UV-blocking Ability Research Articles

Polyvinyl alcohol/cellulose nanocrystals incorporated with apple waste-derived carbon dots as an excellent UV food packaging material

Ultraviolet (UV) radiation has significantly reduced food quality. With the increase in UV radiation to Earth due to ozone layer depletion, the need for eco-friendly UV-blocking food packaging materials is becoming very important. This work synthesized carbon dots (CD) from apple waste and then incorporated them into polyvinyl alcohol (PVA)/cellulose nanocrystals (CNC) to develop UV-blocking packaging materials. The CD was even distributed and highly compatible with the PVA/CNC matrix (5 wt% of CNC) to form a compact and continuous film without defects. In particular, the UV-blocking ability of PVA/CNC/CD was substantially improved. PVA/CNC/CD 1 % (1 wt% of CD) exhibits excellent UV-blocking ability, which can block about 78.2 % of UVA and 91 % of UVB. The UV protection factor of this composite was 5.9 times higher than that of PVA/CNC. In addition, the prepared composite films keep high transparency with over 70 % transmittance of visible light at 660 nm. The potential use of developed composites as UV-blocking packaging materials was demonstrated by lab-scale packaging tests with cherry tomatoes.

Plant-based chitosan for the development of biodegradable packaging materials

Plant-derived materials and edible films have developed as viable substitutes for standard packaging materials, enabling sustainable and ecologically acceptable alternatives. Chitosan, a cationic carbohydrate polymer derived from animal or marine sources, as well as from agricultural waste such as mushrooms or various fungi possesses excellent properties such as film formation, mechanical strength, non-toxicity, biodegradability, edibility, UV-blocking ability, antioxidant activity, and antibacterial functionality, justifying its potential as packaging/coating material for fresh agricultural products. Chitosan is obtained through the deacetylation of chitin. The quantity of waste generated in a mushroom farm varies from 5–20 % of the total yielding quantity. Filamentous fungi's cellular structure, which is rich in chitin, provides a convenient method for chitin extraction. Fungal-derived chitosan offers the advantage of controllable physicochemical characteristics, including degree of deacetylation and molecular weight, compared to chitosan obtained from crustaceans. This versatility makes fungal chitosan suitable for various utilizations in food, pharmaceutical, and biomedical management. It can be utilised for different purposes in these fields. This review primarily emphasizes the extraction of chitin from mushrooms and various fungal sources, comparing different extraction methods and chitosan-based materials fabrication techniques. Additionally, it discusses the crucial characteristics of chitosan that make it convenient for high value-added functions in the food industry. To sum up, plant-based chitosan films have the potential to completely transform the packaging sector by providing environmentally friendly substitutes for traditional materials. Accepting these advances will help build a more resilient and sustainable earth, encourage the circular economy, and reduce the amount of plastic trash produced.

The effects of cellulose nanocrystals (CNC) and halloysite nanotubes (HNT) on selected properties of crosslinked modified tapioca starch films

Abstract Crosslinked modified tapioca starch films with CNC and HNT have the potential to be good renewable and biodegradable food packaging. Starch, CNC, and HNT were used because of their availability and cheap cost. This study aimed to investigate the effect of varying concentrations of CNC and HNT on the morphology, mechanical and optical properties of crosslinked modified tapioca starch films as an initial step in developing an active food package. Both CNC and HNT have high crystallinity and a large amount of OH groups. The OH groups as well as the ion-dipole interaction in HNT increase the tensile strength of the films. The highest tensile strength and the lowest elongation were recorded in films containing 5% CNC and 5% HNT. Beyond 5%, the addition of these nanomaterials diminished the tensile strength due to agglomeration which is the weak point of the films. Below the 5%, the nanomaterials serve as good reinforcing agents which improve the tensile strength. In addition, all films have good transmission capacity for visible light, while films with HNT outperform films with CNC in UV blocking ability.

