Wooden Cutting Boards Found Safer Than Plastic
Every now and then ascientific finding flies in the face of conventional wisdom. And so it was with an accidental discovery by microbiologists at the University of Wisconsin’s Food Research Institute that wooden cutting boards kill food poisoning bacteria that survive very nicely on the plastic boards that have been widely promoted for years as safer than wood.
The scientists, Dean O.Cliver and Nese O. Ak, stumbled upon the finding while seeking ways to decontaminate wooden boards and make them as “safe” as plastic. Much to their surprise, they found that when boards were purposely contaminated with organisms like Salmonella, Listeria and E.coli that are common causes of food poisoning, 99.9 percent of the bacteria died off within three minutes on the wooden boards, while none died on the plastic ones.
When contaminated boards were left unwashed overnight at room temperature, bacterial count, increased on the plastic, but none of the organisms could be recovered from the wooden boards the next morning.
It had long been believed that disease-causing bacteria from raw foods like chicken would soak into a wooden board and be difficult to remove, even when washed; then when other foods, like salad ingredients, that are eaten raw are cut on the same board, the dangerous bacteria could be picked up by them and transferred alive to the consumer. Plastic was assumed to be safer because it is non-porous and contaminating organisms could be readily washed off.
A Word for Safety Based on the new studies, Dr.Cliver said, “Wood may be preferable in that small lapses in sanitary practices are not as dangerous on wood as on plastic.” But he cautioned against being “sloppy about safety” and warned cooks to be sure to wash off cutting surfaces after cutting meat, chicken or fish, whether the surface used is wood or plastic.
The researchers tested boardsmade from seven different species of trees and four types of plastic and found similar results: wood was safer than plastic, regardless of the materials used. Thus far, however, the researchers have been unable to isolate the agents in wood that make it so inhospitable to bacteria.
© The New York Times, February 10, 1993.
Modern plastics not clean enough? Try good old wood
Appearances can be deceptive. Householders have been seduced for years by the idea of fitting out their kitchens with easy-to-wipe surfaces, and throwingout those old wooden cutting boards in favour of shiny new plastic ones. So much more hygienic, it is thought.
Dean Cliver and Nese Ak, two researchers at the University of Wisconsin-Madison, beg to differ. They set out to find ways of decontaminating wooden kitchen surfaces and ended up finding that such surfaces are pretty good at decontaminating themselves.
Working with wood from nine different species of tree, and with four sorts of plastic and even an old rubber chopping board, the results were always the same.
When they spread their gut-wrenching bacteria -salmonella, listeria and E.coli – over the various samples and left them there for three minutes, the level of bacteria on the plastic or rubber remained unchanged while the level on the wood plummeted, often by as much as 99.9 per cent. Left overnight at room temperature, the bacteria on the plastic actually multiplied, while the wooden surfaces cleaned themselves so thoroughly that Dr. Cliver and Ms. Akcould not recover anything from them. At first sight, these results seem astonishing. But, unlike polymer chemists, plants have spent hundreds of millions of years fighting off bacteria. They should be quite good at it by now. And trees might be expected to be the best of the lot. After all, they live longer – not only longer than most plants, but longer than most animals as well. And even when a tree is dead, its wood can hang around for decades, resisting the attacks of micro-organisms. Slaughtering a few salmonella should be child’splay. Dr. Cliver and Ms. Ak do not yet know exactly what is happening, but their guess is that the porous structure of the wood is soaking up the fluid with the bacteria in it.Once inside, the bacteria stick to the wood’s fibres and are “strangled” by one of the many noxious anti-microbial chemicals with which living trees protect themselves – exactly which, they have not yet worked out. But they are searching. In the meantime, perhaps surgeons should search out their old chopping blocks.
© The Globe and Mail