Purpose: This study was conducted to determine the antimicrobial efficacy of emulsified clove bud oil (CBO) or thyme oils (TO) as a post-harvest wash for snacking peppers inoculated with Salmonella spp.
Methods: Oils were saponified and emulsified with gum arabic prior to dilution in wash water. Snacking peppers were spot inoculated with a five-serovar cocktail of Salmonella from human outbreaks. Peppers were washed for 2 min with water, 200 ppm chlorine, 0.2% or 0.5% CBO, 0.2% or 0.5% TO, or received no rinse (control). All treatments were applied after the addition of 1% pepper puree, which simulated organic loading of wash water with continuous use. Uninoculated peppers were subsequently washed in used treatment solutions to show if cross-contamination could be prevented. After washing, Salmonella was enumerated from inoculated and uninoculated peppers. Wash solutions were filtered (0.45 μm) for enumeration.
Results: On inoculated peppers, 0.5% TO (± organic loading) and 0.5% CBO resulted in up to 1 log CFU/g reductions in Salmonella spp. (p < 0.05). Chlorine, 0.5% CBO (± organic loading), and both 0.2% and 0.5% TO (± organic loading) prevented attachment by Salmonella to clean peppers to less than the limit of detection (-1 log CFU/g). No detectable Salmonella were recovered in wash solutions containing chlorine and 0.2% CBO (without organic loading), all TO treatments, and CBO at 0.5% (± organic loading).
Significance: Nanoemulsified essential oils may be suitable for use in organic produce wash systems to limit cross-contamination.