sealPurdue News

May 1996

New test kit adds 'green' value to soybeans

WEST LAFAYETTE, Ind. -- Soybeans now can fight on the front lines in the battle to clean the environment.

Scientists at Purdue University have developed a new, easy-to-use test kit for peroxidase, an enzyme from soybean hulls. That paves the way for peroxidase to replace the potential carcinogen formaldehyde in glues and varnishes and to treat industrial and municipal waste water.

The test kit was developed by Rick Vierling, an assistant professor of agronomy at Purdue and director of the Indiana Crop Improvement Association Genetics Lab. It could be used by breeders to test the soybean lines they are developing, by farmers to test the peroxidase levels of beans in the field, by grain dealers to test beans brought for them to buy, and by industry personnel who want to test peroxidase activity in factory processes.

As peroxidase replaces formaldehyde, other volatile organic compounds and metal catalysts in more and more applications, those markets could add value to soybeans and bring growers additional profits. And farmers won't lose through the extraction process, because researchers have found ways to extract peroxidase from hulls without reducing the value of the oil and meal in the soybeans.

"The kit's a big step," Vierling says. "Now manufacturers can monitor peroxidase activity as part of an overall quality-control program in manufacturing plants, and this will facilitate the use of the enzyme. Monitoring peroxidase activity during a manufacturing process wasn't easy before the kit existed."

Peroxidase from soybeans is a new, but fast-growing, presence in industrial chemistry. The word "peroxidase" describes a class of oxidative enzymes found in plants, milk and white blood cells. It can reduce environmental contamination caused by manufacturing processes, and it's gaining an industrial following.

The baking industry in Europe has started using soybean peroxidase instead of potassium bromate in bread-making and dough conditioning. A U.S. company is finalizing agreements to use it for labeling antibodies in medical and research diagnostics. Bioremediation companies are considering peroxidase for industrial waste water treatment, while other companies are investigating its use in manufacturing computer chips, adhesives, car parts, varnishes and linings of drums and cans. Peroxidase someday may also be used for bioremediation of water or soil, Vierling says.

"In 1994 we were working with one product for one company," says Alex Pokora, vice president for technology for Enzymol International, a worldwide leader in developing peroxidase technology which currently holds 17 patents on the manufacture and use of soybean peroxidase. "Now we are working with many products for many major chemical companies.

"Peroxidase replaces a lot of really harsh chemicals and eliminates harsh reaction conditions. It's a cleaner technology, and it's cost effective."

He predicts that his Columbus, Ohio, company's sales will reach $50 million by the year 2000, only seven years after sales began.

In many industrial applications, the new products that use peroxidase will replace products created through processes that use large amounts of potential pollutants, Pokora says. In cases where peroxidase replaces formaldehyde, it's replacing a potential carcinogen. Overall, it will make many manufacturing environments safer for workers, he says.

Enzymol's first projects used peroxidase enzymes extracted from horseradish, but the supply was limited and the cost was high. The company found a better peroxidase in soybeans and called plant geneticist Vierling for assistance.

"All plants contain peroxidase, but not all peroxidase is created equal," Vierling says. "Soybean peroxidase is highly reactive and thermally stable. I don't think there's a better peroxidase out there."

In addition to its superior performance in industrial applications, soybean peroxidase is relatively easy to get. The beans are widely grown. Production, transportation and storage facilities already are in place to deliver high-peroxidase beans for enzyme extraction.

In 1992, the Indiana Soybean Development Council and the Indiana Institute of Agriculture, Food and Nutrition funded Vierling's work through grants made to the Indiana Crop Improvement Association (ICIA). Vierling started looking at how production practices might change peroxidase levels in growing beans. He studied peroxidase activity in stored beans. Then, with USDA geneticist Jim Wilcox, he started breeding soybeans for higher levels of the enzyme.

As he planned these projects, he saw that a quick chemical test for peroxidase activity would greatly speed his research and plant breeding efforts. Although he wasn't a chemist, he had a hunch that he could develop one. He was right.

"Other peroxidase techniques require a great deal of equipment, aren't precise or can take chemists days to complete," Vierling says. "Ours is made similar to a home pregnancy kit. The kit makes it possible and feasible to test and monitor peroxidase levels all the way through the system, from farmer to processor to end user." It is easy to use and gives results in minutes.

ICIA has applied for a patent for the test kit.

Meanwhile, test kit in hand, Vierling and Wilcox will continue working to bring farmers soybeans with a higher peroxidase content.

"Some currently grown cultivars have zero percent peroxidase by dry weight, and others have up to 5 percent," Vierling says. "Wilcox and I have identified some exotic germ plasm that has three times the current level out there." With the test kit to help speed the screening process, Vierling already has identified and cloned the peroxidase gene and plans eventually to release a new variety or high-peroxidase germ plasm.

If the market for peroxidase continues to expand as it has in the past two years, grain dealers might pay farmers a premium for high-peroxidase beans brought to the elevator. Vierling applauds the prospect of higher prices for added value, but notes that the premium might evaporate once all beans contain high levels of peroxidase.

Sources: Rick Vierling, (765) 474-3494; Internet,
Alex Pokoroa, (614) 529-7333
Writer: Rebecca J. Goetz, (765) 494-0461; Internet,
Purdue News Service: (765) 494-2096; e-mail,

NOTE TO JOURNALISTS: A color photo of Rick Vierling using the peroxidase test kit is available from Purdue News Service, (765) 494-2096. Ask for the photo called Soy Enzyme/Vierling or download here.

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