Effect of Molecular Weight,Acid, and Plasticizer on the Physicochemical and Antibacterial Properties of β‐Chitosan Based Films

Abstract: Effects of chitosan molecular weight (1815 and 366 kDa), type of acid (1% acetic, formic, and propionic acid, or 0.5% lactic acid) and plasticizer (0, 25% glycerol or sorbital w/w chitosan) on the mechanical, water barrier, and antibacterial properties of β‐chitosan films were investigated. Tensile strength (TS) of high molecular weight (Hw) films was 53% higher than that of low molecular weight (Lw) ones, acetate, and propionate films had the highest TS (43 and 40 MPa) among tested acids, and plasticizer‐reduced film TS 34%. Film elongation at break (EL) was higher in Hw films than in Lw ones, in which formate and acetate films were the highest (9% and 8%, respectively), and plasticizer increased the film EL 128%. Molecular weight of chitosan did not influence water vapor permeability (WVP) of the films. Acetate and propionate films had lower WVP than other acid types of films, and plasticizer increased film WVP about 35%. No difference was found between glycerol and sorbitol films in terms of film mechanical and water barrier properties. Lw β‐chitosan films showed significant antibacterial activity against E. coli and L. innocua. This study demonstrated that β‐chitosan films are compatible to α‐chitosan films in physicochemical properties and antibacterial activity, yet with simple sample preparation. Practical Application: β‐chitosan based edible films at molecular weight of about 300 kDa showed great antibacterial activity against Gram‐positive and Gram‐negative bacteria. The films have similar mechanical and water barrier properties to α‐chitosan based films at the similar molecular weight, but simple sample preparation procedures and more attractive color. The release of active chitosan fragment from the film matrix acts as an antibacterial agent, making β‐chitosan films suitable as intelligent food wraps or coatings for a wide range of food products to control moisture loss and prevent surface bacterial growth.     

Physicochemical, nutritional, and antimicrobial properties of wine grape (cv. Merlot) pomace extract-based films

Abstract: Wine grape pomace (WGP) (cv. Merlot) extract‐based films were studied in terms of their physicochemical, mechanical, water barrier, nutritional, and antibacterial properties. Pomace extract (PE) was obtained by hot water extraction and had a total soluble solid of 3.6% and pH 3.65. Plant‐based polysaccharides, low methoxyl pectin (LMP, 0.75% w/w), sodium alginate (SA, 0.3% w/w), or Ticafilm^® (TF, 2% w/w), was added into PE for film formation, respectively. Elongation at break and tensile strength were 23% and 4.04 MPa for TF‐PE film, 25% and 1.12 MPa for SA‐PE film, and 9.89% and 1.56 MPa for LMP‐PE film. Water vapor permeability of LMP‐PE and SA‐PE films was 63 and 60 g mm m^?2 d^?1 kPa, respectively, lower than that of TF‐PE film (70 g mm m^?2 d^?1 kPa) (P < 0.05). LMP‐PE film had higher water solubility, indicated by the haze percentage of water after 24 h of film immersion (52.8%) than that of TF‐PE (25.7%) and SA‐PE (15.9%) films, and also had higher amount of released phenolics (96.6%) than that of TF‐PE (93.8%) and SA‐PE (80.5%) films. PE films showed antibacterial activity against both Escherichia coli and Listeria innocua, in which approximate 5‐log reductions in E. coli and 1.7‐ to 3.0‐log reductions in L. innocua were observed at the end of 24 h incubation test compared with control. This study demonstrated the possibility of utilizing WGP extracts as natural, antimicrobial, and antioxidant promoting film‐forming material for various food applications. Practical Application: WGP extract‐based edible films with the addition of a small amount of commercial polysaccharides showed attractive color and comparable mechanical and water barrier properties to other edible films. The films also demonstrated their potential antioxidant and antimicrobial functions. Hence, they may be used as colorful wraps or coatings for food, pharmaceutical, or other similar applications.     

