Antimicrobial Films Research Articles

Preparation of pectin/carboxymethyl cellulose composite films via high-pressure processing and enhancement of antimicrobial packaging

This study investigated the impact of high-pressure processing (HPP) treatment on the structure and physicochemical properties of pectin (PEC)/carboxymethyl cellulose (CMC) composite films, along with the development of new active films incorporating emodin as an antibacterial agent. The results showed that 500 MPa/20 min HPP treatment significantly improved the tensile strength (from 45.91 ± 4.63 MPa to 52.24 ± 4.87 MPa) and elongation at the break (from 5.00 ± 1.44 % to 11.72 ± 2.97 %) of the films. It also improved the film's thermal stability and had no significant effect on its thermal degradability. Moreover, emodin was incorporated into the PEC/CMC film-forming solution and subjected to 500 MPa/20 min HPP treatment to investigate the structure, functional properties, optical properties, and antibacterial activity of the film. The emodin caused the film structural alteration, but significantly improved the water vapor barrier properties. It also reduced the film brightness and light transmission. The antibacterial assessment demonstrated that the film's antibacterial activity was correlated positively with increasing emodin content, and the number of viable cells of Staphylococcus aureus decreased by 1.29 log10 CFU/mL, 1.70 log10 CFU/mL, and 1.80 log10 CFU/mL with different levels of EM antimicrobial films after 12 h.

Preparation and characterization of porous corn starch-based antibacterial sustained-release intelligent film

A novel porous corn starch-based antibacterial sustained-release intelligent film was prepared with the porous corn starch as the substrate, purple corn cob anthocyanin (PCA) as the indicator, and tangerine peel essential oil as the antibacterial agent, and its properties were studied. The results showed that the porous corn starch-based antimicrobial sustained-release indicator film had good mechanical strength, surface hydrophobicity and light transmittance. The tensile strength of the sustained-release indicator film (PLSt-12) prepared by porous corn starch with an enzymatic hydrolysis time of 12 h was 14.35 MPa and the elongation at break was 6.55 %. The water contact angle was 89.10°, and the water vapor transmittance was 6.62 × 10−4 g·mm2·s−1·Pa−1. The PLSt-12 was brown at pH 10 and had a sensitive color response. The PLSt-12 reduced the release rate of anthocyanins by 25.01 %, and the sustained-release mechanism was non-Fick diffusion. It showed a significant color change when the pork quality deteriorated, which can be used to monitor the freshness of the pork. This type of antibacterial sustained-release intelligent film had considerable application potential in indicating food freshness.

A novel ZnO-TiO2-Bi2WO6/Carboxymethyl chitosan composite with high antimicrobial activity and visible-light catalytic degradation of ethylene towards banana preservation in hot and humid environments

In order to solve the problem of significantly shortened storage time of bananas in hot and humid environment (e.g., 30 °C and 90 % relative humidity), this paper reports the preparation of ZnO-TiO2-Bi2WO6 (ZTB) ternary heterojunction antimicrobial photocatalysts composite carboxymethyl chitosan film (ZTB/CMCS). ZTB were prepared by hydrothermal method and composited with CMCS by surface deposition method to construct ZTB/CMCS edible nano-preservation film. It is noteworthy that the ZTB/CMCS composite film exhibited excellent antibacterial efficiency (>99.99 %) against E. coli and S. aureus suspensions (106 CFU/mL) after 24 h of incubation at 37 °C. Time-resolved photoluminescence (TRPL) spectroscopy showed that the incorporation of Zinc oxide nanoparticles (ZnO NPs) into the ZTB structure led to a decrease in fluorescence lifetime. Moreover, the interfacial interaction between ZnO and TiO2/Bi2WO6 inhibited the recombination of photogenerated electron-hole pairs, promoting carrier separation and improving photocatalytic activity. The combination of high antibacterial activity, photocatalytic degradation of ethylene and inhibition of gas exchange provided multiple protections for fruit preservation. Therefore, this work provides a novel, effective and safe method for prolonging the preservation of bananas in hot and humid environments.

