Combined 222 nm far UV-C and ultrasound treatment for controlling soft rot bacteria on various fresh produce

초록

Pectobacterium carotovorum subsp. carotovorum and Dickeya chrysanthemi are the major soft rot bacteria that decompose the cell walls of fresh produce, leading to considerable socio-economic losses. This study evaluates the bactericidal efficacy of a combination system integrating a 222 nm UV-C krypton-chlorine excimer lamp with 20 kHz ultrasound generators on the surface of various fresh produce (sweet potato, potato, Chinese cabbage, iceberg lettuce, paprika, and tomato) and in the wash water. This combination treatment had significantly higher (P < 0.05) decontamination efficacy of 1-2 log colony-forming unit (CFU)/sample, than each treatment alone regardless of type of sample. When inoculated samples were treated with the combination system for 5 min, populations of soft rot bacteria in wash water were under the detection limit. After ultrasound treatment alone, more than 4.00 log CFU/ml survived in the wash water, and after excimer lamp treatment alone were below 1.50 log CFU/ml. The developed combination system effectively inactivated soft rot bacteria on fresh produce surfaces and in wash water, minimizing the risk of recontamination. To quantitatively compare the inactivation efficiency across different produce types, the treatment time required for a 3-log reduction (T3d) was calculated using the Weibull model. Fresh produce that had lower contact angle values and higher surface roughness values required more T3d. Combination treatment for 5 min did not produce significant differences (P > 0.05) in the texture or color properties between the untreated and treated groups. The developed combination system offers a novel and effective solution for controlling soft rot bacteria, and is expected to contribute to the stable production and distribution of fresh produce. © 2026 Elsevier Ltd

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