Preparation and characterisation of selected physicochemical and functional properties of β‐chitosans from squid pen

Squid pen β‐chitosans prepared under various deacetylation conditions (30%, 35%, 40% and/or 45% NaOH for 15, 30 and/or 60 min) were characterised. β‐Chitosans (deacetylated with 35–45% NaOH for 15–60 min) had 87.1–96.2% degree of deacetylation (DD), 93.5–96.7% solubility and 120.5–654.9 mPa s viscosity. Treatment with 30% NaOH for 15–60 min yielded inadequately deacetylated β‐chitosans (DD = 51.9–80.2%). Two chitosans prepared under 35% NaOH for 15 min and 45% NaOH for 30 min (designated as 35%–15 and 45%–30, respectively) were further compared. Drying (sun‐drying vs. oven‐drying) methods did not affect DD. 35%–15 chitosan exhibited lower nitrogen, DD and bulk density, but higher viscosity compared with 45%–30 chitosan. Higher water‐ and fat‐binding capacity but lower DPPH radical scavenging activity were observed for 35%–15 chitosan compared with 45%–30 chitosan. Compared with 45%–30 chitosan, 35%–15 chitosan exhibited higher antibacterial activity against Salmonella Enteritidis and Listeria monocytogenes, but lower antibacterial activity against Escherichia coli.     

Effects of storage conditions and acid solvent types on structural,mechanical and physical properties of kudzu starch (Pueraria lobata)‐chitosan composite films

Effects of acid solvents (acetic, lactic and malic acid) on properties of kudzu starch‐chitosan composite films were evaluated at −20 or 25°C during storage of 60 days. The yellowness of films enhanced, whereas water content and water vapour permeability of films declined with increasing storage time. Tensile strength of films choosing acetic and lactic acid as solvents, and solubility of all the films increased within 30 days thereafter decreased. Storage temperature had no impact on X‐ray diffraction, water content and solubility. Under the same storage conditions, the film using acetic acid as solvent presented the strongest mechanical property, the smallest solubility and the lightest colour. The film made from lactic acid solution was the most flexible and the yellowiest. The film with malic acid solvent showed the highest ordering degree, the lowest water content and the best water barrier property.     

Antimicrobial Effects of Lactoferrin, Lysozyme, and the Lactoperoxidase System and Edible Whey Protein Films Incorporating the Lactoperoxidase System Against Salmonella enterica and Escherichia coli O157:H7

Lactoferrin (LF), lysozyme (LZ), the lactoperoxidase system (LPOS), and edible whey protein isolate (WPI) films incorporating LPOS were studied for inhibition of Salmonella enterica and Escherichia coli O157:H7. Antimicrobial effects of LF (5 to 40 mg/mL), LZ (1 to 20 mg/mL), and LPOS (0.5% to 5.0% [w/v] [0.03–.25 g/g, dry basis]) were examined by measuring turbidity of antimicrobial‐containing media after inoculation and by examining cell inhibition by WPI films incorporating LPOS (LPOS‐WPI films) on an agar recovery medium. Elastic modulus (EM), tensile strength (TS), percent elongation (%E), oxygen permeability (OP), and Hunter L, a and b of WPI films incorporating 0.03 to 0.25 g/g of LPOS were compared with those of plain WPI films without LPOS. The growth of S. enterica and E. coli O157:H7 (4 log colony‐forming units [CFU]/mL) in tryptic soy broth (TSB) was not prevented by LF at ≥20 and ≥40 mg/mL, respectively. S. enterica and E. coli O157:H7 in TSB were not inhibited by LZ at ≥ 6 and ≥ 20 mg/mL, respectively. LPOS at concentrations of 2.75% (w/v) and 1.0% (w/v) reduced S. enterica and E. coli O157:H7 to below the limit of detection (1 CFU/mL) in TSB, respectively. LPOS‐WPI films (0.15 g/g) completely inhibited S. enterica and E. coli O157:H7 (4 log CFU/cm²), inoculated either onto agar before placing the film disc or onto top of the film disc. Incorporation of 0.25 g/g of LPOS decreased EM, TS, and %E. The oxygen barrier property of WPI films was improved with the incorporation of LPOS at 0.15 to 0.25 g/g.     

