Antibacterial Activity Of Films Research Articles

Controlled release and antibacterial activity of corn starch-based films containing nanocellulose and thymol

The use of nanomaterials such as cellulose nanofiber (CNF) and antimicrobial compounds such as thymol (Thy), in starch films may improve the functional properties of films as active packaging films. This study quantifies the retention of thymol in corn starch (CS) and CS films containing cellulose nanofibers (CS/CNF) and investigates the migration of thymol from the films into a food simulant. A kinetic study was performed to evaluate the release of thymol from films into fatty acid food simulant (95% v/v ethanol) at 40 °C. The antibacterial activity of films was investigated via liquid culture assay. It was found that the addition of thymol significantly affects the surface morphology and cross-section of the films. CS/Thy and CS/CNF/Thy films retained thymol at 2.88 ± 0.50 and 11.21 ± 0.75 mg per g of CS/Thy and CS/CNF/Thy films, respectively. The release of thymol was affected by the presence of an intercalating network of CNF, which exhibited Fickian diffusion behavior. The release of thymol reached equilibrium within 48 h for CS/Thy, and 72 h for CS/CNF/Thy films. The CS/CNF/Thy film had a greater inhibitory effect than the CS/Thy film against Listeria monocytogenes and Salmonella Typhimurium. These findings demonstrate the potential applications of these films in improving the shelf life of perishable food products.

Effect of TEMPO-oxidized bacterial cellulose nanofibers stabilized Pickering emulsion of cinnamon essential oil on structure and properties of gelatin composite films

Pure gelatin film often exhibits high hydrophilicity and a lack of antibacterial activity, hindering its practical application in the field of food preservation. To address these issues, we incorporated 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized bacterial cellulose (TOBC) nanofibers stabilized cinnamon essential oil (CEO) Pickering emulsions into the gelatin matrix to develop active food packaging films. The study revealed that the good distribution of emulsion droplets in the film matrix. While with increasing Pickering emulsion proportion, the microstructures of composite films were more heterogeneous, showing some pores or cavities. In addition, the insertion of TOBC-stabilized CEO emulsions could improve the elongation at break (EAB), water-resistance, UV blocking ability, and antibacterial activity of film, but reduced its tensile strength (TS) and water vapor barrier properties (WVP). Notably, the film prepared with 4 % TOBC-stabilized CEO Pickering emulsion demonstrated enhanced preservation of strawberries. Overall, the as-prepared gelatin-based active composite films have considerable potential for food packaging.

Obtaining Edible Pullulan-based Films with Antimicrobial Properties

A nutrient medium was selected for the efficient production of exopolysaccharide (EPS) by A. pullulans C7 strain. The production of pullulan polysaccharide was evaluated on nutrient media with traditional carbon sources and cheap substrates that were plant wastes. For maximum EPS accumulation, we proposed an optimized Czapek-Dox medium with glucose as a carbon source, sodium nitrate as a nitrogen source, and C/N=232:1 ratio (EPS yield 12.79±0.64 g/l). Medium with grape pomace 5% (EPS yield was 15.08±0.34 g/l) and medium with topinambour tuber hydrolysate 5% (EPS yield was 14.44±0.21 g/l) was proposed as a cheap substrate. Edible films with antimicrobial activity were obtained on the basis of the isolated polysaccharide. The antibacterial activity of films against Escherichia coli 603 and Staphylococcus aureus ST228 was shown when essential oils of rosemary (zones of growth inhibition from 8.41±0.71 to 9.98±0.32 mm) and oregano (zones of growth inhibition from 8.09±0.51 to 9.54±0.24 mm) were added to pullulan. The addition of xanthan gum and glycerol to the films increased their strength and elasticity. The infrared spectrum of the pullulan film showed absorption bands characteristic of polysaccharide structures.

