**4. Conclusions**

TiO2 coatings were deposited either using reactive magnetron sputtering, both with and without subsequent heat treatment, or prepared by spray coating. Photocatalytic activity, determined by methylene blue degradation, was high under UV irradiation. The coatings were also active under fluorescent irradiation. Doping of magnetron sputtered TiO2 with Ag- (0.5 at%) and Mo- (7 at%) increased the activity under fluorescent light. High Ag loading (~30%) had a detrimental effect on the fluorescent light induced photoactivity, possibly due to the replacement of Ti atoms in the TiO2 matrix with Ag. The coatings were placed in three different breweries for three months. The magnetron sputtered TiO2 surfaces which had not undergone heat treatment showed the best mechanical resistance, whilst the spray coated TiO2 and Mo-TiO2 showed the best retention of photoactivity. Irradiation of the coatings resulted in an increase in wettability, but the spray-coated TiO2 was the only coating showing light-induced hydrophilicity after the process trial.

This work presented the potential of magnetron sputtered TiO2 and doped TiO2 coatings for surfaces used in food and beverage processing where there is a requirement for robust coatings. Selection of the optimum deposition parameters and dopants can lead to coatings which retain photoactivity and are durable in harsh processing conditions. The use of spray coatings is preferred on surfaces which do not experience severe mechanical wear and abrasion.
