Superheated steam can kill pathogens in dry food processing
A new tool to thwart deadly pathogens in commercial dry food processing plants may soon capture steam – superheated dry steam – to keep consumers safe.
In the arid world of flour and powder processing, where it’s impossible to hose down equipment to sanitize it with water, Abigail Snyder, Ph.D. ’17, assistant professor of food science, is currently testing the viability of superheated steam to clean these manufacturing environments.
“Cleaning and sanitation in dry food processing and product packaging is a challenge because you can’t use soap or water,” Snyder said. “We see how well superheated steam works to prevent contamination and ensure food safety.”
The work is relevant to the powdered milk and infant formula industry, bakery and snacks, spices, nuts and nut butters, produce industry, as well as chocolate and other confections, she said.
Snyder received a $400,000 grant on Jan. 1 from the Center for Produce Safety, serving as the grant’s principal investigator. This will help the produce industry achieve microbial safety in spaces where the use of traditional wet sanitation is limited. She will join co-investigators VM (Bala) Balasubramaniam, professor of food science and technology at Ohio State University. They will examine product packaging plants to understand how best to apply this technology.
In 2020, Snyder (PI) and Balasubramaniam received a four-year, $1 million grant from the National Food and Agriculture Institute/US Department of Agriculture to research remediation strategies in the dry food manufacturing environment.
Maintaining safe processing production areas for dry foods is a serious task. The pathogen Escherichia coli has been found in foods with low water content. From 2016 to 2019, approximately 100 cases of E. multistate coli were linked to flour and related products, according to the US Centers for Disease Control and Prevention.
Salmonella is a pathogen of concern, as it accounts for 94% of all low-moisture food recalls in the United States and 53% of food outbreaks globally, she said.
“A lot of food products don’t require refrigeration at all,” Snyder said. “Historically, people believed that low-moisture foods were safe because they didn’t support microbial growth. But over the past 15 years, there have been major outbreaks and recalls associated with dry foods, not because germs or pathogens thrive in food, but because they can survive for a long time.
Superheated steam is very different from stovetop steam. When water boils in a tea kettle, it has reached 212 degrees Fahrenheit – and visible cloud-like steam is released. For dry or superheated steam, steam vapor is heated beyond the kettle to over 250 degrees F, in the case of Snyder’s processing unit. It becomes invisible and acts like a hot gas. Because dry steam is applied to production surfaces, where it can kill pathogens and microbes, it leaves no moisture or condensation to harbor other pathogens.
“Our results will be compared to the effectiveness of conventional scraping, vacuuming and brushing methods now commonly applied,” Snyder said, adding that this work will establish best practices in these food processing environments. “We hope that new tools like superheated steam will reduce the demand for water, sanitizers and waste management in food manufacturing, aligning with consumer preferences and sustainability goals.”