Barrier Properties Of Films Research Articles

Nanocomposite films based on chia (Salvia hispanica L.) flour seeds incorporating antioxidant chitosan nanoparticles.

Chia (Salvia hispanica L.) flour seeds produce films with good barrier properties against water vapor and could be used as food packaging; however, their mechanical properties are poor, which limits their application. The incorporation of nanoparticles into natural polymers is a strategy used to improve the properties of films to increase their applications. Furthermore, nanoparticles can encapsulate antioxidant agents and generate active films. The objective of this study was to evaluate the influence of chia flour (4%-7%), glycerol (15%-25%), and chia extract-loaded chitosan nanoparticles (ChCNp) (0%-0.75%) on the physical, mechanical, barrier, structural and antioxidant properties of chia flour nanocomposite films. Chitosan nanoparticles loaded with antioxidant chia extract were synthesized by ionic gelation and incorporated into the films. The thickness, water vapor permeability, tensile strength, and antioxidant properties of the films were evaluated using a Box-Behnken experimental design. Structural analysis was conducted using the FTIR technique. The results of the ANOVA of the responses were adjusted to second and third order polynomial models obtaining determination coefficients of 0.96-0.99. The water vapor permeability of the films was 3.89 × 10-8-1.68 × 10-7gmm/Pa sm2, tensile strength was 0.67-3.59MPa and antioxidant activity was 57.12%-67.84%. The variables presented different effects on the films. Increasing the chia seed flour concentration negatively affected the water vapor permeability but improved the tensile strength and the antioxidant capacity of the films. The increase in glycerol concentration caused the films to become brittle. The nanoparticles had a significant effect on the thickness of the films and improved their mechanical and antioxidant properties. However, they did not show an effect on barrier properties. The results demonstrate that it is possible to obtain nanocomposite films with antioxidant capacity from chia seed flour and with the incorporation of chitosan nanoparticles loaded with antioxidants.

Enhancing PBAT nanocomposite films: The impact of AgVO3 nanorods on mechanical, hydrophobicity, and antibacterial properties

AbstractPoly(butylene adipate‐co‐terephthalate) (PBAT) is popular because of its low cost, biodegradability, good processing properties, flexibility, and mechanical features. In this study, we explore the potential of PBAT‐based bioplastics by adding AgVO3 nanorods with PBAT to reduce costs. We produced nanocomposite films of PBAT reinforced with 1, 3, and 5 wt% of AgVO3 nanorods using solvent casting. The inclusion of AgVO3 in the structure of PBAT was investigated through Fourier transform infrared spectroscopy, x‐ray diffraction, and scanning electron microscopy. The nanocomposite films demonstrate excellent properties, surpassing those of single‐component blends, enhancing mechanical properties, and improving the barrier properties of nanocomposite films. The water vapor transmission rate of AgVO3 reinforced (5 wt%) nanocomposite films improved by 42.45% compared to pure PBAT films. The tensile strength of the PBA‐3 film was 37.19 MPa, exhibiting higher strength than the films produced from clean PBAT (19.73 MPa). The AgVO3‐reinforced films demonstrated increased resistance to moisture and water, as indicated by their higher water contact angle values (88.04°). Food‐borne bacteria like Staphylococcus aureus and Escherichia coli have been stable to the antibacterial activity of the nanocomposites on the addition of AgVO3.The potential applications of these nanocomposite films in food packaging are promising, offering a sustainable and effective solution to food preservation.Highlights The AgVO3‐filled poly(butylene adipate‐co‐terephthalate) (PBAT) nanocomposite films exhibit superior mechanical, barrier, and resistance to moisture and water compared to neat PBAT films. The water vapor transmission rate of the film is significantly enhanced, with a 42.45% enhancement in films reinforced with 5 wt% AgVO3. AgVO3‐filled PBAT nanocomposites demonstrate effective antibacterial activity against Escherichia coli and Staphylococcus aureus.

Incorporation of Nano-Zinc Oxide as a Strategy to Improve the Barrier Properties of Biopolymer-Suberinic Acid Residues Films: A Preliminary Study.

