Purpose: To determine whether brush washing tomatoes increases the survivability of human (Salmonella spp.) or plant pathogens (Pectobacterium carotovorum) on tomatoes.
Methods: Mature green tomatoes were brush treated with water or 100 ppm NaOCl (pH 6.5) for 0, 15, or 60 s, then inoculated with rifampin-resistant Salmonella spp. or Pectobacterium at 8 log CFU/tomato and stored at 25°C 75-85 %RH for 7 days. To model survival on wounded fruit, other tomatoes were superficially punctured at 10 points then inoculated directly into the punctures with each culture independently (at either a 2 or 8 log CFU/tomato level) then stored under the same conditions. For all studies, tomatoes were sampled at days 0, 1, 3, and 7 using the rub-shake-rub method in 100 ml BPW, followed by plating on TSA+rifampin.
Results: Brush treatment did not have a significant impact on the survival of either pathogen; Salmonella and Pectobacterium populations decreased to below the detection limit of 2 log CFU/tomato within the first 3 days for all treatments. When wounded fruit were inoculated at low levels (2 log CFU/tomato), both cultures grew to and maintained near a 5.8 log CFU/tomato level. At high inoculation levels (8 log CFU/tomato), Salmonella cultures maintained near 8 log CFU/tomato for 7 days, whereas Pectobacterium grew to above 11 log CFU/tomato.
Significance: These results suggest that brush washing does not compromise tomato surfaces in such a way to allow enhanced survival of Salmonella spp. or Pectobacterium carotovorum.