Cold plasma has captured scientists’ imagination in almost every field, and food safety is no exception. The USDA and consumer groups continue to fund cold plasma research, and the results are potentially revolutionary.

Plasma, which is considered the fourth state of matter after solids, liquids and gases, is created by breaking apart gas molecules and making a plume of charged electrons and ions, according to Cold plasma is made by sending fast-moving, and hot, electrons through cold gasses. Because cold plasma is energetic, but also cold, it has unique abilities and possibilities.

Cold plasma against Listeria
A study published in May 2019 in LWT Food Science and Technology, investigated antimicrobial and cold plasma combinations as treatments to reduce Listeria monocytogenes on apple surfaces.

In 2014 a deadly Listeria outbreak was traced to fresh apples.  

The study published in LWT found that a combination of antimicrobial solution and cold plasma treatments are effective in killing Listeria monocytogenes. According to researchers led by Dike O. Ukuku of the USDA, cold plasma treatments can significantly reduce sanitizer treatment time. In their study, they reduced sanitizer time from 1 hour to 3 minutes by using cold plasma treatments. The full study can be found here.

Cold plasma as water treatment
A Drexel University research team  is developing a cold plasma wash water treatment that could kill harmful pathogens. The hope is that it can be used with delicate fresh produce with no adverse quality effects, low-cost operations and no added chemicals. This is a potentially huge breakthrough, as delicate fresh produce items, like romaine lettuce, are difficult to clean and can contain potentially harmful pathogens.

Multiple outbreaks have been linked to leafy greens, especially romaine.

Cold plasma against Norovirus
In 2016, food safety scientists found a cold plasma treatment, described as a “purple blow torch,” that can kill 99.9 percent of norovirus on blueberries without damaging the delicate fruit.

The researchers, led by Alison Lacombe, explained why they focused on blueberries: “(They) are susceptible to contamination by biological hazards from pre-harvest to post-harvest stages and are most commonly consumed raw,” according to the research results, published in the May 2017 edition of the journal Food Microbiology.

Cold plasma against Salmonella and E.coli
In 2015, Brendan Niemira, a microbiologist at the USDA, and a team of scientists demonstrated that cold plasma can kill pathogens such as Salmonella and E. coli on blueberries. After just two minutes. The cold plasma treatment killed 99.9 percent of the two viruses after two minutes or less.

“Cold plasma is an emerging non-thermal technology that offers the advantage of being chemical- and water-free, in addition to being able to operate openly and continuously at atmospheric pressure,” Niemira said.

Research into cold plasma treatment is ongoing, and the results are showing promising signs of what the new technology might accomplish in the food safety realm. 

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