Strategies to enhance fresh produce decontamination using combined treatments of ultraviolet, washing and disinfectants

摘要

This study investigated the effect of a water-assisted ultraviolet system (WUV; samples were treated by UV while being immersed in agitated water) on the inactivation ofSalmonellaon baby spinach, iceberg lettuce, blueberry, grape tomato, and baby-cut carrot. TheSalmonellainactivation effect of the WUV system was tested in two scales, and three disinfectants, chlorine, peroxyacetic acid (PAA) and hydrogen peroxide (H2O2), were tested in combination with the system to see whether theSalmonellainactivation effect could be enhanced. The fresh produce samples were dip-inoculated with aSalmonellacocktail to final concentrations of 4.6–7.6?log?CFU/g. To simulate the washing process in the industry, fresh produce extracts and/or silicon dioxide were added in the wash water to adjust chemical oxygen demand to ~2000?mg/L and turbidity to >60?NTU. In general, the decontamination efficacy of WUV treatments followed this order: Tomato?>?Carrot?>?Lettuce?≈?Blueberry?>?Spinach. In the small-scale study, WUV alone was able to achieve 0.9, 2.6, >3.6, 1.7, and 2.0?log?CFU/g reductions ofSalmonellaon fresh produce for spinach, lettuce, tomato, blueberry, and carrot, respectively. For all fresh produce items, WUV combined with PAA could achieve significantly (P??0.05) higherSalmonellareduction on fresh produce than chlorine wash and PAA wash. The WUV treatments combined with chlorine or PAA were able to keep residualSalmonellain wash water below the detection limit (2?CFU/mL) for almost all the replicates. SimilarSalmonellareductions on fresh produce and in wash water were found in the large-scale study. Considering the decontamination efficacy on fresh produce, the ability to disinfect the wash water, and the cost, we recommend chlorine wash for baby spinach, WUV alone for grape tomato and WUV combined with PAA for iceberg lettuce, blueberry and baby-cut carrot.