Biodegradable antimicrobial films prepared in a continuous way by melt extrusion using plant extracts as effective components

Packaging plays an important role in delaying food spoilage. However, conventional packaging films do not have antimicrobial properties. Films with antimicrobial components are receiving growing research interest. However, many of the reported studies use conventional non-degradable polymers during film preparation, posing a significant threat to the environment and sustainable development. Furthermore, conventional inorganic antibacterial agents are commonly used during film preparation, posing a risk to food safety. In this study, antibacterial compounds were extracted from diverse plants, and then biodegradable antimicrobial films were prepared in a continuous way via the melt extrusion method. Especially, films prepared using Vernicia fordii and Phyllanthus urinaria extracts showed effective antibacterial activities against common foodborne pathogens. This study is the first to prepare antibacterial films in a continuous way using natural plant extracts as the effective components, and may shed new light on future research in preparing green antibacterial films via environment-friendly approaches.

Antimicrobial gelatin-based films with cinnamaldehyde and ZnO nanoparticles for sustainable food packaging

Cinnamaldehyde (CIN), a harmless bioactive chemical, is used in bio-based packaging films for its antibacterial and antioxidant properties. However, high amounts can change food flavor and odor. Thus, ZnO nanoparticles (NPs) as a supplementary antimicrobial agent are added to gelatin film with CIN. The CIN/ZnO interactions are the main topic of this investigation. FTIR-Attenuated Total Reflection (ATR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were utilized to investigate CIN/ZnO@gelatin films. Transmission electron microscope (TEM) images revealed nanospheres morphology of ZnO NPs, with particle sizes ranging from 12 to 22 nm. ZnO NPs integration increased the overall activation energy of CIN/ZnO@gelatin by 11.94%. The incorporation of ZnO NPs into the CIN@gelatin film significantly reduced water vapour permeability (WVP) of the CIN/ZnO@gelatin film by 12.07% and the oxygen permeability (OP) by 86.86%. The water sorption isotherms of CIN/ZnO@gelatin were described using Guggenheim-Anderson-de Boer (GAB) model. The incorporation of ZnO NPs into the CIN@gelatin film reduced monolayer moisture content (M0) by 35.79% and significantly decreased the solubility of CIN/ZnO@gelatin by 15.15%. The inclusion of ZnO into CIN@gelatin film significantly decreased tensile strength of CIN/ZnO@gelatin by 13.32% and Young`s modulus by 18.33% and enhanced elongation at break by 11.27%. The incorporation of ZnO NPs into the CIN@gelatin film caused a significant decrease of antioxidant activity of CIN/ZnO@gelatin film by 9.09%. The most susceptible organisms to the CIN/ZnO@gelatin film included Candida albicans, Helicobacter pylori, and Micrococcus leutus. The inhibition zone produced by the CIN/ZnO@gelatin film versus Micrococcus leutus was 25.0 mm, which was comparable to the inhibition zone created by antibacterial gentamicin (23.33 mm) and cell viability assessment revealed that ZnO/CIN@gelatin (96.8 ± 0.1%) showed great performance as potent biocompatible active packaging material.

Production and characterization of antimicrobial nanocomposite film based on Plantago major seed gum/carboxymethyl cellulose reinforced by Cerium oxide nanoparticles and Fenugreek essential oil

Production and characterization of antimicrobial nanocomposite film based on Plantago major seed gum/carboxymethyl cellulose reinforced by Cerium oxide nanoparticles and Fenugreek essential oil

Antimicrobial Hydroxyethyl-Cellulose-Based Composite Films with Zinc Oxide and Mesoporous Silica Loaded with Cinnamon Essential Oil.

Background: Cellulose derivatives are gaining much attention in medical research due to their excellent properties such as biocompatibility, hydrophilicity, non-toxicity, sustainability, and low cost. Unfortunately, cellulose does not exhibit antimicrobial activity. However, derivatives like hydroxyethyl cellulose represent a proper matrix to incorporate antimicrobial agents with beneficial therapeutic effects. Methods: Combining more antimicrobial agents into a single composite material can induce stronger antibacterial activity by synergism. Results: Therefore, we have obtained a hydroxyethyl-cellulose-based material loaded with zinc oxide nanoparticles and cinnamon essential oil as the antimicrobial agents. The cinnamon essential oil was loaded in mesoporous silica particles to control its release. Conclusions: The composite films demonstrated high antibacterial activity against Staphylococcus aureus and Escherichia coli strains, impairing the bacterial cells' viability and biofilm development. Such antimicrobial films can be used in various biomedical applications such as topical dressings or as packaging for the food industry.

