Water Vapor Barrier Properties Research Articles

Modified Composite Biodegradable Mulch for Crop Growth and Sustainable Agriculture.

Using biodegradable films as a substitute for conventional polyolefin films has emerged as a crucial technology to combat agricultural white pollution. To address the shortcomings in the tensile strength, water vapor barrier properties, and degradation period of PBAT-based biodegradable films, this investigation aimed to create a composite film that could improve the diverse properties of PBAT films. To achieve this, a PBAT/PLA-PPC-PTLA ternary blend system was introduced in the study. The system effectively fused PBAT with PLA and PPC, as evidenced by electron microscopy tests showing no apparent defects on the surface and cross-section of the blended film. The developed ternary blend system resulted in a 58.62% improvement in tensile strength, a 70.33% enhancement in water vapor barrier properties, and a 30-day extension of the functional period compared to pure PBAT biodegradable films. Field experiments on corn crops demonstrated that the modified biodegradable film is more suitable for agricultural production, as it improved thermal insulation and moisture retention, leading to a 5.45% increase in corn yield, approaching the yield of traditional polyolefin films.

Preparation and characterization of chitosan-based corn protein composites constructed with TG enzyme and their preservation performance on strawberries

This study describes the synthesis of Chitosan - corn protein (CSZ-TG) composites using TG enzyme (TG) as a cross-linking agent and the preparation of chitosan-based composite membrane material (CSZEO-TG) by blending citrus essential oil (EO) with the synthesized CSZ-TG. The prepared composite membrane material was used for fresh strawberry preservation and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-spectral diffraction, tensile properties, and water vapor and CO2 permeability. Scanning electron microscopy results showed a smooth surface of the composite membrane material after the addition of TG enzyme, while Fourier transforms infrared spectroscopy results showed a structural change of the composite membrane material after the addition of corn protein (Z). The tensile results showed an increase in the tensile strength of the composite membrane material after the addition of TG enzyme, while the flexibility of the composite membrane material was enhanced after the addition of EO. Compared with the pure chitosan membrane (CS), the water vapor and CO2 barrier properties of the composite membrane material after the addition of Z, TG, and EO did not change much, and they all showed better water vapor barrier properties. The results of the antioxidant analysis of the solution of the CSZEO-TG composite membrane material showed that the composite membrane material had efficient antioxidant properties. The effects of the composite film material on the storage period and quality of strawberries were evaluated by the indicators of weight loss, hardness, decay rate, soluble solids, titratable acid content, MDA content, and the content of four enzymes, SOD, POD, PPO and CAT. Comprehensive freshness data analysis showed that CSZEO-TG had the best freshness preservation performance and effectively extended the shelf life of strawberries.

High-compatibility properties of Aronia melanocarpa extracts cross-linked chitosan/polyvinyl alcohol composite film for intelligent food packaging

Although the active and intelligent properties of rich in anthocyanin extracts added to films have been extensively studied, there remains a sparsity of research pertaining to the miscibility of blended films. This work focused on the miscibility of the chitosan/polyvinyl alcohol (CP) film caused by the addition of Aronia melanocarpa extracts (AME), which are rich anthocyanins and phenolic acids, and its effect on physicochemical and functional properties. AME facilitated the amidation reaction and ionic interaction of chitosan in CP films, leading to loss of the crystallinity degree of chitosan. Furthermore, the crystal disruption promoted the formation of hydrogen bonds with polyvinyl alcohol (PVA) with the promoted miscibility. CP film incorporated with 8 % AME possessed the highest tensile strength (26.79 MPa), and elongation at break (66.38 %) as well as excellent ultraviolet–visible (UV–vis) light barrier property, water vapor barrier properties, due to its high miscibility degree. Moreover, this film also showed excellent antioxidant, antibacterial activity, and pH response function, which could be used to monitor the storage of highly perishable shrimp. Hence, the AME provided extra functionality and improved miscibility between chitosan and PVA, which showed great potential for the preparation of high-performance bioactive-fortified and intelligent food packaging films.

