospun film loaded with ε-polylysine and gallic acid as tuna packaging system.

Composite nanofiber films loaded with ε-polylysine (PL) and gallic acid (GA) were prepared using a zein/gelatin (ZG) electrospinning method to develop effective active packaging films for tuna preservation. The morphology, structure, thermal stability, hydrophobicity, antibacterial, and antioxidant properties of the films, and their application for tuna during a period of storage of 4 °C were investigated. PL reduced the average diameter of ZG fibers, whereas GA increased it. The PL/GA/ZG film possessed a well distributed fiber morphology with an average diameter of 810 ± 150 nm. Fourier-transform infrared spectroscopy and X-ray diffraction results showed the physical loading of PL and GA in ZG film with the main chemical bonds and crystal structure unchanged. The addition of both PL and GA reduced hydrophobicity of the ZG film while the PL/GA/ZG film was still hydrophobic. GA enhanced its thermal stability and contributed to its antioxidant activity. PLand GA synergetically enhanced the antibacterial activity of ZG film against Shewanella putrefaciens. PL combined with GA is more suitable for modifying ZG film than GA alone. The PL/GA/ZG film effectively inhibited total viable counts, total volatile base nitrogen, fat oxidation, and texture deterioration of tuna fillets at 4 °C storage, and could extend the shelf life by 3 days. The PL/GA/ZG nanofiber film demonstrated promising potential for application in the preservation of aquatic products as a new antibacterial and antioxidant food packaging. © 2023 Society of Chemical Industry.

Stability of a novel glycosylated peanut protein isolate delivery system loaded with gallic acid

To overcome the shortcomings of gallic acid (GA) application, a novel glycosylated PPI delivery system was prepared for the first time in this study using the interaction between peanut protein isolate (PPI) and GA. The effects of glycosylation on the structural and functional properties of PPI and the functional properties of nanoparticles were investigated. The optimal nanoparticles were prepared at a mass ratio 1:3 of glycosylated PPI to GA with a particle size of 338.351 ± 18.823 nm and a PDI of 0.222 ± 0.039. Hydrophobic interactions were the main force maintaining the nanoparticle structure. The nanoparticles remained stable when exposed to different environmental factors. In addition, the DPPH and ABTS radical scavenging activities of nanoparticle-embedded GA were 35.94 ± 3.24 % and 62.59 ± 5.07 % after 108 h, which were significantly higher than those of the free GA group (P < 0.05). This study is important for developing GA and hydrophilic polyphenol delivery systems.

Preparation and performance testing of corn starch/pullulan/gallic acid multicomponent composite films for active food packaging.

The present study investigated the mechanical characteristics, hydrophobicity, antioxidant and antibacterial properties, FTIR, SEM and XRD of films fabricated with corn starch and pullulan (CS/PUL) by adding different concentrations of Gallic acid (GA) (0%, 0.5%, 1.0%, 1.5% w/v). The mechanical strength and opacity of CS/PUL films were enhanced by the addition of 1.0% GA. The water vapor permeability (WVP) of CS/PUL films was significantly lower in films with GA compared to those without (P < 0.05). The addition of GA, especially at concentrations of 1.0% and 1.5%, resulted in considerably better free radical scavenging activities on DPPH than films without GA (P < 0.05). Interestingly, the highest water contact angle (WCA) value was observed in films with 0.5% GA, indicating stronger hydrophobicity. Furthermore, the antibacterial capabilities of the films, particularly against E. coli and P. aeruginosa, improved with an increase in GA concentration. The results of FTIR, SEM and XRD analyses showed that GA was well distributed in the CS/PUL matrix.

Impact of Bird Cherry (Prunus padus) Extracts on the Oxidative Stability of a Model O/W Linoleic Acid Emulsion

The delivery and uptake of adequate doses of a number of active compounds, including selected saturated and unsaturated fatty acids (frequently in the form of emulsion systems), is crucial to maintaining a healthy diet. The susceptibility of acids to oxidation and the time stability of emulsions are factors limiting their shelf life and storage time. Those parameters could be improved using selected additives, including antioxidants. In this study, we examined the influence of different bird cherry extracts (varying in the content amounts of bioactive compounds) on the oxidative stability of a model O/W linoleic acid emulsion, using C11-BODIPY581/591 as a fluorescent indicator. We also examined the effect of these extracts on the physicochemical properties of the emulsions and the time stability of the produced emulsion using the dynamic laser scattering technique. The antioxidative efficacy of extracts differed significantly, depending on the extraction method and conditions. The observed differences in the results could be attributed to variations in the specific compositions of the extracts used, which were more or less rich in terms of antioxidants or their synergistic effects. Our results indicated that acetone extract was the most effective with regard to both the oxidation stability and time degradation tests of the emulsions produced. Moreover, the addition of gallic acid did not always have a positive effect on the abovementioned properties.

