Antimicrobial Activity Of Films Research Articles

Characterization of active films based on chitosan/polyvinyl alcohol integrated with ginger essential oil-loaded bacterial cellulose and application in sea bass (Lateolabrax japonicas) packaging

The poor mechanical properties, low water-resistance, and limited antimicrobial activity of chitosan (CS)/polyvinyl alcohol (PVA) based film limited its application in aquatic product preservation. Herein, bacterial cellulose (BC) was used to load ginger essential oil (GEO). The effects of the addition of BC and different concentrations of GEO on the physicochemical and antimicrobial activities of films were systematically evaluated. Finally, the application of sea bass fillets was investigated. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD) analysis indicated dense networks were formed, which was verified by enhanced physical properties. The mechanical properties, barrier properties, and antimicrobial activities enhanced as GEO concentration increased. CPB0.8 (0.8 % GEO) film had better tensile strength (TS) and barrier performance, improved the quality, and extended the shelf-life of sea bass for another 6 days at least. Overall, active films are potential packaging materials for aquatic products.

Utilization of marine and agro-waste materials as an economical and active food packaging: Antimicrobial, mechanical and biodegradation studies of O-Carboxymethyl chitosan/pectin/neem composite films

The present work deals with the eco-friendly preparation of highly degradable food packaging films consisting of O-CMC (O-Carboxymethyl Chitosan) and pectin, incorporated with neem (Azadirachta indica) leaves powder and extract. This study aimed to investigate the tensile properties, antimicrobial activity, biodegradability, and thermal behavior of the composite films. The results of tensile strength and elongation at break, showed that the incorporation of neem leaves powder improved the tensile properties (7.11 MPa) of the composite films compared to the neat O-CMC and pectin films (3.02 MPa). The antimicrobial activity of the films was evaluated against a panel of microorganisms including both gram-positive and gram-negative bacteria as well as fungi. The composite films exhibited excellent antimicrobial activity with a zone of inhibition (12–17.6 mm) against the tested microorganisms. The opacity of the composite films ranges from 1.14 to 4.40 mm−1 and the addition of fiber causes a decrease in opacity value. Biodegradability studies were conducted by Soil burial method and the films demonstrated complete biodegradability within 75 days. The results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) of composite films show that they are thermally stable and might be used in food packaging.

Synthesis and characterization of polymeric composites with Cascabela thevetia incorporated zinc nanoparticles: Food packaging applications

AbstractBackgroundMost food packaging materials are non‐biodegradable and do not protect against microbial growth. In the present study, we have synthesized and characterized environmentally friendly packaging material using nanotechnology.ObjectiveCascabela thevetia incorporated zinc nanoparticles and PVP/KC blended films of various ratios were synthesized using the solvent casting method. The nanoparticles were tested for their physical and chemical properties. The antimicrobial activity of films and an in vivo toxicity studies were performed using Drosophila as a model system.ResultsThe thickness of blend films increases as the concentration of nanoparticles is enhanced. The UV–visible spectra of prepared ZnO nanoparticles exhibited maximum absorbance wavelength (λmax) at 360–380 nm. The nanocomposite films' TS and EB and Y were also increased. Scanning electron microscopy (SEM) analysis suggested that all the films were homogenous, crack‐free, and possessed continuous bubble‐free surfaces. FT‐IR results showed chemical interaction between PVP/KC and Zinc oxide nanoparticles. Fifth sample showed greater antibacterial activity. A toxicity study showed that the flies survived >92% in all the samples up to 10 days of continuous feeding, which signifies that the material has low toxicity.ConclusionNanocomposite films can be used as antimicrobial food packaging material to enhance the shelf‐life of food.

