title: Removal of Listeria monocytogenes biofilms from stainless steel by use of ultrasound and ozone.
abstract: The objective of this study was to determine the efficacy of power ultrasound and ozonation used individually, and in tandem, for the removal of Listeria monocytogenes biofilms from stainless steel chips. Stainless steel chips were inoculated with L. monocytogenes. Power ultrasound (20 kHz, 100% amplitude, 120 W) was applied for 30 or 60 s at a distance of 2.54 cm from a biofilm chip while it was submerged in 250 ml of sterile potassium phosphate buffer (pH 7.0). Ozone was cycled through the 250 ml of potassium phosphate buffer containing the biofilm chip also for 30 or 60 s at concentrations of 0.25, 0.5, or 1.0 ppm. Power ultrasound and ozonation were also used in tandem for testing of their combined effect. Each of the treatments alone resulted in a significant reduction in recoverable cells, with power ultrasound being the most effective (3.8-log CFU/ml reduction after 60 s). For the ozone in combination with power ultrasound treatment, reductions were significantly (P < 0.05) higher than by either treatment alone. There were no recoverable cells after 60 s of this combined treatment when an ozone concentration of 0.5 ppm was used (7.31-log CFU/ml reduction). These results indicated that the combination of power ultrasound and ozonation may be an effective treatment for biofilm removal from stainless steel food contact surfaces.
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 486 Animal Sciences Laboratory, 1207 West Gregory Drive, Urbana, Illinois 61801, USA.
authors.forename: Adam R
authors.initials: AR
authors.lastname: Baumann
authors.forename: Scott E
authors.initials: SE
authors.lastname: Martin
authors.forename: Hao
authors.initials: H
authors.lastname: Feng
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D015169:Colony Count, Microbial; D004203:Disinfection / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D004866:Equipment Contamination; D005516:Food Microbiology; D008089:Listeria monocytogenes / Q000187:drug effects / Q000502:physiology*; D010083:Oxidants, Photochemical / Q000494:pharmacology; D010126:Ozone / Q000494:pharmacology*; D013193:Stainless Steel; D013997:Time Factors; D014463:Ultrasonography
chemical_list: D010083:Oxidants, Photochemical; D013193:Stainless Steel; D010126:Ozone