Beating back salmonella on food equipment using oil and acid

Research published in the journal Applied and Environmental Microbiology has suggested that oils may be the key to preventing the spread of salmonella in food manufacturing.

Recent outbreaks of foodborne salmonella have been associated with chocolate and peanut butter. Despite the bacteria struggling to grow on these foods due to their low water content, cells can survive and become resistant to heat-based treatments, which can lead to outbreaks of the disease.

The solution, the researchers say, is to use an oil-based formulation in combination with food-grade organic acids that can kill dried salmonella on stainless steel surfaces.

“Cleaning and sanitation of manufacturing environments are critical for a safe food supply,” said lead author Lynne McLandsborough, PhD, a professor of food science at University of Massachusetts Amherst.

“Also, as anyone who has baked peanut butter cookies can tell you, peanut butter and water do not mix, and clean-up with water is challenging.”

Water-based solutions are rarely used to clean environments used in peanut butter processing as it can encourage bacterial growth. Instead the equipment is cleaned with heated oil and then left to cool overnight, after which a flammable alcohol-based sanitiser is applied.

However, for this study the scientists tried a different method using an acidic component. They dried salmonella on stainless steel surfaces in a controlled humidity environment and then covered the bacteria with oils and acids with various properties.

They found that after using peanut oil that was mixed with a low concentration of acetic acid, which is found in vinegar, and then applying heat, “killing was much greater than expected, indicating a synergistic effect,” McLandsborough said. “Our results show that acidified oils could be used as an effective means of sanitation in low-moisture food processing facilities, where water-based cleaning can be challenging.

“To our knowledge, using oils as a carrier of organic acids is a novel approach to delivering antimicrobial compounds against food-borne pathogens.”

The research may thus lead to adaptation of oil-based systems for industrial cleaning, for example, of machinery for processing chocolate and peanut butter, McLandsborough said.

“That would enable more frequent cleaning, boosting the safety of these products.”

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