Finishing coatings in the wood-based composites industry not only influence the final appearance of the product but also serve to protect against fungi and molds and reduce the release of harmful substances, particularly formaldehyde and volatile organic compounds (VOCs). Carbon-rich materials, such as those derived from birch bark extraction, specifically suberin acids, can fulfill this role. Previous research has demonstrated that adding suberin acid residues (SAR) at 20% and 50% by weight significantly enhances the gas barrier properties of surface-finishing materials based on poly(lactide) (PLA) and polycaprolactone (PCL), particularly in terms of total VOC (TVOC) and formaldehyde emissions. This study aims to explore whether these properties can be further improved through the incorporation of nano-zinc oxide (nano-ZnO). Previous research has shown that these nanoparticles possess strong resistance to biological factors and can positively affect the characteristics of nanofilms applied as surface protection. The study employed PLA and PCL finishing layers blended with SAR powder at 10% w/w and included 2% and 4% nano-zinc oxide nanoparticles. The resulting blends were milled to create a powder, which was subsequently pressed into 1 mm-thick films. These films were then applied to raw particleboard surfaces. TVOC and formaldehyde emission tests were conducted. Additionally, the fungal resistance of the coated surfaces was assessed. The results showed that PLA/SAR and PCL/SAR composites with the addition of nano-zinc oxide nanoparticles exhibited significantly improved barrier properties, offering a promising avenue for developing biodegradable, formaldehyde-free coatings with enhanced features in the furniture industry. Furthermore, by utilizing SAR as a post-extraction residue, this project aligns perfectly with the concept of upcycling.

The effect of polylactic acid-based blend films modified with various biodegradable polymers on the preservation of strawberries

Polylactic acid (PLA) has garnered much attention in the field of fruit and vegetable packaging. Despite its poor flexibility and water resistance, PLA film faces challenges in being used for strawberry storage and freshness preservation due to its inability to maintain flavor quality. In this study, a series of PLA-based modified films was produced by melt blending and extrusion cast processing with PLA as the main component, along with flexible biodegradable polyesters or polycarbonate as the secondary component. First, five different biodegradable polymers were used to investigate the effect of the flexibility and barrier properties of different dispersed phases on the morphology, mechanical properties, and water vapor barrier of PLA-based blend films. Next, the impact on the freshness of strawberries was assessed through examination of fruit color and weight, as well as the levels of O2 and CO2 in the packaging bags. The results showed that the size of the dispersed phase and interfacial bonding with PLA were the key factors determining the mechanical and barrier properties of the blend films. The PLA-polycaprolactone (PCL) blend showed the best compatibility among them, with PCL having the smallest dispersion size (D=0.58 µm), higher toughness than the other four PLA blends, and greater enhancement of PLA. Additionally, it exhibited a similar rate of quality loss in strawberry preservation compared to commercial PE. As a result, the color and luster were more completely preserved. The results of this study may help the future development of degradable plastics, to reduce environmental pollution.

Investigating the morphological, mechanical, barrier, and antibacterial properties of the polycaprolactone nanocomposite films reinforced with hybrid zinc oxide/polyhedral oligomeric silsesquioxane nanoparticles

ABSTRACT The importance of biopolymer-based nanocomposites in food packaging is growing significantly. Therefore, in the present study, we aim to examine the impact of zinc oxide (ZnO), polyhedral oligomeric silsesquioxanes (POSS), and, for the first time, their hybrid on polycaprolactone (PCL) nanocomposites. For this matter, different concentrations of 1, 3, and 5 wt% of each nanoparticle and the hybrid were incorporated into the PCL nanocomposites via the solution casting method. Their chemical structures and interactions, crystalline structures, and morphology were investigated by FT-IR, WAXD, and SEM. Moreover, it was observed through contact angle and surface free energy experiments that an increase in the nanoparticle concentration corresponded to an increase in the contact angle values. The incorporation of hybrid POSS and ZnO equilibrated well between Young’s modulus, tensile strength, and elongation of the samples in their single status. Accordingly, the addition of the hybrid nanoparticles up to 3 wt% significantly increased the modulus and yield strength of PCL nanocomposites without any significant sacrifice in toughness. Also, PPZ3 (containing an optimal 3%wt. of hybrid nanoparticles) demonstrated the lowest permeability against both water vapor and O2 gas, exhibiting reductions of approximately 30 and 55% when compared to pristine PCL. Finally, the antibacterial properties of the nanocomposite films were investigated for S. aureus and E. coli bacteria and revealed. In addition to the antibacterial properties of ZnO and POSS nanoparticles, increasing the concentration of hybrid nanoparticles up to 5 wt% expanded S. aureus’s inhibitory zone. The balanced mechanical, and barrier characteristics, enhanced morphologies, and antibacterial effects of the novel hybrid nanocomposites present novel opportunities in the field of food packaging.