Novel antimicrobial polyvinyl alcohol film by incorporating β-cyclodextrin/berberine inclusion complex preserving the storage quality of salmon fillets

Antimicrobial packaging film mediated by photodynamic inactivation (PDI) based on biodegradable polymers is promising. The photosensitizer berberine chloride (BBR) was encapsulated into the β-cyclodextrin (CD) to exert its aggregation-induced emission (AIE) property. On this basis, novel PDI-mediated polyvinyl alcohol (PVA) films were fabricated by incorporating the CD/BBR inclusion complex. The PVA/CD/BBR films had high light transmittance (∼70 %) in the visible light range, and possessed good biodegradability with the water absorption of 76 % and water solubility of 31 %. Besides, the films exhibited good mechanical properties with the tensile strength of 62.53 MPa at elongation break of 69.14 %, owing to the formation of hydrogen bonds between the PVA and CD/BBR. The PDI-mediated films were irradiated (14.4 J/cm2) to produce ROS to kill ∼4 log CFU/mL of Listeria monocytogenes and Vibrio parahaemolyticus. In addition, the films potently inactivated native bacteria (0.92 log CFU/g) on salmon fillets after 9 days of storage, and maintained their sensory quality, water holding capacity, and notably, inhibited the chemical changes of salmon fillets to extend the shelf-life for at least 3 days.

Green-synthesized silver nanoparticles immobilized on graphene oxide for fruit preservation in alginate films

In this study, silver nanoparticles were synthesized by redox method using tea polyphenol as a reducing agent. These nanoparticles were then immobilized within sodium alginate (SA) composite films using graphene oxide (Go), resulting in films with enhanced food preservation capabilities. Initially, the synthesized silver nanoparticles underwent characterization through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). This characterization affirmed the successful synthesis of silver nanoparticles. Subsequently, the impact of silver nanoparticles and graphene oxide on the properties of the SA composite films was investigated. The SA composite films were analyzed barrier, mechanical, thermal stability, and functional properties. The findings revealed that the inclusion of silver nanoparticles immobilized in Go augmented the tensile strength (23.6 %), degradation temperature of the films, reduced water vapor permeability, and exhibited antioxidant properties (4.16 %–42.09 %), and antimicrobial activities against Escherichia coli and Staphylococcus aureus (19.79–20.37 times). The graphene oxide immobilizes the silver nanoparticles, thereby reducing the release concentration. Packaging blueberry fruits with the SA composite film impregnated with Go-immobilized silver nanoparticles reduced weight loss and wrinkle index and this enhanced blueberry fruit shelf life. Thus, this work presents a novel approach to preparing antimicrobial packaging films for post-harvest fruit preservation.

Development of multilayer composite film based on protein‐polysaccharides with the addition of onion waste extracts and their impact on the shallot quality

