ECJ EUROPEAN Cleaning Journal

Once salmonella has found its way into a food processing plant the bacteria can be extremely hard to eliminate, according to a new study.

Researchers used three types of disinfectant in an attempt to kill a build-up of salmonella bacteria that had formed on a variety of hard surfaces.

"We found that where the biofilm had been allowed to grow for seven days before the disinfectant was applied, it was not possible to kill the salmonella cells using any of the three disinfectants," said National University Ireland researcher Mary Corcoran.

"People need to question whether disinfectants that are promoted for killing various types of bacteria are really as effective in real-life situations as they are claimed to be. The disinfectant may often add very little, if anything, to good cleaning and appropriate food-handling practices."

The surfaces analysed in the project included glass, stainless steel, glazed tiles and plastic. The study revealed that the salmonella biofilm increased in density over time and also attached itself more firmly to the surface. In each case the biofilm survived even after the researchers had soaked it in disinfectant for 90 minutes.

According to Corcoran, further research is needed to find better ways of killing salmonella biofilms. And she adds that food processing facilities need to keep salmonella out of clean areas where cooked foods are processed and packaged.