Has wood nourishment

Wood and hygiene

What used to be part of everyday knowledge but was lost due to enthusiasm for new materials is now being rediscovered by science.

Until the 19th century, wood was mainly used for dishes, tools and as a storage container or base for food, but since then it has been largely replaced by other materials such as ceramics, metal or plastic. However, some things have been preserved, for example the wine from the oak barrel is ascribed a particularly noble aroma and is still popular and used today as a cutting and chopping base due to its slip resistance, good impact absorption and the low dulling of knives.

Since the 1970s, however, with the advent of plastics, the view that wood is unsanitary has become more widespread. In particular, there were increasing numbers of statements about the poor cleanability of wood and the corresponding advantages of plastic boards. This is also reflected in the legislation. Many national and European laws and guidelines contain regulations that prohibit wood in connection with food or at least severely restrict its use.

Up until a few years ago, hardly anything had changed in this opinion. A US study from 1993 therefore caused a sensation, in which cutting boards made of different hardwoods (e.g. beech, maple and oak) were compared with plastics (including polyethylene) under different conditions. These investigations showed that, shortly after contamination with bacteria, under almost all conditions the wooden surfaces show significantly lower germ counts than plastic boards. The results also put the prejudices into perspective with regard to cleaning, as this turned out to be much more difficult than expected, especially with used plastic boards.

This study was received with great skepticism, especially in German-speaking countries, but it resulted in the topic being scientifically rediscovered with new research methods and hygiene assessments. An attempt was made to model real use in household and commercial kitchens.

In all studies, the antibacterial behavior of wood was attributed to two essential factors: to a wood-physical and to a chemical component. The porous structure of wood has always been presented as a disadvantage compared to plastic. Due to its cellular nature, with an almost unimaginably large surface, wood has a strong hygroscopic effect. The associated dehydration creates a hostile atmosphere for bacteria and leads to their death. This physical property applies to all types of wood. In the case of some extra-rich woods, such as pine, oak or larch, the ingredients have an additional effect on the germicidal effect.

In addition to moisture, which can safely be described as a key factor in germ development, the surface properties and surface treatment of the materials are decisive. Investigations on new and used cutting boards, with untreated or greased surfaces, produced surprising results. Whether freshly planed and therefore smooth surfaces or surfaces furrowed by knife cuts - maple and beech wood showed only minimal bacterial growth. This antibacterial effect is reduced by Ā»sealingĀ« the uppermost wood cells with a layer of fat. Since the liquid that is essential for the bacteria cannot be absorbed by the cell material, prolonged bacterial survival is made possible. In comparison, the polyethylene surface showed the strongest bacterial proliferation in all cases. It is also interesting to realize that practically no germs could be registered on all surfaces - wood as well as plastic - after hand washing with a dishwashing detergent. In the scanning electron microscope you can see that after a short period of use, polyethylene boards hardly differ from wooden boards in terms of roughness.

So up to now, wood has been wrongly condemned as an unhygienic material and raw material. With a conscious choice of wood and proper handling, wood products can certainly contribute to improving the hygienic situation in many areas. The use of wood in connection with food, but also as packaging material is often excluded by national or EU-wide regulations. However, the new test results are now causing a rethinking of these legal bases and efforts are being made to bring about the equality of all materials.