Water Vapor Permeability Research Articles

Manufacture of Edible Films from Wheat Germ Protein and Study of its Mechanical Properties

In this study, oil free wheat germ protein (DWGP) was extracted and purified by extraction at pH 9.5 and precipitation at pH 4.0. Its nutritional and functional properties were then evaluated. Microwave drying or room temperature circumstances were used to dry edible films made of (DWGP) isolate. The films needed to cure for 5 minutes in a microwave and 18 hours at room temperature. We measured the consumable coatings’ water vapor permeability (WVP), mechanical, characteristics, glitter, and haziness. The findings showed that while the temperature had an impact on the water vapor transmission rate (WVTR), the water vapor pressure (WVP) did not. Both microwave and room temperature drying for the WVP provided equivalent results. With the use of the microwave, the values for elongation and tensile strength increased.

Hygrothermal properties of hollow brick masonry used in veneer

The material properties of a brick masonry are important when modelling or comparing different veneers. The effect of mortar joint, however, is somewhat an unknown variable. In this study, two different firing batches of a hollow burnt-clay brick product were tested for thermal conductivity, water vapor permeability, water absorption coefficient and capillary moisture content. Brick and mortar materials were tested both exclusively and as masonry specimens. The effect of brick-mortar interface was within margin of error for the first brick batch with slightly lower density, while batch two water vapor permeability, water absorption coefficient and capillary moisture content were noticeably affected. The effect of brick-mortar interface seems to be dependent on brick properties. The differences in hygric properties between brick batches were large, but below 100 %. Accounting for mortar using area weighted properties can improve modelling accuracy, but other factors such as workmanship, degradation and brick batch differences are likely more important.

Hygrothermal Performance of Lime-Based Thermal Insulation Mortars: Water Absorption, Hygroscopic Sorption, and Water Vapour Permeability

Lightweight mortars, which are able to capture carbon, offer moisture buffering and increase the thermal resistance of building elements could be useful for both new and renovated buildings. The hygrothermal properties of lime-based renovation and insulation mortars were studied and the possibilities of reducing water absorption was the main focus of the study. Water absorption coefficient, hygroscopic sorption, and water vapour transmission properties were studied according to EN 1015-18, ISO 12571 and ISO 12572. Hydrated lime was used as the main binder and volcanic sand as an aggregate, white cement and silane in two different concentrations acted as additives. Half of the specimens were kept in forced carbonation conditions (CO2 was added regularly). Drying and carbonation processes were monitored by weighing the specimens regularly. Silane had the ability to reduce water absorption and sorption. Forcing carbonation reduced water absorption and sorption and slightly increased water vapour permeability.

Structural and Physiological Properties of Footwear Textiles

Abstract Textile uppers in the form of fitted knitted fabrics are now gaining in importance in the production of commercial footwear. The subject of this study was twelve different textile uppers and two reference leather materials. Structural properties and parameters of physiological comfort were characterized for selected variants. In order to analyze the thermo-physiological properties of the upper parts of the footwear, air permeability, thermal insulation properties, water vapor permeability and sorption properties were measured. Among the variants of textile uppers analyzed, the most desirable functional properties were shown by knitted fabrics made on cylindrical crochet machines of large diameters. The varnished cowhide leather variant was characterized by the worst hygienic properties.

Liquid Metal–Elastomer Seals for Stretchable Organic Electrolyte‐Based Lithium‐Ion Batteries

AbstractRapid progresses concerning wearable electronics call for stretchable batteries. Owing to the merits of high energy density and wide operating voltage range, organic electrolyte‐based lithium‐ion batteries (LIBs) take a large proportion in the powering markets. Due to the high sensitivity to moisture and oxygen, it is difficult to obtain long‐term reliable stretchable organic electrolyte‐based LIBs when they are directly exposed to the air. Benefiting from the outstanding gas impermeability of liquid metal (LM) and relatively good barrier properties for reactive acid gas molecules by polyisobutylene (PIB), an LM‐PIB seal is demonstrated for organic electrolyte‐based LIBs. In the seal, LM can prevent the inward permeation of oxygen and water vapor, and PIB can block the outward permeation of hydrolysis acid generated from the side reactions during the operation of the organic electrolyte‐based LIBs, which helps prevent the detrimental interaction between the hydrolysis acid and LM. A specific capacity of over 120 mAh g−1 is achieved and the battery shows consistent electrochemical performances under multiple deformations. This study offers a different design approach for long‐term operation of stretchable organic electrolyte‐based LIBs.

