Enhancing physicochemical and antibacterial properties of pectin-based films via PA-Zn nanoparticle doping for antimicrobial food packaging application

Abstract

Maintaining food integrity and preventing microbial contamination are critical concerns in the food industry. The emergence of nanotechnology has opened new avenues for the development of antimicrobial food packaging materials. In this study, we have harnessed the power of nanozymes (PA-Zn), composed of zinc acetate dihydrate and pyrogallol, to enhance the properties of pectin-based composite biodegradable films (P/ZP). The P/ZP was systematically evaluated for its mechanical, barrier, and antimicrobial properties, as well as its potential for food preservation, with varying concentrations of PA-Zn (1 %, 3 %, 5 %, and 7 %) incorporated into the matrix. The addition of 1 % PA-Zn increased tensile strength from 2.25 MPa to 2.60 MPa and elongation at break from 40 % to 50 %, whereas higher concentrations induced nanoparticle aggregation and reduced mechanical performance. Under light, the film with 7 % PA-Zn exhibited strong antibacterial activity, with inhibition zone of 31 mm against MRSA and 26 mm against ESBL-E. coli; films with ≥3 % PA-Zn showed inhibitory effects without light. Oxygen permeability decreased with PA-Zn content, while water vapor permeability reached a minimum at 1 % PA-Zn before increasing due to aggregation. Furthermore, the films degraded completely into the soil within 14 days, unlike conventional plastic films which showed no remarkable degradation. These results demonstrate that PA-Zn-doped pectin films possess a balanced combination of strengthened mechanical properties, tunable antibacterial activity, improved barriers, and rapid biodegradability, highlighting their strong potential as sustainable, active packaging materials for enhancing food safety and extending shelf life.