Development and Characterization of Antimicrobial Nisin/MMT K10/AgNPs Nanocomposite Coatings on Oxygen Plasma Surface-Modified Polypropylene for Food Packaging Applications

In this study, the antimicrobial nisin nanocomposites were prepared by the addition of silver nanoparticles along with varying concentrations of montmorillonite K10 nanoclay into nisin. These nanocomposites were coated on the oxygen plasma surface-modified polypropylene (PP). The coated film was characterized by various techniques, and the novelty of this research work lies in the use of nisin, AgNPs, and MMT K10 which led to positive effects on various properties in food packaging applications. The thickness of the nisin-based coated nanocomposites was calculated by scanning electron microscopy. The functional groups and dispersion of nano clays in the preparation of nisin-based bio nanocomposites were analysed via Fourier transform infrared spectroscopy and X-ray diffraction spectroscopy. Contact angle analysis was used to determine whether the wettability of the coated samples increased due to the addition of AgNPs. The surface colour and opacity were found to be enhanced after the inclusion of MMT K10 and AgNPs. Nisin with 5 wt% MMT K10 nano clay and AgNPs coating provided promising barrier properties such as a low oxygen transmission rate of 369.65 cc/m².day.atm and a low water vapour transmission rate of 1.72 g/m².day. Additionally, the same concentration had the best tensile strength (13.14 MPa) and coating adhesion strength (8.1 N/cm) which were better than those of the other various concentrations. The antimicrobial properties of nisin nanocomposite-coated PP were evaluated against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) microorganisms. The nano migration of AgNPs from the coating was calculated by inductively coupled plasma‒mass spectrometry, and it was under the limit stated by European regulations. This high-performance nisin/MMT K10/AgNPs-coated PP film has potential practical applications in active food packaging.