Evaluation of the antimicrobial activity of sodium alginate films integrated with cinnamon essential oil and citric acid on sliced cooked ham

AbstractBio‐based antimicrobial films have been developed using sodium alginate and 6 wt% of cinnamon essential oil (CEO) as a volatile antimicrobial substance and 4 and 6 wt% of citric acid (CA) as a non‐volatile antimicrobial substance. Antimicrobial activity of the films was tested in in vitro tests against Escherichia coli and Listeria innocua by disc diffusion or vapour diffusion assay. Sodium alginate films containing CA exhibited a zone of inhibition between 30.86 ± 2.55 and 45.87 ± 1.90 against E. coli and L. innocua in the disc diffusion assays. Films containing CEO also showed significant antimicrobial activities in the vapour diffusion assays that resulted in a log reduction of 5.3 for E. coli and 3.2 for L. innocua after 6 days. Antimicrobial activities of all films were also tested against L. innocua on sliced cooked ham. Films containing CEO did not prevent the growth of L. innocua inoculated on ham. On the other hand, sodium alginate films with CA fully inhibited the growth of L. innocua on ham during storage at 7.5°C for 12 days resulting in a bacterial count below the detection limit after 12 days. The addition of antimicrobial substances in sodium alginate films resulted in a slight colour change (but significant) and reduced the tensile strength of the films significantly. Adding CA to sodium alginate films increased the moisture content (from 24.81% to 35.41–48.02%) as well as the elongation at break (from 11.3% to 22.6–33.2%) of the films.

Lignin-chitosan biocomposite film for antimicrobial activity: Fabrication, characterization and in-vitro evaluation

Lignin and chitosan are natural polymers that exhibit antioxidant and wound-healing properties, respectively. In this study, lignin-chitosan polymeric films were prepared using solvent-casting method. Physicochemical characterization of prepared films was carried out using FESEM, FTIR and DSC. An antibiotic neomycin sulphate was loaded onto films and drug-release profile, antioxidant activity, hemolytic activity, cell viability and antimicrobial activity of film were evaluated. The films were observed to be smooth and have uniform surface with homogenous and fibrous nature. The cumulative release of 97.94% in 8 h was observed in drug release study and it followed Weibull_4 order release kinetics. The film was non-hemolytic and exhibited excellent antioxidant activity with no toxicity towards fibroblast cells. Additionally, the drug-loaded film showed significant antimicrobial activity against both Gram-negative and Gram-positive bacteria.

Effects of argon dielectric barrier discharge (DBD) cold plasma treatment on mechanical, barrier and antimicrobial properties of chitosan film

SummaryThis research studied the effects of argon dielectric barrier discharge (DBD) plasma on properties of chitosan film to be used as active food packaging. The effects of plasma treatment time (0, 30, 60, 90 and 120 s) on tensile strength (TS), elongation at break (EAB), colour, water vapour permeability (WVP), oxygen transmission rate (OTR), contact angle and antimicrobial activity of films were investigated. Depending on the plasma treatment time, the TS values of plasma‐treated film increased, but there were no significant differences between the EAB of control and treated films. The formation of the oxygen‐containing groups and the occurrence of etching affected the WVP, contact angle, roughness and antimicrobial activity of plasma‐treated film. Chitosan film treated with 60 s of DBD plasma had good OTR (<0.05 cc m−2 day−1), hydrophilicity and antimicrobial activity against various kinds of bacteria. However, it may need longer than 60 s of the treatment time to increase the WVP of the films. Overall, these results implied that plasma treatment can be used as an alternative non‐thermal approach for improving the characteristics of film packaging.

Production, characterization, and antimicrobial activity of almond gum/polyvinyl alcohol/chitosan composite films containing thyme essential oil nanoemulsion for extending the shelf-life of chicken breast fillets

In this study, thyme essential oil (TEO) nanoemulsion was immobilized within composite films based on almond gum (AG), polyvinyl alcohol (PVA), and chitosan (CS). The physical, mechanical, water barrier, microstructural and antimicrobial properties of composite films were assessed. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the intermolecular interactions in the composite film matrix. The results indicated that the incorporation of TEO into the composite films increased thickness, moisture content, and water vapor permeability, while it reduced light transmittance and transparency value. The antimicrobial activity of films against gram-negative and gram-positive bacteria was tested using a disc diffusion method. The effect of composite on the microbiological properties of chicken breast fillets was investigated during refrigerated storage for 21 days. The microbial populations of total mesophilic, psychrotrophic, and lactic acid bacteria of the samples that were coated with the composite containing TEO were lower than the permitted limit after 21 days while for blank samples they were higher than 7 log CFU/g after 7 days which is considered as the maximum acceptable total count limit. Results disclosed that AG/PVA/CS composite films containing TEO nanoemulsion can be applied as eco-friendly active food packaging to enhance the shelf-life of food products.

