Bactericidal efficiency of UVA-active titanium dioxide thin layers on bacteria from food industry environments

Abstract

Titanium dioxide (TiO₂) thin layers have been deposited on glass substrates using radio frequency magnetron sputtering technique. The photocatalytic activity of the TiO₂ thin layers has been investigated by a methylene blue discolouration test and reveals that films with an anatase structure present the highest performance. Bactericidal activity of the anatase-phase TiO₂ layer against food-borne bacteria has then been tested by enumeration of the adherent cells, after adhesion and a subsequent UVA illumination. A decrease of the adherent bacteria number equal to −1.2, −2.6 and −2.3 log is reached for Y. enterocolitica, L. monocytogenes and P. fragi, respectively. SEM observations exhibit bacterial cells with damaged walls for all bacteria. Applied on materials present in the food plants, these TiO₂ thin layers may be an effective way for the hygienic conception of the equipment to reduce the biofilm formation and thus, to ensure food safety.

Keywords:

• TiO₂
• photocatalysis
• bactericidal activity
• food industry
• food safety

Ackowledgments

We thank Stéphanie Bougeard for her help in statistical analysis.