Effects of food components on the antimicrobial activity of polypropylene surfaces containing silver ions (Ag+)

The aim of this study was to investigate the influence of food components on the antimicrobial properties of surfaces containing silver. The antimicrobial activity of a polypropylene compound with a zirconium phosphate-based ceramic ion exchange resin containing silver was investigated by comparing the surface count of bacteria on sample and reference surfaces. Different food components were added to the inocula to investigate their influence on the extent of antimicrobial activity in comparison with pure inoculum (Pseudomonas fluorescens in saline solution). In the experiments with pure inoculum, a marked reduction in bacterial counts on samples containing silver was observed (7.4 log(10) units). However, protein-rich food strongly reduced or completely inhibited the antimicrobial activity of silver. Almost all other tested components from the carbohydrate or lipid group did not affect the antimicrobial activity. Overall, the effect and the risks of materials containing silver needs to be analysed individually for the respective application.