Sequential Application of Peracetic Acid and UV Irradiation (PAA-UV/PAA) for Improved Bacterial Inactivation in Fresh-Cut Produce Wash Water

Wash water disinfection is a critical step in fresh-cut vegetable processing to reduce water-mediated microbial cross-contamination. This study investigated peracetic acid (PAA), UV irradiation (UV), and the combination of PAA and UV concurrently (UV/PAA) or sequentially (PAA-UV/PAA) as novel disinfection strategies to treat fresh-cut produce wash water by using generic Escherichia coli as a surrogate of pathogenic bacteria. Evaluating the disinfection kinetics under PAA, UV, and UV/PAA revealed that the reactive radicals generated under UV/PAA did not obviously contribute to the inactivation of E. coli in produce wash water with high organic content. Light shielding caused by the wash water matrix hindered E. coli inactivation under UV or UV/PAA. In contrast, the PAA-UV/PAA process was negligibly impacted by the water matrix due to the advantage of PAA diffusion into bacterial cells prior to UV exposure. Furthermore, PAA-UV/PAA is more energy-efficient compared to UV/PAA. To achieve a 4 log E. coli reduction, 3.8, 10.1, and 12.1 J center dot L-1 UV energy was required for PAA-UV/PAA, UV/PAA, and UV, respectively. This study suggests the sequential application of PAA-UV/PAA as a favorable disinfection strategy in fresh-cut produce wash water disinfection owing to high disinfection efficacy, superior performance stability, and low risk of disinfection byproduct formation.