Hygienic aspects of wood and polyethylen cutting boards regarding food contaminations. A comparison

Hygienic aspects of cutting boards made of wood (european maple, beech and oak) and polyethylene (PE) were compared in order to determine the risk of food contamination in household and commercial kitchen. Boards were contami nated with Escherichia coli bacteria, and the colony forming units (cfu) we re retrieved by agar contact methods. Bacteria counts after 15 hour storage at room temperature were compared to values obtained after machine and man ual washing processes. Results showed that in very humid environment, both wood and PE showed very high numbers of bacteria. Even machine washing of t he 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 th ey are easily retrieved. In drier environment, contact plates removed signi ficantly less bacteria from wood samples than from PE. The reason for this effect was not clearly established, but it was observed that the porous woo d surface dried faster than the polyethylene surface. Also, observations of surface samples in a scanning electron microscope proved that after one mo nth of intensive use polyethylene boards obtained a very rough and cavernou s surface similar to wood (but with less profound porosity). On wood, these surface cuts open in the drying process and therefore bacteria cannot surv ive. However, on PE a retention of bacteria enclosed in caverns and the pos sibility of later release is suspected. On all materials a significant decr ease 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 disinf ection could possibly be achieved with the microwave method suggested by Pa rk and Cliver (1996). In general, the results of the present experiments sh ow 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.