Zinc oxide nanoparticle-reinforced pectin/starch functionalized films: A sustainable solution for biodegradable packaging

Environmental pollution caused by non-biodegradable plastic pollutants adversely affects various ecosystems. This study proposes the development of novel functional and biodegradable films based on corn starch (CST) and pectin (PEC) containing zinc oxide nanoparticles (ZnONPs) from the casting method. The films exhibited processability, transparency, low water vapor permeation, and desirable mechanical properties for food packaging and coating applications. The ZnONPs acted as a plasticizer, enhancing the film elongation at the break, increasing the pec25-1 (PEC 25 wt% and ZnONPs 1 wt%) elongation from 79.85 to 162.32 %. The improved film elasticity supported by ZnONPs reduced the material stiffness. However, the films still demonstrated an average tensile strength (0.69 MPa) 17-fold higher than the tensile strength (0.04 MPa) of the non-biodegradable commercial film based on poly(vinyl chloride). Furthermore, the ZnONPs enhanced the UV-blocking capabilities of the films, leading to wettable materials with water contact angles lower than 90°. The films showed high biodegradation rates under natural disposal conditions. The results indicated that the pec25-1/ZnONPs film is a promising eco-friendly coating in food preservation due to its biodegradability, suitable mechanical properties, low water vapor permeability, and UV-blocking properties.

Preparation of an elderberry anthocyanin film and fresh-keeping effect of its application on fresh shrimps.

A smart packaging film was developed employing the pH-indicating activity of elderberry anthocyanins to solve the problem of refrigerated food freshness monitoring. The effect of elderberry anthocyanins on the properties of gellan gum, gelatin composite films and preservation of fresh shrimp as an indicator of freshness was investigated. The results showed that the elderberry anthocyanin-gellan gum/gelatin film had improved on film thickness (7.8×10-2 mm), TS (tensile strength) (14.57×103 MPa), WVP (water vapor permeability) (36.96×10-8 g/m·s·Pa), and a reduced EAB (elongation at break) (17.92%), and water solubility (water-soluble time of 60.5 s). SEM (scanning electron microscopy) and FTIR (infrared spectrum analysis) showed excellent compatibility between its components. Moreover, the elderberry anthocyanin film exhibited good mechanical properties and pH indication effects. Therefore, the film can be considered suitable for maintaining the quality of fresh shrimp. The results could provide a reference for research and development into new active intelligent packaging films.

Deep eutectic solvents (DESs) films based on gelatin as active packaging for moisture regulation in fruit preservation

To develop a novel active packaging for fruit preservation, two different deep eutectic solvents (DESs) comprising choline chloride, betaine and glycerol [ChCl:Gly (1:2) and Be:Gly (1:2)] were prepared and the corresponding DESs-based films (DES@Gel) using gelatin as polymer matrix were fabricated. DES@Gel showed smoother morphologies and better optical and mechanical properties as compared with Gel. Moisture sorption isotherm curves, the enhancement of water vapour permeability (WVP) and the excellent moisture absorption–desorption cyclist performance illustrated the moisture regulation hypothesis mechanism of DES@Gel. Furthermore, cherry tomato preservation experiment was carried out and the groups treated with DES@Gel showed better performances. The moisture regulation property of DES@Gel could broaden new avenues for active packaging.