Thermoplastic agar blended PBAT films with enhanced oxygen scavenging activity

The morphology and properties of biodegradable packaging comprising thermoplastic agar and poly (butylene adipate-co-terephthalate) (PBAT) blends (20/80 and 40/60 ratios) produced via cast extrusion were characterized. These polymers were blended with gallic acid (GA) and determined for oxygen scavenging activity. Increasing agar content formed non-homogeneous PBAT matrices with dispersed clumps, while GA facilitated the unfolding of agar molecules and reduced the number of clumps. GA interacted with agar and PBAT by modifying the CO and C–H stretching vibrations, causing polymer blend plasticization and decreasing the mechanical relaxation temperature. Addition of agar and GA modified the crystallinity, morphology, and barrier properties of PBAT. Compounding GA into the polymer matrices effectively enhanced oxygen scavenging, while oxygen absorption rates increased with increasing relative humidity (RH) from 50% to 100%. Rates and maximum scavenging capacity depended on GA contents and humidity at 50% RH, while higher humidity showed insignificant effects of GA contents, suggesting additional roles of polymer structures involving oxygen diffusion through the matrices. Blending thermoplastic agar at 20% in PBAT films produced biobased sustainable food packaging and effectively enhanced oxygen scavenging active functions.

Biobased ternary films of thermoplastic starch, bacterial nanocellulose and gallic acid for active food packaging

The use of active packaging technologies and biopolymeric materials are among the emerging trends for implementation of sustainability in the food packaging industry. Thus, herein, bioactive transparent nanocomposite films of thermoplastic starch (TPS) reinforced with bacterial nanocellulose (BNC) (1%, 5% and 10% w/w, relative to starch) and enriched with gallic acid (GA) (1 and 1.5% w/w, relative to starch) were prepared by the solvent casting method. The addition of BNC (≥5% w/w) and GA (1 and 1.5% w/w) enhanced both the mechanical properties (Young's Modulus: 1.2–2.0 GPa vs. 1.0 GPa for TPS; tensile strength: 23–39 MPa vs. 20 MPa for TPS) and the water resistance (moisture absorption and solubility in water) of the nanocomposites. All films are thermally stable up to 125 °C. It was also found that the addition of GA imparted the hydrocolloid TPS-BNC nanocomposites with UV-blocking properties and antioxidant activity (DPPH scavenging activity above 80%). In addition, the film with 10% w/w of BNC nanofibers and 1% w/w of GA had good oxygen barrier properties with a coefficient of permeability of 0.91 ± 0.12 cm3 μm m−2 d−1 kPa−1 and antibacterial activity against the gram-positive Staphylococcus aureus (reduction of about 4.5 log10 colony forming units (CFU) mL−1 after 48 h). This is the first time that antibacterial activity is reported for TPS-BNC nanocomposites. The film with 10% w/w of BNC nanofibers and 1% w/w of GA was further demonstrated to have the ability of delaying the browning and weight loss of packaged fresh cut apple stored at +4 °C for 7 days. All these outcomes are of great relevance for the packaging sector, thus attesting the potential of the developed TPS-BNC-GA nanocomposites as sustainable and eco-friendly film materials for active food packaging.

Effect of five polyphenols on the stability of purple cabbage anthocyanins in simulated beverage systems containing L-ascorbic acid

Purple cabbage shows great potential as a natural colorant source for commercial beverages due to its high anthocyanin content and wide availability. However, the application of purple cabbage anthocyanins in the food industry is limited by its unstable characteristics. This study aimed to investigate the effect of 0.4% concentration of catechin, epigallocatechin gallate, vanillin, gallic acid (GA), and rosmarinic acid on the stability of purple cabbage anthocyanins in beverage systems. The results showed that all five polyphenols increased the color intensity of anthocyanins and the copigmentation effect increased with the increased polyphenol. Five polyphenols were observed to enhance the color and thermal stability of anthocyanins in beverage systems, while GA performed best. The addition of GA to the beverage systems achieved a greater improvement in color stability regarding absorbance value (increased by 247.70%) and total color change (decreased by 70.34%). In addition, degradation kinetic reaction showed the lowest k (0.0466 1/d) and highest t1/2 (14.87 d) for anthocyanin degradation with GA addition. This study provides a potential solution to enhance anthocyanin stability and extend beverage shelf life through GA addition.

