Bacterial Retention and Cleanability of Plastic and Wood Cutting Boards with Commercial Food Service Maintenance Practices

The retention of bacteria on wood and plastic cutting board surfaces and their removal by washing, using protocols consistent with commercial food service, was examined. Plastic and wood boards were subjected to repeated hand and machine washing to simulate wear that would occur during commercial usage. Electron microscopy revealed a more pronounced wearing of the wood surface as compared to the plastic, with cracks on the wood that were sufficiently wide to entrap bacteria. New and previously washed wood and plastic surfaces were inoculated with Escherichia coli and then washed using standard food service washing and sanitizing procedures. The cleanliness of the resulting surfaces was estimated by measuring the residual adenosine triphosphate (ATP). The plastic surfaces were consistently cleaner than wood surfaces by this measure, and wood surfaces that had been hand washed five times prior to inoculation were significantly less clean than any other surfaces or treatments. Bacterial retention after washing on the surface was demonstrated by agar overlay. Even after standard food service washing and sanitizing, colonies of the inoculated bacteria were observed sporadically, but only on wood surfaces and not on plastic. These results suggest that wood surfaces can absorb moisture and in effect can absorb contaminating bacteria, and the difficulty in removing these bacteria may make this material less desirable from a food safety perspective.