Many foods produced on an industrial scale include raw ingredients mixed together in enormous stainless steel machines that can be difficult to clean. With repeated use, equipment surfaces get minute scratches and grooves, providing bacteria and biofilms the perfect place to hide.
Professor Ben Hatton of the University of Toronto’s Department of Materials Science & Engineering, Dr. Dalal Asker and Dr. Tarek Awad research cheaper, safer and more effective ways to prevent bacteria from thriving inside these machines. This minimizes the risk of cross-contamination, which can lead to food-borne disease. Their team has proposed a simple new solution: trapping a thin layer of cooking oil at the metal surface to fill in microscopic scrapes, cracks, and fissures and create a barrier to bacterial attachment.
They found that this solution resulted in a 1,000x reduction in bacterial levels inside the industrial machines tested. Their work is recently published in the journal ACS Applied Materials & Interfaces.
“Coating a stainless steel surface with everyday cooking oil has proven remarkably effective in repelling bacteria,” says Hatton who collaborated on the project with AGRI-NEO, an Ontario seed processing company looking for a solution to a common problem in its industry. “The oil fills in the cracks, creates a hydrophobic layer and acts as a barrier to contaminants on the surface.”
This simple and cost-effective alternative builds on the Slippery Liquid-Infused Porous Surfaces (SLIPS) principle, initially developed at Harvard to trap lubricant layers into a surface microstructure and create slippery, non-wetting and non-adhesive properties. The sheer size of the machines makes it harder for cleaning materials to do a thorough job, and leftover bacteria can build up resistance to the cleaning agents. Hatton’s method of filling the scratches with oil prevents bacteria from settling and essentially cleans the surface without leaving chemical residues on the stainless steel surface.
The Hatton research group continues to test new combinations of oils, foods and biofilm types to increase the efficiency of the bacteria barriers. They will also explore options of using this method in developing countries to minimize bacterial infection and improve mortality rates.