Molybdenum doped titanium dioxide photocatalytic coatings for use as hygienic surfaces: the effect of soiling on antimicrobial activity

Abstract

Titanium dioxide (TiO₂) surfaces doped with molybdenum (Mo) were investigated to determine if their photocatalytic ability could enhance process hygiene in the brewery industry. Doping TiO₂ with Mo showed a 5-log reduction in bacterial counts within 4 to 24 h and a 1-log reduction in yeast numbers within 72 h. The presence of a dilute brewery soil on the surface did not interfere with antimicrobial activity. The TiO₂–Mo surface was also active in the dark, showing a 5-log reduction in bacteria within 4 to 24 h and a 1-log reduction in yeast numbers within 72 h, suggesting it could have a novel dual function, being antimicrobial and photocatalytic. The study suggests the TiO₂–Mo coating could act as a secondary barrier in helping prevent the build-up of microbial contamination on surfaces within the brewery industry, in particular in between cleaning/disinfection regimes during long production runs.

Keywords:

• photocatalytic surfaces
• titanium dioxide
• molybdenum
• antimicrobial activity
• brewery microorganisms
• soiling

Acknowledgements

Funding for this work from the Technology Strategy Board is gratefully acknowledged. The work reported in this paper formed part of the Matera+ project, ‘Disconnecting microbes from food and beverage process surfaces’ carried out in partnership with a complementary study in Finland, which was funded by the Finnish Funding Agency for Technology and Innovation (Tekes). Partners in the larger project were Teer Coatings Ltd, Cristal (UK), and VTT Technical Research Centre of Finland, Tampere University of Technology, Millidyne surface technology and PBL Brewing Laboratory (Finland), to whom thanks are also given.