Chitosan/alginate dialdehyde trilayer films with cinnamaldehyde nanoemulsions for grass carp preservation

Chitosan (CS) cross-linked films were prepared using the Maillard reaction (CMR). Layer-by-layer casting created additional layers using alginate dialdehyde (ADA) containing cinnamaldehyde nanoemulsions (CANE) and CS. The ability to preserve grass carp fillets was evaluated along with the effects of CANE concentration on the microstructure, physicochemical properties, controlled-release behavior, antioxidation, and antibacterial activities of the films. In all films, Schiff base-induced bonds, electrostatic interactions, and hydrogen bonds brought the layers closer together, improving the mechanical properties (e.g., a 70% increase in tensile strength and a 34% increase in breaking elongation) and barrier capacity (e.g., inhibiting ultraviolet, water vapor, and oxygen transmission). CANE can improve the antioxidant activity, antibacterial activity, and sustained release characteristics of films. More importantly, over the 8-day storage period, the fish packaged using the active films were better than those in the control, commercial PE, and CS films in terms of thiobarbituric acid reactive substances, pH, texture, total viable counts, and volatile basic nitrogen with indicator species. Fish could have a prolonged shelf life due to the prepared CMR/ADA-CA/CS film. In other words, it may be used as a sustainable food packaging material, with the performance of the film being regulated by different CANE concentrations.

Development and Characterization of Antioxidant and Antibacterial Films Based on Potato Starch Incorporating Viola odorata Extract to Improve the Oxidative and Microbiological Quality of Chicken Fillets during Refrigerated Storage.

In this research, the antioxidant and antibacterial activities of active films based on potato starch containing Viola odorata extract (VOE) were investigated both in vitro and in chicken fillets. The VOE was added to the starch film formulation at 0, 1, 2, and 3% (w/v). The results showed that by increasing the extract level, the total phenol content and antioxidant and antibacterial activity of the films against Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium improved remarkably. The results of the meat tests indicated the significant antioxidant and antimicrobial activity of active films containing different levels of VOE in chicken fillets, and a direct relationship was observed between the concentration of the extract and the functional activity of the films, so with the increase in the concentration of the extract in the films, the rate of lipid oxidation and growth of microorganisms in the chicken fillets decreased significantly during the storage period, and less volatile nitrogen bases, metmyoglobin, and oxidation products were produced in the fillets. In general, the results of this research demonstrated that an active film based on potato starch containing VOE (especially 2 and 3% levels) has the ability to extend the oxidative and microbiological shelf life of chicken fillets during cold storage for at least eight days.

Physical, antioxidant, and preservation properties of chitosan film doped with proanthocyanidins-loaded nanoparticles

The nanoparticles (NPs) loading with proanthocyanidins (PC), obtained by crosslinking of chitosan (CH) and chondroitin sulfate (CS), were used as nanofillers in the matrix of the neat CH film, designing a novel edible bioactive packaging film. The electrostatic interaction and hydrogen bonding between NPs and the CH film matrix made the film denser, greatly enhancing the mechanical strength and barrier ability of the film. Moreover, NPs significantly improved antioxidability of the film and weakened the damage of ultraviolet rays and thermal effects on the biological activities of PC. The positive synergistic effect between the CH film matrix and NPs was established to effectively inhibit Escherichia coli , Staphylococcus aureus , and fish-original spoilage bacteria ( Pseudomonas aeruginosa and Aeromonas hydrophila ). In general, the addition of PC-loaded NPs to the CH film endowed the film with stronger antioxidant, antibacterial, and oxygen barrier effects, and could effectively slow down the quality deterioration of refrigerated grass carp fillets during storage, such as lower accumulation of total volatile base nitrogen and biogenic amines (putrescine, cadaverine, etc.) and more stable texture characteristics when compared to the control, confirming the potential in the application of food active packaging film. • A novel chitosan film was designed with loading of proanthocyanidin nanoparticles. • Electrostatic interaction and hydrogen bonding were formed between NPs and CH film. • Mechanical and barrier abilities of films were enhanced due to the NPs addition. • NPs improved the antioxidant and antibacterial activities of films. • CH-NPs film could offer an ideal preservation effect of fish fillets.