Modification and Characterization of Starch‐Based Food‐Packaging Material by Cold Plasma as a Green Approach

AbstractThis study focuses on the modification of starch using cold plasma (CP) for 0, 30, 60, and 90 seconds. The prepared films are characterized (i.e., thickness, water vapor permeability, intrinsic viscosity, solubility in water, and moisture absorption). The thickness, water vapor permeability (WVP), intrinsic viscosity, solubility in water (SW), moisture absorption (MA), and roughness of the modified starch films increases with longer plasma‐processing time (PPT). Conversely, the contact angle and density of the films decreases. However, there are no significant changes observed in the moisture content and UV–Vis spectrum of the cold plasma‐irradiated starch (CPS) films. The CP treatment has some effects on the mechanical properties of the films, such as elongation at break and tensile energy to break, but the tensile strength remains unaffected by PPT. Additionally, CP has a significant impact on the visual properties of CPS films, with increased lightness and white index with longer PPT. Most of the observed characteristics are attributed to physical changes in the starch structure caused by etching. Overall, CP is considered a green, and easy for modifying starch‐based packaging materials. However, it is not an effective method for reducing the sensitivity of the films to moisture at the applied PPT.

Enhancing fresh pear preservation with UV-blocking film coatings based on κ-carrageenan, cassava starch, and copper oxide particles

Renewable material packs have been an alternative to traditional petroleum-based products. Thus, this work aimed to develop an active and biodegradable coating based on κ-carrageenan/starch containing copper oxide particles (CuOPs) for fresh pears. The composite material was extensively characterized. Digital images of the coatings suggested stable and highly transparent materials. The composites presented handleability and flexibility. However, only the κ75 films prepared at 75:25 κ-carrageenan/starch weight ratio containing 0, 1, 1.5, and 2% (wt/wt) of CuOPs concerning the polysaccharide content demonstrated applicability as surface coatings for fresh pears. The water vapor permeation, tensile strength, and elongation at the break ranged from 1.14 × 10−10 to 1.59 × 10−10 Pa⋅m2·s−1, 26.19–101.67 MPa, and 6.73 to 17.05 wt%, respectively. Micrographs showed composite films with slight roughness and homogenous surfaces exhibiting hydrophilic characteristics supported by water contact angle measurements (between 71 and 84°). The films were durable for approximately 90 min in an aqueous solution, with the ability to expand their mass up to 3847% (sample κ75-0). The materials were tested as coatings on fresh pears under consumption conditions. The film κ75-2 conserved the fruit for consumption over 30 days, supporting better results than the commercial poly (vinyl chloride) pack. The composite material based on κ-carrageenan/starch containing CuOPs, especially the κ75-2 composite at 2.0% (wt/wt) of CuOPs, can be applied as a surface coating for fresh pears.

Addition of Silver Nanoparticles to Composite Edible Films and Coatings to Enhance Their Antimicrobial Activity and Application to Cherry Preservation.

The aim of this study was to examine the potential enhancement of the antimicrobial activity of edible films, composed of (i) chitosan (CH), cellulose nanocrystals (CNC) and beta-cyclodextrin (CD) (50%-37.5%-12.5%) and (ii) hydroxypropyl methylcellulose (HPMC), cellulose nanocrystals (CNC) and beta-cyclodextrin (CD) (50%-37.5%-12.5%), with silver nanoparticle (AgNP) incorporationat levels 5, 10 and 15% v/v. According to the results, the AgNP addition led to very high antimicrobial activity of both films, reducing by more than 96% the microbial growth of the Gram-negative bacterium Escherichia coli (E. coli) in all cases. On the other hand, by adding AgNPs to films, their thickness as well as oxygen and water vapor permeability decreased, while their transparency increased. Furthermore, the contribution of these specific edible films to preserve cherries under cold storage was investigated. All edible coatings resulted in an improvement of the fruit properties under consideration, and especially the color difference, hardness and total microbial load.