High-barrier, flexible, hydrophobic, and biodegradable cellulose-based films prepared by ascorbic acid regeneration and low temperature plasma technologies

Regenerated cellulose (RC) films are considered a sustainable packaging material that can replace non-degradable petroleum-based plastics. However, their susceptibility to water vapor and oxygen can limit their effectiveness in protecting products. This study introduces a novel approach for enhancing RC films to create durable, flexible, hydrophobic, high-barrier, and biodegradable packaging materials. By exploring the impact of ascorbic acid coagulation bath treatment and plasma-enhanced chemical vapor deposition (PECVD) on the properties of RC films, we found that the coagulation bath treatment facilitated the organized reconfiguration of cellulose chains, while PECVD applied a dense SiOx coating on the film surface. The results demonstrated a significant enhancement in water vapor and oxygen barrier properties of the composite film, almost reaching the level of commercial barrier films. Moreover, the composite film displayed exceptional biodegradability, fully degrading in soil within 35 days. Additionally, it showcased impressive mechanical strength, hydrophobic characteristics, and freshness preservation, positioning it as a valuable option for bio-based high-barrier packaging applications.

Development and characterization of innovative bio-based edible films supplemented with cell-free supernatant and whole-cell postbiotic of Lactobacillus gasseri

More recently, the concepts of cell-free supernatants (CFS, so-called postbiotics) and whole-cell postbiotics (WCP) of probiotics have gained increasing attention for the development of bio-based films. However, reports on CFS and WCP of Lactobacillus gasseri remain scarce. In this study, pea protein isolate/psyllium mucilage was incorporated with CFS and WCP of L. gasseri to produce bio-based edible films. pH, total soluble solid content, antioxidant activity, total phenolic content, antimicrobial activity, and structural analyses were conducted to characterize the CFS and WCP of L. gasseri. Furthermore, the effects of CFS (10% and 20%, v/v) and WCP (10% and 20%, v/v) on the physicochemical, mechanical, barrier, optical, microstructural, and antimicrobial properties of the bio-based films were investigated. The results showed that CFS and WCP exhibited antioxidant and antibacterial activities and were significant sources of phenolic compounds. The incorporation of 20% WCP caused a significant increase in the thickness and water vapor permeability of films, while a significant increase in moisture content was observed with 10% WCP. The control and 10% WCP films had the highest tensile strength values. Furthermore, the addition of 10% WCP resulted in a significant increase in elasticity. Films incorporating CFS and WCP exhibited lower opacity values and darker, yellow, and red color intensities. The addition of CFS and WCP caused a rough texture and cracked structure on the surface of the film. In conclusion, pea protein/psyllium mucilage-based films containing CFS and WCP of L. gasseri can be considered as a new alternative for environmentally friendly bio-based films.

Enhancement of cellulose nanofibril (CNF) film barrier properties by nanofibril alignment

Enhancement of cellulose nanofibril (CNF) film barrier properties by nanofibril alignment

Active films based on bio-polyethylene and natural extracts rich in tocopherols for food packaging applications

Antioxidant/antifungal active films based on bio-polyethylene (BPE) added with Nutrabiol®T90 and Tocobiol®Plus natural extracts rich in tocopherols at different concentrations (1 and 3 wt%) were developed by melt-blending followed by compression-molding. Thermal, barrier, mechanical, optical and functional properties of the developed active films were evaluated. The addition of active extracts did not cause important changes in thermal and barrier properties of active films whereas a significant increase in oxidative stability was found. Release kinetics of active additives migration showed higher tocopherol diffusion coefficient and antioxidant capacity, determined by the DPPH and ABTS methods, for films containing 3 wt% of Nutrabiol®T90. This film also delayed polymer oxidation in 260 min and extended strawberries shelf-life during storage for 7 days compared to neat BPE, showing a significant antifungal effect. The studied biomaterials offer great potential to substitute conventional petrol-derived materials at the industrial scale as active food packaging systems to increase the shelf-life of perishable foodstuff.

