Feature   | Winter 2012

Food science + engineering = safer food
Common Denominators

By Brian Wallheimer

Microbiologist Arun Bhunia researches ways to detect dangerous food pathogens. His breakthrough research—a laser that scatters unique light patterns as it passes through bacterial colonies—came after he joined forces with engineering researchers. This type of collaboration is at the heart of Purdue's Center for Food Safety Engineering.

Arun Bhunia is not an engineer, although scientists confuse him with one sometimes at conferences.

This mistaken identity can be traced to a decade ago, when a group of engineering students and postdocs approached him about using lasers to detect bacteria. Bhunia, a microbiologist in Purdue University's Department of Food Science, had never thought about pathogen detection using a laser, and he wasn't sure it was possible.

But he was intrigued. Bhunia had hit dead ends in research before, so he decided to see what he could do with a bunch of engineers. "Before I came to Purdue, I was doing pathogen detection work," he says. "But you could only go so far before your expertise was no longer enough."

Bhunia and the engineering students who worked with former head of Mechanical Engineering E. Dan Hirleman gathered in Bhunia's lab and pointed the laser at bacteria. They watched the light scatter after it passed through the bacterial colonies. Based on what they saw, it seemed that different bacteria produced different patterns of scattered light.

To be sure, they contacted J. Paul Robinson, a professor of biomedical engineering, and Bartek Rajwa, a research assistant professor, both experts in image analysis.

Working together, the group, which now includes research assistant professor of mechanical engineering Euiwon Bae, found that bacteria do scatter light in different and predictable ways. A library of the images could be built, and food safety inspectors could use a laser-based device to quickly test samples to detect harmful pathogens, such as E. coli and Salmonella.

Bhunia now speaks regularly at conferences about the BARDOT (Bacterial Rapid Detection using Optical Scattering Technology) light-scattering device. Based on his work with Robinson, Rajwa and others, Bhunia can talk with confidence about some of the engineering components of the project, which is why he's mistaken for an engineer.

"I have to be able to talk about all aspects of the device. My engineering knowledge is limited, but I know a lot more now than I did before this project," Bhunia says.

The Early Years
The BARDOT light-scattering project is one of the successes to come out of Purdue's Center for Food Safety Engineering, which marked its 10th anniversary this year. And it perfectly illustrates the mission of the center: to bring together chemists, biologists, engineers and other scientists to improve food safety through advancements in the detection and control of foodborne pathogens and chemical hazards.