Polyethylene Films Containing Silver Nanoparticles for Applications in Food Packaging: Characterization of Physico-Chemical and Anti-Microbial Properties

Abstract

This paper reports the antibacterial effect and physico-chemical characterization of films containing silver nanoparticles for use as food packaging. Two masterbatches (named PEN and PEC) con- taining silver nanoparticles embedded in distinct carriers (silica and titanium dioxide) were mixed with low-density polyethylene (LDPE) in different compositions and extruded to produce plain films. These films were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). The morphology of the films showed the formation of agglomerates of nanoparticles in both PEN and PEC composites. X-ray analyses confirmed the presence of SiO2 in PEN samples and TiO2 in PEC samples. Thermal analyses indicated an increase in thermal stability of the PEC compositions. The antimicrobial efficacy was determined by applying the test strain for Escherichia coli and Staphylococcus aureus, according to the Japanese Industrial Standard Method (JIS Z 2801:2000). The films analyzed showed antimicrobial properties against the tested microorganisms, presenting better activity against the S. aureus than E. Coli. These findings suggest that LDPE films with silver nanoparticles are promising to provide a significant contribution to the quality and safety of packaged food.

Increasing the shelf life of pikeperch (Sander lucioperca) fillets affected by low-density polyethylene/Ag/TiO2 nanocomposites experimentally produced by sol-gel and melt-mixing methods

“…Similar to this study, Zhang and Chen [37] applied Ag (7.4 wt%)/TiO 2 NPs as the anti-bacterial compound for cultures of E. coli (10 5 CFU/mL) and confirmed that treatment with TiO 2 (200 µg/mL) produced only weak growth inhibition, while growth was remarkably prohibited when Ag was added. [38] Mihaly Cozmuta and colleagues [12] documented that fresh lettuce packaging composed of one polypropylene/TiO 2 decreased E. coli contamination from 6.4 to 4.9 log CFU/g after 1 day, while that of the control group decreased from 6.4 to 6.1 log CFU/g. It was concluded that applying LDPE/Ag/TiO 2 nanocomposite films produced through the meltmixing and sol-gel methods is beneficial for fish packaging in terms of inactivate representative pathogens including E. coli, S. aureus, C. albicans, and A. niger.…”

Facile fabrication of polyethylene/silver nanoparticle nanocomposites with silver nanoparticles traps and holds early antibacterial effect

“…The incorporation of AgNPs in polymers such as plastics [e.g., polyethylene (PE), polypropylene (PP), polystyrene, and poly(vinyl chloride)] to form nanocomposites is always interesting because of their possible antibacterial activity in combination with the mechanical properties of conventional plastics . Various silver nanocomposites have been reported as suitable for antimicrobial packaging . However, the development of techniques for producing AgNPs with enhanced antibacterial activity with the aim of mass production in some countries is still challenging.…”

“…There are three basic methods for producing nanocomposites: (1) melt compounding, (2) solution blending, and (3) in situ polymerization . Melt compounding is suitable for producing PE or PP silver nanocomposites with raw high‐density polyethylene (HDPE) and low‐density polyethylene (LDPE) or PP materials in which the final nanocomposites will be produced by compression‐molding equipment. A bottleneck for this type of silver nanocomposite production is the introduction of AgNPs into the PE or PP matrix.…”

“…This influences the antibacterial activity of the nanocomposites and is critical. AgNPs can be first immobilized on SiO 2 or TiO 2 to form colloidal SiO 2 /AgNPs and TiO 2 /AgNPs, and then, these are mixed with LDPE granules to form AgNPs/PE nanocomposites after melting/blending . In case of an AgNPs/PP nanocomposites, the colloidal AgNP solution is diluted with ethanol and directly mixed with PP granules and extruded to give the product .…”

Applications of Nanomaterials in Food Packaging

“…35 AgNPs can be also directly dispersed into the polymer matrix of the plastic. [36][37][38] Figure 1. Schematic representation of the proposed antimicrobial mechanism of AgNP.…”