Functional composite films incorporating triphala-derived carbon dots for extending chicken preservation

Triphala-based carbon dots (T-CDs) were successfully prepared using a simple one-step hydrothermal method. T-CDs were characterized by absorbance, fluorescence, Fourier-transform infrared, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. T-CDs showed bright blue fluorescence at 434 nm upon excitation at 360 nm. Functional composite films were prepared using poly(vinyl alcohol) and gelatin mixture by incorporating T-CDs and applied as a packaging film to extend the shelf life of chicken. The antibacterial activity of T-CDs against Listeria monocytogenes and Staphylococcus aureus was evaluated using well diffusion and colony count methods. T-CDs were evenly dispersed throughout the PVA/Gel solution to form a dense and uninterrupted film. They also formed strong bonds with polymer chains, which improved the tensile strength of the film from 32.44 to 42.70 MPa. Furthermore, the presence of T-CDs significantly enhanced the UV-blocking ability of the PVA/Gel films, achieving 99.7 % for UV-B and 97.2 % for UV-A. In addition, the PVA/Gel/T-CDs composite films showed excellent antioxidant, antimicrobial and UV-barrier properties, extending the shelf life of chicken. Therefore, the PVA/Gel/T-CDs composite films showed great potential as an active food packaging material to extend the shelf life and preserve the visual quality of packaged meat.

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.

Versatile synthesis of cellulose film with excellent electrothermal/photothermal dual responsiveness by introducing MXene and small molecule self-assembled nanosphere

Plant-derived biomaterials have great application prospects in solving environmental pollution and sustainable resource utilization, but the insufficient mechanical strength and lack of functional responsiveness often limit their further development. Inspired by natural small molecules functionalization, a vacuum-assisted filtration nanofibrillated cellulose (NFC)-based film with excellent antibacterial properties, mechanical strength, and electrothermal/photothermal dual-responsiveness was fabricated. As a natural bioactive molecule, antibacterial cinnamaldehyde (CA) is grafted onto tannic acid (TA) rich in pyrogallols via a small molecule self-assembly strategy, and then co-assembled with zinc acetate (ZA) through ion crosslinking to synthesize the functional TACA@ZA nanospheres. After incorporating the MXene and TACA@ZA, an inorganic-organic 3D network system was established in the NFC matrix through dynamic intermolecular hydrogen bonding and strong ionic cross-linking. The mechanical strength and toughness of hybrid composites are remarkably improved by 83.6 % and 418.9 %, respectively. Due to the synergistic effects of MXene and TACA@ZA, the designed NFC-based film also shows significantly enhanced antibacterial activity, UV-blocking ability, as well as photothermal and electrothermal performance. This bioinspired small molecule functionalization strategy opens an innovative design concept for the fabrication of multirole NFC-based biomaterials, which has great application prospects in the commercial fields of multifunctional adhesives, electronic devices, UV shielding coatings, and antibacterial materials.

Structural and Physiochemical Properties of Polyvinyl Alcohol-Succinoglycan Biodegradable Films.

Polyvinyl alcohol (PVA)-bacterial succinoglycan (SG) biodegradable films were developed through a solvent-casting method. Effects of the PVA/SG ratio on the thickness, transmittance, water holding capacity, and structural and mechanical properties were investigated by various analytical methods. All the prepared films were transparent and uniform, and XRD and FTIR analyses confirmed that PVA was successfully incorporated into SG. The films also showed excellent UV-blocking ability: up to close to 80% with increasing SG concentration. The formation of effective intermolecular interactions between these polymers was evidenced by their high tensile strength and moisture transport capacity. By measuring the biodegradation rate, it was confirmed that films with high SG content showed the fastest biodegradation rate over 5 days. These results confirm that PVA/SG films are eco-friendly, with both excellent biodegradability and effective UV-blocking ability, suggesting the possibility of industrial applications as a packaging material in various fields in the future.

UV-blocking, antibacterial, corrosion resistance, antioxidant, and fruit packaging ability of lignin-rich alkaline black liquor composite film

The novel multifunctional active packaging composite film with antimicrobial, antioxidant, water-vapor and UV-barrier, and corrosion resistance properties was successfully prepared from waste biomass. In this study, waste poplar sawdust was pretreated using green liquor to extract black liquor (BL). BL was then mixed with polyvinyl alcohol (PVA) solution for synthesizing silver nanoparticles (AgNPs). PVA-BL-AgNPs film was fabricated by solution casting method, and the microstructure characterization and macroscopic performance testing of the composite film were conducted. The results revealed that PVA-BL-AgNPs film exhibited inhibitory effects against Staphylococcus aureus (inhibition zone: 33.6 mm), Pseudomonas aeruginosa (inhibition zone: 31.6 mm), and Escherichia coli (inhibition zone: 32.0 mm). It could eliminate over 99 % of 2,2-diazodi (3-ethyl-benzothiazol-6-sulfonic acid) (ABTS) free radicals and provided 100 % UV-blocking, reducing light-induced food damage. It exhibited the improvement of water-vapor barrier properties and corrosion resistance. In vitro cytotoxicity assays demonstrated that no significant impact occurred on cell proliferation, confirming the safety of the film. Packaging experiments showed that PVA-BL-AgNPs film effectively inhibited milk spoilage and prolonged the shelf-life of bread and bananas. Therefore, PVA-BL-AgNPs film might extend the shelf-life of food and offer significant opportunities in addressing the issues of low safety and environmental pollution associated with traditional packaging films.

