Water Vapor Permeability Research Articles

Sorghum starch: Extraction, characterization and film development

Sorghum starch was extracted from sorghum grain (24.27 % average yield) and had a high carbohydrate content (86.66 %), indicating its high purity. This starch was used for the production of films with different concentrations of sorghum starch (2, 3 and 4 %) and glycerol (20, 30 and 40 g/100 g of starch). Most films were homogeneous and practically amorphous; however, the micrographs revealed the presence of some starch granules. These films also had relevant barrier properties to ultraviolet light, with infrared spectrum characteristic of sorghum starch, high lightness (L* = 87.77–90.19) and a tendency of color for the pink, but with low intensity of hue (h° = 297.06–315.20; chroma = 7.00–9.47). Thickness varied from 0.048 to 0.081 mm and the water solubility from 27 % to 48 %. Thermogravimetric analysis revealed the existence of three thermal events, correspondents to the elimination of water, decomposition of glycerol and starch, respectively. The glass transition temperature decreased with increasing glycerol content, keeping in range of 9–15°C. The film with the best mechanical performance was the one composed of 4 % starch and 30 g/100 g glycerol, as it presented a tensile strength of 3.63 MPa and elongation of 44.10 %. Water vapor permeability varied from 5.504 a 14.234 g.mm.m−2.dia−1.kPa−1, due to the increase in the concentrations of starch and glycerol. The characterization directed the usage of such films to pack vegetables and, therefore, proved that the sorghum starch is a promising source for the production of biodegradable films.

Screening and Characterization of Antioxidant Film Applicable to Walnut Kernels from Juglans sigillata.

Walnuts play a positive role in human health due to their large amounts of unsaturated fatty acids, whereas lipid oxidation can easily occur during storage. Herein, three natural antioxidants (epicatechin, sesamol, and myricetin) were added to the composite film cross-linked with chitosan and soy protein peptide, and the antioxidant film appropriate for the preservation of walnut kernels from Juglans sigillata was screened to improve the storage quality of walnuts. The results showed that three antioxidant films could all enhance the storage performance of walnut kernels, with sesamol being the best. The characterization of antioxidant film cross-linked with chitosan and soy protein peptide containing sesamol (C/S-ses film) revealed that the composite film improved the slow release and stability of sesamol; in addition, the presence of sesamol could effectively reduce the light transmittance and water vapor permeability of the composite film, together with significantly enhancing the antioxidant and antimicrobial activities, resulting in an effective prolongation of the storage period of walnut kernels. These findings indicated that C/S-ses possess excellent potential for retarding the oxidative rancidity of unsaturated fatty acids and will provide an effective strategy for the preservation of walnut kernels.

Three-dimensional simulation of heat and moisture transfer in woven fabric structures

Fabric structure parameters have a significant impact on the comfort of heat and moisture transfer in garments. Previous numerical simulations required extensive mathematical calculations and mostly investigated one- or two-dimensional models of fiber assembly without considering the weave structure, which is a key parameter, that significantly influences the porosity of the woven structure and consequently its heat and moisture management. While the finite element method supports the simulation of the optimal shape and material properties with better visibility, previous finite element models focused on heat transfer and neglected water vapor transfer in fabrics. In this article, the finite element simulation of heat and moisture transfer in woven fabrics is established based on the testing principle of thermal resistance and moisture resistance tester using COMSOL Multiphysics software. In this simulation, three-dimensional parametric geometrical models of the fabric are created using curve interpolation methods by acquiring the control point coordinates of different weaves (plain, 2/2 balanced twill, and 4/1 unbalanced twill weaves). Heat and moisture transfer properties of fabric models in the horizontal and vertical directions were analyzed, including the heat flux, moisture resistance, water vapor permeability, and water vapor concentration. The article also deals with the effects of weave structure and fabric cover in a range of 72.1–85.1% on the fabric heat flux and water vapor concentration. Comparison between model and experimental results revealed that the three-dimensional simulation can accurately predict the impact of weave pattern and fabric cover on the fabric heat and moisture transfer performance. In addition, this model can be utilized to study the distribution of heat and water vapor within fabrics, providing a theoretical foundation for optimizing heat and moisture comfort in woven fabrics.