Physicochemical properties of active films of rose essential oil produced using soy protein isolate-polyphenol conjugates for cherry tomato preservation

Soy protein isolate (SPI)-polyphenol conjugates were produced by grafting SPI individually with curcumin, naringenin, and catechin. The resulting conjugates showed better emulsifying properties and were used to develop active films containing rose essential oil. The effect of conjugation on the physicochemical and mechanical properties of these emulsion-based films was evaluated. The results showed that the barrier and mechanical properties of the films were improved when the SPI-polyphenol conjugates were used to emulsify the essential oil; in particular, the SPI-curcumin conjugate showed significant improvement. The improvements on the water vapor and oxygen barrier properties in the films were attributed to the formation of compact structure. Emulsion-based films stabilized by SPI-polyphenol conjugates showed antioxidant and antibacterial activities. They also demonstrated an ability to extend the shelf life of cherry tomatoes, as indicated by better preservation of weight, firmness, and ascorbic acid content.

Effect of shear and legume protein-type on the mechanical and water vapour barrier properties of composite based edible films

Effect of shear and legume protein-type on the mechanical and water vapour barrier properties of composite based edible films

Improving the Barrier and Mechanical Properties of Paper Used for Packing Applications with Renewable Hydrophobic Coatings Derived from Camelina Oil.

This study looked at using modified camelina oil to develop sustainable coatings that could replace those derived from petroleum-based materials for use in packaging and other industrial sectors. Solvent-free synthesis of maleic anhydride grafted camelina oil (MCO) was carried out at two different temperatures (200 and 230 °C) to obtain sustainable hydrophobic coating materials for paper substrates. Maleic anhydride grafting of camelina oil was confirmed with attenuated total reflectance-Fourier transform infrared and NMR spectroscopic techniques, and up to 16% grafting of maleic anhydride was achieved, as determined by the titration method. MCO, obtained at different reaction temperatures, was coated onto cellulosic paper and evaluated for its hydrophobicity, mechanical, oxygen, and water vapor barrier properties. Scanning electron microscopy indicated the homogeneous dispersion of coating material onto the paper substrate. MCO-coated papers (MCO-200C paper and MCO-230C paper) provided a water contact angle of above 90° which indicates that the modified oil was working as a hydrophobic coating. Water vapor permeability (WVP) testing of coated papers revealed a reduction in WVP of up to 94% in comparison to the uncoated paper. Moreover, an improved oxygen barrier property was also observed for paper coated with both types of MCO. Analysis of the mechanical properties showed a greater than 70% retention of tensile strength and up to a five-fold increase in elongation at break of coated versus uncoated papers. Overall, the results show that camelina oil, a renewable resource, can be modified to produce environmentally friendly hydrophobic coating materials with improved mechanical and water vapor barrier properties that can serve as a potential coating material in the packaging industry. The results of this research could find applications in the huge paper packaging industries, specially in food packaging.

Active Fish Gelatin/Chitosan Blend Film Incorporated with Guava Leaf Powder Carbon Dots: Properties, Release and Antioxidant Activity.

Active packaging is an innovative approach to prolonge the shelf-life of food products while ensuring their quality and safety. Carbon dots (CDs) from biomass as active fillers for biopolymer films have been introduced to improve their bioactivities as well as properties. Gelatin/chitosan (G/C) blend films containing active guava leaf powder carbon dots (GL-CDs) at various levels (0-3%, w/w) were prepared by the solvent casting method and characterized. Thickness of the control increased from 0.033 to 0.041 mm when 3% GL-CDs were added (G/C-CD-3%). Young's modulus of the resulting films increased (485.67-759.00 MPa), whereas the tensile strength (26.92-17.77 MPa) and elongation at break decreased (14.89-5.48%) as the GL-CDs' level upsurged (p < 0.05). Water vapor barrier property and water contact angle of the film were enhanced when incorporated with GL-CDs (p < 0.05). GL-CDs had a negligible impact on film microstructure, while GL-CDs interacted with gelatin or chitosan, as determined by FTIR. The release of GL-CDs from blend films was more pronounced in water than in alcoholic solutions (10-95% ethanol). The addition of GL-CDs improved the UV light barrier properties and antioxidant activities of the resultant films in a dose-dependent manner. Thus, GL-CD-added gelatin/chitosan blend films with antioxidant activities could be employed as potential active packaging for the food industry.