Development of active film based on collagen and hydroxypropyl methylcellulose incorporating apple polyphenol for food packaging

Collagen (COL)-hydroxypropyl methylcellulose (HPMC) blended films with apple polyphenol (AP) as cross-linking agent and antioxidant compound were developed to produce biodegradable active packaging film. The effects of AP content on the rheological behavior of the blended solution, the structure, physicochemical and functional properties of the blended film were systematically investigated. The incorporation of AP increased the viscosity and reduced the fluidity of COL-HPMC solution. The results of rheological tests and FTIR analysis manifested the formation of hydrogen bonding interactions between collagen, HPMC and AP, which made the structures of COL-HP-AP films more compact. The mechanical strength, UV-blocking ability, water-resistance performance and thermostability were gradually enhanced as increasing AP content. DPPH free radical scavenging experiment showed that a small amount of AP could efficiently improve the antioxidant activity of COL-HP film, and with increasing AP content to 5 wt%, the scavenging rate was as high as 94.23 %. Active film containing 5 wt% AP showed obvious antibacterial effect on E. coli and S. aureus, and it could effectively prevent the oxidation of vitamin C and reduce the accumulation of MDA on green pepper during the storage. COL-HP-AP films have great potential in food packaging field for extending the shelf life of food.

Sustainable chitosan/polyvinyl alcohol composite film integrated with sulfur-modified montmorillonite for active food packaging applications

Sulfur-functionalized montmorillonite (S-MMT), which has strong antioxidant and antibacterial activities, was prepared by forming a sulfur-amine complex using ethylenediamine (EDA). S-MMT was added to the chitosan/polyvinyl alcohol (Chi/PVA) blend polymer to develop an active food packaging film. The composite film, especially 4 wt% S-MMT-added Chi/PVA film (Chi/PVA/S-MMT4%), showed significant increases in tensile strength (∼25.1 %), elongation at the break (∼94.1 %), and UV-blocking ability (98.2 % UV-A and 100 % UV-B) compared to the neat Chi/PVA film. The Chi/PVA/S-MMT4% film also exhibited remarkable antioxidant properties (100 % ABTS and 65.4 % DPPH scavenging activity) and potent antibacterial activity (stopped the growth of L. monocytogenes and E. coli). Chicken packaged in the composite film showed a significant reduction in quality changes, including appearance, pH, thiobarbituric acid reactive substances (TBARS), and total viable colonies (TVC) over 20 days of storage. Multifunctional Chi/PVA/S-MMT films have high potential in active food packaging applications.

UV blocking edible films based on corn starch/moringa gum incorporated with pine cone extract for sustainable food packaging

Corn starch (CS) is a good alternative to synthetic polymers due to its sustainability; nevertheless, because of its weak tensile strength, the matrix requires another polymer. Therefore, 0.5 % (w/v) moringa gum (MG) was added. The purpose of this study was to assess how pine cone extract (PCE) affected the physiochemical and mechanical properties of corn starch and moringa gum (CS/MG) films and their use as UV-blocking composites. The findings suggest that the PCE improved the elongation at break from 3.27 % to 35.2 % while greatly reducing the tensile strength. The hydrogen bonding between CS/MG and PCE was visible in the FTIR spectra. The XRD graph indicated that the films were amorphous. In comparison to CS/MG films, PCE-incorporated edible films demonstrated significant UV-blocking ability indicating their potential as sustainable packaging material for light-sensitive food products.

