Bacteria gets a zap from Purdue’s cold plasma

WEST LAFAYETTE, Ind. (WLFI) – Purdue University researchers have been awarded a $75,000 state grant to further develop cleaning food with cold plasma technology. The process, which works best with cantaloupe and other fruits, could change the way we clean some of our favorite foods.

Though the technology is not yet approved for commercial use, Purdue researchers say cold plasma could one day revolutionize the way we treat all kinds of produce.

Cold plasma forms when an electrical current is run through certain gases, such as helium, nitrogen or oxygen. The process is similar to what occurs inside neon light or a spark that briefly causes the air around us to turn into ozone.

“Those gases undergo transformations and become very reactive,” said Bruce Applegate, Purdue associate professor of food science. “When they’re very reactive, they can kill bacteria very quickly.”

Despite advances in food safety and government oversight, bacteria and pathogens are a common problem for food scientists. In 2011, an outbreak of listeria in Colorado cantaloupe killed 33 people. In 2012, cantaloupe tainted with salmonella from an Owensville, Ind. killed two people and sickened at least 78 more.

Salmonella most often occurs in the United States when people eat undercooked chicken, but cantaloupe and other raw fruits and vegetables are susceptible to the bacteria.

“They’re ready-to-eat foods or are raw products — where we consume it, and we don’t have a whole lot of ways of ensuring that there are no pathogens or bacteria that would cause illness there,” Applegate said.

To test the process, researchers put a cantaloupe in a plastic bag, fill the bag with helium, then run an electric current through the bag using two metal plates above and below it. Once the current is turned on, the helium gas gives off a purple glow while disinfecting the fruit, according to Applegate.

Though the team has also tested tomatoes, lettuce and eggs, the main target is cantaloupe — especially with several cantaloupe farms in Indiana.

“What brought it to our attention to it is to be able to penetrate the webbing and the nooks and crannies,” Applegate said. “[We can] get to where the bacteria might be, where they couldn’t effectively be removed by washing or standard techniques.”

Part of the $75,000 grant will be used for outreach on farms in Indiana, Applgate said. Eventually getting the technology to farmers is one thing, but seeing how it meets their needs is another.

“[We will] be able to educate them on better practices and things they might consider in terms of making cantaloupe a safer product,” said Applegate.

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