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.

Experimental analysis of building components with paper and textile waste

The fast growth of building constructions industry and of the universal population is the main cause of increase in global energy consumption. Therefore, the improvement of the building envelope encourages the scientific community to investigate the use of alternative materials that assure indoor comfort conditions and at the same time promote the reduction of energy consumption by adopting energy saving strategies in the manufacturing process. The present research contribution aims to focus on the potential use of innovative building materials developed with waste paper, classified as urban non-hazardous discard component. The use of paper pulp originated from recycled paper and cardboard with the addition of textile fibers from industrial by-products was explored. Here, an effort has been made to realize sustainable insulating panel for internal use, considering different mix design and recycled components in various percentages. The research focuses on hygric, thermal, and physical performances of recycled waste based panels, measuring physical aspects as bulk porosity and bulk density and testing hygrothermal performances as the dry-state thermal conductivity, thermal diffusivity, volumetric heat capacity, and water vapour permeability. Furthermore, in order to assess the hygrothermal behaviour of the building envelope, a numerical simulation, carried out by WUFI® Plus in a Mediterranean context, was developed using as inputs the results collected from the measurement campaign in laboratory.

Characterization of multilayer bacterial cellulose-chitosan films loaded with grape bagasse antioxidant extract: Insights into spectral and water properties, microstructure, and antioxidant activity

This work explores the development and characterization of composite multilayer films comprising bacterial cellulose (BC) and chitosan enriched with antioxidant compounds from grape bagasse extract (GE) and glycerol. SEM images revealed a compact structure with successful interactions between BC and chitosan, confirmed by FT-IR analysis. Equilibrium moisture content, water vapor permeability (WVP), swollen capacity, and solubility were systematically investigated, unveiling the influence of glycerol and GE concentrations. Moisture content increased with elevated glycerol and GE levels, attributed to their hydrophilic nature. WVP rose with higher concentrations of hydrophilic compounds, affecting the films' permeability. Swollen capacity decreased, and solubility increased with the addition of GE and glycerol, indicating a more compact film structure. The incorporation of GE conferred antioxidant properties to the films, as evidenced by DPPH and ABTS+ assays, and Total Phenolic Content (TPC) determination. TPC values varied from 0 to 1.75 mg GAE/g dried film, depending on GE. Fourier Transform Infrared Spectroscopy (FT-IR) highlighted polymeric associations, and UV–Vis spectra demonstrated enhanced UV-blocking properties. Overall, these multilayer films offer promising applications in food packaging, leveraging natural antioxidant sources for an enhanced functionality.

Recycling of wheat gluten wastewater: Recovery of arabinoxylan and application of its film in cherry and strawberry preservation

This study investigated the effect of an edible water-extractable arabinoxylan (WEAX) coating on the postharvest preservation of strawberries and cherries. The WEAX film was prepared using carboxymethyl chitosan (CMCS) film as a control, with thorough characterization of its film properties. Subsequently, strawberry and cherry fruits were submerged in a solution containing edible film-forming materials and left to be stored at room temperature, followed by the analysis of their physicochemical parameters to assess their preservation efficacy. The results show that the WEAX film exhibited enhanced flexibility, superior water vapor permeability, thermal stability, and surface morphology. Furthermore, the implementation of WEAX film effectively mitigated weight loss, decay, color degradation, softening process, ascorbic acid decline, anthocyanin accumulation, and an increase in malondialdehyde content in fruits. Thus, the incorporation of WEAX coating demonstrates its capability in prolonging the shelf life of fruits post-harvest, underscoring its potential in fruit preservation practices.

