Cutting Boards of Plastic and Wood Contaminated Experimentally with Bacteria

The microbiology of Plastic and wooden cutting boards was studied, regarding cross-contamination of foods in home kitchens. New and used Plastic (four polymers plus hard rubber) and wood (nine hardwoods) cutting boards were cut into 5-cm squares (“blocks”). Escherichia coli (two nonpathogenic strains plus type O157:H7), Listeria innocua, L. monocytogenes, or Salmonella typhimurium was applied to the 25-cm² block surface in nutrient broth or chicken juice and recovered by soaking the surface in nutrient broth or pressing the block onto nutrient agar, within 3–10 min or up to ca. 12 h later. Bacteria inoculated onto Plastic blocks were readily recovered for minutes to hours and would multiply if held overnight. Recoveries from wooden blocks were generally less than those from plastic blocks, regardless of new or used status; differences increased with holding time. Clean wood blocks usually absorbed the inoculum completely within 3–10 min. If these fluids contained 10³–10⁴ CFU of bacteria likely to come from raw meat or poultry, the bacteria generally could not be recovered after entering the wood. If ≥10⁶ CFU were applied, bacteria might be recovered from wood after 12 h at room temperature and high humidity, but numbers were reduced by at least 98%, and often more than 99.9%. Mineral oil treatment of the wood surface had little effect on the microbiological findings. These results do not support the often-heard assertion that Plastic cutting boards are more sanitary than wood.