Antimicrobial and antioxidant films formed by bacterial cellulose, chitosan and tea polyphenol – Shelf life extension of grass carp

To alleviate the environmental pressure caused by plastic pollution, biodegradable films made from natural polymers are gaining popularity. In the current paper, biodegradable films were successfully prepared by incorporating tea polyphenols (TP) into chitosan-bacterial cellulose (CS-BC) matrix. The effects of different concentrations (2–10% w/w) of TP on physicochemical, antioxidant and antimicrobial activities of films were systematically evaluated. The water solubility (WS), oxygen barrier property, antioxidant and antimicrobial activities enhanced as TP increased, whereas thermal stability and moisture content (MC) declined. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) analysis indicated dense networks were formed, which was verified by enhanced physical properties. The CBT 8（8% TP）had the most significant values for elongation at break (EB), contact angle (CA), and water vapor barrier performance, and could significantly prolong the shelf life of grass carp. Overall, the findings indicated that these biodegradable films could be used for food packaging applications and reduce the environmental pollutions caused by plastics.

Antimicrobial Activity of Films and Coatings Containing Lactoperoxidase System: A Review.

The production of safe and healthy foodstuffs is considered as one of the most important challenges in the food industry, and achieving this important goal is impossible without using various processes and preservatives. However, recently, there has been a growing concern about the use of chemical preservatives and attention has been focused on minimal process and/or free of chemical preservatives in food products. Therefore, researchers and food manufacturers have been induced to utilize natural-based preservatives such as antimicrobial enzymes in their production. Lactoperoxidase, as an example of antimicrobial enzymes, is the second most abundant natural enzyme in the milk and due to its wide range of antibacterial activities, it could be potentially applied as a natural preservative in various food products. On the other hand, due to the diffusion of lactoperoxidase into the whole food matrix and its interaction and/or neutralization with food components, the direct use of lactoperoxidase in food can sometimes be restricted. In this regard, lactoperoxidase can be used as a part of packaging material, especially edible and coating, to keep its antimicrobial properties to extend food shelf-life and food safety maintenance. Therefore, this study aims to review various antimicrobial enzymes and introduce lactoperoxidase as a natural antimicrobial enzyme, its antimicrobial properties, and its functionality in combination with an edible film to extend the shelf-life of food products.

Fabrication of anti-Listeria film based on bacterial cellulose and Lactobacillus sakei-derived bioactive metabolites; application in meat packaging

More recently, probiotics-derived bioactive metabolites (so-called postbiotics; P) have gained more attention for antimicrobial food packaging. In this study, anti-Listeria active packaging films containing bacterial nanocellulose (BNC) and postbiotics of Lactobacillus sakei were fabricated, and their antibacterial performance was examined in in vitro condition and patty of buffalo meat. To facilitate postbiotics incorporation, ultrasound-assisted coating (UC, 40-kHz) and common coating (CC) were applied. The concentration of postbiotics and coating time were optimized by response surface methodology (RSM) and central composite design, and the antimicrobial activity of films was assessed by the disk diffusion method. The FTIR, mechanical, and surface morphologies of BNC-CC-P and BNC-UC-P films in optimized conditions (17 and 30% of postbiotics and 10 min coating time) were investigated. Based on the FTIR and SEM data, UC facilitated postbiotics incorporation into BNC, while tensile strength and elongation at break of BNC-CC-P and BNC-UC-P films were decreased and increased, respectively. Even though Listeria counts in patties with BNC film followed a similar trend with control samples without film and passed 107 CFU/g, samples wrapped with BNC-CC-P and BNC-UC-P films represented a 2.3 and 2.6 log CFU/g reduction in the bacterial count during storage (9 days at 8 °C), respectively. The findings of this work have provided worthwhile insights into the use of postbiotics in antimicrobial meat packaging for the control of foodborne pathogens. Ultrasound-assisted coating facilitated the rapid release of postbiotics from BNC into the meat matrix, signifying the importance of such a film for the packaging of foods having a short shelf life.

