Sanitation of tomatoes based on a combined approach of washing process and pulsed light in conjunction with selected disinfectants

Abstract

In this study, we evaluated the performance of a large-scale decontamination system based on a washing process in combination with pulsed light (PL) exposure and H2O2/chlorine. In order to identify optimum processing condition, we first evaluated the effect of single and combined PL treatments on the inactivation of Salmonella on grape tomatoes using a small sample size of 50 g. Two inoculation methods, spot and dip, were used to simulate different contamination scenarios and two wash water quality, clear tap water and turbid tap water with extremely high levels of organic load and soil, were used to represent clean and very dirty wash water. In general, the combined PL-Chlorine and PL-H2O2 treatments were more or as effective as chlorine washing in killing Salmonella on grape tomatoes and were able to keep residual Salmonella in wash water below the detection limit of 2 CFU/mL. The PL alone and combined PL-H2O2 treatments were chosen and further tested for their decontamination efficacy under turbid wash water condition using large sample sizes, 300, 1000 and 2000 g. Sample size did not negatively affect the single and combined PL treatments on the inactivation of Salmonella on grape tomatoes. The combined PL-H2O2 treatment in general showed better inactivation effect of Salmonella on tomatoes than the PL alone treatment. Additionally, the combined PL-H2O2 treatment reduced Salmonella in turbid wash water below the detection limit of 2 CFU/mL in the majority of cases. In conclusion, the combined PL-H2O2 treatment could potentially be used as an environmentally friendly alternative to chlorine washing for tomato decontamination and cleaning.