Investigation of the pectin grafting with gallic acid and propyl gallate and their antioxidant activities, antibacterial activities and fresh keeping performance

Pectin based Maillard reaction products: Formation mechanism and fluorescence characteristics

Pectin-based MR fluorescent product (PCD) was prepared using green-renewable pectin and l-lysine under the hydrothermal condition, which was characterized by bright yellow scaly powder. The chemical structural analysis showed that α-1,4-glucoside bonds linked active carbonyl compounds produced by demethoxylation and decarboxylation reactions in pectin, further react with l-lysine to form PCD with a moderate amount of π-conjugated structure, CN, CN, pyridine ring and pyrrole ring structure, causing yellow fluorescence in solid-state and stable blue fluorescence in liquid-state. Importantly, the steric hindrance and structural rigidity caused by pectin-like reticulated structure, more crystalline surfaces and structural complexity made PCD a good optical performance including covert apparent color, higher fluorescence quantum yield, less susceptibility to aggregated fluorescence quenching, excellent photostability, higher ion resistance, better solvent stability and wider pH application range than glucose-based MR product (GCD). This is favorable in the future for its potential application in anti-counterfeiting, fluorescence-responsive film preparation and bio-imaging.

Study of phenolic-polysaccharide interactions in brown seaweed

Brown seaweed has a rich source of bioactives, notably antioxidative phenolic compounds and sulphated polysaccharides. Despite their importance, the interactions between these compounds and their resultant antioxidant activities have not been extensively studied. This research aims to investigate the interaction between seaweed-derived phenolics and polysaccharides in terms of their antioxidant activity, exploring their potential interactions through in silico molecular docking, and validating them using Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and differential scanning calorimetry (DSC). Reduced antioxidant activities were observed in the seaweed-derived phenolics and polysaccharides combination. The in silico molecular docking studies and experimental analyses revealed non-covalent interactions, mainly driven by hydrogen bonding between fucoidan and catechin or phloroglucinol. The resulting 'complex' formation varied in size and thermodynamic stability, suggesting structure-dependent interactions between fucoidan and phenolic compounds. This research helps to understand the marine phenolic-polysaccharide interaction, contributing to their effective application in the functional food and nutraceutical industries.

Interactions between polyphenols and polysaccharides/proteins: Mechanisms, effect factors, and physicochemical and functional properties: A review

Polyphenols have attracted much attention in the food industry and nutrition because of their unique biological activities. However, the health benefits of polyphenols are compromised due to their structural instability and sensitivity to the external environment. The interaction between polyphenols and polysaccharides/proteins largely determines the stability and functional characteristics of polyphenols in food processing and storage. Hence, this topic has attracted widespread attention in recent years. This review initially outlines the basic properties of polyphenols and their applications in food. Subsequently, the interaction mechanisms between polyphenols and polysaccharides/proteins are discussed in detail including non-covalent bonding, covalent modification, and conformational changes. These interactions can display profound impacts on the nutritional value, taste, stability, and safety of food. Additionally, this article also systematically reviews the influencing factors (type, concentration, temperature, pH, and other factors) of interaction between polyphenols and proteins/polysaccharides. Finally, this paper also summarizes systematically the effects of the interaction between polyphenols and polysaccharides/proteins on the physicochemical and functional properties of polyphenols/proteins. The findings provide prospects for the application of composite materials in food preservation, functional food development, and nanocarrier development, which can provide theoretical references for the in-depth development of polyphenols in the food industry.

An efficient fluorescence analysis for plant gallic acid based on dual-ligand Ag/Au nanoclusters

Gallic acid (GA) is a secondary metabolite derived from plant phenolics. It is essential to maintain normal physiological activities in plants facing adversity. This, in turn, helps maintain crop integrity. Consequently, the surveillance of GA levels in plants is of significant importance. This study developed a near-infrared (NIR) red fluorescent Ag/Au nanocluster sensor, utilizing glutathione and bovine serum albumin as dual ligands. This modification shifts the emission wavelength to the red spectrum, mitigating the interference from the plant's inherent fluorescence. The fluorescence resonance energy transfer (FRET) mechanism is exploited. When the presence of Ag+ induces the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to oxTMB, which in turn quenches the fluorescence at 650 nm. GA's abundant phenolic hydroxyl group will reduce oxTMB to TMB, so the material's fluorescence will be turned on to detect GA. The established platform can quantify a wide range of GA thanks to the above reasons. In particular, this platform has a recovery of 96.09%-104.7 % for detecting GA in tomato samples with an error of no more than 3 % and a detection limit as low as 38.29 nM. On the other hand, a combination of probes and the fluorescence platform was used to visualize GA levels in tomato leaves under drought and salt stress. This can assist in elucidating the physiological adaptations of plants to environmental changes. The groundbreaking GSH/BSA-Au/Ag nanosensor shows great potential for trace detection of GA in plants and will contribute to a deeper understanding of plant physiology.

