Salmonella population to rebound in humid storage

The uninterrupted cold storage is a key factor for safer produce operations
The potential of Salmonella population to rebound on non-washed and washed roma tomatoes and jalapeño peppers in humid storage at 4°C, 10°C, 15°C, 21°C, or 35°C for ≤12 days was investigated.
The initial inoculation levels of Salmonella on peppers and tomatoes were 5.6 and 5.2 log CFU/cm2, respectively. Air-drying of fruit surfaces resulted in contamination levels of 3.9 and 3.7 log CFU/cm2 on inoculated peppers and tomatoes, respectively. At 21°C and 35°C, the levels of air-dried Salmonella inoculums on produce surfaces increased ≥2 log cycles, with the most rapid growth in the first 3 days.
Mechanical washing on rollers (rinsing; R-treatment) or revolving brushes (rinsing and brushing; RB-treatment) with water decreased Salmonella counts by ≥2.5 log CFU/cm2 on both peppers and tomatoes. After R- or RB-treatment, peppers stored at 21°C and 35°C permitted residual Salmonella (≤1.4 log CFU/cm2) to grow to 2.6–3.9 log CFU/cm2. During storage, residual Salmonella (≤1.0 log CFU/cm2) on washed tomatoes increased to 3.1 log CFU/cm2 at 35°C following R-treatment and 3.8 log CFU/cm2 at 21°C following RB-treatment.

Cold storage at 4°C and 10°C effectively prevented the proliferation of Salmonella on both washed and non-washed produce. The current study on jalapeño peppers and roma tomatoes demonstrated that Salmonella population can rebound on produce in humid storage before or after washing. The finding highlights the benefit of uninterrupted cold storage for safer produce operations.

Source: http://www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1002647
Foodborne Pathogens and Disease, April 2012, 9(4): 361-366