Nanoemulsion-integrated gelatin/bacterial cellulose nanofibril-based multifunctional film: Fabrication, characterization, and application

The current requirements of food safety regulations and the environmental impact stemming from plastic packaging can only be addressed by developing suitable bio-nanocomposite films. Therefore, this study is dedicated to the fabrication of multifunctional film composed of gelatin, bacterial cellulose nanofibrils (BCNF), and black pepper essential oil nanoemulsion (BPEONE) and application for duck meat preservation. BCNF was prepared through ultrasonication of cellulose derived from Komagataeibacter xylinus. BPEONE observed spherical morphology with a diameter ranging from 83.7 to 118 nm. A film matrix containing a higher gelatin proportion than BCNF was more effective in trapping BPEONE. However, increasing the BPEONE fraction showed more surface abrasion and voids in the film morphology. A flexible film with good interaction, crystallinity, and greater thermal stability (421 °C) was developed. Nevertheless, film hydrophobicity (118.89°) declined, resulting in a notable effect on water solubility, swelling, and water vapor permeability. Moreover, the film had improved antibacterial and antioxidant activities, coupled with controlled release characteristics. Consequently, the developed film effectively retarded the lipid oxidation, inhibited microbial growth, and extended the shelf life of duck meat at refrigeration (4 °C) by 3 days, and made the film a promising alternative in the realm of bio-active packaging technology.

Performance analysis and structural characterization of flaxseed gum/chitosan/cinnamaldehyde composite films

The low mechanical strength, water deficiency, and oxidative protection of organic membranes impede their use as food-grade packaging materials. Cinnamaldehyde (CIN) tends to lose its activity owing to its instability. In this study, CIN was added to flaxseed gum (FG)/chitosan (CS) films prepared in a “sandwich” structure. The influence of CIN dosage on the properties of the composite films was studied, and the film formation mechanism of the membrane was explored. The elongation at break, water vapor permeability, oxygen permeability, and light transmittance of the composite film with 1.5% CIN were lower than those of the FG/CS/FG film. Supplementation of the composite membrane with CIN generated new hydrogen bonds, electrostatic interactions, and C-O-C bonds, which converted the structure of the composite film into a sheet and increased its crystallinity without markedly affecting its thermal stability. Therefore, CIN is an extremely useful additive for improving the applicability of flaxseed gum/CS membranes as food-grade packaging films.

Evaluation of the barrier and antimicrobial properties of biodegradable films based on potato waste starch containing natural additives

This study investigates the antimicrobial and water vapor barrier properties of biodegradable films made from potato (Solanum tuberosum) waste starch and the natural additives glycerol, propolis, and montmorillonite ("chaco"). Films were produced using the casting method, and their physical, antimicrobial, and barrier properties were analyzed. Film compositions were established using an experimental design of mixtures. The water vapor permeability values ranged from 0.44 × 10−10 to 8.55 × 10−10 g/(m·s·Pa). The permeation energy was lower than that of polyvinyl chloride and polypropylene films but higher than that of cellophane films. The solubility values ranged from 58 to 66%, and the tensile modulus ranged from 2.15 to 5.15 MPa. The largest inhibition halo diameter obtained for Staphylococcus aureus was 17 mm. The developed packages completely biodegrade within 30 days under composting conditions at ambient temperatures. These findings suggest the potential application of these biodegradable packages for fresh products such as fruits and vegetables.

Improving the performance of Ca-alginate films through incorporating zein–caseinate nanoparticles-loaded cinnamaldehyde

This study aimed to fabricate and characterize the Ca-alginate films functionalized by incorporating zein nanoparticles containing cinnamaldehyde (CA). The zein nanoparticles were coated with Na-caseinate (CN) to inhibit the precipitation of zein in the alginate solution. Afterward, the physical, mechanical, morphological, and barrier properties of the nanocomposite films were evaluated. The particle sizes of different zein nanoparticles (with/without CA and CN) ranged between 43.58 and 251.66 nm. The addition of free CA, zein, and CN nanoparticles significantly increased the thickness, opacity, thermal stability, and water contact angle and improved the mechanical properties of the films. The water vapor permeability was not affected but the antimicrobial activity was improved on fresh-cut apples. The lightness of nanocomposite films decreased and the yellowness and greenness increased. According to SEM and AFM images, a dense and organized interlayer arrangement with a rougher surface was detected in the nanocomposite films. FTIR analysis showed that no new interactions were formed between the Ca-alginate and zein/CN nanoparticles. An excellent sustained CA release into the water was observed for the CA/zein nanoparticles-loaded alginate films. Overall, the results showed that Ca-alginate nanocomposite films of zein nanoparticles have good potential to carry hydrophobic bioactive compounds for specific pharmaceutical and food applications.