Effects of coffee bean types on the characteristics of carbon dots and their use for manufacturing cellulose nanofibers-based films for active packaging of meat

CDs (carbon dots) were made through a hydrothermal process using three different types of coffee grounds (raw, roasted, and spent), and their physicochemical and optical properties were thoroughly studied. CNF (cellulose nanofibers)-based active packaging films were made and characterized by incorporating the CDs. The introduction of CDs improved the tensile strength of the CNF-based films by 26.1% and provided excellent UV-blocking ability by blocking 98.8% of UV-B and 87.4% of UV-A without sacrificing the film’s transparency. The CD-loaded CNF films showed strong antioxidant properties with ABTS radical and DPPH radical removal rates of 98.2% and 78.8%, respectively. Additionally, these films showed effective antimicrobial potential and significantly reduced the progress of E. coli and L. monocytogenes after 12 h of exposure. Packaging tests were performed at 4 °C for 21 days, which depicted that minced pork packaged with the CD-added CNF films preserves the quality of packaged meat in terms of appearance, pH, total viable colonies, and TBARS (thiobarbituric acid reactive substances). It is expected that manufacturing functional fillers (CDs) using waste resources generated in the food industry and developing active packaging films using them will not only extend the shelf life of packaged foods but also help in resource recycling and solving environmental problems.

A novel multifunctional carboxymethyl cellulose packaging film with encapsulated lemon oil for quality enhancement of cherry tomato and baby spinach leaves

This is the first report on fabricating an active edible film based on CMC and lemon essential oil (LEO) micro/nanocapsules for packaging cherry tomatoes and baby spinach leaves. LEO extracted by hydrodistillation from lemon peels was efficiently encapsulated by oil-in-water emulsification method using high dextrose equivalent maltodextrin (MD) as the sole wall material, yielding physically stable MD-LEO micro/nanocapsules with potent cytotoxicity against Caco-2 cells, and antimicrobial activity against foodborne pathogens. Incorporating LEO micro/nanocapsules into CMC confirmed by SEM/FTIR analyses, significantly improved the film's water vapor permeability by 37.50%, increased its thermal stability by 25 ℃, and reduced its moisture content/water absorption. The transparent film demonstrated strong DPPH radicle scavenging activity, UV-blocking ability, low moisture, enhanced tensile strength, and soil biodegradability (96.84%) within 14 days. Direct application of the novel film as a single-layer overwrap to cherry tomatoes and spinach leaves stored at abusive temperature for up to 4 days revealed good prospects of preserving physical appearance, preventing water/texture loss, maintaining pH, and inhibiting growth of aerobic mesophilic/E. coli O157:H7 populations by 0.65 and 1.0 log units, respectively, highlighting that CMC is an optimal vehicle for encapsulated LEO. The data emphasizes the significant contribution of the novel film to active packaging of minimally processed fresh produce and its potential to compete with inert plastic films dominating food markets. Extending the film's applicability range to other pertinent food systems may promote industrial interest for production upscaling as a commercially viable postharvest preservation strategy to meet the demands of sustainable packaging industry in Egypt.

Effect of TEMPO-oxidized bacterial cellulose nanofibers stabilized Pickering emulsion of cinnamon essential oil on structure and properties of gelatin composite films

Pure gelatin film often exhibits high hydrophilicity and a lack of antibacterial activity, hindering its practical application in the field of food preservation. To address these issues, we incorporated 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized bacterial cellulose (TOBC) nanofibers stabilized cinnamon essential oil (CEO) Pickering emulsions into the gelatin matrix to develop active food packaging films. The study revealed that the good distribution of emulsion droplets in the film matrix. While with increasing Pickering emulsion proportion, the microstructures of composite films were more heterogeneous, showing some pores or cavities. In addition, the insertion of TOBC-stabilized CEO emulsions could improve the elongation at break (EAB), water-resistance, UV blocking ability, and antibacterial activity of film, but reduced its tensile strength (TS) and water vapor barrier properties (WVP). Notably, the film prepared with 4 % TOBC-stabilized CEO Pickering emulsion demonstrated enhanced preservation of strawberries. Overall, the as-prepared gelatin-based active composite films have considerable potential for food packaging.