AbstractAt present, multilayer composite film is attractive in the production of biodegradable films due to its essential film properties. The current study mainly focused on overcoming the problems of poor water barrier and mechanical strength observed in monolayer films (SA‐CMC and G/SA‐CMC) made from gluten (G), sodium alginate (SA), and carboxymethylcellulose (CMC). The film was developed with the addition of onion waste extracts (OWEs), primarily from peel and stalk, to enhance functional properties. The multilayer composite film consists of three layers: an outer layer made of G, an inner layer made of SA, CMC, and a middle layer made of G/SA‐CMC. The developed composite film exhibited improved physical properties (thickness: 0.348–0.629 mm and moisture: 20.889%–21.403%), mechanical properties (tensile strength: 21.943–20.640 MPa), and barrier properties (WVP: 0.212–0.516 g/m.s.Pa × 10−14) compared to monolayer films (SA‐CMC and G/SA‐CMC). The addition of OWEs enhanced the multilayer film's phenolic (20.076 and 36.175 mgGAE/g) and antioxidant activity (73.850% and 42.667%). The study found that the multilayer control film had minimal changes in weight loss (9.75% ± 0.18%) and firmness (6.68 ± 0.64 N) compared to OWEs‐added films (9.93% ± 0.49–10.02% ± 0.14% and 6.61 ± 0.37 to 6.64 ± 0.18 N). However, fresh‐peeled shallot onion packed with control film exhibited higher bacterial counts (6.70 ± 0.42 CFU/g) and yeast and mold counts (5.08 ± 0.20 CFU/g) than those packed with the OWEs‐added film (6.49 ± 0.28–6.56 ± 0.27 CFU/g and 4.75 ± 0.18–4.89 ± 0.21 CFU/g), indicating that OWEs protect the onions from microbial degradation. Overall, the multilayer control film (without OWEs) showed better results for storing the fresh‐peeled shallot onion at 4°C for 21 days.Highlights Onion waste extracts have potent high antioxidant and antimicrobial properties Multilayer film's physical, mechanical, barrier, and functional properties improved Addition of onion waste extracts increased the film's antimicrobial activity Control film showed a better effect for storing fresh‐peeled shallot onion Developed film can store fresh‐peeled shallot onion for 21 days at 4°C.

Valorization of whey through green synthesis of silver nanoparticles for developing biodegradable plastic films with bactericide properties

This study explores the synthesis of silver nanoparticles (AgNPs) using untreated whey as a green approach, followed by their integration into biodegradable gelatin films for potential applications in antimicrobial packaging. UV–visible spectroscopy and scanning electron microscopy confirm the successful synthesis of AgNPs, which are seamlessly incorporated into flexible and semi-transparent gelatin films. Comparing films with and without AgNPs, subtle changes are observed in UV–visible and Fourier-transform infrared spectra that are attributed to the low AgNP concentrations. However, the resulting films with AgNPs exhibit effective bactericidal efficacy against E. coli. Moreover, soil burial tests demonstrate significant biodegradability, with up to 80% mass loss within two weeks, showing comparable rates between films with and without AgNPs. These results show the prospects of whey-derived AgNPs in the development of sustainable, antimicrobial biodegradable films with potential applications in various industries.

Cassava starch‐based film infused with biogenic selenium nanoparticles (bio‐SeNPs) to reduce foodborne pathogens

SummaryThe urgent investigation of antimicrobial films is imperative to mitigate the proliferation of pathogens in food, extending product shelf life and ensuring food safety, crucial aspects for public health and the sustainability of the global food system. We developed cassava starch‐based films containing 1% and 2% biogenic selenium nanoparticles (Bio‐SeNPs) produced by enterocin MF5 to assess antimicrobial activity. The addition of Bio‐SeNPs altered the luminosity and gave a reddish hue to the films. UV–visible, FTIR, and thermogram analyses revealed intermolecular interactions between the starch and Bio‐SeNPs. Scanning electron microscopy showed a smooth and homogeneous surface of the nanocomposite films. Water vapour permeability ranged from 9.4 to 0.68 g mm h−1 m−2 kPa−1, lower than control values. Swelling values were higher in the film containing 1% Bio‐SeNPs, and water vapour transmission was lower. The films exhibited MICs of 5.5 μL mL−1 for Listeria spp., 10.9 μL mL−1 for Salmonella spp., and 250 μL mL−1 for Escherichia coli. Antimicrobial activity ranged from 1.5–1.9 log and 1.6–2.0 log in liquid medium and dry film, respectively, after 24 h. The films were also applied to cherry tomatoes without altering their characteristics compared to the positive control. Our study demonstrated the high potential of using Bio‐SeNPs in biodegradable films to prevent food contamination.