Long term antibacterial effect cellulose film was modified with polyhexamethylene biguanide (PHMB)

Cellulose products such as textile, paper, package and so on are apt to breed bacterial. In this study, AA-PHMB antibacterial agent was synthesized innovatively. It was grafted onto cellulose by the addition polymerization of carbon carbon double bonds and hydroxyl groups to prepare cellulose antibacterial film with excellent performance. The structures, elements, mechanical properties and antibacterial activities of films were studied. The results showed that CN absorption at 1631 cm−1 of guanidine and the amide group absorption peak at 1554 cm−1 appeared on cellulose graft copolymers; employing SEM-EDS, a great quantity of deposited materials, with the elements of C, O and N, were observed on the grafted cellulose. The graft percentage of cellulose-AA-PHMB was about 62%. Compared with unmodified cellulose films, the mechanical properties of PHMB-AA-cellulose film were lower, and the crystallinity of the PHMB-AA-cellulose film was lower than that of original cellulose film. The modified film as a raw material had a good inhibitory effect on Escherichia coli and Staphylococcus aureus was proved by bacteriostatic experiments. Under the condition of continuous culture for 15 days, it still had a good bacteriostatic effect on the above strains, and therefore the cellulose-AA-PHMB films were long term antibacterial effect materials.

Characterization of Sodium Alginate-Locust Bean Gum Films Reinforced with Daphnetin Emulsions for the Development of Active Packaging.

In this study, we characterized an active film made of sodium alginate (SA)—locust bean gum (LBG) containing daphnetin-based film. Physicochemical characteristics, as well as antioxidant and antibacterial properties, were investigated. The results showed that the addition of a low concentration of daphnetin increased the flexibility of SA–LBG cling film, leading to an improvement in elongation at break and tensile strength. As the daphnetin content increased, solubility, brightness and transparency of the cling film decreased, and the moisture permeability increased. The antioxidant capacity and antibacterial activity of films with daphnetin were improved compared to those of the basal film. In addition, the cling film formed by adsorption had higher bacterial (Shewanella putrefaciens and Pseudomonas fluorescens) inhibition and antioxidant activity rates than direct film formation. The results indicate that the combination of daphnetin in SA–LBG film provides an active film with antioxidant and antibacterial properties, with potential for the development of food-grade packaging material.

Novel Temperature Responsive Films Impregnated with Silver Nano Particles (Ag-NPs) as Potential Dressings for Wounds

Silver nanoparticles have attracted wide interest in medicine on account of their antibacterial activity. We report in this paper, the antibacterial activity and biocompatibility of a temperature responsive topical film fabricated from pullulan-g-pNIPAM and impregnated with two different concentrations (15 ppm and 30 ppm) of silver nanoparticles (Ag-NPs). The release of silver from the film under the influence of temperature above the LCST has been studied and the in vitro release profile of the films has been compared with a marketed silver nano formulation, ‘Meganano gel’. The release of silver from the films has a distinctive profile characterized by a sustained release over a period of 48 hrs, which is comparable to the marketed formulation. The films exhibit excellent swelling properties, making them ideal materials for absorption of exudates from wounds. The antibacterial activity of the films has been established at physiological temperature against gram-positive S. aureus and gram-negative E. coli and compared with the marketed formulation. A cytotoxicity evaluation on HeK293 cells has demonstrated their biocompatibility. The nanocomposite films are thus a new therapeutic device for management of non-healing wounds being constructed from temperature responsive polymers that release Ag-NPs when the temperature of the wound exudate is slightly higher than normal.

Copper coating formed by micro-arc oxidation on pure Mg improved antibacterial activity, osteogenesis, and angiogenesis in vivo and in vitro.