Surface modification of jute-cotton union fabric using TiO2 and ZnO nanoparticles for multifunctional properties

In this study TiO2 and ZnO nanoparticles were employed as a protective coating to impart multifunctional properties, i.e. self-cleaning, water repellency, UV protection and antimicrobial activity onto jute-cotton union fabric. Through the sol-gel method, using titanium (IV) isopropoxide (TTIP) and zinc acetate as precursors, TiO2 and ZnO nanoparticles have been synthesized. Following the dip-pad-dry-cure method along with a 2 wt% of acrylic binder, the synthesized particles were applied on the jute-cotton union fabric. Subsequently, antibacterial activity, self-cleaning properties and physical properties like water absorbency, crease recovery, water vapor permeability, tensile strength, and tear strength of the treated fabric were tested and evaluated. The structural properties of the nano-particles were distinguished by Fourier Transform Infrared Spectroscopy (FTIR) and SEM. Upon comparing the test results of the coated fabric with the uncoated fabric, the results were found to be extremely satisfactory. This study provided valuable insights into the potential of TiO2 and ZnO coating in enhancing properties of jute-cotton union fabric.

Aloe vera Gel–Reinforced Biodegradable Starch–PVA Blends for Sustainable Packaging of Green Chillies

ABSTRACTThe objective of the current study was to evaluate the feasibility of Aloe vera gel as a plasticizer and crosslinker in improving the properties of starch–polyvinyl alcohol blends that could find applications in packaging. The concentration of Aloe vera gel was varied (1%, 3%, 5% and 7% wt/wt) to produce SPA‐1, SPA‐3, SPA‐5 and SPA‐7 films, respectively. The plasticizing and crosslinking characteristics associated with Aloe vera gel had a positive influence on the mechanical properties of the films. Addition of Aloe vera gel increased the tensile strength of films from 27.45 MPa (control) to 32.98, 32.53 and 32.32, for SPA‐1, SPA‐3 and SPA‐5 films, respectively. Among all the films, highest elongation at break (20.62%) was observed for SPA‐3 films. Due to crosslinking, degree of swelling, water solubility and water vapour permeability for SPA‐3 films decreased by 5.58%, 38.29% and 21.44%, respectively, compared to control films. The contact angle of the SPA‐3 film significantly increased by 49.25% when compared to control samples. Scanning electron microscope images revealed compact and smooth surface microstructure of control films, and crosslinking was evident in presence of Aloe vera gel. The rate of degradation for SPA‐3 films in soil after 40 days was enhanced by 32.25% compared to control films. SPA‐1 and SPA‐3 films were tested for use as packaging material for storage of green chillies. Chillies under unpacked conditions, in control and SPA‐1 films, turned red in 3 days. Those stored in films with 3% Aloe vera gel began to change colour later (after 5 days) with no visual evidence of microbial or fungal growth. In summary, starch–polyvinyl alcohol matrix films with 3% Aloe vera gel (SPA‐3) were effective as a sustainable alternative in increasing shelf life of foodstuff.

Alginate-coated functional wrapping paper incorporated with sulfur quantum dots and grapefruit seed extract for preservation of potato hash browns

This study explores the impact of alginate-based functional coatings incorporating sulfur quantum dots (SQDs) and grapefruit seed extract (GFSE) on the antioxidant and antibacterial properties of kraft paper for food packaging. Applying these coatings effectively fills the porous interfibrillar spaces of the paper, significantly improving oil resistance and mechanical properties. However, the water vapor permeability and moisture absorption rate decreased slightly due to the hydrophilic nature of constituents. In particular, the addition of 5 wt% SQDs to the paper coating formulation resulted in remarkable antioxidant activity, with approximately 100% reduction in ABTS and 60% reduction in DPPH free radicals. The addition of SQDs significantly reduced the bacterial cell viability of E. coli and L. monocytogenes by ∼2 log CFU/mL and ∼4.5 log CFU/mL, respectively. Co-addition of SQDs and GFSE significantly improved antimicrobial activity with ∼3 log CFU/mL reduction of E. coli and complete (100%) eradication of L. monocytogenes even at lower concentrations (2.5 wt% each). The lipid oxidation in the hash brown potato patties wrapped in functional coated paper was reduced by nearly 50% compared to uncoated paper. This effect persisted even after an extended storage period of 15 days, demonstrating the superior ability of the coated paper to improve the shelf life of processed, ready-to-eat foods.

