Antibacterial activity of cutting boards containing silver

In the present study the antibacterial effect of three commercially available cutting boards containing silver zeolites or nanosilver was studied. Mixtures of five strains of Staphylococcus aureus were added to coupons of cutting boards followed by incubation at 35–93% relative humidity on open surfaces or at 100% relative humidity in the Japanese industrial standard film-test for 24 h. The silver zeolite containing boards showed antimicrobial effect in the standard test. However, at lower humidity more bacteria were killed at the control boards, and no additional reduction was observed for the silver zeolite containing boards. When the bacteria were suspended in full strength growth medium no antibacterial effects of any of the silver-containing boards were observed. The board containing nanosilver only showed effect in the presence of sodium chloride at low nutrient conditions. Lack of effect at high nutrient conditions and humidity was confirmed with other food associated bacteria (coagulase negative staphylococci, Escherichia coli, Salmonella spp., Serratia spp. and Listeria monocytogenes). In conclusion, the lack of activity of cutting boards with silver at dry or soiled conditions may limit the hygienic effect at practical use. The commonly used Japanese industrial standard film-test may overestimate antibacterial effects of cutting boards with silver, compared to practical food preparation situations.