Micro-arc oxidation (MAO) was used to improve the resistance of pure magnesium (Mg). Copper (Cu), a good antibacterial, angiogenic, and osteogenic element, was added by reaction in a Cu-containing electrolyte to improve the osteogenic and pro-angiogenic activities of Mg. The surface microstructures of the resulting MAO were evaluated by a scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) mapping. The release of Cu ions was detected by ICP-OES. The antibacterial activity of films with different concentrations of Cu ions was assessed against Staphylococcus aureus (S. aureus). The osteogenesis of films was confirmed by cell morphology and proliferation, ALP activity, alizarin red staining, and osteogenic-related gene expression in the MC3T3-E1 cell line. The angiogenesis of the films was tested in human umbilical vein endothelial cells (HUVECs) by cell migration, tube formation, and VEGF quantification in vitro, and by a chicken embryo chorioallantoic membrane (CAM) assay in vivo. The results showed that the microporous structure was shaped by MAO, and the Cu group was denser and more uniform. The Cu coating showed effective antibacterial activity against S. aureus while also enhancing osteogenesis and angiogenesis in vitro. According to the CAM assay, the Cu group showed not only biocompatibility but also a significant angiogenic response, which was consistent with in vitro studies. The findings indicate that a Cu coating on Mg-MAO enhances osteogenesis and angiogenesis.

Physicochemical Properties and Biological Activity of Active Films Based on Corn Peptide Incorporated Carboxymethyl Chitosan

Active films based on carboxymethyl chitosan incorporated corn peptide were developed, and the effect of the concentration of corn peptide on films was evaluated. Physicochemical properties of the films, including thickness, opacity, moisture content, color, mechanical properties, water vapor permeability, and oil resistance, were measured. Biological activities of the films, including the antioxidant and antibacterial activities, were characterized in terms of 2, 2-diphenyl-1-picrylhydrazyl free radical scavenging activity, reducing power, the total antioxidant activity, and the filter disc inhibition zone method. The results indicated that the incorporation of corn peptide caused interactions between carboxymethyl chitosan and corn peptide in Maillard reaction and gave rise to the films light yellow appearance. Compared with the Control, the degree of glycosylation, browning intensity, thickness, opacity, tensile strength, antioxidant activity, and antibacterial activity of films were increased, but the elongation, vapor permeability, and oil resistance of films were decreased. The films based on corn peptide and carboxymethyl chitosan can potentially be applied to food packaging.

Antibacterial activity testing methods for hydrophobic patterned surfaces

One strategy to decrease the incidence of hospital-acquired infections is to avoid the survival of pathogens in the environment by the development of surfaces with antimicrobial activity. To study the antibacterial behaviour of active surfaces, different approaches have been developed of which ISO 22916 is the standard. To assess the performance of different testing methodologies to analyse the antibacterial activity of hydrophobic surface patterned plastics as part of a Horizon 2020 European research project. Four different testing methods were used to study the antibacterial activity of a patterned film, including the ISO 22916 standard, the immersion method, the touch-transfer inoculation method, and the swab inoculation method, this latter developed specifically for this project. The non-realistic test conditions of the ISO 22916 standard showed this method to be non-appropriate in the study of hydrophobic patterned surfaces. The immersion method also showed no differences between patterned films and smooth controls due to the lack of attachment of testing bacteria on both surfaces. The antibacterial activity of films could be demonstrated by the touch-transfer and the swab inoculation methods, that more precisely mimicked the way of high-touch surfaces contamination, and showed to be the best methodologies to test the antibacterial activity of patterned hydrophobic surfaces. A new ISO standard would be desirable as the reference method to study the antibacterial behaviour of patterned surfaces.