Effects of Sorbic Acid‐Chitosan Microcapsules as Antimicrobial Agent on the Properties of Ethylene Vinyl Alcohol Copolymer Film for Food Packaging

This paper discusses the possibility of using sorbic acid‐chitosan microcapsules (S‐MPs) as an antibacterial component of active ethylene vinyl alcohol copolymer (EVOH) film. S‐MPs with a diameter of approximately 1 to 4 μm showed a sorbic acid loading capacity of 46.5%. Addition of S‐MPs (3%, w/w) increased the tensile strength, haze, oxygen, and water vapor barrier properties, as well as reduced the elongations at break and transmittance of S‐MPs‐EVOH (S‐MP‐EVOH) film. Antibacterial tests showed that the inhibitory capacity of S‐MP‐EVOH film against Salmonella Enteritidis and Escherichia coli was higher than that against Listeria monocytogenes. Moreover, the antibacterial effect of sorbic acid‐EVOH (S‐EVOH) film was stronger than that of S‐MP‐EVOH film. However, S‐MP‐EVOH film demonstrated a longer effective time than S‐EVOH film. Using the total viable counts and total volatile base nitrogen as the judgment standard, S‐MP‐EVOH/polyethylene terephthalate (PET) composite film could extend the shelf life of fish fillets by 4 d at 4 °C, compared with EVOH/PET film. For this reason, S‐MP could be a potential antibacterial component of active films.     

Functional Properties of Antimicrobial Lysozyme-Chitosan Composite Films

ABSTRACT: Lysozyme-chitosan composite films were developed for enhancing the antimicrobial properties of chitosan films. A 10% lysozyme solution was incorporated into 2% chitosan film-forming solution (FFS) at a ratio of 0%, 20%, 60%, and 100% (w lysozyme/w chitosan). Films were prepared by solvent evaporation. Lysozyme release from the film matrix, the antimicrobial activity of films against Escherichia coli and Streptococcus faecalis , and basic film properties were investigated. The lysozyme release proportionally increased with increasing initial concentration of lysozyme in the film matrix, and the amount of released lysozyme was in natural log relationship with time. The films with 60% lysozyme incorporation enhanced the inhibition efficacy of chitosan films against both S. faecalis and E. coli , where 3.8 log cycles reduction in S. faecalis and 2.7 log cycles reduction in E. coli were achieved. Water vapor permeability of the chitosan films was not affected by lysozyme incorporation, whereas the tensile strength and percent elongation values decreased with increased lysozyme concentration. Scanning electron microscopy images revealed that lysozyme was homogeneously distributed throughout the film matrix. This study demonstrated that enhanced antimicrobial activity of lysozyme-chitosan composite films can be achieved by incorporating lysozyme into chitosan, thus broadening their applications in ensuring food quality and safety.     

Enhanced thermal and antibacterial properties of cross‐linked waxy maize starch granules by chitosan via dry heat treatment

Cross‐linked starch was synthesised using chitosan as cross‐linking agent via a dry heating method. Thermal properties measured by DSC showed transition temperatures increased as compared with that of native starch (P < 0.001), which might indicate the starch and chitosan molecules interacted with each other. XRD demonstrated that the crystalline pattern of the starch remained the same, but there was slight change in the crystallinity degree after the cross‐links. The significant reduction of solubility, swelling power and transparency (P < 0.001) indicated that the cross‐links restricted the starch granules swelling and molecules leaching. Agar diffusion test showed that chitosan‐cross‐linked starch had excellent bacterial growth inhibition, and its antibacterial activity was stronger against Gram‐negative bacteria than against Gram‐positive bacteria. Its antibacterial activity was further confirmed using liquid broth method. Thus, the cross‐linked starch may be directly used in the food formula for protecting food as a natural antimicrobial ingredient.     

Antimicrobial Activity of a Pullulan–Caraway Essential Oil Coating on Reduction of Food Microorganisms and Quality in Fresh Baby Carrot

This research evaluated the antimicrobial efficacy of pullulan films containing caraway essential oil (CEO). The films were prepared from a 10% of pullulan, containing from 0.12% to 10.0% of CEO. The composition of the CEO was analyzed with the use of gas chromatography. The antimicrobial activity of the CEO was evaluated with the method of serial microdilutions, and the films containing CEO—with the agar diffusion method against selected Gram‐negative, Gram‐positive bacteria, and fungi. The structure of the film surface and its cross‐section were analyzed using a scanning electron microscope (SEM). Analyses were also carried out to determine the efficacy of a pullulan coating with 10% CEO on baby carrots experimentally inoculated with Salmonella enteritidis, Staphylococcus aureus, Saccharomyces cerevisiae, or Aspergillus niger and stored at a room temperature for 7 d. At a concentration of 0.12%, CEO inhibited the growth of all the tested microorganisms. Pullulan films containing 8% to 10% of CEO were active against all tested microorganisms. Populations of S. aureus on carrot samples were reduced by approximately 3 log CFU/g, while those of A. niger and S. cerevisiae by, respectively, 5 and 4 log CFU/g, after 7 d of storage. S. enteritidis was the most resistant among the tested species, since it was not significantly reduced after 7 d of storage. At the end of storage, samples treated with pullulan–caraway oil coating maintained better visual acceptability than control samples. Results of this study suggest the feasibility of applying a pullulan film with incorporated CEO to extend the microbiological stability of minimally processed foods.     