Efficacy and safety of preventing catheter-associated urinary tract infection by inhibiting catheter bacterial biofilm formation: a multicenter randomized controlled trial

BackgroundCatheter-associated urinary tract infection (CAUTI) remains the most significant challenge among hospital-acquired infections (HAIs), yet still unresolved. The present study aims to evaluate the preventive effectiveness of JUC Spray Dressing (name of U.S. FDA and CE certifications, while the medical device name in China is Long-acting Antimicrobial Material) alone for CAUTI without combining with antibiotics and to evaluate the impact of bacterial biofilm formation on CAUTI results on the inserted catheters of patients.MethodsIn this multicenter, randomized, double-blind study, we enrolled adults who suffered from acute urinary retention (AUR) and required catheterization in 6 hospitals in China. Participants were randomly allocated 1:1 according to a random number table to receive JUC Spray Dressing (JUC group) or normal saline (placebo group). The catheters were pretreated with JUC Spray Dressing or normal saline respectively before catheterization. Urine samples and catheter samples were collected after catheterization by trial staff for further investigation.ResultsFrom April 2012 to April 2020, we enrolled 264 patients and randomly assigned them to the JUC group (n = 132) and the placebo group (n = 132). Clinical symptoms and urine bacterial cultures showed the incidence of CAUTI of the JUC group was significantly lower than the placebo group (P < 0.01). In addition, another 30 patients were enrolled to evaluate the biofilm formation on catheters after catheter insertion in the patients’ urethra (10 groups, 3 each). The results of scanning electron microscopy (SEM) showed that bacterial biofilm formed on the 5th day in the placebo group, while no bacterial biofilm formed on the 5th day in the JUC group. In addition, no adverse reactions were reported using JUC Spray Dressing.ConclusionContinued indwelling urinary catheters for 5 days resulted in bacterial biofilm formation, and pretreatment of urethral catheters with JUC Spray Dressing can prevent bacterial biofilm formation by forming a physical antimicrobial film, and significantly reduce the incidence of CAUTI. This is the first report of a study on inhibiting bacterial biofilm formation on the catheters in CAUTI patients.

A low-cost, antimicrobial aloe-alginate hydrogel film containing Australian First Nations remedy ‘lemon myrtle oil’ (Backhousia citriodora) – Potential for incorporation into wound dressings

Chronic wounds pose a global public health challenge, particularly in remote settings where access to specialised wound care and dressings can be limited and cost-prohibitive. First Nations communities in Australia are at a significantly higher risk for developing chronic wounds and this risk further increases for people living in remote regions. There is an urgent need to develop inexpensive but effective wound dressings to improve wound outcomes. Over the past decade, sodium alginate (SA)-based hydrogel polymers have emerged as a cost-effective and biocompatible component in wound dressings, and many have been successfully commercialised. In this study, we have developed and evaluated various prototypes of SA-based hydrogels with the addition of another low-cost component, aloe vera (AV) to further tailor the physicochemical properties of the hydrogel. Since the presence of microbes is a major contributor to the pathophysiology of chronic wounds, we also evaluated the antimicrobial activity of lemon myrtle oil (LMO) (Backhousia citriodora) incorporated into the hydrogel, a remedy used traditionally by First Nations Australians. Novel formulations of AV-SA-LMO hydrogel prototypes in the absence and presence of lemon myrtle oil (at a concentration of 5 μg/mL) were assessed for their physicochemical and antimicrobial properties and compared to a commercially available hydrogel-based dressing. The addition of lemon myrtle oil imparted viscoelastic behaviour for improved processability of AV-SA-LMO hydrogel prototypes, while increasing protein adhesion, enhancing physical properties, and demonstrating antimicrobial activity against the common wound-infecting microbes Staphylococcus epidermidis and Candida albicans. Fourier transmission infrared (FTIR) spectra confirmed the molecular structures of the hydrogel prototypes as predicted. The prototypes also demonstrated biocompatibility with the HaCaT human keratinocyte cell line. This study has provided preliminary evidence that a 25:75 aloe vera:sodium alginate hydrogel with 5 μg/mL lemon myrtle oil has comparable physicochemical characteristics to a commercial hydrogel-based wound dressing and antimicrobial properties against S. epidermidis and C. albicans.

