Cooking oil coating protects food processing equipments from bacteria

Dr. Tarek Awad showing two samples: a stainless steel surface treated to trap simple cooking oil (left) and an uncoated surface (right). | Credit: Liz Do

Foods produced in large quantities is usually made through the raw ingredients being mixed together in giant stainless steel food processors. These food processors are usually very cumbersome to clean. When used repeatedly, it is natural for the equipment to get scratches and from grooves which leads to the growth of bacteria and biofilms.

What might appear small almost insignificant scratches to us, are usually like canyons to bacteria, since these micrometer sized organisms can find enough space to grow in these scratches. These surface trapped food residues and microorganisms like Salmonella and E. coli can cause severe cases of contamination.

Ben Hatton, Professor at the Department of Materials Science & Engineering of the University of Toronto, Dr. Dalal Asker and Dr. Tarek Awad together decided to find a cheaper and safer way to stop bacteria from multiplying inside these food processing equipments. They came up with a simple solution- trap a thin layer of cooking oil on the metal surface that can fill these small scratches and fissures that will act as a barrier between the food and the bacteria.

The research team found that a simple coating can reduce the number of bacteria growing inside the machines by 1000 times. Researchers also collaborated with AGRI-NEO, which is an Ontario seed processing company. The study was published recently in the journal ACS Applied Materials & Interfaces.

“Coating a stainless steel surface with an everyday cooking oil has proven remarkably effective in repelling bacteria. The oil fills in the cracks, creates a hydrophobic layer and acts as a barrier to contaminants on the surface”, said Hatton.

This solution provided by Hatton and his team is based on the Slippery Liquid-Infused Porous Surfaces (SLIPS) principle, which was first developed at Harvard University to find a way to “trap lubricants layers into a surface microstructure” that gives slippery and non-adhesive properties to the surface.

Cooking oils like olive oil and canola oil are much safer than harsh industrial chemical disinfectants that are currently used for cleaning these enormous food processing machines. Adding a layer of these oils will dramatically reduce the number of bacteria that tend to grow in the scratches and wouldn’t lead to chemical residuals.

“Contamination in food preparation equipment can impact individual health, cause costly product recalls and can still result after chemical-based cleaning occurs,” added Hatton. “The research showed that using a surface treatment and a cooking oil barrier provides greater coverage and results in 1,000 less bacteria roaming around.”


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