Treated tomatoes were placed in individual sterile stomacher bags containing 20 ml of
universal preenrichment broth (Becton, Dickinson and Company, Sparks, MD). Tomatoes were
manually shaken for 30 s, hand-rubbed for 30 s at the inoculation spot, and shaken for another 30
s. Serial dilutions were made using 9 ml of universal preenrichment broth and dilutions were
spiral plated (Autoplate 4000; Spiral Biotech, Inc., Bethesda, MD) onto TSAR. All plates were
incubated at 35°C for 24 h before enumerating surviving Salmonella. Negative control tomatoes
were plated on both TSA and TSAR plates to check for background microflora.