Solving the Sticky, Microbial Mess of Cleanup in Peanut Butter Factories

Recently published research from food scientist Lynne McLandsborough describes a novel, water-free method of cleaning machinery for processing peanut butter and chocolate, reducing the high risk for Salmonella contamination.

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Cleaning and sanitation of manufacturing environments are critical for a safe food supply,” says McLandsborough, head of the food science department and lead author of the paper published in Applied and Environmental Microbiology. “Also, as anyone who has baked peanut butter cookies can tell you, peanut butter and water do not mix, and cleanup with water is challenging.” In fact, she adds, liquid can promote the growth and survival of microorganisms in low-moisture environments.

In the study, McLandsborough and colleagues – UMass Amherst Ph.D. students Mrinalini Ghoshal in microbiology and Shihyu Chuang in food science, and Ying Zhang at the University of Shanghai for Science and Technology in China – 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 antimicrobial formulations. 

They found that using peanut oil mixed with acetic acid at a concentration about half that of household vinegar and applying heat was an effective cleaning and disinfecting method.

“Killing was much greater than expected, indicating a synergistic effect,” McLandsborough says. “Our results show that acidified oils could be used as an effective means of sanitation in low-moisture food processing facilities. To our knowledge, using oils as a carrier of organic acids is a novel approach to delivering antimicrobial compounds against food-borne pathogens.”

Oil-based cleaning offers several benefits to the industry, including “more frequent cleaning, boosting the safety of these products.”  

Currently, water-based cleaning agents require a plant shutdown for nearly a week to carry out cleaning.

The research was funded with one of 19 food safety and defense grants totaling $8 million that were awarded in 2020 by the USDA’s National Institute of Food and Agriculture.