Maize starch-PVA nanocomposite biodegradable antimicrobial packaging films for enhancement of shelf-life of Agaricus bisporus

Nanocomposite antimicrobial packaging can effectively cater to the postharvest losses of button mushrooms. This study aimed for fabrication of novel antimicrobial biodegradable packaging films using a double composite system comprised of nano-clay-essential oil (EO) composite blended with maize starch (MS) /Polyvinyl alcohol (PVA) polymers which was plasticized with glycerol. The results confirmed superior water barrier properties with the lowest film solubility (16.52 %) and water holding capacity (13.55 %) in MS+ PVA+ Nano-bentonite-basil EO blend film. The surface morphology of this blend film appeared smooth, was thermally stable with the lowest mass loss (97.92 %), and exhibited the highest tensile strength (182.15 Kg/cm2) which makes it suitable for food packaging applications. Furthermore, all the prepared films were fully degraded in the soil after 147 days except the control cling film. The addition of EOs enhanced the antimicrobial activity of starch blend films with the highest inhibition against Gram-positive microorganisms (Staphylococcus aureus and Listeria monocytogenes). Packaging of freshly harvested button mushrooms with nanocomposite blend film enhanced the shelf-life up-to 14 days of storage under refrigerated conditions (4 °C) with the lowest physiological weight loss (4.69 %) and highest firmness (1.5 Kg F). Nutritional qualities and ROS-mitigating enzymatic activity of mushroom fruiting bodies were also maintained through packaging. This innovative nanocomposite packaging films could provide a green, environment-friendly, and antimicrobial system to combat the shorter shelf life of button mushrooms.

Polyphenolic truxillic acid crosslinked sodium alginate film with notable antimicrobial and biodegradable properties for food packaging

This work demonstrated an innovative antimicrobial and biodegradable food packaging film CBDA-10-SA which was prepared by crosslinking a natural polyphenolic truxillic acid (cyclobutane-dicarboxylic acid, CBDA-10) and sodium alginate (SA). The CBDA-10-SA film exhibited improved tensile strength (148 MPa) and UV shielding capabilities. The maximum thermal decomposition temperature was achieved of 249 °C. Compared to SA film, CBDA-10-SA showed increased antibacterial activities. In food packaging test, the CBDA-10-SA inhibited the rapid growth of potential of hydrogen (pH) value, slowed down the weight loss, reduced total plate count (TPC) value of pork, and delayed the spoilage process of pork. Notably, CBDA-10-SA displayed remarkable degradability in soil, with 60 % degrading in four weeks. In this study, CBDA-10-SA showed enhanced physicochemical and mechanical properties compared to traditional SA film. Those improvements make it anticipated to be used in not only food packaging but also mechanical, pharmaceutical, and agricultural fields.

Macroscopic preparation of polylactic acid/graphene composite fiber film with efficient antibacterial and thermal properties

AbstractPhotothermal antibacterial composite membranes have a broad range of clinical applications such as wound dressing, drug delivery, and physiotherapy. However, existing photothermal antimicrobial films have limitations related to biosafety, stability, and degradability. Herein, we develop an environmentally‐friendly composite membrane with antibacterial properties, photothermal conversion capability, and facile processing. The composite membrane film is comprised of polylactic acid (PLA) with graphene (G) and is synthesized via melt co‐blending and hot pressing. We verify that graphene is uniformly dispersed in the PLA phase, and an antibacterial rate of 99.7% can be achieved by a PLA/G composite membrane with only 3.0 wt.% graphene added. Moreover, the obtained films exhibit efficient photothermal conversion, reaching thermal treatment temperatures (40–60°C) within 10 s and maintaining temperature stability for extended periods. Additionally, the composite fiber film exhibited a tensile strength of 3.5 cN/dtex and good hydrophobicity (&gt;90° contact angle). The combination of antibacterial properties, efficient photothermal conversion, noninfiltration, high strength, hydrophobicity, and mechanical stability, along with the inherent degradability of PLA and the scalability of the synthesis process for mass production, offer broad application prospects for PLA‐based composite materials.