Development and characterization of pH-sensing films based on red pitaya (Hylocereus polyrhizus) peel treated by high-pressure homogenization for monitoring fish freshness

High pressure homogenization (HPH) was used to physically modify red pitaya (Hylocereus polyrhizus) peel (RPP) dispersions to develop pH-sensing films for monitoring fish freshness. Effects of HPH treatment at various pressures of 0 (control), 10, 20, 30, 40, 60 and 80 MPa on microstructure and properties of RPP film-forming dispersions (FFDs) and their resultant films were systematically investigated. Results showed that due to the structure destructing effect of HPH, the mean particle size of RPP dispersion treated at 80 MPa decreased significantly from 129.17 to 37.41 μm and its total soluble solids content increased from 7.64 to 8.62 °Bx. Rheological analysis manifested that all FFDs exhibited a shear thinning behavior with higher apparent viscosities as well as storage modulus and loss modulus with increasing HPH pressure. Besides, the HPH treated FFDs had a higher total betacyanins content and showed an obvious color response to pH variation. Consequently, the resultant films had not only smoother surfaces and more transparent appearance, but also better water vapor barrier and mechanical properties than the control. Particularly, film obtained from RPP treated at 60 MPa showed a highest tensile strength of 21.87 MPa and elongation at break of 22.09%, together with a lowest water vapor permeability of 11.41 g⋅mm⋅m−2⋅d−1⋅kPa−1. Notably, this film also exhibited high sensitivity to volatile ammonia and showed a remarkable color variation when applied for monitoring fish spoilage at 25 °C. Thus, the pH-sensing films developed from HPH treated RPP had desirable properties to be potentially used in intelligent food packaging.

Swan-feathers inspired smart-responsive sustainable carboxymethyl cellulose/polyvinyl alcohol based food packaging film for robustly integrated Intelligent and Active Packaging

The integration of advanced packaging technology with innovative multifunctional bio-based materials emerges as a promising next-generation strategy to tackle two enduring challenges in food storage technology: food spoilage and counterfeiting. Inspired by the superhydrophobic properties of swan feathers, this study developed a smart-responsive, sustainable food packaging film called C-CPQ using carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVA). The as-prepared C-CPQ film exhibited remarkable hydrophobicity and water-vapor barrier properties owing to its novel design featuring an asymmetric bionic feather-like barbed texture, representing significant advancements in CMC/PVA-based packaging materials. Additionally, C-CPQ exhibited satisfactory mechanical strength, biodegradability, and film-forming capabilities. Notably, incorporating quercetin（QR） endowed C-CPQ with exceptional pH-sensing, fluorescence, antioxidant, UV-shielding, and antibacterial properties, enabling intelligent and active food packaging. Consequently, C-CPQ exhibited UV-stimulated photochromic characteristics and fatigue-resistant food anti-counterfeiting capabilities while extending food shelf life to 5 days, surpassing conventional PE packaging by 2 days. Moreover, the integration of smartphones enabled highly sensitive, rapid, and real-time visual monitoring of food degradation under natural light. The findings of this study present promising outcomes under real-world conditions, serving as a framework for the development of sustainable, high-performance modern food packaging with comprehensive real-time visual freshness monitoring, anti-counterfeiting, and preservation functionalities.

