Reduction of salmonella on valencia oranges by cold plasma treatment

Authors: Niemira, Brendan; Hertrich, Sarah; Boyd, Glenn; Sites, Joseph

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/20/2018
Publication Date: 6/18/2018
Citation: Niemira, B.A., Hertrich, S.M., Boyd, G., Sites, J.E. 2018. Reduction of salmonella on valencia oranges by cold plasma treatment. Meeting Abstract. Volume 1, Page 1; International Conference on Plasma Medicine; June 2018.

Interpretive Summary:

Technical Abstract: Orange juice has been the source of recurrent food borne illness outbreaks, primarily associated with Salmonella. There is a need for antimicrobial interventions which can effectively eliminate pathogens from fruit surfaces and reduce the risk of cross-contamination during peeling and processing. To evaluate atmospheric pressure cold plasma as a means to inactivate Salmonella on peel-on oranges, Valencia oranges (n=9) were lab-inoculated with Salmonella Anatum on the peel, in the stem scar, or in the blossom end. The inoculated fruit were allowed to air dry for 2 hours to promote adherence before treatment with air-based, atmospheric pressure cold plasma, created with high-voltage electrical discharge. During treatment, the site of inoculation on the oranges was passed in and out of the plasma plume to simulate “tumbling” of oranges on a conveyor belt that are being exposed to cold plasma from above. Cold atmospheric pressure plasma (4 cubic feet/minute) was applied for 0 (control), 1, 3, or 5 minutes to the sites of inoculation on the oranges (stem scar, blossom scar, and peel). Oranges were treated at distances of 0 cm or 7.5 cm from the cold plasma emitter head. All treatments significantly (P<0.001) reduced Salmonella on oranges, on all surfaces tested. The 0 cm treatments yielded log reductions ranging from 0.94 – 2.09 (stem scar), 1.57 – 3.56 (blossom end), and 2.4 – 4.09 (peel), with longer treatment times yielding greater reductions. The 0cm were uniformly more effective than the 7.5 cm treatments, which yielded log reductions ranging from 0.15 – 1.57 (stem scar), 1.01 – 1.80 (blossom end), and 0.37 -1.22 (peel). Temperature measurements confirm plasma treatment as a nonthermal process. These results suggest cold plasma could be a waterless, chemical-free sanitation step for peel-on fruits such as Valencia oranges, and could serve as an in-line means to reduce the potential for cross-contamination.