Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 2/16/2018
Publication Date: N/A
Technical Abstract: Introduction: Fresh fruits such as oranges are an increasingly popular food, consumed directly or as ingredients in “raw” juice blends prepared at home or commercially at the point of consumption. However, because of past outbreaks associated with orange juice, and the risk of cross-contamination during peeling and processing, there is a need for antimicrobial interventions which can effectively eliminate pathogens from fruit surfaces. Purpose: To evaluate atmospheric pressure cold plasma as a means to inactivate Salmonella on peel-on oranges. Methods: Valencia oranges (n=9) were lab-inoculated with Salmonella Anatum on the peel, in the stem scar, or in the blossom end, and allowed to air dry for 2 hours to promote adherence. The oranges were treated 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. The site of inoculation on the oranges (stem scar, blossom scar, and peel) were treated with 4 cubic feet/minute atmospheric cold plasma for 0 (control), 1, 3, or 5 minutes, at distances of 0 cm or 7.5 cm from the cold plasma emitter head. Results: 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. Significance: These results suggest cold plasma could be a waterless, chemical-free sanitation step for peel-on fruits such as Valencia oranges.