Enhancing Polyvinyl Alcohol Nanocomposites with Carboxy-Functionalized Graphene: An In-Depth Analysis of Mechanical, Barrier, Electrical, Antibacterial, and Chemical Properties.

To enhance the various properties of polyvinyl alcohol (PVA), varying concentrations of carboxy-functionalized graphene (CFG) were employed in the preparation of CFG/PVA nanocomposite films. FTIR and XRD analyses revealed that CFG, in contrast to graphene, not only possesses carboxylic acid group but also exhibits higher crystallinity. Mechanical testing indicated a notable superiority of CFG addition over graphene, with optimal mechanical properties such as tensile and yield strengths being achieved at a 3% CFG concentration. Relative to pure PVA, the tensile strength and yield strength of the composite increased by 2.07 and 2.01 times, respectively. XRD analysis showed distinct changes in the crystalline structure of PVA with the addition of CFG, highlighting the influence of CFG on the composite structure. FTIR and XPS analyses confirmed the formation of ester bonds between CFG and PVA, enhancing the overall performance of the material. TGA results also demonstrated that the presence of CFG enhanced the thermal stability of CFG/PVA nanocomposite films. However, analyses using scanning electron microscopy and transmission electron microscopy revealed that a 3% concentration of CFG was uniformly dispersed, whereas a 6% concentration of CFG caused aggregation of the nanofiller, leading to a decrease in performance. The incorporation of CFG significantly enhanced the water vapor and oxygen barrier properties of PVA, with the best performance observed at a 3% CFG concentration. Beyond this concentration, barrier properties were diminished owing to CFG aggregation. The study further demonstrated an increase in electrical conductivity and hydrophobicity of the nanocomposites with the addition of CFG. Antibacterial tests against E. coli showed that CFG/PVA nanocomposites exhibited excellent antibacterial properties, especially at higher CFG concentrations. These findings indicate that CFG/PVA nanocomposites, with an optimized CFG concentration, have significant potential for applications requiring enhanced mechanical strength, barrier properties, and antibacterial capabilities.

Bioinspired fabrication of transparent poly(vinyl alcohol)-based films with excellent strength, ultraviolet blocking performance, and water vapor barrier properties

The development of biodegradable plastics with advanced mechanical performance and multifunctionality using renewable materials is highly important for their industrial applications. In this work, a novel eco-friendly and high-performance film was constructed by incorporating lignin–Cu nanoparticles (LNP@Cu) to poly(vinyl alcohol) (PVA) to mimic the granular nanostructure in mussel byssus cuticle. LNP@Cu with abundant o-quinone and o-phenol groups was prepared by the reduction of Cu(NO3)2 using alkaline lignin. The nanoparticles were found to have a spherical morphology with a diameter of approximately 500 nm and the LNP@Cu formed dense hydrogen bonds with the PVA matrix. The mechanical properties of the bioinspired films were dramatically improved and far superior to previously reported PVA films and the majority of engineering plastics. With 5 wt% of LNP@Cu loading, the films showed the optimal tensile strength of 106.9 MPa and toughness of 76.6 MJ m−3, which are 2.27 and 4.04 times as high as those of the neat PVA film, respectively. In addition, the fabricated PVA films exhibited excellent ultraviolet (UV)-shielding property and high transparency. Compared with the pristine PVA film, reinforced films showed decreased hydrophilicity and water vapor transmission rates. Overall, these excellent properties make the fabricated films a great potential for applications in packaging and UV shielding fields, giving inspirations for the design of robust green polymeric materials that meet industrial requirements.

Characterization and Antioxidant and Antibacterial Activities of Carboxymethylated Tamarind Seed Polysaccharide Composite Films Incorporated with ε-Polylysine and Their Application in Fresh-Cut Green Bell Pepper Preservation.