Design, Characterization and Clinical Evaluation of Curcumin Dental Film for the Treatment of Periodontitis

Background::Periodontitis is one of the most widespread oral diseases. Curcumin, a hydrophobic polyphenolic compound derived from the rhizomes of Curcuma longa has a great potential for biological and pharmacological activities. The introduction of local controlled delivery of curcumin directly into the periodontal pocket is a promising approach for the treatment of periodontitis.Objective::The study has been designed to formulate intrapocket dental film loaded with curcumin to be used for insertion into the periodontal pockets and evaluate its clinical efficacy.Methods::Curcumin dental films were prepared by the solvent casting technique using polymers such as Ethylcellulose, HPMC K4M, Eudragit RL 100, Chitosan with Dibutyl Phthalate and Poly Ethylene Glycol 400 as the plasticizer. The prepared films (CDF1-CDF16) were evaluated for various physicochemical parameters employing established pharmaceutical procedures such as surface pH, folding endurance, tensile strength, swelling index, drug content, in-vitro drug release, antibacterial efficacy, stability studies, and clinical efficacy.Results::Experimental parameters of the obtained film exhibited results within the desired limit. Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry studies revealed the formulated film to be stable during drug stability and compatible between drugs and excipients. The surface morphology of the formulation using Scanning Electron Microscope images showed the presence of free drug particles on the surface, causing a burst effect at the desired site. In-vitro dissolution studies showed an initial burst release to achieve an immediate therapeutic level of drug in the periodontal pocket followed by a progressive fall and extended-release of the drug for 10 days. The therapeutics effects, such as antibacterial activity of films on P. gingivalis, were also observed. Furthermore, the clinical trials of formulation CDF16 on affected patients proved the therapeutic efficacy of the dental films showing a statistically significant (p < 0.05) decrease in the clinical markers of periodontitis, i.e. periodontal probing depth, plaque index, and sulcular bleeding index.Conclusion::The experimental results suggest that Curcumin dental film can be experimentally identified as a potential drug delivery device. Hence, curcumin dental film can be used for topical treatment of periodontal diseases and to achieve optimum therapeutic efficacy.

Physicochemical properties and antibacterial activity of corn starch-based films incorporated with Zanthoxylum bungeanum essential oil

Herein, corn starch-based films were prepared by casting method and different concentrations of Zanthoxylum bungeanum essential oil (ZYO) were added to evaluate the morphological, optical, mechanical, and barrier properties of the resultant films. Additionally, structural analysis was carried out via atomic force microscopy and the antibacterial activities against Staphylococcus aureus, Escherichia coli, and Listeria monocytogenes were assessed. We found that the elongation at break was significantly increased (P < 0.05), whereas tensile strength, moisture content, solubility in water, and water vapor permeability rate were significantly decreased (P < 0.05) in films incorporated with ZYO compared with oil-free films. Furthermore, incorporation of ZYO increased the opacity and decreased the gloss of films. Incorporation of ZYO appears to increase the surface roughness and the antibacterial activity of the films. In sum, ZYO can potentially be used in food packaging, particularly food intended to be protected from light and susceptible to spoilage by microorganisms.

Bacterial and oxidative control of local butter with smart/active film based on pectin/nanoclay/Carum copticum essential oils/β-carotene

In this study, Pectin/Nanoclay (montmorillonite)/Carum copticum Essential oils/β-Carotene (Pec/Clay/CCE/βC) composite film was prepared. The effect of β-Carotene (βC) and Carum copticum Essential oils (CCE) concentration on the antioxidant activity and color/mechanical properties of Pec/Clay/CCE/βC film was studied. The morphology and antibacterial activity of film were studied. The films containing maximum essential oil and β-carotene showed the best antibacterial activity, antioxidant activity, flexibility and firmness. So the Pec/Clay/CCE0.5%/BC0.03% film as the optimum film was used for packaging of local butter. Oxidative stability, microbial count, and color properties (L*, a* and b*) of butter packaged with active film (Pec/Clay/CCE/βC) were investigated. Results showed that Pec/Clay/CCE/βC film was effective against Bacillus cereus (B. cereus) more than Escherichia coli (E. coli). According to the results active packaged butter had the highest oxidative stability, lowest microbial load, and the least color change during storage. In the packaging process, Pec/Clay/CCE/βC film color was changed from orange to light yellow and this color change was used as a smart color indicator to detect the oxidation of butter and expiration time of butter.