改性壳聚糖的研究及其在金秋梨保鲜中的应用

采用纳米SiOx对壳聚糖进行改性得到复合涂膜,考察水蒸汽透过率、氧气透过率及抑菌性等指标.用改性后的壳聚糖对果蔬涂膜保鲜,并测试室温下的VC含量、保鲜时间和好果率.结果表明:壳聚糖纳米SiOx复合膜(CTS-SiOx)与壳聚糖单膜(CTS)相比,其水蒸气透过率下降35%、氧气透过率下降21%,复合涂膜抗菌效果明显,室温下果蔬保鲜时间得到明显延长,其中金秋梨由20d延长至60d,好果率为80%.     

Antimicrobial activity of chitosan‐based films against Salmonella typhimurium and Staphylococcus aureus

The antibacterial effect of polyamide 6/66‐chitosan blend and chitosan‐coated plastic films was compared to chitosan films and chitosan solution, against Salmonella typhimurium and Staphylococcus aureus. The chitosan films did not show inhibition halos; however, contact inhibition was observed. During the tests, the films absorbed moisture, increasing of the diameter discs in relation to the concentration of the chitosan for both microorganisms at least 31%. Chitosan plastic film coating (bilayer system) showed only contact inhibition, without increase in contact area. The films from polyamide 6/66‐chitosan blend had no antibacterial activity. The highest inhibitory effect resulted from a chitosan solution at 1000 and 2000 ppm for S. typhimurium and S. aureus, respectively. The results of this study showed that the antimicrobial activity was lessened when the chitosan was combined with the plastic matrix because of the absence of contact inhibition, and the best activity was obtained with films prepared by casting of chitosan solution.     

Comparison of physicochemical,binding, antioxidant and antibacterial properties of chitosans prepared from ground and entire crab leg shells

Physicochemical, binding, antioxidant and antibacterial properties of chitosans prepared from ground and entire crab leg shells were compared. Chitosan prepared from ground shell (designated as g‐chitosan) had significantly higher nitrogen content, degree of deacetylation, solubility and viscosity, but lower ash content, bulk density and colour redness (a*) value than chitosan prepared from entire shell (designated as e‐chitosan). Compared with e‐chitosan, g‐chitosan had comparable water‐binding capacity, but higher fat‐binding and dye‐binding capacity, DPPH radical scavenging activity and antibacterial activity against two Gram‐negative (Salmonella Enteritidis and Escherichia coli) and two Gram‐positive (Listeria monocytogenes and Staphylococcus aureus) bacteria. This study demonstrated that chitosans prepared from ground and entire crab leg shell exhibited drastic differences in their physicochemical and functional characteristics. These differences were contributed by the particle size of the crab shell.     

Bacterial inactivation and quality changes in fresh-cut avocado treated with intense light pulses

This study investigated the impact of intense light pulses (ILP) on inactivation of Listeria innocua and Escherichia coli as well as quality changes in fresh-cut avocado. Cylinders of avocado inoculated with L. innocua or E. coli were placed in plastic trays, which were sealed with a 64-μm-thick polypropylene film (oxygen permeability of 110 cm³ O₂ m⁻² bar⁻¹ day⁻¹ at 23 °C and 0% RH) and subjected to 15 or 30 pulses at fluencies of 0.4 J/cm² per pulse and then stored for 15 days at 5 °C. In addition to L. innocua and E. coli counts, the headspace atmosphere, pH, colour and firmness were measured. The growth of E. coli and L. innocua was more effectively inhibited when increasing treatment intensity. Hence, significant inactivation was obtained in samples treated with 15 and 30 pulses for L. innocua (2.61 and 2.97 log CFU/g, respectively) and E. coli (2.90 and 3.33 log CFU/g, respectively) just after processing. Oxygen concentrations were significantly reduced, whereas CO₂ and ethanol concentrations increased due to product respiration; however, ethylene production was decreased by the effect of ILP treatments. The use of 30 pulses affected the colour and firmness of fresh-cut avocado, causing browning and softening.     

