Application of pulsed light (PL)-surfactant combination on inactivation of Salmonella and apparent quality of green onions

- PL-surfactant (SDS) combination decontaminated Salmonella on green onions.
- PL--SDS showed synergistic effect on green onion leaves decontamination.
- PL-SDS maintained significantly lower survival population during 15 days storage.
- PL-1000 ppm SDS had negative impact on color and texture of green onion leaves during storage.
- SDS at 10 ppm was suggested with PL for decontamination to protect the quality.

In our previous study using pulsed light (PL) and PL-sanitizer/surfactant to inactivate Escherichia coli O157:H7 on green onions, the combination of PL and 1000 ppm of surfactant (sodium dodecyl sulfate, SDS) was more effective than single treatments. In this study, whether PL-surfactant combination would provide similar inactivation efficacy of Salmonella on green onions was tested. Different surfactants (SDS and Tween 80) as well as different concentrations (10, 100 and 1000 ppm) of each surfactant combined with PL were tested. Survival populations of Salmonella and quality of green onions (color and texture) were evaluated after treatments as well as during storage (15 days) at 4 °C. The results showed that PL-SDS and PL-Tween 80 combinations at various surfactant concentrations provided synergistic inactivation efficacy on green onion leaves (2.6-2.9 log10 CFU/g and 2.4-2.7 log10 CFU/g, respectively), but not on their stems (0.4-1.0 log10 CFU/g and 0.3-0.6 log10 CFU/g, respectively). PL-1000 ppm SDS combination negatively impacted color and texture of green onions during 15 day storage at 4 °C. To consider both safety and quality of green onions, PL-10 ppm SDS was selected since it showed similar Salmonella inactivation on green onions as PL-1000 ppm SDS but did not affect quality of green onions during shelf-life.