Tuning the amphiphilicity of agarose by grafting phenolic acids: A versatile approach for developing lutein-loaded emulsion gels

In this study, three phenolic acids, namely 3,4-Dihydroxybenzoic acid (DBA), 3,4-Dihydroxyphenylacetic acid (DPA), and 3,4-Dihydroxyphenylpropanoic acid (DPPA), were grafted onto agarose molecules to improve the physicochemical and biological properties of agarose. DBA-grafted agarose (DBA-AG), DPA-grafted agarose (DPA-AG), and DPPA-grafted agarose (DPPA-AG) were prepared and used as encapsulation materials to construct a lutein-loaded emulsion gel delivery system. The results confirmed that phenolic acids were successfully grafted onto the agarose backbone via ester bonds, with a grafting degree of approximately 8 %. As the length of the phenolic acid side chain increased (DBA < DPA < DPPA), the agarose gel exhibited decreased strength, thermal stability, and transparency while displaying increased hydrophobicity and emulsifying activity. Phenolic acid grafting significantly enhanced the radical scavenging ability of agarose and improved its inhibitory activity against Staphylococcus aureus (100 %) and Escherichia coli (78.44 %-100 %). DPPA-AG exhibited the highest antioxidant activity, while DBA-AG showed the best antibacterial effect. Moreover, phenolic acid grafting transformed agarose from a hydrophilic gel to an amphiphilic emulsion gel, greatly increasing lutein's encapsulation efficiency (87.3 %-94.2 %), chemical stability, and bioavailability. DPPA-AG demonstrated the optimal emulsifying activity and lutein encapsulation performance. In vitro hemolysis experiments indicated good prospects for applications in food, pharmaceutical, and cosmetic industries.

Caffeic Acid-Modified Mushroom Chitosan as a Natural Emulsifier for Soybean Oil-Based Emulsions and Its Application in β-Carotene Delivery

In this study, we developed a soybean oil-based emulsion system stabilized by caffeic acid-modified mushroom-derived chitosan, significantly enhancing its functional properties. The modification increased the grafting ratio from 5.02% to 8.26%, which greatly improved antioxidant activity and antimicrobial efficacy against Escherichia coli and Staphylococcus aureus. The modified chitosan exhibited superior rheological properties, including increased viscosity and elasticity, contributing to improved emulsification performance. Emulsions stabilized with caffeic acid-modified chitosan showed smaller and more uniform droplet sizes, along with greater stability, as indicated by a higher zeta potential (55.63 mV). These modifications resulted in enhanced β-carotene encapsulation efficiency (up to 87.46%) and improved bioaccessibility (up to 52.13%), highlighting the system's potential as an efficient food-grade carrier for hydrophobic bioactive compounds. In conclusion, caffeic acid-modified mushroom chitosan is an effective natural emulsifier, enhancing stability, antioxidant activity, and nutrient delivery, and has promising applications in functional foods and nutraceuticals.

Biomimetic Design of Underwater Adhesives Based on Tea Polyphenol-Modified Gelatin

Although many tissue adhesives with good biocompatibility are currently available, their lack of wet adhesion capacity significantly hinders their clinical application. Therefore, further development and exploration of new medical adhesives are necessary. Inspired by the adhesion mechanism of marine mussels, through modifying gelatin protein with gallic acid (GA) for wet adhesion and cross-linking gelatin (Gel) molecular chains with tea polyphenols (TP), the adhesive TP-GA/Gel was developed. The adhesive exhibited an adhesion strength of up to 130.47 kPa to porcine skin tissues and maintained a high adhesion state in various aqueous environments, demonstrating excellent and reproducible adhesion. Additionally, TP-GA/Gel possessed outstanding antimicrobial, antioxidant, and biocompatibility properties. In an in vivo wound healing study with SD rats, the wound area treated with TP-GA/Gel adhesive decreased from 10.3 mm2 to 0.9 mm2 after 15 days, promoting effective and scarless wound healing. These results highlight the promising clinical potential of TP-GA/Gel as a medical adhesive.

A boronic acid functionalized terbium metal-organic framework for fluorescence detection and adsorption of gallic acid

Gallic acid (GA) is widely applied as an antioxidant in foods and pharmaceuticals. In this study, a boronic acid functionalized metal-organic framework (Tb-MOF) is developed for fluorescence detection and adsorption of GA. Tb-MOF is constructed by coordination polymerization of terbium ions (Tb3+) with 3,5-dicarboxyphenylboronic acid (BBDC). The resulted Tb-MOF exhibits green fluorescence emission at 546 nm under an excitation of 280 nm. However, the green emission of Tb-MOF decreases in the presence of GA due to the formation of borate esters between phenolic hydroxyl groups of GA and hydroxyl groups of Tb-MOF. Under optimized conditions (40 mmol·L-1 Tris-HCl buffer solution of pH = 6.2 and reaction time of 25 min), the sensor shows a wide detection range of 5 ∼ 200 μmol·L-1 with a correlation coefficient (R2) of 0.9950. Meanwhile, Tb-MOF shows good selectivity and sensitivity to GA (the limit of detection (LOD) is 0.44 μmol·L-1). Additionally, Tb-MOF is used to investigate GA adsorption. The corresponding adsorption data can be suitably described by Langmuir isotherm and pseudo-second-order models with a maximum adsorption capacity of 6.03 mg·g-1. The above results demonstrate the potential of prepared Tb-MOF in integrating GA detection and adsorption in water samples.

