Characterization of antimicrobial efficacy of photocatalytic polymers against food-borne biofilms

Biofouling of food industry equipment and other surfaces that food products contact during processing is a threat to food safety, which results in infectious outbreaks and economic losses due to corrosion, equipment impairment, and reduced heat transfer efficiency. Once firmly attached to a surface, biofilms can be almost impossible to remove using current sanitation procedures. Self-cleaning surfaces with TiO₂ coatings that are activated with ultraviolet (UV) light may be effective in preventing bacterial growth or killing or removing adherent organisms but require studies to demonstrate their efficacy and determine optimum conditions for use. Therefore, we examined the efficacy of TiO₂-based polymer coatings against key food-borne pathogens namely, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, and Salmonella typhimurium. Upon photo-catalytic activation of the coatings, the viability of early stage biofilms formed on each coated surface and the relative contribution of reactive oxygen species was evaluated. Results show that the relative antimicrobial activity strength was dependent on the length of UV irradiation; 5-10 min exposure was sufficient to inhibit/kill biofilms of each pathogenic species tested. The results of this study render contact surfaces less attractive for pathogenic biofilms while doubling as an effective mitigation strategy to remove biofilms that form despite coating.