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.

Comparative study on the effects of chitosan, carrageenan, and sodium alginate on the film-forming properties of fish skin gelatin

Polysaccharides are commonly used to improve the film-forming properties of gelatin due to their wide range of sources, safety, and edible properties. However, there has been no systematic study comparing the effects of different polysaccharides on the film-forming properties of gelatin. Effects of chitosan, carrageenan, and sodium alginate on the optical properties, mechanical properties, thermal stability, hydrophilicity, and structure properties of gelatin films were systematically compared. Adding chitosan effectively reduced the ultraviolet transmittance of gelatin film. With an increase in chitosan concentration from 2 g/L to 8 g/L, the melting transition temperature (Tm) of gelatin film increased from 74 °C to 101 °C. Additionally, water vapor permeability decreased from 2.2 ± 0.23 (g.mm)/m2.h.kpa to 1.2 ± 0.18 (g.mm)/m2.h.kpa and water solubility decreased from 75% to 66%. Adding carrageenan and sodium alginate respectively increased the Tm of gelatin film to 92 °C and 84 °C; however, their addition reduced hydrophobicity and elongation at break for gelatin films. X-ray diffraction results suggested good compatibility between gelatin and all three polysaccharides while Fourier transform infrared spectrum results confirmed hydrogen bond interaction between gelatin and polysaccharides with a more orderly structure observed in gelatin films after adding polysaccharides.

New gas sensitive films containing anthocyanin/curcumin for real-time monitoring of strawberries quality

Gas sensitive films (GSFs) of polyvinyl alcohol (PA), soluble starch (SS), and polyethylene glycol bis (3-aminopropyl) ether (PGE) containing blueberry anthocyanin (BA), curcumin (CU), and anthocyanin/curcumin complexes were created to monitor the quality changes of strawberries during storage (room temperature, 24 ± 2 °C). Using headspace-gas chromatography-mass spectrometry (HS-GC-MS), the volatile aroma gases released during storage of strawberries were analyzed. Results showed that the release of aldehydes was more closely associated to the quality of the strawberries. The BA, CU and BA/CU complexes (mass ratio: 1:2 and 2:1) were well dispersed in GSFs and improved the films' hydrophilicity, however, there was no effect on the water vapor permeability. The four GSFs were employed to monitor strawberry quality changes over the course of storage. The results showed that the changes in color of the four GSFs had a strong correlation with the quality of strawberries, which could be classified as fresh, sub-fresh and spoiled.

Mechanisms of permeation of helium, hydrogen, oxygen, and water vapor through silicate-based composite barrier coating layers

When considering coating of flexible films for the packaging of sensitive products, a common goal is to meet all gas barrier requirements in a single process step. One way to achieve this is to improve the barrier performance of polymeric coating layers by incorporating silicate particles. In order to tailor the gas barrier performance of the coatings, understanding the permeation mechanisms through these composite coating layers is required. In this study, polyethylene terephthalate films were coated with composite lacquers comprising montmorillonite particles and a polymer matrix. The compatibility of montmorillonite with polymer matrices of polypropylene, polyacrylate, polycarboxylic acid, and polyvinyl alcohol was tested. The permeation behavior of helium, hydrogen, oxygen, and water vapor in these coatings was investigated. For a composite coating layer comprising montmorillonite and polyvinyl alcohol at a mixing ratio of 1:1 by weight, barrier improvement factors of ▪ compared with the pure polymer coating were found for helium, hydrogen, and oxygen, respectively. It was shown that the permeability coefficients of composite coating layers decrease with increasing permeant kinetic diameter. A comparison of calculated and measured permeability values indicated that the integration of montmorillonite leads to a tortuous permeation path and changes in the free volume and crystallinity of the polymer matrix. The permeation mechanism for water vapor turned out to be completely different from that for non-polar helium, hydrogen, and oxygen and is determined by the so-called polar path effect.