The synergistic effects of zinc oxide nanoparticles and fennel essential oil on physicochemical, mechanical, and antibacterial properties of potato starch films.

The purpose of this study was to evaluate the effects of a combination of zinc oxide (ZnO‐N) nanoparticles and fennel essential oil (FEO) on the functional and antimicrobial properties of potato starch films. Films based on potato starch containing a combination of ZnO‐N (1, 3, and 5%(w/w)) and FEO (1, 2, and 3% (w/w)) produced by casting method and water solubility, water absorption capacity (WAC), barrier properties, mechanical properties, color indexes, and antimicrobial activity of the films against Staphylococcus aureus, Escherichia coli, and Aspergillus flavus were studied. The combination of ZnO‐N and FEO had a significant decreasing effect on solubility, WAC, water vapor and oxygen permeability, elongation, and L* index. These additives had an increasing impact on tensile strength, Yang's modulus, and a* and b* indexes (p < .05). By increasing the concentration of ZnO‐N and FEO, the antimicrobial activities of bionanocomposite films significantly increased (p < .05). Both ZnO‐N and FEO had a significant effect in this respect, although the effects of ZnO‐N were more significant. In conclusion, an excellent synergistic effect of ZnO‐N and FEO was observed in potato starch films.

Flavor, antimicrobial activity and physical properties of gelatin film incorporated with of ginger essential oil.

Adding essential oil into the gelatin-based film can enhance the antibacterial activity of the film, but excessive amounts of addition will bring the film an unpleasant flavor and reduce its mechanical performance. Hence, we prepared functional gelatin-based films by incorporating low content of ginger essential oil (GEO). The flavor of GEO was not detected from the films containing less than 1% GEO. The antimicrobial activity of films was found to be proportional to GEO content. As GEO content increased from 0 to 1%, the value of water vapor permeability (WVP) and elongation at break (EAB) increased, whereas the value of tensile strength (TS) of film decreased. The Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy analysis revealed the vibration of gelatin film was affected by adding low content of essential oil. Surface morphologies demonstrated oil droplets and a discontinuous structure, and cross-section morphologies proved the formation of a loose structure as GEO was incorporated in the film through SEM. Sensory evaluation revealed that composite films incorporated with 0.5% GEO exhibited the best performance. The resulting films can be used as antimicrobial packaging materials with good physical properties and sensory performance.

The effects of methylcellulose coating containing carvacrol or menthol on the physicochemical, mechanical, and antimicrobial activity of polyethylene films.

In this study, the physicochemical, mechanical, and antimicrobial activities of polyethylene (PE) films coated with peppermint (Menthol) and Origanum vulgare (Carvacrol) essential oil were evaluated. For this reason, PE films were coated with MC‐HPMC solution containing different concentrations of menthol and carvacrol (0, 1, 1.5, and 2%), and mechanical, electromagnetic, barrier, and antimicrobial properties of all prepared films were examined. The obtained results demonstrated that by increasing the concentration of menthol and carvacrol in film coatings, tensile strength (from 36 to 23 MPa), water vapor permeability (from 12 to 11 g.m‐1s‐1Pa‐1), and L* and b* indexes were decreased, while the oxygen permeability (OP) and elongation at break significantly were increased (p < .05). Increment of menthol and carvacrol concentration in PE film coating leads to an increase in the antimicrobial activity of films against Escherichia coli, Staphylococcus aureus, Listeria innocua, and Saccharomyces cervicea. Finally, the results obtained from this study demonstrated that PE film coated with high levels of carvacrol and menthol could be used as active antimicrobial packaging in the food packaging industry.