Traditional petroleum-based food-packaging materials have poor permeability, limited active packaging properties, and difficulty in biodegradation, limiting their application. We developed a carboxymethylated tamarind seed polysaccharide composite film incorporated with ε-polylysine (CTPε) for better application in fresh-cut agricultural products. The CTPε films exhibit excellent water vapor barrier properties, but the mechanical properties are slightly reduced. Fourier transform infrared spectroscopy and X-ray diffraction spectra indicate the formation of hydrogen bonds between ε-PL and CTP, leading to their internal reorganization and dense network structure. With the increase of ε-PL concentration, composite films showed notable inhibition of postharvest pathogenic fungi and bacteria, a significant enhancement of 2,2'- azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical-scavenging activity, and gradual improvement of wettability performance. Cytotoxicity experiments confirmed the favorable biocompatibility when ε-PL was added at 0.3% (CTPε2). In fresh-cut bell pepper preservation experiments, the CTPε2 coating effectively delayed weight loss and malondialdehyde increase preserved the hardness, color, and nutrients of fresh-cut peppers and prolonged the shelf life of the fresh-cut peppers, as compared with the control group. Therefore, CTPε composite films are expected to be a valuable packaging material for extending the shelf life of freshly cut agricultural products.

Konjac glucomannan-based nanocomposite spray coating with antimicrobial, gas barrier, UV blocking, and antioxidation for bananas preservation

Fruit is prone to rot and deterioration due to oxidative browning and microbial infection during storage, which can cause serious economic losses and food safety problems. It is urgent to develop a multifunctional composite coating to extend the shelf life of fruits. In this work, multifunctional quaternized chitosan nanoparticles (QCs/TA NPs) with excellent antibacterial and antioxidant properties were prepared based on electrostatic interaction using tannic acid instead of conventional cross-linking agents. Meanwhile, konjac glucomannan (KGM) with high viscosity, edible and biodegradable properties was used as a dispersant to disperse and stabilize the nanoparticles, and as a film-forming agent to form a multifunctional composite coating. The composite coating exhibited excellent oxygen and water vapor barrier properties, antioxidant, antibacterial, mechanical properties, hydrophobicity, and UV shielding properties. Surprisingly, the oxygen permeability of the K-NPs-15 composite film was as low as 1.93 × 10−13 (cm3·cm)/(cm2·s·Pa). The banana spray preservation experiments proved that the K-NPs-15 composite coating could effectively prolong the shelf life of bananas. Therefore, this study provides a new idea for designing multifunctional freshness preservation coatings, which has a broad application prospect.

Development of multilayer films based on PLA/PBAT and sodium alginate for active packaging

AbstractIn this study, polylactic acid (PLA) and polyadipic acid/butylene terephthalate (PBAT) blend polymer were used as matrix to prepare PLA/PBAT substrate film by twin‐screw extruder. A series of multilayer films were prepared by starch‐based adhesive by loading 1% chitosan (CS), 1% zinc oxide nanoparticles (ZnONPs) or 1% silver nanoparticles (AgNPs) with sodium alginate (SA) as three different coatings. Compared with PLA/PBAT, the combination of adhesive and SA‐based antibacterial coating significantly improved the water vapor barrier, oxygen barrier and mechanical properties of the film, regardless of the type of antibacterial agent. The water vapor transmission of SA‐based AgNPs coating film decreased from the original 5.77 × 10−14 to 3.41 × 10−14 g·cm·cm−2·Pa−1·s−1. The oxygen permeability of SA‐based chitosan coating decreased from the original 74.35 × 10−14 to 6.40 × 10−14 cm3·cm·cm−2·Pa−1·s−1. The tensile strength of the SA‐based AgNPs coating film increased from the original 264.79 to 286.22 MPa. The film is yellow and has good ultraviolet absorption capacity. Membranes doped with CS, ZnONPs or AgNPs inhibited the growth of Escherichia coli and Staphylococcus aureus. Among them, chitosan doped membrane has weak antibacterial activity, AgNPs doped membrane has the best antibacterial activity against E. coli and S. aureus, and has potential application prospects in active packaging.

