Biodegradable zein active film containing chitosan nanoparticle encapsulated with pomegranate peel extract for food packaging

The aim of the study was to prepare zein active film incorporated with pomegranate peel extract (PE) encapsulated in chitosan nanoparticles (CSNPs) for food packaging. Ultrasonic treatment was employed to enhance the polyphenols extraction from pomegranate peel using ethanol and methanol as extraction solvents. The ionic gelation method was employed to prepare the CSNPs/PE nanocomposite and was successfully incorporated into the zein film. The obtained CSNPs and CSNPs/PE nanocomposite exhibited spherical shape in the range of 225.28-289.8 nm as observed by scanning electron microscope (SEM) and dynamic light scattering (DLS) device. The success of PE encapsulation and molecular interactions between zein, CSNPs, and PE was confirmed by FTIR and XRD studies. Cold nitrogen plasma was applied to modify film surface to maintain the sustained release of pomegranate polyphenols from the nanocomposite film. The surface modification of nanocomposite film was further disclosed with an X-ray photoelectron spectroscopy (XPS) study. Thermogravimetric (TGA) and differential scanning calorimetry (DSC) studies revealed that zein/CSNPs/PE nanocomposite film had better thermal stability than the neat zein film. Antimicrobial property of zein/CSNPs/PE nanocomposite film was investigated for pork sample inoculated with L. monocytogenes. Plasma treated nanocomposite film displayed a slower release rate of PE and effectively restricted the growth of L. monocytogenes than the control film and plasma untreated nanocomposite film during refrigerated storage.