Boosting functional properties of active-CMC films reinforced with agricultural residues-derived cellulose nanofibres.

The search for packaging alternatives that reduce the presence of non-biodegradable plastics in water is a focus of much research today. This fact, together with the increasing demand for active packaging capable of prolonging the shelf life of foodstuffs and the rise in the use of natural biopolymers such as cellulose, motivate the present work. This work evaluates CMC films loaded with gallic acid reinforced with (ligno)cellulose nanofibres from various agricultural residues as candidates for use in active food packaging. The first stage of the study involved the evaluation of different nanofibres as the reinforcing agent in CMC films. Increasing proportions of nanofibres (1, 3, 5 and 10% w/w) from horticultural residues (H) and nanofibres from vine shoots (V), containing residual lignin (LCNF) and without it (CNF), and obtained by mechanical (M) or chemical (T) pretreatment, were studied. The results of this first stage showed that the optimum reinforcement effect was obtained with 3% H-MCNF or 3% V-MCNF, where up to 391% and 286% improvement in tensile strength was achieved, respectively. These films offered slightly improved UV-light blocking ability (40-55% UV-barrier) and water vapor permeability (20-30% improvement) over CMC. Next, bioactive films were prepared by incorporating 5 and 10% wt of gallic acid (GA) over the optimised formulations. It was found that the joint addition of cellulose nanofibres and GA enhanced all functional properties of the films. Mechanical properties improved to 70%, WVP to 50% and UV light blocking ability to 70% due to the synergistic effect of nanofibres and GA. Finally, the bioactive films exhibited potent antioxidant activity, 60-70% in the DPPH assay and >99% in the ABTS assay and high antimicrobial capacity against S. aureus.

Pickering emulsions stabilized by zein–gallic acid composite nanoparticles: Impact of covalent or non-covalent interactions on storage stability, lipid oxidation and digestibility

Studies have shown that covalent and non-covalent zein–polyphenol complexes exhibit significant differences in structure and properties, but their effects on the characteristics of Pickering emulsions are still unclear. In this study, zein nanoparticles (ZNPs), non-covalent (N-ZGANPs) and covalent (C-ZGANPs) zein–gallic acid nanoparticles were fabricated to investigate the influence of complexation types on the properties of an algal oil-in-water Pickering emulsion. Results indicated that the addition of gallic acid was associated with the decrease of interfacial tension of particles. C-ZGANPs possessed the strongest interfacial adsorption capacity, which contributed to the optimum physical stability of the covalent emulsion during storage. The rheological experiment demonstrated that C-ZGANPs decreased the viscoelasticity of the emulsion, while N-ZGANPs showed the opposite effect. Moreover, the emulsions stabilized by C-ZGANPs significantly delayed the oxidation of the encapsulated algal oil, protected astaxanthin (AST) from heat, as well as increased the bioaccessibility of AST in simulated digestion.

Lubrication behavior of ex-vivo salivary pellicle influenced by tannins, gallic acid and mannoproteins

The objective of this study was to investigate the influence of tannins and gallic acid on the salivary lubrication behavior. Furthermore, the effects of pH and mannoproteins in combination with gallic acid on the lubrication of saliva were studied. The addition of gallic acid and tannins were found to increase friction caused by the removal of the saliva film. Tannins resulted in higher friction compared to gallic acid. Lowering pH increased friction of gallic acid mixtures with saliva, due to stronger interactions between gallic acid and saliva. The increased friction caused by gallic acid was inhibited by the addition of mannoproteins due to the hydrogen bond interactions between gallic acid and mannoproteins, thereby decreasing the complex formation between gallic acid and salivary proteins. A correlation of 0.96 was found between the hydrodynamic diameter of the aggregate and the delta friction suggesting that the formation of aggregates determined the lubrication behavior.