Transparent maltitol- cellulose nanocrystal film for high performance barrier

The broad applications of cellulose nanocrystal (CNC) films are restricted by their low resistance against water and brittleness. In this study, high barrier transparent films composed of CNCs and maltitol, used as a bio-plasticizer (at up to 30% weight), were prepared by spray deposition. Addition of plasticizer increased the optical transmittance of the films. It also improved elongation at break and flexibility of the films, while reducing Young’s modulus and tensile strength. The barrier properties of CNC films plasticized with maltitol were significantly improved over CNC. In particular, films containing 30 wt.% maltitol showed a water vapor permeability of 3.67 × 10–12 (g/Pa.s.m) and oxygen permeability of 4.75 (cm3.µm/m2.day.Pa) corresponding to 94% and 78% reductions over CNC films, respectively. This remarkable barrier improvement is attributed to a combination of decreased porosity and the interaction of hydroxy groups of maltitol and CNCs. This interaction led to a reduction of the free hydroxy groups available to interact with the water molecules diffusing in the nanocomposite films, as confirmed by dynamic vapor sorption measurements. This study presents maltitol as a green plasticizer significantly improving the CNC film properties and enabling new barrier applications.

Biodegradable monolayer film based on the collagen extracted from Oreochromis sp. processing byproducts blended with chitosan and assembled with PCL and PLA monolayers to form bilayers films

AbstractThe objective of the study is to develop and characterize biodegradable monolayer and bilayer films using collagen extracted from tilapia skin and scales (Oreochromis sp.) with chitosan in combination with biodegradable polyester; polylactic acid (PLA) or polycaprolactone (PCL). Collagen extraction was conducted with acetic acid (0.5 M). Monolayer films based on collagen and chitosan were formed by the casting process with a solution of chitosan (2% w/w) in 1.5% acetic acid, followed by the addition of skin collagen at concentrations of 0.5%, 1%, or 2% w/w, and dried at 45–50°C. The PLA and PCL films were made by compression molding. The films were characterized according to their appearance, structure, morphology, interaction with water, thermal stability, and mechanical and barrier properties. The results indicated that collagen from tilapia skin and scales yielded 36.5% and 2.57%, respectively. The results showed that adding chitosan increased the tensile strength but decreased the elongation of the films. An improvement in thermal stability was observed by increasing the proportion of collagen or chitosan, and it also influenced water solubility and water vapor permeability. Microscopy showed a crack‐free interface between collagen and chitosan. The color of the films varied depending on the composition, highlighting the influence of chitosan in yellow and reddish tones. The bilayers with PLA had lower water vapor permeability and higher gloss compared to those with PCL. Finally, the developed films showed promising properties for their application in food packaging and promote the use of fishery waste.Practical applicationsThe study aims to develop and characterize biodegradable monolayer and bilayer films using collagen extracted from tilapia skin and scales (Oreochromis sp.) combined with chitosan and biodegradable polyester such as polylactic acid or polycaprolactone. The practical applications of this research span a wide range of industrial fields. For instance, monolayer films could be used as sustainable food packaging, offering enhanced barrier properties and biodegradability, thus reducing the environmental impact of conventional packaging. Furthermore, bilayer films could find applications in the healthcare industry, such as controlled‐release drug patches or dressings leveraging the antimicrobial properties of chitosan. This research also provides valuable insights into improving the mechanical, thermal, and barrier properties of biodegradable films, potentially leading to the production of more efficient and versatile materials for a variety of industrial applications.