Films properties of QPM corn starch with Delonix regia seed galactomannan as an edible coating material

Plant-based polysaccharides are considered a good alternative for obtaining edible films and coatings. In this research the objective was to determine the physicochemical characteristics of corn starch obtained from QPM Sac-Beh (SBCS) and Delonix regia galactomannan (DRG) and use them to produce films. Films were elaborated from 1 %(w/v) film-forming solutions (FFS) with SBCS:DRG 1:0, 1:1, and 0:1 ratio. Some films were prepared with glycerol 0.4 %(w/v) and vanillin 0.1 %(w/v). SBCS and DRG were characterized by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. SBCS presented low crystallinity which agrees with a low gelatinization ΔH observed. The SBCS:DRG 1:0 FFS without glycerol did not form films; however, DRG addition allows film formation. It was also found that glycerol addition reduced tensile strength to 10.3 MPa, from 41.3 MPa. The lowest water vapor permeability was found in films with 1:1 SBCS:DRG and 0.1 %(w/v) vanillin. This formulation was used to coat D'Anjou pears. This coating conserved the pears' color for 24 days while the control ones started to get a brown color on day 6. Based on the results obtained, FFS elaborated with 1:1 SBCS:DRG and 0.1 %(w/v) vanillin had potential use as edible film material for coating on climacteric fruits preservation.

Properties of sodium alginate-based nanocomposite films: Effects of aspect ratio and surface charge of cellulose nanocrystals

Three cellulose nanocrystals (CNCs) were prepared to reinforce sodium alginate (SA) films. This study investigated effects of aspect ratio (L/D) and surface charge of three CNCs (CCNC, MCNC, and WCNC) on the properties of films. At CNC concentrations ≤3 wt%, MCNC, with a medium L/D but the lowest surface charge density among the three CNCs, exhibited the highest efficiency in enhancing the Young's modulus and tensile strength of films. This indicated that, apart from L/D, CNC's surface charge density also affected its reinforcing effects in anionic SA-based films. Compared with other CNCs, MCNC with the lowest charge density exhibited weaker repulsion with SA, potentially contributing to stronger interfacial interactions between them. At concentrations >3 wt%, the reinforcing efficiency of MCNC was extremely close to that of WCNC, which had the highest L/D but medium charge density. This was possibly because, according to SEM results, MCNC with the lowest absolute value of zeta potential aggregated more severely than other CNCs. However, both MCNC and WCNC were consistently more efficient than CCNC. Moreover, FTIR results revealed that WCNC formed more hydrogen bonds with SA than other CNCs. Consequently, adding WCNC was more effective in reducing films' water vapor permeability and hydrophilicity.

Cross-linked poly(ester urethane)/starch composite films with high starch content as sustainable food-packaging materials: Influence of cross-link density

This study focused on the development of cross-linked poly(ester urethane)/starch (PEUST) composites containing 50 wt% starch content for food-packaging materials. The NCO-terminated poly(caprolactone-urethane) prepolymer (PCUP) was first synthesized through bulk condensation. Then, low-moisture starch (0.21 wt%) and PCUP-based PEUST films were fabricated through an intensive extrusion process, followed by thermo-compression molding. The chemical structure of PCUP and PEUST was confirmed using Fourier transform infrared spectroscopy. Moreover, a comprehensive evaluation was conducted to assess the influence of cross-link density on the physicochemical properties of the composite films. The results showed that an increase in the cross-link density within the composites improved component compatibility and tensile strength but reduced crystallinity, water sensitivity, hydrolytic degradability, and water vapor permeability (WVP) of the films. In addition, the cytotoxicity tests were conducted to evaluate the safety of the composite films, and the high cell viability demonstrated non-toxicity for food application. The PEUST-II films with moderate cross-link density exhibited a suitable degradation rate (27.7 % weight loss at degradation for 140 d), optimal tensile properties (tensile strength at break: 12.4 MPa; elongation at break: 352 %), and low WVP (68.4 g/(m2⋅24h) at 30 % relative humidity). These characteristics make them highly promising as fresh-keeping food packaging.

