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Combined treatment of UV-A radiation and acetic acid to control foodborne pathogens on spinach and characterization of their synergistic bactericidal mechanisms

Jeong, Yoon-Jae, Ha, Jae-Won
Food control 2019 v.106 pp. 106698
Escherichia coli O157, Listeria monocytogenes, Salmonella Typhimurium, acetic acid, antibacterial properties, bacteria, cell membranes, color, esterases, food pathogens, fresh produce, leaves, phenols, product quality, spinach, synergism, texture, ultraviolet radiation, virulent strains
This study was conducted to evaluate the antimicrobial effect of the combined treatment of UV-A radiation (UVA) and acetic acid (AA) against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on spinach leaves and to investigate the effect of this combined treatment on product quality. Spinach leaves inoculated with three pathogenic bacteria were treated individually or simultaneously with UV-A light and AA. Simultaneous application of UVA and AA for 90 min resulted in 3.50-, 3.29-, and 4.30-log CFU/mL reductions in E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, which involved 2.44-, 2.21-, and 3.42-log CFU reductions, respectively, and were attributed to the synergistic effect. To clarify the mechanism of this synergistic bactericidal effect, four mechanistic investigations were performed. Analyses showed that both damage to the bacterial cell membrane and intracellular esterase were closely related to the synergistic lethal effect. In addition, UVA-AA treatment for 90 min did not adversely affect the color, total phenols, and texture of spinach. These results suggest that a UVA-AA combined process could be an innovative antimicrobial intervention for fresh produce.