Active biodegradable bacterial cellulose films with potential to minimize the plastic pollution: Preparation, antibacterial application, and mechanism

Petroleum-based films have triggered a serious global pollution crisis because they are difficult to recycle, degrade, and reuse. Developing alternative sustainable active films represents a powerful strategy to address these issues. Here, a multifunctional biodegradable bacterial cellulose (BC) film incorporated with guanidine-based polymer (PHGH)/gallic acid (GA) was constructed (termed OBC-PHGH/GA). The resulting OBC-PHGH/GA film exhibited a highly interweaved nanofiber network structure with excellent tensile strength and ductility. The OBC-PHGH/GA film showed an excellent antibacterial effect against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with inhibition efficiencies of ∼99.99 % compared with the OBC film. Moreover, the as-prepared film showed excellent UV-shielding, antioxidant, and antifungal activities, showing great potential in food packaging. More importantly, the OBC-PHGH/GA film can be degraded into safe and reusable sugars, demonstrating outstanding environmental friendliness and sustainability. This work provides a promising and unique strategy for designing and fabricating green active packaging materials.

Antioxidant packaging films based upon starch-montmorillonite with forsythia flower extract: characterization and application

Plastic pollution is one of the most acute environmental problems in the world, so active packaging materials made from biodegradable natural polymers have received widespread attention in recent years. In this paper, forsythia flower extract, serving as an active ingredient, was integrated into the starch-sodium alginate-montmorillonite composite film. The physicochemical properties and functional packaging applications of the composite films were investigated. The results demonstrate the formation of a tightly-knit network structure through molecular interactions among forsythia flowers, starch, sodium alginate, and montmorillonite. Notably, the addition of forsythia flower extracts conferred better UV resistance (from 200 nm to 400 nm) and outstanding antioxidant properties to the composite films. After 18 days of storage, in comparison with the control group, the decay rate of fresh cherry tomatoes packaged with the composite film containing forsythia flower extract showed a significant reduction of 40%, the hardness increased by 25%, and the content of vitamin C was enhanced by 33%. Hence, the forsythia flower extract composite film offers a novel perspective for the design and development of bio-based packaging films for preserving fresh fruits. The results serve as a foundation for the subsequent advancement and application of forsythia flower in the field of packaging.

Antibacterial Effect of Fermented Pomegranate Peel Polyphenols on Vibrio alginolyticus and Its Mechanism

Vibrio alginolyticus frequently breaks out in aquatic animal breeding operations involving shrimp, and it can endanger human health through food and wound infections. The antibacterial effect and mechanism of fermented pomegranate peel polyphenols (FPPPs) on V. alginolyticus were investigated. The results indicated that FPPPs had a strong inhibitory effect on the growth of V. alginolyticus, and their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were 2 and 4 mg/mL. FPPPs significantly reduced biofilm formation and biofilm metabolic activity in V. alginolyticus, down-regulated the expression levels of lafA, lafK, fliS and flaK genes involved in flagellar synthesis and inhibited swimming and swarming motility (p < 0.05). Meanwhile, under the treatment of FPPPs, the activities of catalase (CAT) and superoxide dismutase (SOD) in V. alginolyticus were significantly reduced, and the levels of reactive oxygen species (ROS) and extracellular malondialdehyde (MDA) were significantly increased (p < 0.05). FPPPs also resulted in a significant increase in alkaline phosphatase (AKP) activity, protein and nucleic acid content, as well as conductivity from V. alginolyticus cultures. Scanning electron microscopy (SEM) images further revealed that V. alginolyticus treated with FPPPs showed leakage of intracellular substances, abnormal cell morphology and damage to cell walls and cell membranes, with the severity of the damage in a clear dose-dependent manner. Therefore, FPPPs can be used as a promising food-grade antibacterial agent, notably in seafood to control V. alginolyticus.

High methoxyl pectin grafted onto gallic acid by one- and two-pot redox-pair procedures

The aim of this research was to graft gallic acid (GA) onto high methoxyl pectin (HMP) through the redox-pair of ascorbic acid (Aa) and hydrogen peroxide (H2O2) with one- and two-pot procedures. The effectiveness of the both procedures and the chemical, physical and antioxidant properties of the obtained HMP-GA were evaluated. HMP-GAone-pot (23.3 ± 0.21 mg GA Equivalent (GAE)/g) and HMP-GAtwo-pot (32.3 ± 0.52 mg GAE/g) were best obtained at H2O2/Aa molar ratio-HMP/GA weight ratio of 9.0-0.5 and 16.0-0.5, respectively. The UV-Vis and FT-IR spectra and along with their derivative and thermal gravimetric analyses, revealed differences between HMP-GAone-pot and HMP-GAtwo-pot. The latter exhibited a greater antioxidant capacity than the former in single electron transfer (ET), hydrogen atom transfer (HAT), and ET-HAT mixed assays. The chemical differences can be attributed to side reactions that may have interfered with the grafting reaction. Consequently, HMP-GA, possessing unique antioxidant and prebiotic properties, can be synthesized through redox-pair procedures.

