Food safety research: Ultrasound may offer another layer of safety

High-powered ultrasound may have a place in the sanitizing mix when it comes to organic leafy greens.

Scientific American reports today on promising preliminary results from research into using high-power ultrasound to clean salad greens. Working with salad producers Earthbound Farm, the Institute for Food Safety and Health (IFSH) at the Illinois Institute of Technology has conducted what IFSH director Robert Brackett told Fresh Cut has been “some preliminary work within the lab” regarding high-power ultrasound.

“Some people had hoped it might be a new sanitizer, but I don’t think it’s going to come to that,” Brackett said. “It’s meant to be an adjunct to whatever sanitizers are in the water that’s been approved anyway.”

The idea, he said, is that “if one thing is good, let’s add another, and another, and then there will be a multiplying synergistic effect.

“We’ve tried it on different things. We’re aiming right now at leafy greens.”

High-powered ultrasound creates millions of tiny bubbles when applied to the surface of leafy greens. The process is strong enough to dislodge tucked-away pathogens that are then washed off during sanitizing.

Efficacy depends on both product and process.

“It depends on … whether it’s lettuce versus spinach, and what type of lettuce, and it depends on what type of sanitizer happens to be in the water at the time,” Brackett said. “At this point, we’ve been sort of teasing out all these different factors.”

High-powered ultrasound would not be an option with cantaloupe, tied to a recent deadly listeria outbreak, since it entails dipping and agitation – neither suited to cantaloupe, Brackett said.

Photo courtesy of IFSH: Washing fresh-cut romaine lettuce using the 1 kW ultrasound system.