Can Cooking Oil Prevent Bacteria Growth on Processing Equipment?

Cooking oils may one day have a new use—preventing bacterial growth.

Today, most food processing facilities rely on chemical disinfectants such as quaternary ammonium compounds and hydrogen peroxide for sanitizing. But disinfectants may not reach bacteria in grooves, cracks, and scratches and other hard-to-clean parts of food processing equipment. Oftentimes, bacteria live in protective biofilm colonies, which make disinfectants ineffective. Furthermore, disinfectants may contain chloramines or hypochlorites that damage the passivating oxide of stainless steel.

To prevent ongoing growth on food processing surfaces, finding ways to prevent bacteria from attachment is key. By building upon the Slippery Liquid-Infused Porous Surfaces principle developed by Harvard researchers, which showed resistance to microorganism adhesion and colonization, Benjamin Hatton, PhD, associate professor, Materials Science and Engineering, University of Toronto in Canada, and colleagues set out to do just that.

The researchers developed and tested a way to trap regular cooking oils such canola, sunflower oil, and olive oils at a stainless steel surface. The two-step method involves first making a surface hydrophobic, and then spreading a thin layer of any food-grade oil over the surface to activate it. The research work was published in ACS Applied Materials & Interfaces in July 2018.

“Our research showed that oils deter food residue and bacterial attachment because they make surfaces slippery,” Dr. Hatton says. “Even when the oil is worn away, it remains trapped in microscale grooves and scratches, acting as a barrier and making surfaces much easier to clean.” The researchers measured between a 1000× and 100,000× reduction in bacterial cell counts after an oil treatment.

“By using inexpensive food-safe materials, this method can be scaled up and applied to large systems,” says Dr. Hatton, who adds that the researchers want to begin large-scale testing of their methodology soon.

In commenting on the research, Angela Anandappa, PhD, executive director of Alliance for Advanced Sanitation, University of Nebraska-Lincoln, says the research proposes an inexpensive and practical option to a complex microbiological challenge.

“But there are various challenges in using an oil coating on food processing equipment—the safety of the coating, its contribution to the food as an additive in the food, quality issues such as oxidation, and suitability for use,” Dr. Anandappa says. In addition, some bacterial species use oils as their food and may find oil coatings favorable for survival.

Unfortunately, Dr. Anandappa says coatings-based approaches often pose quality challenges to food and have little evidence of being feasible for routine or large-scale manufacturing operations. Furthermore, oils are not suitable for every type of food, so an oil coating may have value in certain types of operations but may be limited or detrimental to others.

“If it can be proven through additional research that a cooking oil coating can prevent bacterial growth, the next steps would include real-world scale-up evaluation,” Dr. Anandappa concludes.