Fabrication of fiber-particle structures by electrospinning/electrospray combination as an intrinsic antioxidant and oxygen-releasing wound dressing

In this study, we employed a combination of electrospinning and electrospray techniques to fabricate wound dressings with a particle-fiber structure, providing dual characteristics of oxygen-releasing and intrinsic antioxidant properties, simultaneously. The electrospun part of the dressing was prepared from a blend of polycaprolactone/gallic acid-grafted-gelatin (GA-g-GE), enabling intrinsic ROS scavenging. To the best of our knowledge, this is the first time that PCL/GA-g-GE was fabricated by electrospinning. Furthermore, polyvinyl pyrrolidone (PVP) microparticles, containing calcium peroxide nanoparticles (CNPs), were considered as the oxygen production agent through the electrospray part. The CNP content was 1% and 3% w/w of PVP while biopolymer:PCL was 10% w/w. The fabricated structures were characterized in terms of fiber/particle morphology, elemental analysis, oxygen release behavior, ROS inhibition capacity, and water contact angle assessments. The covalent bonding of gallic acid to gelatin was confirmed by 1H-NMR, UV spectroscopy, and FTIR. According to the SEM results, the morphology of the prepared PCL/biopolymer fibers was bead-free and with a uniform average diameter. The analysis of released oxygen showed that by increasing the weight percentage of CNPs from 1 to 3 wt%, the amount of released oxygen increased from 120 mmHg to 195 mmHg in 24 h, which remained almost constant until 72 h. The obtained DPPH assay results revealed that the introduction of GA-g-GE into the fibrous structure could significantly improve the antioxidant properties of wound dressing compared to the control group without CNPs and modified gelatine. In vitro, the fabricated wound dressings were evaluated in terms of biocompatibility and the potential of the dressing to protect human dermal fibroblasts under oxidative stress and hypoxia conditions by an MTT assay. The presence of GA-g-GE led to remarkable protection of the cells against oxidative stress and hypoxia conditions. In vivo studies revealed that the incorporation of intrinsic ROS inhibition and oxygen-releasing properties could significantly accelerate the wound closure rate during the experimental period (7, 14, and 21 days). Additionally, histopathological investigations in terms of H&E and Masson's trichrome staining showed that the incorporation of the two mentioned capabilities remarkably facilitated the wound-healing process.

Gallic Acid Based Polymers for Food Preservation: A Review

The extensive usage of nonbiodegradable plastic materials for food packaging is a major environmental concern. To address this, researchers focus on developing biocompatible and biodegradable food packaging from natural biopolymers, such as polysaccharides, proteins, and polyesters. These biopolymer-based packaging materials extend the shelf life of food due to their inherent antimicrobial and antioxidant properties. An important additive that enhances these beneficial effects is gallic acid (GA), a naturally occurring phenolic compound. GA exhibits potent antioxidant activity by scavenging free radicals and excellent antimicrobial activity against a wide range of bacteria by disrupting cell membranes. These gallic acid based active packaging solutions have demonstrated remarkable abilities to inhibit lipid oxidation, enzymatic browning, and microbial contamination and even retard the ripening processes in mushrooms, walnuts, strawberries, fresh-cut apples, bananas, fish, pork, and beef. This review focuses on the antioxidant, antibacterial, and food preservation capabilities of GA-incorporated biodegradable food packaging materials as an eco-friendly alternative to conventional plastic packaging.

Novel Hydrogel Adjuvant of Chinese Medicine External Preparations for Accelerated Healing of Deep Soft Tissue Injuries

Traditional Chinese medicine external prescriptions have displayed excellent clinical effects for treating deep soft tissue injuries. However, the effects cannot be fully utilized due to the limitations of their dosage forms and usage methods. It is still a challenge to develop a satisfactory adjuvant of traditional Chinese medicine external prescriptions. Herein, a hydrogel adjuvant was prepared based on gallic acid coupled ε-poly-l-lysine and partially oxidized hyaluronic acid. The resulting adjuvant shows great physicochemical properties, low hemolysis rate (still much less than 5% at 5 mg/mL), excellent antibacterial ability (about 95% at 2 mg/mL), strong antioxidant ability (1.687 ± 0.085 mmol FeSO4/(g hydrogel) at 1 mg/mL), as well as outstanding biocompatibility. A clinically used Chinese medicine external preparation was selected as an example to investigate the effectiveness of the adjuvant in treating deep soft tissue injuries. The results show that the prescription can be evenly dispersed in the adjuvant. Moreover, the introduction of the prescription has not significantly changed these advanced properties of the adjuvant. Importantly, the hydrogel adjuvant significantly improves the effectiveness of the prescription in treating deep soft tissue injuries. This work offers an alternative approach to the development of a new-type adjuvant of Chinese medicine external preparations and also provides a new strategy for the combination of traditional Chinese medicine and hydrogel to treat clinical diseases.

