Hygienic aspects of wood and polyethylen cutting boards regarding food contaminations. A comparison | Hygienische Eigenschaften von Holz- und Kunststoffbrettern in der Nahrungsmittelverarbeitung und -präsentation: Ein Vergleich

ESCHERICHIA COLI: bacteria, and the colony forming units (cfu) were retrieved by agar contact methods. Bacteria counts after 15 hour storage at room temperature were compared to values obtained after machine and manual washing processes. Results showed that in very humid environment, both wood and PE showed very high numbers of bacteria. Even machine washing of the wet samples hardly reduced the cfu counted. Probably, the high bacteria density observed was due to the high surface moisture of the samples which led to ideal conditions for the microorganisms on the surface from where they are easily retrieved. In drier environment, contact plates removed significantly less bacteria from wood samples than from PE. The reason for this effect was not clearly established, but it was observed that the porous wood surface dried faster than the polyethylene surface. Also, observations of surface samples in a scanning electron microscope proved that after one month of intensive use polyethylene boards obtained a very rough and cavernous surface similar to wood (but with less profound porosity). On wood, these surface cuts open in the drying process and therefore bacteria cannot survive. However, on PE a retention of bacteria enclosed in caverns and the possibility of later release is suspected. On all materials a significant decrease of bacteria count was achieved upon manual washing with detergent and brush followed by rinsing under warm water. After this treatment, bacteria were recovered only sporadically. For wood, an even higher degree of disinfection could possibly be achieved with the microwave method suggested by Park and Cliver (1996). In general, the results of the present experiments show that wood is not, as commonly assumed, less hygienic than polyethylene. The statement that the use of wood in food processing increased the risk of infestation by microorganisms could therefore not be supported.