Development and characterization of antimicrobial active packaging enriched with thyme essential oil based on starch

Abstract

This article aims to find solution to the problem of environmental pollution caused by synthetic packaging waste by improving the functional specifications of starch films with antimicrobial properties. In this study, starch-based biodegradable films infused with thyme essential oil were developed and characterized for their structural, mechanical, and antimicrobial properties. The processing technique—solution casting—was employed to produce packaging materials suitable for food applications. Vacuum degassing significantly improved film thickness consistency, surface homogeneity, and overall integrity compared to ultrasonic homogenization. Contact angle measurements showed increased surface hydrophobicity from 38° (control) to 56° with thyme oil addition, indicating enhanced moisture barrier properties. Mechanical testing revealed that higher oil concentrations reduced tensile strength (from 1.63 to 0.68 MPa) while increasing flexibility (from 31.70% to 53.87%). Antimicrobial assays demonstrated concentration-dependent inhibition against Bacillus subtilis, Escherichia coli, and Candida albicans. B. subtilis showed complete suppression in control and 1% oil films, with inhibition zones increasing to 1.5 mm (2%) and 16 mm (3%). E. coli exhibited progressive sensitivity, reaching 5 mm at 3% oil concentration, while C. albicans showed modest inhibition up to 2.25 mm. Overall, this research presents a scalable and eco-friendly solution for biodegradable packaging, combining structural versatility with antimicrobial protection.