Extraction and Characterization of Cellulose from Broccoli Stems as a New Biopolymer Source for Producing Carboxymethyl Cellulose Films.

The use of food and agricultural waste-derived carboxymethyl cellulose (CMC) has become of interest due to their biodegradability and cost-effectiveness. In the current research, cellulose was extracted from broccoli stems to produce carboxymethyl cellulose using a carboxymethylation reaction via chloroacetic acid (CAA) and sodium hydroxide (5-10 M). The effects of different synthesis conditions on the degree of substitution (DS) and viscosity of the synthesized CMC powder were investigated. The mechanical properties, water vapor permeability (WVP), and colour of CMC films were also evaluated. The results showed that CMC with the highest DS value (0.60) and the highest viscosity of 0.5 Pa·s could be synthesized from broccoli stems at a concentration of 7.5 M NaOH and a cellulose-to-chloroacetic acid ratio of 1 : 1.2. At CMC concentration of 4 g/100 mL with 0.8 g/100 mL of glycerol, the films had the highest tensile strength (31.91 MPa), whereas with 1.2 g/100 mL glycerol, more flexible films with elongation at break of 27.56% were produced. CMC films with the highest WVP (7.87 × 103 gm2·mmHg-1/day) were made with 6 g/100 mL of CMC and 1.8 g/100 mL of glycerol. This research proposes a new source of cellulose to produce biodegradable packaging materials to initiate a practical basis for food waste reuse.

Preparation and characterization of quercetin@ZIF-L/GO@AgNPs nanocomposite film for room-temperature strawberry preservation

Fresh strawberries are easily contaminated by microorganisms after picking. Therefore, how to effectively store and keep fresh strawberries has been a hot topic for scientists to study. In this study, we prepared a leaf shaped metal organic framework nanomaterial loaded with quercetin (Quercetin@ZIF-L) at first, which can achieve effective loading of quercetin (96%) within 45 min and has a controlled release effect under acidic conditions. In addition, by cleverly combining satellite graphene oxide @ silver nanoparticles (GO@AgNPs) with slow precipitation performance, Quercetin@ZIF-L/GO@AgNPs nanocomposite film with larger pore size and larger specific surface area was prepared by scraping method. The characterization data of water flux, retention rate, flux recovery rate and water vapor permeability show that the composite film has good physical properties. The experiment of film packaging showed that the fresh life of strawberry could be extended from 3 to 8 days, which significantly improved the storage and freshness cycle of strawberry. At the same time, the metal migration test proved that the residual amount of silver ion in strawberry met the EU standard and zinc ions are beneficial to the health, enriching the types of high-performance fresh-keeping materials and broadening the application.

Structure and properties of starch - BaSO4 composite obtained using mechanical activation techniques

The aim of this study is to obtain and characterize starch films structurally modified by in situ precipitation of BaSO4 combined with mechanical activation of casting dispersion in a rotor-stator device. By the rheological method, it was found that the modification causes a decrease in the ability of casting dispersions to structure over time. Composite films with a filler content of 0 %–15 % (w/w) were characterized using optical and SEM microscopy, FT-IR spectroscopy, and tensile and moisture resistance testing data. The maximum increase in strength (by 70 %) and elongation at break (by 870 %) is achieved with a filler content of 5 % and 15 %, respectively. An increase in the filler content to 5 % causes an increase in starch recrystallization rate, but at concentrations above 5 % of BaSO4, it inhibits retrogradation. The films obtained by mechanical activation with optimized parameters were uniformly translucent, had lower water vapor permeability than films made from starch alone, had high flexibility, and did not warp or shrink. The developed high-performance, environmentally friendly method can be recommended for the large-scale production of starch-based composite materials.