New insights into greener skin healthcare protection: Lignin nanoparticles as additives to develop natural-based sunscreens with high UV protection

Despite lignin nanoparticles (LNPs) being extensively employed as assistant agents to improve the UV-blocking performance of sunscreens, there is a lack of information addressing how and to what extent the chemical and structural features of these particles relate to the improvements observed in the Sun Protection Factors (SPF) of the sunscreens. In this study, lignin oligomers were prepared by a solvothermal extraction process of five typical biomasses in a water–acetone co-solvent without noticeable degradation of the cellulose fraction. Afterward, LNPs were produced from the self-assembly of these lignin oligomers via the solvent-shifting methodology. When incorporated into the sunscreen, these had different morphologies, and exerted different UV-blocking capacities. The effects of the chemical structure and size distribution of the LNPs were systematically studied and compared to those of the original lignin oligomers. LNPs exhibited better UV-blocking ability than soluble lignin oligomers due to the more exposed chromophore on the surface. Besides, compact LNPs with conjugating CO and β-O-4 linkages, as well as the presence of the syringyl unit rich in the methoxyl group in the structures, were beneficial in boosting the UV resistance of the sunscreens. Even though smaller LNPs with higher surface area favored the UV shielding performance, LNPs with widely distributed sizes could further help decrease the UV transmittance. These findings provide an excellent basis for using lignin-derived materials as sunscreen additives and pave the way to developing new environmentally friendly materials for the cosmetic industry.

Structural, morphological, optical and antibacterial performances of rare earth (Sm)-doped ZnO nanorods

The significant rise of ultra-violet (UV) radiation and pathogenic infectious bacteria poses a serious threat to global health. Numerous researchers’ interests are attracted by novel materials with strong UV-blocking ability, antibacterial activity and low toxicity to other species. In this case, a simple wet chemical method with different annealing temperatures (400, 500, and 600 °C) was employed to create highly effective rare earth (Sm)-doped ZnO nanorods. The (101) plane of wurtzite ZnO shifts towards a lower angle with increasing annealing temperature, according to the X-ray diffraction (XRD) study findings, which additionally establishes the consequence of lattice expansion. Occurrence of doublet peaks of Sm 3d (Sm 3d5/2 and Sm 3d3/2) in the X-ray photoelectron spectroscopy (XPS) spectrum clearly validates the substitution of Sm3+ ions in the 500 °C-annealed samples. The 500 °C-annealed nanorods exhibit combined performances of the wide band gap, improved UV absorbance, and vivid green luminescent emission (563 nm). Additionally, the nanorods have favorable UV-blocking execution of 96% for UVA at 360 nm, 92% for UVB at 320 nm, and 57% for UVC at 225 nm, which is greater than the majority of ZnO-related materials that have been reported up to this date. Sm doping is also appropriate for improving bacterial inhibition against the two studied strains (Escherichia coli and Staphylococcus aureus), in addition to the intriguing features discussed above. Furthermore, with maximum inhibition zone diameters of 20 ± 0.72 and 18 ± 0.57 mm, respectively, these nanorods exhibit high inhibitory action against E. coli and S. aureus bacterial strains. The rare earth-doped material developed during the current experiment, which was annealed at 500 °C, could potentially serve as an effective replacement for UV-blocking and antibacterial material, especially for biomedical applications.

Sprayed water-based lignin colloidal nanoparticle-cellulose nanofibril hybrid films with UV-blocking ability.

In the context of global climate change, the demand for new functional materials that are sustainable and environmentally friendly is rapidly increasing. Cellulose and lignin are the two most abundant raw materials in nature, and are ideal components for functional materials. The hydrophilic interface and easy film-forming properties of cellulose nanofibrils make them excellent candidates for natural biopolymer templates and network structures. Lignin is a natural UV-shielding material, as it contains a large number of phenolic groups. In this work, we have applied two routes for spray deposition of hybrid films with different laminar structures using surface-charged cellulose nanofibrils and water-based colloidal lignin particles. As the first route, we prepare stacked colloidal lignin particles and cellulose nanofibrils hybrid film through a layer-by-layer deposition. As the second route, we spray-deposite premixed colloidal lignin particles and cellulose nanofibrils dispersion to prepare a mixed hybrid film. We find that cellulose nanofibrils act as a directing agent to dominate the arrangement of the colloidal lignin particles in a mixed system. Additionally, cellulose nanofibrils eliminate the agglomerations and thus increase the visible light transparency while retaining the UV shielding ability. Our research on these colloidal lignin and cellulose nanofibril hybrid films provides a fundamental understanding of using colloidal lignin nanoparticles as functional material on porous cellulose-based materials, for example on fabrics.

