M: Food Microbiology & Safety
Cold Plasma Rapid Decontamination of Food Contact Surfaces Contaminated with Salmonella Biofilms
Article first published online: 17 APR 2014
© 2014 Institute of Food Technologists®
Journal of Food Science
Volume 79, Issue 5, pages M917–M922, May 2014
How to Cite
Niemira, B. A., Boyd, G. and Sites, J. (2014), Cold Plasma Rapid Decontamination of Food Contact Surfaces Contaminated with Salmonella Biofilms. Journal of Food Science, 79: M917–M922. doi: 10.1111/1750-3841.12379
- Issue published online: 8 MAY 2014
- Article first published online: 17 APR 2014
- Manuscript Accepted: 23 DEC 2013
- Manuscript Received: 20 SEP 2013
- cold plasma;
- food safety;
Cross-contamination of foods from persistent pathogen reservoirs is a known risk factor in processing environments. Industry requires a rapid, waterless, zero-contact, chemical-free method for removing pathogens from food contact surfaces. Cold plasma was tested for its ability to inactivate Salmonella biofilms. A 3-strain Salmonella culture was grown to form adherent biofilms for 24, 48, or 72 h on a test surface (glass slides). These were placed on a conveyor belt and passed at various line speeds to provide exposure times of 5, 10, or 15 s. The test plate was either 5 or 7.5 cm under a plasma jet emitter operating at 1 atm using filtered air as the feed gas. The frequency of high-voltage electricity was varied from 23 to 48 kHz. At the closer spacing (5 cm), cold plasma reduced Salmonella biofilms by up to 1.57 log CFU/mL (5 s), 1.82 log CFU/mL (10 s), and 2.13 log CFU/mL (15 s). Increasing the distance to 7.5 cm generally reduced the efficacy of the 15 s treatment, but had variable effects on the 5 and 10 s treatments. Variation of the high-voltage electricity had a greater effect on 10 and 15 s treatments, particularly at the 7.5 cm spacing. For each combination of time, distance, and frequency, Salmonella biofilms of 24, 48, and 72 h growth responded consistently with each other. The results show that short treatments with cold plasma yielded up to a 2.13 log reduction of a durable form of Salmonella contamination on a model food contact surface. This technology shows promise as a possible tool for rapid disinfection of materials associated with food processing.
Pathogens such as Salmonella can form chemical-resistant biofilms, making them difficult to remove from food contact surfaces. A 15 s treatment with cold plasma reduced mature Salmonella biofilms by up to 2.13 log CFU/mL (99.3%). This contact-free, waterless method uses no chemical sanitizers. Cold plasma may therefore have a practical application for conveyor belts, equipment, and other food contact surfaces where a rapid, dry antimicrobial process is required.