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Inside Iowa State, a newspaper for faculty and staff, is published by the Office of University Relations.

September 24, 2004

Proponent of clean burgers

by Debra Gibson

His pedigree is impeccable -- Yale undergrad, a chemistry Ph.D. from the University of Chicago, a four-year postdoc in France. His work is nationally acclaimed; he was a full professor by age 40.

So one doesn't expect this renowned scientist to summarize his research in quite these terms:

"Nobody wants doo-doo on their burgers."


Thanks to Jacob Petrich and collaborators Thomas Casey and Mark Rasmussen, such food contamination may in time be eradicated. The men have created the technology for VerifEye, a handheld device that detects the presence of feces on beef carcasses. Used in three U.S. packing plants so far, the device helps identify meat that contains harmful bacteria not seen by the human eye.

Casey and Rasmussen, both scientists with the National Animal Disease Center in Ames, contacted Petrich in the late 1990s after hearing of E. coli outbreaks at fast food restaurants in the Pacific Northwest. Knowing of Petrich's work in photochemistry (studying how light interacts with matter), the microbiologists wanted to pursue whether light-based technology could hone in on bacteria.

"We basically put cow doo-doo in my machines, and found out that it glowed," Petrich said. "Actually, it fluoresced, which was pretty cool, because we never thought it would do that."

The scientists then had to determine why the feces glowed.

"We knew that cows eat grass, so we had to determine what's in grass to cause this," Petrich continued. "We realized it was the chlorophyll, which is really what we're detecting with the device."

The technology spots chlorophyll

The scientists devised a prototype detector that involved a thin fiber optic cable equipped with a laser and attached to a small handheld box. The prototype used specific wavelengths or colors of light to illuminate the carcass. The collected light returned from the carcass was electronically analyzed for the presence of fecal matter.

Today, the prototype has evolved into a seven-foot scanner and a smaller, handheld version, both of which are used in meatpacking plants in the United States. The technology is licensed by eMerge Interactive Inc., a small company based in Florida.

Though the devices detect chlorophyll, not salmonella or E. coli bacteria specifically, "even if there is no bacteria present in the feces, you don't want to eat feces," Petrich said.

Currently, he is pursuing the creation of a similar technology to study the factors contributing to bovine spongiform encephalopathy, more commonly known as mad cow disease. With the aid of a $545,000 U.S. Department of Defense grant, Petrich stresses that his research is "very experimental" at this stage, but he's excited to pursue this line of study.

"Light is a great way to look at all this," he explained. "You don't have to touch anything, there's no additional contamination from poking around the subject, and light-based measurements are fast because you don't need to take samples for further investigation."

This technology has landed its inventors numerous prestigious citations, including an R&D100 Award, the Agricultural Research Services Technology Transfer Award and the USDA's Secretary's Honor Award for Enhancing Protection and Safety of the Nation's Agriculture and Food Supply.

The awards were made somewhat sweeter by the fact that the scientific community initially scoffed at Petrich's idea for the detection system.

"People didn't think it would work," he explained with a slight smile. "It was considered just too simple."

The Chicago native also hopes to adapt the technology for organizations in which hand washing is crucial to preventing bacteria and virus dissemination. These hand-held bacteria detectors could be used in hospitals, fast-food restaurants and daycare centers, for example.

Other options for light research

Petrich's light-based research may have other health-related implications. For several years, Petrich has conducted studies on hypericin, a molecule found in the herb St. John's Wort. This herb often is used to treat mild depression.

In the early 1990s, ISU scientists Susan Carpenter, professor of veterinary microbiology and preventative medicine, and George Kraus, University professor of chemistry, discovered that shining light on a mixture of hypericin and some viruses killed the viruses. Carpenter and Kraus turned to Petrich to find out why. Since then, he has been researching hypericin and light interactions, and studying how hypericin interacts with other molecules in the body to modify their behavior.

While this research ultimately could have implications for the treatments of the HIV virus and some cancers, Petrich is quick to rule out an impending announcement.

"We are certainly making progress, but we are nowhere near a cure or a drug," he said. This work has received funding from the National Institutes of Health, and Petrich also collaborates on it with other scientists at ISU's Center for Research on Botanical Dietary Supplements.

When he's not in the lab, Petrich teaches physical chemistry courses, coaches his young children's soccer teams and reads. And he continues the never-ending pursuit for research funding, a process he finds "a very competitive business."

"You have to be very aggressive these days to get money for your projects, and sometimes you really have to fight for your ideas," he said. "People have certainly thought we were was off-base with our proposals, but I think we're doing a pretty good job of proving people wrong so far."

Jacob Petrich

Jacob Petrich is the "go-to" guy in photochemistry. Photo by Bob Elbert.


"We knew that cows eat grass, so we had to determine what's in grass to cause this. We realized it was the chlorophyll, which is really what we're detecting with the device."

Jacob Petrich