Purpose: The aim of this study was to investigate the anti-biofilm efficacy of nanoscale plasma coating of trimethylsilane (TMS) to prevent biofilms of important foodborne pathogens from forming on stainless steel which is widely used in food processing.
Methods: Stainless steel wafers (1 cm × 1 cm) were coated with TMS plasma to an approximate thickness of 30 nm using direct current power supply, and Listeria monocytogenes, Escherichia coli O157:H7 and Staphylococcus aureus each was allowed to form biofilms on the wafers for 48h. The biofilms were removed by rinsing and ultrasonicating each wafer four times for 30s each time and the pour-plate method was conducted to determine bacterial counts. In addition, the efficacy of TMS-coated wafers in combination with a sanitizer was also tested by dipping the wafers in a Quat solution for 15s and rinsing before sonicating and plating.
Results: The number of L. monocytogenes dropped from 107-108 to 104-105 CFU/wafer, on average. E. coli O157:H7 and S. aureus showed a 1-log reduction (108 to 107 CFU/wafer) in numbers. With the combined use of plasma coating and sanitizer, a 100% kill of L. monocytogenes was achieved, while for the sanitizer-only group, as many as 105 CFU/wafer remained.
Significance: Results of this study show that TMS-coating deposited on stainless steel surfaces could significantly reduce biofilm formation. Moreover, when combined with sanitizers, TMS coating shows greater promise to remove and prevent biofilm from forming on food contact surfaces.