Purpose: The objectives of this study were to determine specific locations on iceberg lettuce coring tools prone to attachment by Salmonella and evaluate efficacy of sanitizers on these tools.
Methods: Three different designs (original and modified) of coring tools were inoculated with Salmonella Newport overnight culture (8 log CFU/ml) and treated with deionized water (DI water), 50 ppm bleach, 3% hydrogen peroxide, 5% Chico wash, 0.1% Oregano oil, or 0.4% SaniDate 5.0 for 5 min. Four locations on tools were sampled before and after treatment for enumeration of surviving Salmonella.
Results: Salmonella populations of 6.35±0.26, 6.31±0.10 and 6.26±0.25 log CFU/cm2 attached onto the original, modified design 1, and modified design 2 coring tools, respectively. Locations 1 and 4 on the original tool had the highest populations of Salmonella, 6.47±0.18 and 6.64±0.20 log CFU/cm2, respectively. When comparing the efficacy of sanitizers, SaniDate® had the highest Salmonella reductions of 5.86±0.58-6.23±0.28 log CFU/cm2. Treatments with 3% H2O2 and 0.1% oregano oil were comparable which yielded reductions of 5.82±0.38 and 5.68±0.39 log CFU/cm2, respectively. The average reductions due to 50 ppm bleach were 2.72±0.69-3.65±1.65 log CFU/cm2. The wash water after treatment with each sanitizer was sampled after enrichment to check for Salmonella survivors; however, no survivors were detected (except DI water) suggesting that these organic sanitizers and plant antimicrobial have bactericidal effects on Salmonella.
Significance: The results indicate that organic sanitizer SaniDate and plant antimicrobial oregano oil, showed better efficacy against Salmonella on coring tools compared to 50 ppm bleach. The results could provide guidelines regarding the areas on coring tools that may require rigorous sanitization and also suggest potential alternative organic sanitizers that could be more effective than those currently used against Salmonella for application on coring tools.