Effect of cinnamaldehyde incorporation on the structural and physical properties, functional activity of soy protein isolate‐egg white composite edible films

Cinnamaldehyde (CIN) was added to edible composite films of soy protein isolate (SPI) and egg white (EW) to develop active food packaging. The effects of adding 2%–10% CIN on the structural, physical, and functional properties of the SPI/EW films were systematically evaluated. Fourier-transform infrared spectroscopy and X-ray diffraction suggested the excellent compatibility of the components because hydrogen bonding occurred. Scanning electron microscopy indicated CIN affected the structure of the films. The incorporation of CIN significantly improved the antioxidant and antimicrobial activities of the films, but reduced the tensile strength and water vapor permeability. In particular, the addition of CIN at different concentrations significantly increased the elongation at break, water resistant, and UV–vis light barrier properties of the films. Therefore, SPI/EW/CIN films can be used as eco-friendly bioactive materials in food packaging. Practical applications In recent decades, many studies were devoted to the development of biodegradable and edible natural biopolymers to replace petroleum-based polymer packaging. The edible bioactive packaging film can be prepared by adding active substances to the food packaging materials instead of directly adding it to the food, which not only maintains the original characteristics of the food, but also delays the deterioration and autoxidation of the food. This study evaluated the Microstructural, physical, and functional properties (antioxidant and antimicrobial activities) of composite films for use in food packaging and it is proved that it is possible in practical application.

The physiochemical and preservation properties of fish sarcoplasmic protein/chitosan composite films containing ginger essential oil emulsions

AbstractActive films with essential oils have attracted more attention in recent years. In order to improve the solubility and stability of ginger essential oil (GEO) in film forming solutions, GEO coarse emulsion and nanoemulsions were prepared named CGEO (z‐average = 799.53 nm), NGEO‐1 (z‐average = 114.71 nm) and NGEO‐2 (z‐average = 59.30 nm), respectively. And the effect of concentration (0.5% and 1.0% v/v) and particle sizes of GEO emulsions on the physiochemical and preservation properties of fish sarcoplasmic protein and chitosan blend based edible films were studied in this study. The elongation at break significantly (p &lt; .05) increased after adding GEO emulsions, and the light transmittance, water vapor permeability and water solubility were the lowest when NGEO‐2 was incorporated into films. The antioxidant and antimicrobial activities of films were concentration‐dependent. Furthermore, all the films were applied into packaging red sea breams fillets, and the results of total viable counts, pH and thiobarbituric acid demonstrated that SP‐CH films with GEO emulsions, especially nanoemulsions obviously prolonged the shelf‐life of fillets during 4°C.Practical ApplicationsIn recent years, the research about incorporating essential oils into edible films to prepare active edible films due to their antimicrobial and antioxidant properties have been more documented. In this study, fish sarcoplasmic protein and chitosan were chosen as film‐forming materials to prepare active films with ginger essential oil emulsions. The physicochemical, mechanical, optical properties of films showed that the films have the basic characteristics as food packaging materials. The releasing and antioxidant property of films indicated that the active films have a potential application in packaging food which was easy oxidized. The basic properties of films combined with oxidation indicators (total viable count, pH and thiobarbituric acid reactive substances) would provide the scientific basis for developing active films and their application for food packaging, such as seafood, meat, fruits and vegetables.

Application of essential oil of Pistacia atlantica Gum, polypropylene and silica nanoparticles as a new milk packaging.

The aim of current study was to investigate the antimicrobial effect of gum essential oil of Pistacia atlantica (wild pistachio) tree (GEO) and design a new film based on polypropylene polymer coated with silica nanoparticles and GEO. The antimicrobial activity of the packaging film was evaluated with or without milk on Staphylococcus aureus, Salmonella enterica, Escherichia coli, and Listeria monocytogenes during 35 days. The results showed that GEO has significant antibacterial properties. It was most effective on Salmonella enterica, while its effect on Listeria monocytogenes was the weakest. Antimicrobial activity of the film without milk showed no significant differences among the different sizes of nanoparticles used (0.05, 0.025, and 0.051 g) (p ≥ .05). It can be concluded that polypropylene incorporated with GEO and silica nanoparticles active film had antimicrobial properties up to 35 days, while using with milk or without milk. Therefore, this type of packaging is effective to enhance the shelf life of milk.

