Nature is Better than Plastic

A study by University Professor Dr. Rupert Wimmer, University for Floor Culture Vienna:

Coming to terms with Wood

On the question of whether wood would also be used in hospitals, Robert Stingl, a dedicated wood researcher at the University of Floor Culture Vienna (Boku), already fairly often got a slightly amused “NO” as an answer. For the hygiene departments in many Austrian hospitals, the use of wood is clearly still a taboo. This wood discrimination has a long tradition: until recently the use of wood in all conceivable areas of meat processing businesses was forbidden. That even went so far as to frown upon wooden windows “for hygienic reasons”. Wood researchers and Foodstuff hygienists from the Boku have since collected new facts and in cooperation with the Austrian Chamber of Commerce, have achieved the removal of wood from the lists of forbidden products in the hygiene guidelines. An important partial success!

The healthy intestinal flora of an adult contains between 10 and 100 billion bacteria, distributed across some hundred types. But these harmless intestinal residents can, for example through a viral infection, become genetically altered and rather dangerous. If these bacteria should reach our intestines via vegetables or meat, the consequences can be serious illnesses.

Wood as perfect material for a healthy kitchen

A kitchen is often a playground for bacteria. Preferential breeding places are the kitchen sponge, the tea towel or the sink. Multiple bacteria also crowd on working surfaces. Wood is porous, whereas synthetic material, metal or ceramics are non-porous. Therefore, years ago it was thought that wood would be hard to clean and therefore represented an ideal breeding ground for bacteria after contact with perishable foods, like meat. If a salad is then prepared on a board on which raw meat was just cut, then bacteria can very easily be transferred. This fear of germ transfer led to wood as a material was always replaced by synthetic materials.

Long history of studies on wood as hygienic material

In 1993, a scientific study from the United States drew attention to the fact that wood has very good hygienic qualities in comparison with synthetic material. At first these results were viewed sceptically in the German speaking world. Subsequent German and British studies confirmed the American results. In particular, that pine heartwood showed good antibacterial qualities – far better than synthetic material.

The different studies explain the antibacterial effect of wood through two causes: a chemical one and a physical one. The chemical cause refers to the contents of the wood. Tannine or Polyphenols contribute to the germ killing effects of extract rich woods such as pine or oak. With larch, the antibacterial effect was derived from the component Arabinogalactan.

Open pores as benefit

However, the real surprise lies in the physical cause: the pore structure of the wood, which was and still is considered a disadvantage compared to the synthetic material, is actually an advantage. Due to its porous cell structure, wood has an enormously high inner surface area. With 1g of wood this is actually 200 m². This high porosity causes a strongly hygroscopic effect. This results in humidity being quickly absorbed into the wooden working surface, the conditions of life for bacteria deteriorate and the bacteria die rapidly. This physical effect can be proven in all types of wood.

Besides the humidity, the surface roughness is also of importance on cutting boards. Examinations of both new and second hand cutting boards made of wood produced astonishing results: regardless of whether freshly planed down and therefore smooth cutting boards or boards furrowed by knife cuts, only a minimal bacterial growth was observed in boards made from maple or beech wood. The reason for this is also the active pore structure. In comparison with wood, the synthetic cutting board made from white Polyethylene showed the largest bacterial increase. It was positive to note that after cleaning with a washing up liquid, practically no further bacteria were registered neither on synthetic material nor on the wood.

A further example from the transport industry: wooden pallets used for the transportation of foodstuffs showed a 15% lower bacteria count than synthetic material pallets. If wood is used in the production and preparation of foodstuffs, whether as a working surface, cutlery, crockery or as stock and transport containers, then this is a very hygienic process.

Hygiene getting more and more important

The topic of hygiene and wood shows that sensible application fields for wood must be won over again and again. This is particularly clear with this topic in that sound scientific results are required. The challenge of using wood is in its complexity when compared to other materials. The interplay of physical, chemical and biological qualities is with any material, nowhere as hard to understand as in the case of wood. We have only just begun to understand this material, and can be excited with how wood may still surprise us.