Mechanical, structural and barrier properties of starch-based film reinforced with cellulose microfibres extracted from midribs of Musa Saba'

Mechanical, structural and barrier properties of starch-based film reinforced with cellulose microfibres extracted from midribs of Musa Saba'

Antimicrobial and food barrier properties of polyvinyl alcohol–lactic acid food packaging films

AbstractMicrobial contamination and the need for sustainable food production are driving the shift toward biodegradable food packaging materials. There is an urgent need to develop smart food packaging materials that can prevent contamination and prolong the shelf life of meat. To achieve this, the physical–chemical characteristics of polyvinyl alcohol (PVA)‐based packaging films were enhanced through incorporation of lactic acid and anthocyanins to act as a pH indicator. The mechanical, hydrophilic, barrier, and antibacterial properties of the composite films were then evaluated to test the ability of the film to act as a packaging material. In addition, the surface morphology was studied by scanning electron microscopy (SEM), the functional groups by Fourier transform infrared (FTIR) spectroscopy, optical transparency using ultraviolet–visible (UV–vis) spectrophotometer, crystallinity by powder diffraction, and their thermal properties by thermal gravimetric analysis (TGA). The films had a swelling degree (SD) of 222.60 ± 21.19%, dry content (DC) of 70.56 ± 2.54%, moisture content (MC) of 29.44 ± 2%, ALRO moisture (AM) content of 41.85 ± 5.06, and total soluble matter (TSM) of 8.05 ± 1.05%. Moreover, incorporation of lactic acid enhanced the mechanical and the thermal properties of the films but it reduced their optical transparency. The water vapor permeability (WVP) was found to be 14.32 × 10−3 g−1 s−1 Pa−1 and it inhibited the growth of Escherichia coli (EC) (10.67 ± 0.58 cm), Staphylococcus aureus (SA) (10.50 ± 0.40 cm), Pseudomonas aeruginosa (PA) (10.33 ± 0.58 cm), and Staphylococcus epidermidis (11 ± 1 cm) but not Bacillus subtilis (BS). The film's hue changed from red to green over time when used as a packaging material for meat under ambient condition indicating a deterioration in freshness. In conclusion, the developed packaging film exhibited enhanced mechanical, antimicrobial, and hydrophilic properties and it can be used to store and relay information when stored meat begins to decompose through a visible color change of the films.

Enhancing mechanical and water barrier properties of starch film using chia mucilage

Biodegradable packaging materials are increasingly being investigated due to rising concerns about food safety and environmental conservation. This study examines the incorporation of chia mucilage (CM) into starch-based films using the casting method, aiming to understand its effects on the structure and functionality of the films. CM, an anionic heteropolysaccharide, is hypothesized to enhance the mechanical and barrier properties of the films through polymer interactions and hydrogen bonding. Our findings confirm that CM incorporation results in films with uniformly smooth surfaces, indicating high compatibility and homogeneity within the starch matrix. Notably, CM improves film transparency and crystallinity. Mechanical assessments show a remarkable elevation in tensile strength, soaring from 5.21 MPa to 12.38 MPa, while elongation at break decreases from 61.73 % to 31.42 %, indicating a trade-off between strength and flexibility. Additionally, water solubility decreases from 57.97 % to 41.40 %, and water vapor permeability is reduced by 30 % with CM loading. These results highlight the role of CM in facilitating the formation of a dense, interconnected polymeric network within the starch matrix. Given the soluble dietary fiber nature of CM, the CS/CM (corn starch/chia mucilage) blended films are expected to be safe for food packaging and applicable as edible films with health benefits.

Development of breadfruit flour (Artocarpus altilis) with the addition of gelatine as a potential edible film

