Evaluation of pulsed light treatment for inactivation of Salmonella in packaged cherry tomato and impact on background microbiota and quality

Abstract The microbial safety of produce continues to be a real concern. The objective of this study was to investigate the efficacy of high intensity short time pulsed light (PL) application on survival of Salmonella in packaged cherry tomato. Treatment effects on reduction of native microbiota and quality were also evaluated. Stem scars of cherry tomatoes, inoculated with a three serotypes cocktail of Salmonella enterica, was treated with PL for up to 60 s. Polyethylene (PE) films of 25.4, 50.8 and 76.2 μm thickness were used for packaging treatment. A10 s treatment equivalent to a fluence dose of 10.5 J/cm 2 was considered optimum. Both packaged and direct PL treatments provided >1 log reduction of the pathogen in 10 s (10.5 J/cm 2 ). Direct treatment for 10 s resulted in 1.9 ± 0.17 log CFU/g reduction of Salmonella . For packaged tomatoes, log reductions decreased with increasing film thickness but not significantly ( p < .05). Also, no significant difference in PL decontamination efficacy between packaged and unpackaged tomatoes was observed. Treatment significantly reduced the initial populations of aerobic mesophilic bacteria (3.6 ± 0.31 log), molds and yeast (2.43 ± 0.22 log) by >1 log, respectively. Packaged tomatoes were softer after treatment but not significantly. Storage time did not affect fruit firmness. No significant change in the visual appearance of fruits were observed after treatment and during 14 days of storage. Overall, the results of this study demonstrate that high intensity short time PL treatment may be used to enhance microbial safety and reduce postprocessing contamination of packaged cherry tomato.