Biodegradable polymer films: processability, technological properties and their viability for flexible packaging applications

AbstractNowadays, there is a rising interest in the packaging industry regarding more environment‐friendly (i.e. biodegradable and/or compostable) polymer‐based solutions, especially for film blowing applications. However, replacing traditional, fossil resource‐based polymers typically used for such applications is not an easy task, since the more environment‐friendly solutions must have adequate features in terms of processability and final properties. In this work, three commercial biodegradable (and, at least partially, biobased) polymers were investigated by a preliminary rheological and mechanical analysis, in order to perform film manufacturing experiments in laboratory equipment. Furthermore, oxygen and water vapour barrier properties were studied by permeability measurements. The investigation was ultimately performed on films produced in industrial equipment, and the results were compared to those for a typical, standard polypropylene (PP) film used in flexible packaging applications. It was found that the mechanical properties were adequate (in some cases, even up to 25–30% higher than for the PP counterpart), as well as oxygen permeability. On the other hand, water permeability was significantly higher than that of PP films, and this should be taken into account in cases where high water vapour barrier properties are required. © 2024 Society of Industrial Chemistry.

Active whey protein/hydroxypropyl methylcellulose edible films incorporated with cinnamaldehyde: Characterization, release kinetics and application to Mongolian cheese preservation

Edible films with modulated release of antimicrobial agents are important for food preservation. Herein, antimicrobial edible films were prepared using whey protein (WP) and hydroxypropyl methylcellulose (HM) as polymer matrix materials and cinnamaldehyde (CIN) as antimicrobial agent. The mass ratios of WP and HM were 100/0, 75/25, 50/50, 25/75 and 0/100. The release kinetics of CIN through the film was studied, applying the Fickian model, power law and Weibull model. The films were also characterized by physical and structural characteristics, and antibacterial activity. In comparison to other films, the CIN-loaded film with a WP/HM ratio of 50/50 had better moisture resistance, water vapor barrier properties and mechanical properties. High correlation factors were obtained by fitting the CIN release data with the power law (R2 > 0.96) and Weibull model (R2 > 0.97). The diffusion mechanism of CIN was pseudo-Fickian. The diffusion coefficients (D1 and D2) had a positive linear relationship with the HM ratio, suggesting that a high HM ratio was beneficial to the CIN release. Finally, the WH50-C film was successfully used to preserve Mongolian cheese. This research provides a new perspective on the design of active packaging film with sustained-release characteristics.

Characterization of acid-modified polyvinyl alcohol and its application to barrier-coated paper for eco-friendly food packaging

Polyvinyl alcohol(PVA) can be used as a barrier film against gases such as oxygen because of its dense thin-film structure formed by hydrogen bonding; however, its poor water/moisture resistance and low water vapor barrier properties limit its application in food packaging. Herein, oxalic acid-modified PVA(POA) was prepared and crosslinked with Ca2+ to develop a PVA coating solution with improved water resistance for application on paper-based food packaging materials. The crosslinking reaction to improve the water resistance of conventional PVA requires a long reaction time, and preparing a coating solution with crosslinked PVA is virtually impossible. However, the newly developed PVA coating solution may be suitable for the paper-coating industry because crosslinking proceeds simultaneously with drying after coating. Furthermore, in eco-friendly processes using water as a solvent, multilayer-coating is not possible with conventional PVA, whereas the developed coating is resistant to water-soluble processes through crosslinking and can be stacked on top of each other. The Ca2+-crosslinked POA layer exhibited excellent oxygen and water vapor barrier properties through an additional acrylic emulsion coating resulting in OTR and WVTR of 0.13 mL/m2·day and 0.82 g/m2·day. To evaluate recyclability of the coated paper, alkali dissociation and recyclability tests were conducted, and the results showed a repulpability rate of 99.7%, indicating that the paper pulp can be recycled. Biodegradability tests under lab-scale simulated industrial composting conditions showed 91.8% biodegradability, confirming eco-friendliness of the coated paper. Those multifunctional properties of the developed multicoated paper make it excellent additions to paper packaging, particularly for food packaging applications.