The potential application of biodegradable films for food applications has gained interest as an alternative to synthetic plastic packaging. Breadfruit is a common starchy fruit in nature and due to its unique and wide availability, it can be good a source for developing biopolymers. This study aimed to develop packaging films made from unripe green breadfruit (Artocarpus altilis) flour with different concentrations of bovine gelatine. The ratios of gelatine and breadfruit flour (G:BF) were 0:5 (G0), 1:5 (G2), 2:5 (G4), 3: 5(G6), 4:5 (G8) and 5:5 (G10). The physical, mechanical and optical properties of these films were investigated. The findings of this study showed that the addition of bovine gelatine in flour solutions had significantly (P<0.05) improved the film thickness, tensile strength (TS), optical properties and water vapour permeability (WVP). Breadfruit film with no gelatine (control) showed the lowest WVP (P<0.05). Based on the Fourier transform infrared spectroscopy (FTIR) spectra, the chemical interaction of hydroxyl group from gelatine and the carboxyl group of breadfruit flour occurred. Therefore, gelatine helped to improve the water barrier and mechanical properties of the BF films as supported by the scanning electron microscopy (SEM) images. Further study to enhance film properties is necessary to apply the material to food products.

Stepwise reinforcement strategy for guar gum/sodium alginate based films: Introduction of carboxylated cellulose nanofibers by different methods and further calcium ion crosslinking

Insufficient mechanical, barrier and water resistance properties of guar gum (GG) films limit their application in food packaging field. Herein, the properties of GG films were enhanced by a stepwise modification strategy. The mechanical and water vapor barrier properties of GG films were initially reinforced by doping with a different type of polysaccharide (sodium alginate; SA). Next, carboxylated cellulose nanofibers (CCN) were introduced as a reinforcing agent to improve film properties via two methods (blending and layer-by-layer (LBL) assembly method). Finally, the water resistance of composite films was further enhanced by calcium ion cross-linking treatment. GG/SA composite films exhibited better mechanical strength and water vapor barrier capacity compared to pristine GG film. In addition, the introduction of CCN, either by blending or LBL method, improved the light barrier, water vapor barrier and tensile strength. The calcium ion cross-linking treatment further enhanced the water vapor barrier, thermal stability, tensile strength and water resistance capacity. The potential applications of GG/SA/CCN films in real food packaging were also explored. In short, this study presents a simple and feasible performance enhancement strategy for GG and other underperforming polysaccharide matrix films, with potential applications in the development of high-performance bio-based food packaging materials.

Fabrication and Characterization of Chitosan and Gelatin-Based Antimicrobial Films Incorporated with Different Essential Oils.

This study was performed to check the effect of different essential oils on chitosan and gelatin-based antimicrobial films. Films prepared from biopolymers contain better mechanical strength but lack in moisture barrier properties. In order to increase the moisture barrier properties of chitosan and gelatin-based films in the current research work, different essential oils, i.e., thyme, cinnamon, basil, ginger, and cumin, at varying concentrations (1.0, 1.5, and 2.0%) were incorporated. Moreover, the concentrations of glycerol (plasticizer) and emulsifier (Tween 20) were kept constant to maintain homogeneity in the research. Antimicrobial films composed of gelatin and chitosan infused with essential oils were evaluated for their physicochemical (emulsion stability, particle size, and viscosity), FT-IR, microstructural (scanning electron microscopy), moisture barrier (water vapor permeability), and antimicrobial properties (E. coli, Salmonella, and S. aureus). Study outcomes elucidated significant variations (p < 0.05) as the concentration of essential oil was increased in the film solutions. An increased concentration of essential oil (2.0%) significantly enhanced the moisture barrier properties (1.12 ± 0.03 g.mm/kPa.h.m2). Nevertheless, the tensile strength decreased (38.60 ± 1.4 to 31.50 ± 1.5 MPa) from 1 to 2%. The increase in essential oil concentration in the emulsion-based films also influenced their physicochemical characteristics, such as droplet size, viscosity, and emulsion stability. At lower concentrations (1.0%), films exhibited a uniform microstructure but lacked moisture barrier properties. Antimicrobial properties against E. coli, Salmonella, and S. aureus showed an increased inhibition effect as the concentration of essential oil was increased. Of the essential oil-based films, ginger- and basil-based films showed greater inhibition effects as compared to the other essential oils. Overall, antimicrobial films containing a 1.5% concentration of ginger and basil oil showed better results as compared to the other treatments for mechanical, moisture barrier, and antimicrobial properties, while films with a 2.0% oil concentration showed better antimicrobial and moisture barrier properties but lacked in mechanical properties. Essential oil-based antimicrobial films have prospective applications in foods, specifically in fresh and processed food items such as seafood, meat, chicken, and sausages.

