Using plasma to kill food pathogens wins third place for Auburn student

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Katherine Sofia Sierra is researching using room-temperature plasma technology to kill Listeria bacteria in the food processing industry. Photo courtesy of Auburn University

Research applying new room-temperature plasma technology to kill infectious Listeria monocytogenes bacteria in the food processing industry has won an Auburn University food science graduate student third place overall in the university’s Student Research Symposium 2023 held March 28.

“People want non-chemical preservation of foods, and that the foods should be safe to eat,” says Katherine Sofia Sierra, a second-semester master’s degree student who is from Comayagua, Honduras. “Room temperature plasma is one such technology that is non-chemical.”

Sierra is advised by Dr. Amit Morey, associate professor in Auburn’s Department of Poultry Science.

“She worked diligently on the project from the planning stage to data analytics and presentation,” Dr. Morey says. “It shows her dedication to science and ability to conduct cutting-edge research.”

listeria can be fatal

When Listeria gets into the food chain, it causes gastrointestinal distress, fever and other symptoms that can be fatal to newborns, infants and the elderly, as well as immunocompromised and immunosuppressed individuals.

The research uses funds from the National Science Foundation’s Established Program to Stimulate Competitive Research Future Technologies & enabling Plasma Processes (FTPP), a five-year, $20 million effort to transition plasma research into agricultural, manufacturing, space science, space weather prediction and other applications.

“The project consists of using room temperature plasma, which is a new technology that generates molecules, atoms and reactive species that affect the microorganism,” Sierra says.

“So, this technology damages the cell wall and DNA, killing some of the bacterial cells, and interestingly, what we found is that it leaves some cells injured on different surfaces like neoprene, stainless steel and polypropylene that are most commonly used in a food processing plant.” 

The cells injured by the plasma treatment otherwise could survive intact to evolve stress resistance that would cause a big problem for the food industry, the research showed.

“We can make a prediction model with equations to know how much time is necessary to kill one logarithm of Listeria monocytogenes on different surfaces,” says Sierra. “And how much time is needed to kill all the population of the pathogenic bacteria.” 

many food applications

The plasma process is nearing a stage where it could be widely adopted, she says.

“This is something that we expect to use in the food processing and manufacturing industry in the closer future,” Sierra says. “Currently in the lab, we are working on different projects using room temperature plasma with food, such as chicken skin and milk powder. Also, it can be used in fruits, vegetables and powdered foods, and to purify the water and air used in the food industry.”

Auburn’s Student Research Symposium 2023 was organized by the Office of Vice President of Research and Economic Development, and nearly 300 students presented posters and explained their various scientific projects. Judges queried the students on aspects of their research.

“I decided to enter because I like to participate in different activities that involve science. I like to do science and show people the impact that we are doing with the projects developed,” says Sierra.

“The fact that I won among all the competitors and ended up in one of the three top positions is a great feeling, because there were good competitors with great research,” she says. “Mine was one of the top projects due the importance of this topic in society, and that makes me feel that I am contributing to the industry and all the population of the world.”

Workforce development

The newness of the technology is what inspired her interest in research using Auburn’s room temperature plasma machine, Sierra says. Her experience presenting her research has improved her communication skills.

“I encourage people not to be afraid to participate in events where they can show your work,” she says. “As a Latin person whose native language is not English, I was afraid to participate in this type of event, but I am gaining experience and the skill to talk and present in front of different people.”

One goal of FTPP is to develop the highly-skilled technical workforce necessary for thousands of high-paying careers in Alabama and the Southeast, and Sierra says she’d like it if her continuing research evolves into a career. “I want to stay in the plasma field, because it seems such a great technology and an alternative that the food industry might be seeking to kill various bacteria.”