Fabrication and characterization of an active bionanocomposite film based on basil seed mucilage and ZnO nanoparticles

In this study, active nanofilms were developed using basil seed mucilage (BSM) containing zinc oxide nanoparticles (ZnO-NPs), according to casting method. Different amount of ZnO-NPs at the range of 0% (control), 0.1, 0.25, and 0.5% were incorporated into BSM film, then the physical, permeability, mechanical, thermal, and antimicrobial properties, as well as color index of fabricated films were examined. The results showed that moisture content, water absorption, water solubility, water vapor permeability (WVP), melting temperature (Tm), glass transition temperature (Tg) decreased with increasing the amount of ZnO, while the melting enthalpy of films increased (P < 0.05). The addition of ZnO-NPs up to 0.25% resulted in significant increase in the ultimate tensile strength, light (L*) and white indexes. Additionally, the basil seed mucilage film did not show antibacterial performance, while added of ZnO-NPs to the film, caused an increased trend in the antibacterial activity of films. The fabricated nanofilms prevented the growth of Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium (P < 0.05). All in all, the developed nanobiocomposite film using BSM containing 0.25% ZnO-NPs could be used as biodegradable and antibacterial film for food active packing to increase the shelf life of food.

Antibacterial properties and biocompatibility in vivo and vitro of composite coating of pure magnesium ultrasonic micro-arc oxidation phytic acid copper loaded.

Bone infection and implant secondary removal remains a clinical challenge. We used ultrasonic micro-arc oxidation (UMAO) and conversion of phytic acid copper plating to prepare a pure magnesium polyhydric biofilm; we evaluated the surface microstructures, phase, element composition, and wettability of the film in vitro. The antibacterial activity of films with different Cu contents was confirmed by coating method, imaging examination, and microbiological cultures in vitro. The biocompatibility of biofilms was confirmed by cell proliferation, vitality, and morphology assays in vitro and histological evaluation in vivo. MC3T3-E1 cells were co-cultured with different films to assess cell viability on the films. The results showed that the mass fraction of Cu increased with increasing time of copper plating, and the surface of the Cu group was more dense and uniform. Additionally, copper coating significantly inhibited the growth of E. coli and Staphylococcus aurous. We also found that the adhesion, proliferation, and differentiation of the cells on the surface of copper plating were enhanced. Copper implantation of animals in vivo showed fine ability to promote bone growth. Antibacterial activity and biocompatibility of pure magnesium UMAO-phytic acid-Cu3min implant film are excellent, so the film has potential application value in the treatment of bone implantation.

Potential of Incorporation of Antimicrobial Plant Phenolics Into Polyolefin-Based Food Contact Materials to Produce Active Packaging by Melt-Blending: Proof of Concept With Isobutyl-4-Hydroxybenzoate.