中心组合试验优化葛根淀粉-壳聚糖复合膜性能

利用玻璃板延流法制取葛根淀粉-壳聚糖复合膜,运用流变仪、质构仪等仪器测定葛根淀粉、壳聚糖、甘 油不同配比下复合膜的成膜特性,并通过响应面法分析和优化3种物料的配比。结果表明,以抗拉强度、延伸率、 水蒸气透过率和透明度为评价指标,通过Design-Expert软件分析得到在葛根淀粉质量分数1.5%,壳聚糖质量分数 1.29%,甘油质量分数24.27%时,葛根淀粉-壳聚糖复合膜的性能最好。     

Structural,Thermal, Physical,Mechanical, and Barrier Properties of Chitosan Films with the Addition of Xanthan Gum

Films based on chitosan and xanthan gum were prepared using casting technique aiming to investigate the potential of these polymers as packaging materials. Six formulations of films were studied varying the proportion of chitosan and xanthan gum: 100:0 (chitosan:xanthan gum, w/w, C100XG0 film); 90:10 (chitosan:xanthan gum, w/w, C90XG10 film); 80:20 (chitosan:xanthan gum, w/w, C80XG20 film); 70:30 (chitosan:xanthan gum, w/w, C70XG30 film); 60:40 (chitosan:xanthan gum, w/w, C60XG40 film); and 50:50 (chitosan:xanthan gum, w/w, C50XG50 film). The total quantity of solids (chitosan and xanthan gum) in the filmogenic solution was 1.5 g per 100 mL of aqueous solution for all treatments, according to the proportion of each polymer. The films were evaluated by their functional groups, structural, thermal, morphological, physical, mechanical, and barrier properties. All films have presented endothermic peaks in the range of 122 to 175 °C and broad exothermic peaks above 200 °C, which were assigned to the melting temperature and thermal decomposition, respectively. These results demonstrated that films with xanthan gum have the highest T_m and Δ_mH. The films containing higher content of xanthan gum show also the highest tensile strength and the lowest elongation. Xanthan gum addition did not affect the water vapor permeability, solubility, and moisture of films. This set of data suggests the formation of chitosan–xanthan complexes in the films.     

Preparation of antibacterial chito‐oligosaccharide by altering the degree of deacetylation of β‐chitosan in a Trichoderma harzianum chitinase‐hydrolysing process

BACKGROUND: Chito‐oligosaccharide (COS) is generally known to possess many specific biological functions, especially antibacterial activity, depending on its size. To prepare a specific size range of COS, however, has proved difficult. The aim of this study was to establish a method for preparing a specific size range of antibacterially active COS by adjusting the degree of deacetylation (DD) of β‐chitosan in a Trichoderma harzianum chitinase‐hydrolysing process. RESULTS: The molecular weight spectrum, elucidated by viscosity‐average molecular weight, high‐performance liquid chromatography and thin layer chromatography, of COS in chitosan hydrolysate was significantly related to the DD of its original chitosan. Compared with the original form, COS produced at 90% DD showed superior activity against most Gram‐negative bacteria tested, with a minimum inhibition concentration (MIC) ranging from 55 ± 27 to 200 ± 122 µ g mL^?1. Conversely, most Gram‐positive strains tested were less sensitive to COS (MIC > 880 ± 438 µ g mL^?1) than to its original form. Among the Gram‐positive strains, Staphylococcus xylosus was the only exception in that it showed a high susceptibility to COS and had an MIC as low as 45 ± 11 µ g mL^?1. CONCLUSION: The results indicate that the production of a specific size range of COS product is possible by altering the DD of chitosan in the chitinase‐catalysed process. To produce various sizes of COS for versatile biological functions, as seen in this study to inhibit various types of bacteria, is made possible in this established process. Copyright © 2008 Society of Chemical Industry     

Mechanical,Physical, Antioxidant,and Antimicrobial Properties of Gelatin Films Incorporated with Thymol for Potential Use as Nano Wound Dressing