Eco-friendly cellulose-based antioxidation film by partial esterification

Cellulose nanocrystals (CNCs) have received increasing attention because of their superior dispersion and thermal stability. In this study, TEMPO-oxidized cellulose nanocrystal (TOCNC) multifunctional antioxidationantioxidation films (TOCNC-GA film) were prepared by the esterification of TOCNC and gallic acid (GA). TOCNC-GAX films, where X represents the ratio of the amount of GA to the amount of TOCNC, were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The films with the GA:TOCNC ratio of 1:1 achieved higher interfacial compatibility than the other films. The mechanical properties and water resistance of the TOCNC-GA films were superior than those of pure TOCNC films. Moreover, the original TOCNC structure changed owing to the presence of GA, which endowed a certain thermoplasticity owing to the formation of ester groups. The antioxidation properties of the TOCNC-GA1 films reached 43.8 % and 71.85 % after 6 and 24 h, respectively, as evaluated by the 2,2-biphenyl-1-picrylhydrazyl method and the free radical scavenging activities of the TOCNC-GA1 films. The innovative development of the functional antioxidation film presented in this paper has great potential for use in antioxidation packaging materials and food preservation.

Influence of chitin nanofibers and gallic acid on physical-chemical and biological performances of chitosan-based films

In this work, chitosan films loaded with gallic acid and different content of chitin nanofibers were prepared and subjected to different characterization techniques. The results showed that the inclusion of gallic acid to chitosan films caused moderate decrease in water vapor permeability (by 29 %) and increased tensile strength of films (by 169 %) in comparison to the neat chitosan films. Furthermore, it was found that the addition of chitin nanofibers up to 30 % into chitosan/gallic acid films additionally improved tensile strength (by 474 %) and reduced plasticity of films (by 171 %), when compared to the chitosan/gallic acid films. Increased concentration of chitin nanofibers in films reduced the overall water vapor permeability of films by 51 %. In addition, gallic acid and chitin nanofibers had synergic effect on high chitosan film's antioxidant and antifungal activity toward Botrytis cinerea (both above 95 %). Finally, chitosan/gallic acid/chitin nanofibers films reduced decay incidence of strawberries, increased total soluble solid content, and promoted high production of some polyphenols during cold storage, in comparison to the control chitosan films and uncoated strawberry samples. Hence, these results suggest that chitosan/gallic acid/chitin nanofibers can present eco-sustainable approach for preservation of strawberries, giving them additional nutritional value.

Exploring the emulsification potential of chitosan modified with phenolic acids: Emulsifying properties, functional activities, and application in curcumin encapsulation

This study successfully grafted caffeic acid and 3,4-dihydroxybenzoic acid into chitosan through a coupling reaction, yielding grafting ratio of 8.93 % for caffeic acid grafted chitosan (CA-GC) and 9.15 % for 3,4-dihydroxybenzoic acid grafted chitosan (DHB-GC) at an optimal concentration of 4 mmol phenolic acids. The characterization of modified chitosans through ultraviolet visible spectrometer (UV-vis), Fourier transform infrared spectrometer (FTIR), proton nuclear magnetic resonance (1H NMR), and x-ray photoelectron spectrometer (XPS) confirmed the successful grafting of phenolic acids. In the subsequent step of emulsion preparation, confocal laser scanning microscope images confirmed the formation of O/W (oil-in-water) emulsions. The phenolic acid-grafted chitosans exhibited better emulsification properties compared to native chitosan, such as reduced droplet size, more uniform emulsion droplet distribution, increased ζ-potential, and enhanced emulsifying activity and stability. Moreover, the modified chitosans demonstrated increased antioxidant activities (evidenced by DPPH and β-carotene assays) and displayed greater antimicrobial effects against E. coli and S. aureus. Its efficacy in curcumin encapsulation was also notable, with improved encapsulation efficiency, sustained release rates, and enhanced storage and photostability. These findings hint at the potential of modified chitosans as an effective emulsifier.

Dietary gallic acid as an antioxidant: A review of its food industry applications, health benefits, bioavailability, nano-delivery systems, and drug interactions

Gallic acid (GA), a dietary phenolic acid with potent antioxidant activity, is widely distributed in edible plants. GA has been applied in the food industry as an antimicrobial agent, food fresh-keeping agent, oil stabilizer, active food wrap material, and food processing stabilizer. GA is a potential dietary supplement due to its health benefits on various functional disorders associated with oxidative stress, including renal, neurological, hepatic, pulmonary, reproductive, and cardiovascular diseases. GA is rapidly absorbed and metabolized after oral administration, resulting in low bioavailability, which is susceptible to various factors, such as intestinal microbiota, transporters, and metabolism of galloyl derivatives. GA exhibits a tendency to distribute primarily to the kidney, liver, heart, and brain. A total of 37 metabolites of GA has been identified, and decarboxylation and dihydroxylation in phase I metabolism and sulfation, glucuronidation, and methylation in phase Ⅱ metabolism are considered the main in vivo biotransformation pathways of GA. Different types of nanocarriers, such as polymeric nanoparticles, dendrimers, and nanodots, have been successfully developed to enhance the health-promoting function of GA by increasing bioavailability. GA may induce drug interactions with conventional drugs, such as hydroxyurea, linagliptin, and diltiazem, due to its inhibitory effects on metabolic enzymes, including cytochrome P450 3A4 and 2D6, and transporters, including P-glycoprotein, breast cancer resistance protein, and organic anion-transporting polypeptide 1B3. In conclusion, in-depth studies of GA on food industry applications, health benefits, bioavailability, nano-delivery systems, and drug interactions have laid the foundation for its comprehensive application as a food additive and dietary supplement.