Fabrication of multifunctional ethyl cellulose/gelatin-based composite nanofilm for the pork preservation and freshness monitoring

In this study, an active and intelligent nanofilm for monitoring and maintaining the freshness of pork was developed using ethyl cellulose/gelatin matrix through electrospinning, with the addition of natural purple sweet potato anthocyanin. The nanofilm exhibited discernible color variations in response to pH changes, and it demonstrated a higher sensitivity towards volatile ammonia compared with casting film. Notably, the experimental findings regarding the wettability and pH response performance indicated that the water contact angle between 70° and 85° was more favorable for the smart response of pH sensitivity. Furthermore, the film exhibited desirable antioxidant activities, water vapor barrier properties and also good antimicrobial activities with the incorporation of ε-polylysine, suggesting the potential as a food packaging film. Furthermore, the application preservation outcomes revealed that the pork packed with the nanofilm can prolong shelf life to 6 days, more importantly, a distinct color change aligned closely with the points indicating the deterioration of the pork was observed, changing from light pink (indicating freshness) to light brown (indicating secondary freshness) and then to brownish green (indicating spoilage). Hence, the application of this multifunctional film in intelligent packaging holds great potential for both real-time indication and efficient preservation of the freshness of animal-derived food items.

Fractionated lignin as a green compatibilizer to improve the compatibility of poly (butylene adipate-co-terephthalate) /polylactic acid composites

Blending poly (butylene adipate-co-terephthalate) (PBAT) and polylactic acid (PLA) is a cost-effective strategy to obtain biodegradable plastic with complementary properties. However, the incompatibility between PBAT and PLA is a great challenge for fabricating high-performance composite films. Herein, the ethyl acetate fractionated lignin with the small glass transition temperature and low molecular weight was achieved and incorporated into the PBAT/PLA composite as a compatibilizer. The fractionated lignin can be uniformly dispersed within the PBAT/PLA matrix through a melt blending process and interact with the molecular chain of PBAT and PLA as a bonding bridge, which enhances the intermolecular interactions and reduces the interfacial tension of PBAT/PLA. By adding fractionated lignin, the tensile strength of the PBAT/PLA composite increased by 35.4 % and the yield strength increased by 37.7 %. Owing to lignin, the composite films possessed the ultraviolet shielding function and exhibited better water vapor barrier properties (1.73 ± 0.08 × 10−13 g·cm/cm2·s·Pa). This work conclusively demonstrated that fractionated lignin can be used as a green compatibilizer and a low-cost functional filler for PBAT/PLA materials, and provides guidance for the application of lignin in biodegradable plastics.

Functional pH-Sensitive Film Containing Purple Sweet Potato Anthocyanins for Pork Freshness Monitoring and Cherry Preservation.

An antioxidative and pH-sensitive multifunctional film, incorporating anthocyanin-rich purple sweet potato extract (PPE) was fabricated from polyvinyl alcohol (PVA) and sodium alginate (SA)/sodium carboxymethyl cellulose (CMC-Na). The film was composed of 6:4 PVA:SA/CMC-Na (mass ratio, SA:CMC-Na at 1:1) with added PPE, and changed color with changes in pH, and also had useful UV-blocking, antioxidant, mechanical, and water vapor barrier properties, which enable its use as a food coating film. In addition, the incorporation of 300 mg PPE increased the biodegradability of the film in soil from 52.47 ± 1.12% to 64.29 ± 1.75% at 17 days. The pH sensitivity of the film enabled its successful use for the evaluation of pork freshness. Cherries coated with the film had an extended shelf life from 3-4 to 7-9 days, during storage at 25 °C. Consequently, the multifunctional film can be applied to packaging for real-time pH/freshness monitoring and for effectively preserving the freshness of meat and fruit.