Innovative edible film for fresh fruit packaging: Formulation and characterization

Edible packaging films are gaining attention as an innovative and sustainable solution for food preservation, providing a protective barrier against physical damage, microbial contamination, and environmental factors. This study aimed to develop an advanced edible packaging film by incorporating galactooligosaccharides (GOS) to strengthen intermolecular interactions and improve film integrity. The composite film, consisting of chitosan (CS), zein, and GOS, was carefully optimized and thoroughly characterized for its physicochemical properties. The impact of GOS incorporation on the film's mechanical strength, barrier properties, and performance in food preservation was systematically investigated. The resulting CS-Zein-GOS film, fabricated with a 1 % (w/v) concentration using the solvent casting technique, exhibited enhanced light-blocking capabilities, improved hydrophobicity, and significantly improved barrier properties against water vapor and oxygen permeability compared to the CS counterpart. Moreover, the composite film displayed thermal stability up to 303.91 °C and superior flexibility, as indicated by elongation at break and tensile strength values. Application tests showed that the CS-Zein-GOS coating effectively extended the shelf life of strawberries and cherries at room temperature by up to three days. Analytical techniques revealed the interaction between the components and confirmed the potential of this novel water-soluble, edible film in food packaging applications, particularly for fresh produce, to extend shelf life and reduce plastic waste. These findings highlight the promising prospects of edible packaging films in addressing sustainability challenges in the food industry.

Utilization of Pickering emulsion stabilized by chitin nanofibers for improving water and oxygen resistance of gelatin films

The hydrophilicity of gelatin films obviously limits their application. In this work, novel protonated chitin nanofiber was prepared with green methods, surficial deacetylation combined with acidic and mechanical treatment. Composite films with excellent water and oxygen barrier properties were successfully prepared by blending O/W Pickering emulsions stabilized by chitin nanofibers with gelatin substrates. The films were characterized by Fourier-transform infrared, X-ray diffraction, mechanical properties, water and oxygen permeability, moisture content, water solubility, water contact angle and optical properties. The results demonstrated that the amino groups of chitin nanofibers bound to the carboxyl groups of gelatin via electrostatic interactions, which contributing to the excellent mechanical and barrier properties of composite films. The elongation at break of composite film (the concentration of chitin nanofiber was 0.2 wt%) was 2.66 times of gelatin film. And the water vapor and oxygen permeability of composite films lowered to 65.9 % and 52.9 %, respectively. The introduction of O/W Pickering emulsion significantly enhanced the hydrophobicity of gelatin-based film and the chitin nanofibers played a positive role in stabilizing the gelatin chains to a certain extent. This study expands the application fields of gelatin-based films and provides valuable technical route for the preparation of barrier films.

The Role of WO3 Nanoparticles on the Properties of Gelatin Films.

Gelatin films are very versatile materials whose properties can be tuned through functionalization with different systems. This work investigates the influence of WO3 nanoparticles on the swelling, barrier, mechanical, and photochromic properties of gelatin films. To this purpose, polyvinylpirrolidone (PVP)-stabilized WO3 nanoparticles were loaded on gelatin films at two different pH values, namely, 4 and 7. The values of swelling and solubility of functionalized films displayed a reduction of around 50% in comparison to those of pristine, unloaded films. In agreement, WO3 nanoparticles provoked a significant decrease in water vapor permeability, whereas the decrease in the values of elastic modulus (from about 2.0 to 0.7 MPa) and stress at break (from about 2.5 to 1.4 MPa) can be ascribed to the discontinuity created by the nanoparticles inside the films. The results of differential scanning calorimetry and X-ray diffraction analysis suggest that interaction of PVP with gelatin reduce gelatin renaturation. No significant differences were found between the samples prepared at pH 4 and 7, whereas crosslinking with glutaraldehyde greatly influenced the properties of gelatin films. Moreover, the incorporation of WO3 nanoparticles in gelatin films, especially in the absence of glutaraldehyde, conferred excellent photochromic properties, inducing the appearance of an intense blue color after a few seconds of light irradiation and providing good resistance to several irradiation cycles.