Reducing cherry rain-cracking: Enhanced wetting and barrier properties of chitosan hydrochloride-based coating with dual nanoparticles

The synergistic effects of phosphorylated zein nanoparticles (PZNP) and cellulose nanocrystals (CNC) in enhancing the wetting and barrier properties of chitosan hydrochloride (CHC)-based coating are investigated characterized by Fourier Transform Infrared Spectra (FTIR), X-ray Diffraction (XRD), atomic force microscopy and by investigating the mechanical properties, etc., with the aim of reducing cherry rain cracking. FTIR and XRD showed dual nanoparticles successfully implanted into CHC, CHC-PZNP-CNC combined moderate ductility (elongation at break: 7.8 %), maximum tensile strength (37.5 MPa). The addition of PZNP alone significantly improved wetting performance (Surface Tension, CHC: 55.3 vs. CHC-PZNP: 48.9 mN/m), while the addition of CNC alone led to a notable improvement in the water barrier properties of CHC (water vapor permeability, CHC: 6.75 × 10−10 vs. CHC-CNC: 5.76 × 10−10 gm−1 Pa−1 s−1). The final CHC-PZNP-CNC coating exhibited enhanced wettability (51.2 mN/m) and the strongest water-barrier property (5.32 × 10−10 gm−1 Pa−1 s−1), coupled with heightened surface hydrophobicity (water contact angle: 106.4°). Field testing demonstrated the efficacy of the CHC-PZNP-CNC coating in reducing cherry rain-cracking (Cracking Index, Control, 42.3 % vs. CHC-PZNP-CNC, 19.7 %; Cracking Ratio, Control, 34.6 % vs. CHC-PZNP-CNC, 15.8 %). The CHC-PZNP-CNC coating is a reliable option for preventing rain-induced cherry cracking.

Effect of nanofibrillated cellulose on alginate and chitosan film properties as potential barrier coatings for paper food packaging

This study aimed to test the utility of ammonium persulfate (APS) oxidised nanofibrillated cellulose (NFC) as an additive for chitosan- and alginate-based biopolymer films that could eventually be used as paper coatings for food packaging applications. Sodium alginate and chitosan were used as the base for the films. Various concentrations of APS oxidised NFC ranging from 0% to 10% were used as a reinforcing agent, resulting in six combinations of either alginate-NFC or chitosan-NFC composite films. Biofilms were tested for their mechanical properties (tensile strength and strain), grease barrier properties, air permeability, water vapour permeability, and degradation in the soil. Overall, when using the ammonium persulfate oxidation pretreatment method, the best performance of the films was estimated with the addition of 2.5% NFC.

The improvement of water barrier property in gelatin/carboxymethyl cellulose composite film by electrostatic interaction regulation and its application in strawberry preservation

Gelatin (GL) and carboxymethyl cellulose (CMC) are common natural components for edible films, but their water barrier performance are finite as hydrophilic polymers. In this study, a GL/CMC water barrier film was prepared, characterized and applied. The microstructure results showed that complex coacervation at pH 2.0 and cross-linking effect of sodium benzoate resulted in strong interaction forces and dense structure of this film. Compared with pure GL or CMC film, this novel composite film decreased water vapor permeability by approximately 90%, and possessed applicable water solubility (51.5%) and stronger barrier to oxygen and UV light. Acidic environment and sodium benzoate endowed antibacterial activity. Furthermore, the water barrier coating film decreased water loss by 47.8% and improved overall quality of fresh strawberries stored at 25 °C for 6 d. Therefore, the novel water barrier film based on complex coacervation and cross-linking is promising to control the postharvest quality of perishable berries.