Active packaging incorporating chitosan, casein phosphopeptide, and plasmonic modification to maintain quality and regulate the respiration rate of fresh-cut Pyrus serotina Rehder during storage

In this study, chitosan (CS), casein phosphopeptide (CPP), and plasm modification were used to develop an active packaging that can extend the shelf-life of fresh-cut pear (FCP) (Pyrus serotina Rehder) at 4 °C. Results show that CS, CPP, and plasmonic modification increase water vapour permeability (WVP), improved the antibacterial (8%) and antioxidant properties (58–69%) of low-density polyethylene (LDPE) without adverse effects on mechanical strength. The application of CS/CPP active packaging resulted in significant improvements in various quality parameters of the packaged product. Browning was reduced by 48.80%, while weight loss decreased by 14.56%. The active packaging also exhibited potent inhibitory effects on microbial growth and respiration, with reductions of 47.74%. Additionally, the packaging demonstrated the ability to reduce the activity of crucial enzymes such as phospholipase D (PLD) by 35.71%, lipoxygenase (LOX) by 40.74%, polyphenol oxidase (PPO) by 35.71%, and malondialdehyde (MDA) by 34.79%. These combined effects extended the shelf-life of the FCP from 6 to 12 days. A comprehensive analysis of film properties, including moisture migration and respiration characteristics, indicated that the CS/CPP active packaging primarily contributed to mass loss reduction by inhibiting respiration rather than transpiration. This result proves that combining cold plasma, antioxidants, and antibacterial agents with modified LDPE can create a preservation package with composite functions.

Designing antimicrobial active packaging films based on chitosan plus fungus comb ethyl acetate extract from Indo-Malayan termite mounds

Abstract. Witasari LD, Lizar DP, Florencia OM, Ramadhan A, Fiana NAO, Supriyadi S, Pratiwi SUT, Nandika D, Karlinasari L, Arinana A, Batubara I, Santoso D, Rachmayanti Y, Firmansyah D, Sudiana IK, Hertanto DM, Rachmayanti Y, Firmansyah D. 2023. Designing antimicrobial active packaging films based on chitosan plus fungus comb ethyl acetate extract from Indo-Malayan termite mounds. Biodiversitas 24: 5947-5955. Antimicrobial active packaging systems incorporate antimicrobial compounds into polymer films, i.e., chitosan, thus suppress spoilage microorganism growth in foods. Chitosan films itself cannot prevent microbial growth, thus other antimicrobial agent must be added. Fungus comb extract from Indo-Malayan termite (Macrotermes gilvus (Hagen, 1858)) mounds is a potential active organic antimicrobial compound, which can be incorporated into chitosan films. The purpose of this study was to develop and characterize active packaging films based on chitosan plus an antimicrobial fungus comb ethyl acetate extract. Films contained 1% chitosan and fungus comb ethyl acetate extract (0.5, 1, 2, and 5% w/v). Notably, films containing 2 and 5% extracts inhibited Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), and Pseudomonas aeruginosa (ATCC 27853), but not fungi. Films plus 2% extract showed a thickness, tensile strength, and strain of 0.13 mm, 2.15 MPa, and 32.55%, respectively. Films had a moisture content of 0.26%, water solubility of 2.68%, swelling property of 2.37%, and water vapor permeability (WPV) of 3.31×10?10 g.m?1s?1.Pa?1. They displayed smooth morphology but no new functional groups. Thus, chitosan plus 2% of fungus comb ethyl acetate extract can be used in antimicrobial active packaging films for food application. It could be applied as a green alternative to prolong the shelf-life of food products.