Antimicrobial effects of pulsed light activated TiO₂-Polylactic acid film

A study was conducted to evaluate the antimicrobial effect of TiO₂ incorporated polylactic acid (PLA) films, activated by pulsed light (PL). TiO₂-PLA films with 0, 0.5, 5, 10, and 20 % TiO₂/PLA ratio were developed by the solvent casting method. Populations of Escherichia coli and Listeria on film surfaces were determined after the films were PL-treated in three ways: PL treatment on the inoculated film surface; PL treatment from the reverse side of the inoculated film surface; PL treatment before the inoculation on the film surface. A 5 s PL treatment reduced E. coli populations on PLA film from 6.2 to 2.5 log CFU/cm² and on TiO₂-PLA film from 6.2 to 1.1 log CFU/cm², indicating the combined antibacterial effect of PL and TiO_2. Light-activated TiO₂-PLA films maintained antibacterial activity against E. coli and L. innocua for 2 h after the 5 s PL treatment, as the activated TiO₂-PLA films were still able to reduce bacterial populations by up to 2.5 log CFU/cm². These findings suggest that pre-activated TiO₂-PLA films have potential for packaging foods that are sensitive to UV light.