Purpose: This study evaluated the efficacy of chlorine (200 ppm), peracetic acid (80 ppm), and chlorine dioxide (5 ppm) for inactivating Salmonella on mangoes and in wash water under simulated mango packing house conditions.
Methods: Nalidixic-acid resistant strains of Salmonella Montevideo, Salmonella Newport, Salmonella Baildon, Salmonella Braenderup, and Salmonella Poona were used in this study. Disinfectants were added to inoculated wash water (~ seven log CFU/ml). Mangoes (var. Ataulfo and Tommy Atkins) were washed under simulated dump tank wash (24°C for 2 min), hot water treatment (46°C for 75 and 110 min), and hydrocooling conditions (21°C for 30 min). Wash water and mangoes were collected at different times for microbiological analysis. Additionally, pH, temperature, and disinfectant concentration of wash water were monitored throughout the study.
Results: Chlorine (200 ppm) and PAA (80 ppm) were effective in completely inactivating Salmonella populations on mangoes and in wash water during dump tank wash, hot water treatment, and hydrocooling in the presence and absence of organic matter. However, mango and water samples were positive (<0.9 CFU/mango or wash water sample) for Salmonella following treatment with chlorine dioxide, which could be attributed to the sharp drop in its residual concentration upon addition to water.
Significance: This study showed that commonly used disinfectants, chlorine and PAA were effective in controlling Salmonella in wash water and on mango surfaces. However, regular monitoring and replenishment of the disinfectant were critical to their sustained antimicrobial efficacy.