ScholarWorks@중앙대학교

초록

Considering the foodborne pathogens on fresh-cut fruits and limited information regarding differences in pathogen sensitivity to ultraviolet light-emitting diode (LED) irradiation, we evaluated the efficacy of 275 nm LED irradiation against Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes in phosphate-buffered saline (PBS) and on fresh-cut apples. The color and nutritional quality of irradiated apples was also assessed. E. coli O157:H7 was reduced to below the detection limit (1.0 log CFU/mL) at 20 mJ/cm2, while Salmonella spp. and L. monocytogenes were reduced by 6.2 and 6.6 log CFU/mL, respectively, at 24 mJ/cm2 in PBS. Sensitivity to LED irradiation was the highest in Salmonella spp., followed by E. coli O157:H7 and L. monocytogenes. Notably, Salmonella spp. and E. coli O157:H7 showed higher cyclobutane pyrimidine dimer (CPD) formation upon irradiation than L. monocytogenes, consistent with their greater inactivation. On fresh-cut apples, bacterial reduction ranged from 2.5 to 2.8 log CFU/cm2 at 20 mJ/cm2 to 3.6–4.2 log CFU/cm2 at 120 mJ/cm2, with no significant difference in inactivation among pathogens. Pathogen growth on both irradiated and non-irradiated apples at 20 mJ/cm2 was only observed at 25 °C but not at 4 °C or 10 °C over 72 h. Apple color or nutritional quality were not affected by irradiation. Overall, the sensitivity of bacteria to 275 nm UV-LED irradiation was mainly associated with CPD formation in DNA. This treatment can improve the microbial safety of fresh-cut apples by effectively inactivating major foodborne pathogens without affecting their color and ascorbic acid and total phenolic contents.

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