Development of Pomegranate Peel Extract and Nano ZnO Co-Reinforced Polylactic Acid Film for Active Food Packaging

The multifunctional packaging used for fresh food, such as antioxidant and antimicrobial packaging, can reduce food waste. In this work, a polylactic acid (PLA)-based composite film with antioxidant and antibacterial properties was prepared by using nano-zinc oxide (ZnONPs) and pomegranate peel extract (PEE) via the solvent-casting method. Different amounts of PEE (0.5, 1, 1.5 and 2 wt%) and 3 wt% ZnONPs were added to PLA to produce the active films. The results of various characterizations (SEM, XRD, etc.) showed that ZnONPs and PEE were uniformly dispersed in PLA film. Compared to PLA films, the PLA/ZnONPs/PEE films showed an increased UV barrier, water vapor permeability and elongation at break, and decreased transparency and tensile strength. In addition, the antioxidant activity of the composite film was evaluated based on DPPH and ABTS. The maximum DPPH and ABTS scavenging activities of PLA/ZnONPs/PEE were 96.2 ± 0.8% and 93.1 ± 0.5%. After 24 h, PLA/ZnONPs/PEE composite film inhibited 1.4 ± 0.05 Log CFU/mL of S. aureus and 8.2 ± 0.35 Log CFU/mL of E. coli, compared with the blank group. The results showed that PLA/ZnONPs/PEE composite film had good antibacterial and antioxidant activities. Therefore, the composite film showed great potential for food packaging.