Nanomaterial loaded chitosan nanocomposite films for antimicrobial food packaging

Food loss due to spoilage, constitutes is a great economic concern for the food industry. Nanotechnology, being an advanced field comes into play in order to overcome this major global issue of food spoilage. With the help of nanotechnology, unique food packaging techniques can be designed, which can minimise the spoilage and increase the shelf life of food materials. In this study, we prepared and characterised zinc oxide and silver nanomaterials and then prepared chitosan nanocomposite films followed by their characterization. The antimicrobial activity of these films was also evaluated on S. aureus and E. coli by disc assay and cell growth curve analysis. The results showed dose dependent antimicrobial activity of nanocomposites films. It was concluded that the silver-chitosan nanocomposite were more efficient, for use in antimicrobial food packaging applications as compared to the ZnO-chitosan nanocomposite.

Production of Biodegradable Film Based on Polylactic Acid, Modified with Lycopene Pigment and TiO2 and Studying Its Physicochemical Properties

In this study, a new film based on polylactic acid (PLA) modified with titanium dioxide and lycopene pigment (PLA/TiO2/Lyc) was prepared. To study the effect of titanium dioxide and lycopene pigment on the physicochemical properties of the film, a central composite statistical design was used. The film properties including moisture, thickness, water vapor permeability, antioxidant activity, antimicrobial properties, and color were studied. The SEM, XRD, FT-IR and DSC techniques were used to study film properties. The results showed that moisture content, antioxidant activity, and film thickness was increased and water vapor permeability was decreased significantly with increasing lycopene and titanium dioxide (P < 0.5). Also, with increasing lycopene concentration, the color indices of a*, b* were increased and the lightness of the films was decreased significantly (P < 0.05). The results of antimicrobial activity showed that the addition of titanium dioxide nanoparticles and lycopene pigment caused antimicrobial activity of film against Escherichia coli and Staphylococcus aureus. Surface morphology analysis showed that the titanium dioxide particles (30–100 nm) were dispersed within the film and the lycopene pigment was distributed evenly in the polymer matrix. Lycopene and TiO2 reduced the pores on the polymer surface. The FT-IR results confirmed the interactions between polylactic acid, titanium dioxide and lycopene pigment. XRD showed that both titanium dioxide and lycopene pigment improved the crystalline structure of the poly lactic acid film. DSC results showed that lycopene and titanium dioxide improved the crystalline melting point of the film. The overall results showed that the prepared film can be used as an antimicrobial and antioxidant film with suitable color properties for active and intelligent packaging in food.

The fabrication of a degradable film with high antimicrobial and antioxidant activities

Apricot kernel skin (AKS) is rich of antioxidant and antimicrobial ingredients, which might be used to prepare the degradable films with good antioxidant or antimicrobial properties. In this study, the effects of different size or loading (0, 10, 20, 30%, based on soy protein isolate) of AKS on physical properties (optical, mechanical, water vapor permeability), antioxidant and antimicrobial activities of the degradable films were investigated. The results indicated that the antioxidant and antimicrobial activities of the films containing the ultrafine AKS powder (UP) were significantly improved. In addition, the films incorporated with 20% UP had the highest tensile strength (7.20 MPa). This approach provides a novel way to develop the degradable films with excellent antioxidant and antimicrobial activities and the synthesized films show potential value in packaging applications.

Effect of emulsifier hydrophilic-lipophilic balance (HLB) on the release of thyme essential oil from chitosan films

In order to investigate the effects of different hydrophilic-lipophilic balance (HLB) emulsifying agents on the physical properties, structure and release of essential oil in chitosan-essential oil composite films, the diacetyl tartaric acid ester of mono glycerides (DATEM, HLB 8–9.2), Tween 85 (HLB 11), Tween 80 (HLB 15) and Tween 20 (HLB 16.7) were used to prepare composite film. The results showed that the particle size of the essential oil in the film forming solution decreased with the increase of emulsifier HLB value. Fluorescence microscopy and scanning electron microscope reflected that the particle size of thyme essential oil in composite films depended on the type and HLB of emulsifier. The addition of emulsifier also decreased the water vapor permeability and tensile strength of films. However, the physical properties, the release of essential oil from films and antimicrobial activity of films were not closely related to the HLB of emulsifier, which depended on the solvent type, microbial species and the interaction between emulsifier and film matrix. Lower water vapor permeability (compared with the control film), higher elongation at break and antimicrobial activity (E.coli) were found in Tween 85 composite films, which could be optimal choice to produce active chitosan-essential oil composite films.