Ultrasensitive detection of glucose oxidase and alkaline phosphatase in milk based on valence regulated upconversion nanoprobes

Fresh milk should undergo sterilization before consumption to eliminate bacteria that can cause foodborne illnesses. Additional antimicrobial measures are beneficial to extend its shelf life. The nanoprobe developed herein can not only inspect the activity of alkaline phosphatase (ALP) for evaluating the degree of pasteurization, but also detect the activity of glucose oxidase (GOD), which is added as a chemical preservative. The facile preparation of the nanoprobe involved introducing gallic acid-Fe complex (GA-Fe) into lanthanide doped upconversion nanomaterials (UCNPs). Based on the alteration of iron's valence state in the complex through a straightforward redox reaction, both enzyme activities could be determined through colorimetric and luminometric dual-signal readouts. With detection limits of 1.669 × 10-5 for GOD and 9.81 × 10-6 U/mL for ALP respectively, this nanoprobe shows merits of easy operation and high sensitivity. Successful application in milk samples demonstrates its potential as an innovative and cost-effective approach to food safety inspection.

Bio-based active packaging: Gallic acid modified agarose coatings in grass carp (Ctenopharyngodon idellus) preservation

Antioxidant and antimicrobial agarose coatings were developed by grafting gallic acid through the carbodiimide coupling method. Structural characterization revealed that the carboxyl group of gallic acid was successfully grafted onto the C6-OH of D-galactose in agarose, with the highest observed grafting ratio being 13.73 %. The grafting of gallic acid significantly increased the antioxidant and bacteriostatic activities of the agarose. As the grafting ratio of gallic acid-modified agarose (GaAg) increased from 0 to 13.73 %, the scavenging ratio of DPPH and the inhibition ratio of β-carotene bleaching were observed to increase from 0 % to 65.92 % and 6.89 % to 73.46 %, respectively. GaAg exhibited up to 100 % inhibition of Escherichia coli and Staphylococcus aureus. The physicochemical properties of gel strength, viscosity, gelling temperature and melting temperature decreased to 971.3 g/cm2, 17.9 mPa·s, 31.7 °C and 84.1 °C, respectively. The gel contact angle was increased from 22.1° to 73.6°. Fish preservation tests have demonstrated that it effectively inhibited bacterial growth, prevented fat oxidation, blocked light, reduced moisture loss, and enhanced the overall quality of grass carp (Ctenopharyngodon idellus) fillets during refrigeration, which was more effective than native agarose in extending the shelf life of fish. Therefore, GaAg holds promise as an aquatic product preservative.

Modification methods, biological activities and applications of pectin: A review

Pectin is a complex and functionally rich natural plant polysaccharide that is widely used in food, medical, and cosmetic industries. It can be modified to improve its properties and expand its applications. Modification methods for natural pectin can be divided into physical, chemical, enzymatic, and compound methods. Different modification methods can result in modified pectins (MPs) exhibiting different physicochemical properties and biological activities. The objectives of this paper were to review the various pectin modification methods explored over the last decade, compare their differences, summarize the impact of different modification methods on the biological activity and physicochemical properties of pectin, and describe the applications of MPs in food and pharmaceutical fields. Finally, suggestions and perspectives for the development of MPs are discussed. This review offers a theoretical reference for the rational and efficient processing of pectin and the expansion of its applications.

An injectable, self-healing, and antioxidant collagen- and hyaluronic acid-based hydrogel mediated with gallic acid and dopamine for wound repair

Injectable self-healing hydrogels with antioxidation are required in wound dressings. Because oxidative damage caused by excessive reactive oxygen species (ROS) is a common issue associated with chronic non-healing wounds. Here, collagen (COL) - and hyaluronic acid (HA)-based hydrogel with antioxidant and injectable self-healing mediated with gallic acid (GA) and dopamine (DA) offers unique advantages for wound repair. The hydrogel is constructed by COL-grafted GA (CG), HA-grafted DA (HD) and γ-poly(glutamic acid) (γ-PGA) coupled with 3-aminophenylboric acid (APBA) via the dynamic boronic ester bonds. Rheological measurements and direct visual observation demonstrated the hydrogel's desirable injectability and self-healing properties. Additionally, the hydrogel exhibits tissue adhesion properties. Biocompatibility and cell migration tests showed that the hydrogel promotes cell proliferation and migration. In vitro, antioxidant and intracellular free radical scavenging assays confirmed the hydrogel's antioxidant property and ability to scavenge excess ROS. In vivo wound healing studies have demonstrated that hydrogel can promote angiogenesis, inhibit inflammation, and promote collagen fiber deposition to accelerate wound healing.