There is an increasing interest for active food packaging incorporated with natural antimicrobial agents rather than synthetic preservatives. However, most of plastics for direct contact with food are made of polyolefins, usually processed by extrusion, injection, or blow-molding methods while most of natural antimicrobial molecules are thermolabile compounds (e.g., essential oils). Therefore, addition of plant phenolics (with low volatility) to different polyolefins might be promising to design active controlled release packaging processed by usual plastic compounding and used for direct contact with food products. Therefore, up to 2% (wt/wt) of isobutyl-4-hydroxybenzoate (IBHB) was mixed with 3 polyolefins: EVA poly(ethylene-co-vinyl acetate), LLDPE (Linear Low Density Polyethylene), and PP (PolyPropylene) by melt-blending from 75 to 170°C and then pelletized in order to prepare heat-pressed films. IBHB was chosen as an antibacterial phenolic active model molecule against Staphylococcus aureus to challenge the entire processing. Antibacterial activity of films against S. aureus (procedure adapted from ISO 22196 standard) were 4, 6, and 1 decimal reductions in 24 h for EVA, LLDPE, and PP films, respectively, demonstrating the preservation of the antibacterial activity after melt processing. For food contact materials, the efficacy of antimicrobial packaging depends on the release of the antimicrobial molecules. Therefore, the three types of films were placed at 23°C in 95% (v/v) ethanol and the release rates of IBHB were monitored: 101 ± 1%, 32 ± 7%, and 72 ± 9% at apparent equilibrium for EVA, LLDPE, and PP films, respectively. The apparent diffusion coefficients of IBHB in EVA and PP films were 2.8 ± 0.3 × 10−12 and 4.0 ± 1.0 × 10−16 m2s−1. For LLDPE films, IBHB crystals were observed on the surface of films by SEM (Scanning Electron Microscopy): this blooming effect was due the partial incompatibility of IBHB in LLDPE and its fast diffusion out of the polymer matrix onto the film surface. In conclusion, none of these three materials was suitable for a relevant controlled release packaging targeting the preservation of fresh food, but a combination of two of them is promising by the design of a multilayer packaging: the release could result from permeation through an inner PE layer combined with an EVA one acting as a reservoir.

INFLUENCE OF TITANIUM TETRAISOPROPOXIDE CONCENTRATION ON THE ANTIBACTERIAL ACTIVITY OF TiO2 THIN FILMS

In this study, titanium dioxide thin films were successfully prepared via sol–gel method. Titanium tetraisopropoxide (TTIP) as a precursor solution was used to prepare different concentrations and deposited by spin coating. All prepared films were inspected by X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). XRD patterns show that all samples have anatase crystal structure. Transmittance spectra were measured by using UV-Vis spectrophotometer. The optical band gaps were 3.55, 3.62 and 3.78 eV for TTIP concentrations of 6, 6.3 and 6.6[Formula: see text]ml, respectively. Antibacterial activity of TiO2 films against S. aureus and E. coli was evaluated by international recognized test (JIS Z 2801). The test revealed incrementally increase in antibacterial activity of the films with TTIP concentrations activated by UV light.

Novel antimicrobial zein film for controlled release of lauroyl arginate (LAE)

Novel antimicrobial biopolymer films based on the incorporation of ethyl-Nα-dodecanoyl-l-arginate hydrochloride (LAE) in zein matrices were manufactured and characterized as materials for LAE controlled released applications such as active food packaging. Characterization of the films’ functional properties revealed that incorporation of LAE (5 and 10%) in the biopolymer matrix did not cause substantial changes in morphological, optical, thermal, mechanical and barrier properties.As the mechanism of action of these films is mainly based on release of the antimicrobial, this process was characterized when the active biofilms were exposed to three food simulants (water, 3% acetic acid, and 10% alcohol) at three temperatures (4, 23, and 37 °C). The data obtained revealed that, with the exception of exposure to water at 4 °C which achieved a release of more than 80% of the LAE incorporated, the agent was almost completely extracted in all conditions. Release of LAE was faster at higher temperatures, and the diffusion coefficient values varied according to the Arrhenius law, and increased with temperature. Antibacterial activity of films was assayed against Listeria monocytogenes and Escherichia coli. Zein films with 5% LAE produced 2.02 and 3.07 log reduction against L. monocytogenes and E. coli, respectively, after 5 days of storage at 4 °C. Greater antibacterial activity was observed with films containing 10% LAE (5 log reduction) at 37 °C. This work highlighted that LAE incorporation in a packaging film constructed with renewable polymer materials offers an interesting and efficient hurdle for control of bacterial contamination in foods.