The aim of this study was to determine the properties of gelatin films incorporated with thymol. Gelatin films were prepared from gelatin solutions (10% w/v) containing thymol (1, 2, 4, and 8% w/w), glycerol (25% w/w) as plasticizer, and glutaraldehyde (2% w/w) as cross‐linker. Cross‐likened films showed higher tensile strength, higher elongation at break, lower Young's modulus, lower water solubility, lower swelling, lower water uptake, and lower water vapor permeability. Incorporation of thymol caused a significant decrease in tensile strength, increase in elongation at break, decrease in Young's modulus, increase in water solubility, decrease in swelling and water uptake, and increase in water vapor permeability slightly. The films incorporated with thymol exhibited excellent antioxidant and antibacterial properties. The antibacterial activity of the films containing thymol was greatest against Staphylucoccus aureus followed by Bacillus subtilis followed by Escherichia coli and then by Pseudomonas aeruginosa. Thus, gelatin films‐containing thymol can be used as safe and effective source of natural antioxidant and antimicrobial agents with the purpose of evaluating their potential use as modern nano wound dressing. Practical Application : This study clearly demonstrates the potential of gelatin films incorporated with thymol as natural antioxidant and antimicrobial nano film. Such antimicrobial films exhibited excellent mechanical, physical, and water activities and could be used as antibacterial nano wound dressing against wounds burn pathogens.     

Effect of rapeseed protein–gelatin film containing grapefruit seed extract on ‘Maehyang’ strawberry quality

To develop a packaging film for ‘Maehyang’ strawberries, an edible film containing antimicrobial grapefruit seed extract (GSE) was manufactured. Addition of GSE to the rapeseed protein–gelatin (RG) film inhibited the growth of pathogenic bacteria such as Escherichia coli O157:H7 and Listeria monocytogenes. Packaging of ‘Maehyang’ strawberries with the RG film containing 1.0% GSE decreased the populations of total aerobic bacteria and of yeast and moulds in the strawberries by 1.03 and 1.34 log CFU g^?1, respectively, after 14 days of storage, compared to that of the control. Sensory evaluation of the GSE‐RG film‐packaged strawberries produced better sensory scores than did the control. These results suggest that RG film containing GSE can be used to package strawberries and to extend shelf life.     

不同淀粉的壳聚糖/淀粉复合薄膜结构性能比较

为改善功能因子的生物利用率,本文采用流延法,分别将壳聚糖(分子量150000g/mol)与玉米淀粉、马铃薯淀粉和木薯淀粉制备复合薄膜及其包衣片剂,并通过红外光谱、扫描电镜、拉伸仪、模拟消化实验等手段对壳聚糖/淀粉复合薄膜结构性能进行分析。借助壳聚糖上的-NH3+与淀粉的-OH间的氢键作用,可形成壳聚糖/淀粉复合结构,受淀粉结构差异的影响,复合薄膜中壳聚糖/淀粉复合结构的有序性存在差异,进而影响复合薄膜的机械力学性能、耐酸性及其薄膜包衣片剂的控释性能。其中,复合薄膜CTS/Potato、CTS/Tapioca中壳聚糖/淀粉复合结构的有序性优于复合薄膜CTS/Corn,其耐酸性能良好,在模拟胃液中运转2h,薄膜的损失率分别在18.71%～26.15%、16.14%～19.64%之间。同时,这两种复合薄膜包衣片剂的控释性能亦表现良好,约有60%的模型功能因子可顺利递送至小肠、结肠部位,具有作为药物、活性功能因子小肠、结肠定向释放载体材料的可能。     

Composite and bi-layer films based on gelatin and chitosan

The aims of this work were: to develop composite, bi-layer and laminated biodegradable films based on gelatin and chitosan, to determine film barrier and mechanical properties and to characterize their microstructure.Gelatin and chitosan concentrations used were 7.5% and 1% (w/w), respectively. Glycerol (0.75%) was added as plasticizer.Physicochemical properties such as moisture content, transparency and color were analyzed. Composite and bi-layer systems showed a compact structure indicating a good compatibility between components.Water vapor permeability (WVP) was independent of film thickness up to 120 μm for gelatin films and 60 μm for chitosan ones. Both, bi-layer and laminated systems resulted effective alternatives to reduce WVP of composite films (at least 42.5%). Bi-layer systems showed better mechanical properties than laminated ones. The resistance at break increased from 54.3 for composite to 77.2 MPa for bi-layer films, whereas elongation at break values of both composite and bi-layer films were similar (2.2–5.7%).