Structural characterization, antioxidant and antimicrobial activities of polysaccharide from Akebia trifoliata (Thunb.) Koidz stem

Polysaccharides have a variety of beneficial pharmacological impact on human health. Akebia trifoliata (Thunb.) Koidz. has promising development prospects as a food resource with medicinal value. The aim of this study was to investigate the structural characterization, antioxidant, and antibacterial properties of A. trifoliata (Thunb.) Koidz polysaccharides (ATKPs). ATKP-II was purified from ATKP by DEAE-cellulose column with NaCl solution as eluent. ATKP and ATKP-II structures were characterized by high performance gel permeation chromatography, gas chromatography, ultraviolet-visible, Fourier transform infrared spectroscopy, thermogravimetry analysis and scanning electron microscopy. ATKP and ATKP-II were primarily composed of rhamnose, arabinose, xylose, mannose, glucose, and galactose in a molar percent of 1.6: 22.1: 3.6: 6.3: 55.7: 10.7, and 0.5: 22.1: 3.7: 10.2: 42.1: 21.4, respectively. Their structure may contain β-D-glucopyranose. The thermogravimetry analysis showed that ATKP and ATKP-II have good thermal stability at 230 °C and 200 °C, respectively. ATKP had the best antioxidant activities for 2, 2-diphenyl-1-picrylhydrazyl, hydroxyl, and superoxide free radical scavenging activities in vitro, and reducing ability than that of the purified polysaccharides. Moreover, ATKP was demonstrated an appreciable in vitro antibacterial activity, against Staphylococcus aureus, Bacillus subtilis, Salmonella, Penicillium italicum, Rhizopus and Aspergillus niger, but showed no activity against Escherichia coli and Saccharomycetes. These results demonstrated that ATKP displayed excellent antioxidant and antibacterial activities. This study provides a basis for the development and utilization in ATKP.

Ce(IV)-coordinated organogel-based assay for on-site monitoring of propyl gallate with turn-on fluorescence signal

Propyl gallate (PG) is a commonly used synthetic phenolic antioxidant in foodstuffs and industrial products. Due to the potential health risk of PG, rapid and on-site detection in food and environment samples are important to guarantee human health. Herein, we demonstrated rapid monitoring of PG by a fluorescence turn-on strategy based on a specific fluorogenic reaction between PG and polyethyleneimine (PEI). Specifically, Ce4+ with oxidase-mimicking activity oxidized PG to its oxides, which then reacted with PEI through the Michael addition to generate the fluorescent compound. The proposed fluorogenic reaction had good specificity for PG, which could distinguish PG from other phenolic antioxidants and interferences. Furthermore, portable and low-cost organogel test kits were prepared using poly(ethylene glycol) diacrylate for quantitative and on-site detection of PG via a smartphone-based sensing platform. The organogel-based assay detection limit was 1.0 μg mL-1 with recoveries ranging from 80.2% to 106.2% in edible oils and surface water. Suitability of the developed assay was also validated by high-performance liquid chromatography. Our study provides an effective fluorescent approach to rapid, specific, and convenient monitoring of PG, which is useful for diminishing the risk of PG exposure.

Pectin grafted with resorcinol and 4-hexylresorcinol: Preparation, characterization and application in meat preservation

To augment the functional attributes of pectin and expand its prospective utilization in food preservation, this research explored the enzymatic grafting of resorcinol and 4-hexylresorcinol onto pectin. Structural analysis verified the successful grafting of both resorcinol and 4-hexylresorcinol to pectin via esterification, with the 1-OH of resorcinol and 4-hexylresorcinol and the carboxyl group of pectin functioning as grafting sites. The grafting ratios of resorcinol-modified pectin (Re-Pe) and 4-hexylresorcinol-modified pectin (He-Pe) were 17.84 % and 10.98 %, respectively. This grafting modification notably enhanced the antioxidative and antibacterial properties of pectin. Specifically, DPPH clearance and the inhibition ratio in the β-carotene bleaching assay increased from 11.38 % and 20.13 % (native pectin, Na-Pe) to 41.15 % and 36.67 % (Re-Pe), and 74.72 % and 53.40 % (He-Pe). Moreover, the inhibition zone diameter against Escherichia coli and Staphylococcus aureus rose from 10.12 and 10.08 mm (Na-Pe) to 12.36 and 11.52 mm (Re-Pe), and 16.78 and 14.87 mm (He-Pe). Additionally, the application of native and modified pectin coatings effectively impeded pork spoilage, with the modified pectins demonstrating a more potent effect. Among the two modified pectins, He-Pe exhibited the most significant enhancement in pork shelf life.

Green synthesis of chitosan/erythritol/graphene oxide composites for simultaneous removal of some toxic species from simulated solution

In this study, chitosan (Ch) is adapted via green methodology including sonication induced crosslinking with different weight ratios of erythritol (Er) from (Ch-Er)1 to (Ch-Er)4. The products were casted in the form of thin films. The chemical modification was proved via FTIR spectroscopy. Then, the modified products were verified via an atomic force microscopy (AFM) investigation for their topography and surface properties. The data revealed that the optimized sample was (Ch-Er)3. This sample was further modified by different weight ratios of graphene oxide 0.1, 0.2, 0.4, and 0.8 wt./wt. (symbolized as (Ch-Er)3GO1, (Ch-Er)3GO2, (Ch-Er)3GO4, and (Ch-Er)3GO8 respectively). The prepared samples were investigated by different analytical tools. Then, the adjusted sample (Ch-Er)3GO2 was irradiated by electron beam (e-beam) at 10 and 20 kGy of irradiation doses to give samples (Ch-Er)3GO2R10 and (Ch-Er)3GO2R20, respectively. The AFM data of the irradiated samples showed that the pore size decreases, and surface roughness increases at higher energy e-beam due to the formation of more crosslinking points. The optimum samples of the prepared formulations were tested as sorbent materials for simultaneous elimination of methylene blue (MB) dye and mercury cation (Hg2+) from simulated solutions. The maximum removal of both MB dye and Hg2+ cation was achieved by (Ch-Er)3GO2R10 (186.23 mg g-1 and 205 mg g-1) respectively.

