Antimicrobial biodegradable film based on corn starch/Satureja khuzestanica essential oil/Ag–TiO2 nanocomposites

Abstract

Biosynthesis of nanoparticles (NPs) using plant extract is an eco-friendly method, in which natural materials are used and is a simple, non-toxic, and environmentally friendly green synthesis. In this study, corn starch (CS) film containing Satureja khuzestanica essential oil (SEO) and Ag–TiO2 nanocomposites (size: nearly 30–60 nm) were prepared and its antimicrobial, morphological, physical, and mechanical characteristics were investigated. Ag–TiO2 nanocomposites with different molar percentages were synthesized by S. khuzestanica extract and based on the best antibacterial results against Gram-negative bacteria (Escherichia coli ATCC 25922 and Salmonella typhimurium ATCC 14028) and Gram-positive bacteria (Staphylococcus aureus ATCC 25923), were chosen to prepare the films. Four types of biodegradable films were provided: simple CS film, the film incorporated with SEO (essence film), the film incorporated with Ag–TiO2 nanocomposites (nanofilm), and nano/essence film. The scanning electron microscopy (SEM) was employed for investigating the morphology of the films. The combined energy-dispersive x-ray spectroscopy with SEM was applied to analyze the near-surface elements. Physical characteristics of the films containing water vapor permeability (%) and their moisture content, mechanical tests, and antibacterial properties were examined. Antimicrobial evaluation of the films revealed a 3–4 log and 6–7 log (CFU ml−1) reduction in S. aureus and E. coli species respectively, compared to the control group. The bio-polymer film incorporated with extracted essential oil of S. khuzestanica and Ag–TiO2 nanocomposites are effective to package foods and can delay chemical, physical, and microbial spoilage.