Photocatalytic Ag-MOF confers efficient antimicrobial activity to modified polyvinyl alcohol films

Antimicrobial packaging films are an effective means to avoid food infections. PVA has good film-forming and mechanical properties, but its water resistance and antimicrobial properties are insufficient. In this study, a rod-shaped Ag-MOF with photocatalytic properties was synthesized as an antimicrobial agent by a hydrothermal method using citrate esterified PVA as a film-forming substrate. The MICs of Ag-MOF against Escherichia coli and Staphylococcus aureus were 16 μg/mL and 32 μg/mL, respectively, and it had good biocompatibility. Under blue light irradiation, Ag-MOF induced the production of ROS, which increased the inhibition rate by more than 83.78%. The antimicrobial mechanism experiments showed that it caused irreversible damage to the bacterial cell membrane through the synergistic effect of Ag+ and ROS. The best mechanical properties of the films were obtained at 3% citric acid content, with the water vapor transmission rate, water solubility and swelling rate reduced by 0.19 g·mm·m−2·h−1·kPa−1, 65.33% and 11.26%, respectively. The antimicrobial rate of the composite film could reach more than 98% by adding only 1 MIC of Ag-MOF. In conclusion, photocatalytic antimicrobial agents have great potential for application in food packaging.

Antimicrobial guar gum films optimized with Pickering emulsions of zein-gum arabic nanoparticle-stabilized composite essential oil for food preservation

In this study, composite essential oil Pickering emulsion stabilized with zein-gum arabic (GA) nanoparticles (ZGCEO) was prepared to improve the characteristics of guar gum (GG) films. ZGCEO exhibited commendable stability and compatibility with GG, while leading to a noticeable improvement in the light barrier (from 3.98 A mm−1 to 17.09 A mm−1) and water vapor barrier characteristics of GG films, concomitantly mitigating their hydrophilic nature, with decreasing moisture content (from 17.70 % to 10.50 %), water solubility (from 84.41 % to 71.79 %), water vapor permeability (from 5.64 × 10−11 g (m s Pa)−1 to 4.97 × 10−11 g (m s Pa)−1), and an increasing water contact angle (from 69.8° to 94.2°). The addition of 2 % ZGCEO yielded a notable increase in the tensile strength of the GG-ZGCEO films, but the elongation at break decreased with increasing ZGCEO concentration. Moreover, the incorporated ZGCEO demonstrated outstanding antioxidant and antimicrobial characteristics, featuring a slow-release behavior of essential oil. The GG-ZGCEO coating also showed an excellent preservation effect in pork and “Huangguan” pears during storage. Collectively, we substantiated the efficacy of ZGCEO in augmenting the functional attributes of GG films, thereby establishing their potential utility as antimicrobial packaging materials conducive to food preservation.

Development of poly(lactic acid)-based natural antimicrobial film incorporated with caprylic acid against Salmonella biofilm contamination in the meat industry

Using a solvent-casting method, a poly(lactic acid) (PLA) film incorporated with caprylic acid (CA) was developed as an active packaging against Salmonella enterica ser. Typhimurium and S. enteritidis to reduce the risk of microbial contamination during distribution and storage of meat. According to the minimum inhibitory concentration (MIC) test results of the natural antimicrobial, CA was introduced at 0.6, 1.2, 2.4, and 4.8 % (v/v) into neat PLA. The biofilm inhibitory effect and antimicrobial efficacy of CA-PLA film against both Salmonella strains, as well as the intermolecular interactions and barrier properties of CA-PLA film, were evaluated. Biofilm formation was reduced to below the detection limit (<1.0 log CFU/cm2) for both S. typhimurium and S. enteritidis when co-cultured overnight with 4.8 % CA-PLA film. The 4.8 % CA-PLA film achieved maximum log reductions of 2.58 and 1.65 CFU/g for S. typhimurium and 2.59 and 1.76 CFU/g for S. enteritidis on inoculated chicken breast and beef stored at 25 °C overnight, respectively, without any quality (color and texture) losses. CA maintained its typical chemical structure in the film, as confirmed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra. Furthermore, film surface morphology observations by field emission scanning electron microscopy (FESEM) showed that CA-PLA film was smoother than neat PLA film. No significant (P > 0.05) changes were observed for water vapor permeability and oxygen permeability by the addition of CA into PLA film, suggesting that CA-PLA film is a promising strategy for active packaging to control Salmonella contamination in the meat industry.