U.S – Research published in Applied and Environmental Microbiology suggests that oil formulations with food-grade organic acids can kill dried Salmonella on stainless steel surfaces.

Recent Salmonella outbreaks have been linked to peanut butter and chocolate. Although Salmonella cannot grow in either of these low-water foods, the cells survive, becoming more resistant to heat treatment, which has contributed to recent outbreaks.

When processing low-moisture, high-fat foods such as peanut butter and nuts, water-based sanitization is unsuitable due to the immiscible nature of water and fats.

“Cleaning and sanitation of manufacturing environments are critical for a safe food supply. However, water-based cleaning is rarely used in processing peanut butter, because it promotes microbial growth.

“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,” said Lead Author Lynne McLandsborough, a Professor of Food Science at University of Massachusetts Amherst.

In its place, manufacturers often use heated oil to remove residual peanut butter from manufacturing systems followed by overnight cooling and application of flammable alcohol-based sanitizing agents.

In the study, McLandsborough and collaborators dried Salmonella on stainless steel surfaces at controlled relative humidity.

They then covered the dried bacteria with various oils with organic acids, varying the acid type, concentration, contact time and treatment temperature to identify highly antimicrobial formulations.

By using peanut oil mixed with acetic acid at a concentration about half that of household vinegar and applying heat, “killing was much greater than expected, indicating a synergistic effect,” revealed McLandsborough.

“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,” she said.

She stated that through the research, industries might resort to oil-based systems for industrial cleaning which would enable more frequent cleaning, hence boosting the safety of products.

Dry sanitization mainly uses flammable compounds such as isopropanol, requiring equipment cooling before application.

Currently, dry sanitization products used during food processing often contain flammable compounds which require processing to stop and equipment to cool before application. This leads to processing downtimes and consequently, economic losses.

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