P1-198 Essential Oil Nanoemulsions as Post-harvest Wash Solutions on Snacking Peppers

Monday, July 10, 2017
Exhibit Hall (Tampa Convention Center)
Laurel Dunn , University of Tennessee, Department of Food Science , Knoxville , TN
Marion Harness , University of Tennessee, Department of Food Science , Knoxville , TN
Dara Smith , University of Tennessee, Department of Food Science , Knoxville , TN
Stuart Gorman , University of Tennessee, Department of Food Science , Knoxville , TN
Alexis Hamilton , University of Tennessee, Department of Food Science , Knoxville , TN
P. Michael Davidson , University of Tennessee, Department of Food Science , Knoxville , TN
Qixin Zhong , University of Tennessee, Department of Food Science , Knoxville , TN
Faith Critzer , University of Tennessee, Department of Food Science , Knoxville , TN
Introduction: Consumer-driven demand for organic produce has resulted in increased research on alternative post-harvest wash solutions to control pathogens. Chlorine is a widely used compound due to low cost and antimicrobial efficacy. However, consumers and organic growers are interested in naturally sourced alternatives, such as essential oils, not only to reduce cross-contamination in a wash system, but also to inactivate attached pathogens, something chlorine does not readily do.

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.