Microwave-assisted DES fabrication of lignin-containing cellulose nanofibrils and its derived composite conductive hydrogel

Deep eutectic solvents (DES) have been regarded as green solvents in the biorefinery of lignocellulosic biomass, but long duration time has severely limited efficiency. The microwave-assisted DES pretreatment along with enzymatic hydrolysis and high-pressure homogenization process was proposed to produce lignin-containing cellulose nanofibrils (LCNF) from corncob. Benefiting from microwave-assisted DES pretreatment, the duration time was greatly shortened; meanwhile the effects of different kinds of DES on the resultant LCNF were investigated. The results showed that, the microwave-assisted DES fabricated LCNF (M-LCNF) was successfully obtained, exhibiting good nano size, thermal stability, colloidal stability, and fluorescence. M-LCNF was further introduced into phytic acid (PA) enhanced poly(acrylamide-co-acrylic acid) (P(AM-co-AA)) network and constructed composite conductive hydrogels (PLP). The obtained hydrogels exhibited good mechanical strength, UV blocking ability, fluorescence, and conductivity. A simple battery assembled with the resultant PLP as electrolyte had an out voltage of 2.41 V. The composite conductive hydrogel showed good sensing performance towards different stimuli (e.g., stretching and compression) and human motions in real time. It is expected that this research would provide an alternative way for green fabrication of LCNF and potential application of LCNF in flexible sensors.

Ultrasonically functionalized chitosan-gallic acid films inactivate Staphylococcus aureus through envelope-disruption under UVA light exposure

The significant threat of foodborne pathogens contamination has continuously promoted the development of efficient antimicrobial food packaging materials. Here, an antimicrobial film was prepared with gallic acid-grafted-chitosan (CS/GA) that obtained by a two-step ultrasound method. The resultant films exhibited good transparency, improved UV barrier performance, and enhanced mechanical strength. Specifically, with the grafting of 1.2 % GA, the UV blocking ability of CS/GA film at 400 nm was significantly increased by 19.7 % and the tensile strength was nearly two times higher than that of CS film. Moreover, the CS/GA films exhibited an inspiring photoactivated bactericidal ability under 400 nm UVA light irradiation that eradicated almost 99.9 % of Staphylococcus aureus (S. aureus) cells within 60 min. To gain more insights into the antibacterial mechanism, the treated S. aureus cells were further investigated by visualizing bacterial ultrastructure and analyzing membrane properties. The results pointed to the peptidoglycan layer as the primary action target when bacteria come into contact with CS/GA films. Afterward, the intracellular oxidative lesions, disrupted bacterial integrity, and disordered membrane functional properties collectively resulted in eventual cell death. The findings revealed the unique peptidoglycan targeting and membrane disruptive mechanisms of CS/GA films, confirming the application values in controlling foodborne pathogens.

Facile fabrication of arecanut palm sheath based robust hydrophobic cellulose nanopapers via self-assembly of ZnO nanoflakes and its shelf-life prediction for sustainable packaging applications

Cellulose nanofibers have been extracted from arecanut palm sheath fibers via mild oxalic acid hydrolysis coupled with steam explosion technique. Cellulose nanofibers with diameter of 20.23 nm were obtained from arecanut palm sheath fibers. A series of robust hydrophobic cellulose nanopapers were fabricated by combining the synergistic effect of surface roughness induced by the successful deposition of zinc oxide (ZnO) nanoflakes and stearic acid modification via a simple and cost-effective method. In this work, agro-waste arecanut palm sheath was employed as a novel source for the extraction of cellulose nanofibers. 2 wt% of ZnO nanoflakes and 1 M concentration of stearic acid were used to fabricate mechanically robust hydrophobic cellulose nanopapers with a water contact angle (WCA) of 134°. During the deposition of zinc oxide nanoflakes on the CNP for inducing surface roughness, a hydrogen bonding interaction is formed between the hydroxyl groups of cellulose nanofibers and the zinc oxide nanoflakes. When this surface roughened CNP was dipped in stearic acid solution. The hydroxyl groups in zinc oxide nanoflakes undergoes esterification reaction with carboxyl groups in stearic acid solution forming an insoluble stearate layer and thus inducing hydrophobicity on CNP. The fabricated hydrophobic cellulose nanopaper displayed a tensile strength of 22.4 MPa and better UV blocking ability which is highly desirable for the sustainable packaging material in the current scenario. Furthermore, the service life of the pristine and modified cellulose nanopapers was predicted using the Arrhenius equation based on the tensile properties obtained during the accelerated ageing studies. The outcome of this study would be broadening the potential applications of hydrophobic and mechanically robust cellulose nanopapers in sustainable packaging applications.