Investigation of the structure of gallate xylose polymers and their antioxidant properties for skin care products

Xylose is the second most abundant monosaccharide in nature, and gallic acid (GA) has properties of antioxidant, anti-inflammatory and anti-bacterial. Hence, the gallate xylose (GX) polymers were synthesized from d-xylose and gallic acid for skin care applications in this paper. Then, the structure, generation mechanisms and the antioxidant activity of the generated polymer were studied. It got the results that: The generated GX polymers have strong antioxidant properties, yielded in 80.1% of GA mass. The DPPH scavenging activity was over 80.0% under the polymer's solution over 0.2 mg/mL. Moreover, the reaction mechanisms of DPPH removal were explained in a new theory based on Mass spectral analysis. Therefore, it demonstrates that the GX polymers of is a potential antioxidant material for skin care products, and it does contribution to the theory of DPPH removal for application in the fields of chemistry, biology and medicine researches.

Construction of double-network hydrogel based on low methoxy pectin/polyvinyl alcohol and its structure and properties

In this study, an interpenetrating double-network hydrogel (LMP/AA/PVAH) was prepared based on low methoxy pectin (LMP), acrylic acid (AA) and polyvinyl alcohol (PVA). The first rigid network of chemical crosslinking was constructed via free radical polymerization of LMP and AA, and the second of ductile physical crosslinking network was constructed via cyclic freeze-thaw of PVA. The first cycle hardness and elasticity of the LMP/AA/PVAH significantly increased from 13.08 N and 0 to 24.28 N and 0.79, respectively, when the second network structure was constructed in the hydrogel by PVA. Besides, the PVA network might enhance the ductile and limit the swelling of hydrogel. In addition, the adsorption properties of LMP/AA/PVAH were evaluated by adsorption of methylene blue (MB). The adsorption behavior of MB by LMP/AA/PVAH conformed to the pseudo-second-order kinetic model. Besides, after 4 cycles of adsorption, there was no significant difference in adsorption capacity of LMP/AA/PVAH. The results showed that LMP/AA/PVAH had good reusability.

Ferulic acid- and gallic ester-acylated pectin: Preparation and characterization

In this study, pectin was modified with ferulic acid (Fa), trans-ferulic acid (trans-Fa), methyl gallate (MG), and ethyl gallate (EG) via the enzymatic method using aqueous/organic phases to enhance its physiochemical and bio-active properties. Results revealed that lipase might catalyze the hydrolysis of the ester bond within pectin in aqueous phase and prompt the transesterification between the hydroxyl group in the para position in Fa/trans-Fa or the 2'-OH group of MG/EG and the carboxylic group of pectin in the organic phase. The graft ratio was 21.00%, 21.67%, 13.24%, and 11.93% for the Fa-, trans-Fa-, MG-, and EG-modified pectin, respectively. In addition, compared with native pectin, the modified pectin exhibited improved apparent viscosity and emulsion activity. Moreover, the clearance of 1,1-diphenyl-2-picryl hydrazine (DPPH) and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) was effectively enhanced for the modified pectin. Furthermore, the modified pectin exhibited strong antibacterial activity against Escherichia coli and Staphylococcus aureus while no cytotoxic effects based on the results of cell culture experiments. Our results provide a theoretical basis for the expansion of pectin applications in the food and pharmaceutical industries.

Functionalized injectable hyaluronic acid hydrogel with antioxidative and photothermal antibacterial activity for infected wound healing

Infected wound healing has always been a challenge in clinic. Effective and economic wound dressings with combined antibacterial activity and pro-healing function are highly desirable, especially in the context of infected wounds. An obvious advantage of antibacterial wound dressing is to avoid the overuse of antibiotics and the occurrence of drug resistance. Herein, an injectable hyaluronic acid hydrogel with antioxidative and photothermal antibacterial activity as a functional dressing was prepared, characterized and evaluated in an experimental infected wound model. This hydrogel was developed by loading graphene oxide (GO) in a natural polymer network consisting of hyaluronic acid grafted with tyramine (HT) and gelatin grafted with gallic acid (GGA). The HT/GGA/GO hydrogels have a porous cross-linked network structure and demonstrate a good stability, biocompatibility, antioxidant, hemostatic and photothermal antibacterial activity against Escherichia coli and Staphylococcus aureus. In addition, in vivo studies have shown that HT₁/GGA₂/GO_0.1 hydrogel dressing combined with photothermal therapy can effectively prevent early infection and accelerate wound healing. These results indicated this functionalized injectable hydrogel HT₁/GGA₂/GO_0.1 has a great potential in wound dressing application.