“He’s an important collaborator because the project is at the intersection of produce safety and process engineering,” said Snyder, whose background is microbial food safety. “This is an interdisciplinary approach to developing novel sanitation technology.”
Superheated steam differs from the visible, wet steam vapor emitted by a tea kettle in that it is invisible and acts like a hot gas at super-high temperatures. Applied to surfaces, superheated steam has been shown to kill pathogens without leaving moisture or condensation.
The researchers used portable pilot-scale roll-along and backpack units fabricated by a collaborating manufacturer. As part of the project, they reviewed Occupational Safety and Health Administration guidelines and developed worker safety and operator compliance training.
Initial trials looked at thermal distribution across stainless steel coupons — or discs — at ambient temperatures using three different coupon thicknesses and three different nozzle distances.
Temperatures at the contact point ranged from 170 to 320 degrees Celsius (338 to 608 degrees Fahrenheit), depending on nozzle distance. Compare that to commercial pizza ovens, which typically range from 400 F to 800 F.
High temperatures support short exposure times, and the team also plans to characterize how rapidly temperature dissipates across the surface. The researchers plan to conduct similar tests with concrete coupons as well as ones made of materials used in picking bags.
Although superheated steam doesn’t use large amounts of water, it is unknown whether prolonged use of the technology could change ambient relative humidity in enclosed spaces, depending on size and ventilation. As part of the project, Snyder said they will look at whether those relative humidity changes could potentially lead to condensation with extended superheated steam use.
One of the project’s objectives is to better understand how much the industry would be willing to pay for SHS technology. To that end, Snyder is conducting a brief online survey that proposes different scenarios. Respondents remain anonymous. To participate in the survey, visit https://cornell.ca1.qualtrics.com/jfe/form/SV_3axMz1q0jTV4St8.
Because superheated steam doesn’t use large amounts of water, Snyder said the technology could offer the produce industry potential water savings. But it also could provide the industry with more sanitation options.
“I think these practical findings will lead to the development of better sanitation equipment in the produce industry. We’re moving it forward from theoretical research to something practical.”