Evaluation of inoculation method and inoculum drying time for their effects on survival and recovery of foodborne pathogens inoculated onto raw vegetables and treated with chlorine

This study evaluated methods for inoculation and inoculum drying time on survival and recovery of foodborne pathogens on the surface of tomatoes, iceberg lettuce, and parsley. Five-strain mixtures of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes were applied to produce by dip, spot, or spray inoculation. Inocula were dried for 1 or 24 h at 22C on tomatoes or 2 h at 22C and 2 h followed by 22 h at 4C on lettuce and parsley before being treating with water or chlorine (200 g/ml). Results indicate that inoculation method, drying time, and treatment affect survival and/or recovery of pathogens inoculated onto the surface of tomatoes, lettuce, and parsley. It is recommended that spot inoculation be used for applying pathogens to produce and drying times be 24 h at 22C for tomatoes, and 2 h at 22C followed by 22 h at 4C for lettuce and parsley before chlorine treatment is applied.