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Sept. 16, 2010 Volume 32, No. 4

Researchers find a new breed of soybean can lead to heart-healthy oils


MU team targets alternative to trans-fat

It’s no secret that trans-fat is a killer. 

Denmark, the state of California and cities such as New York and Philadelphia have effectively banned restaurants from using oils and spreads containing the substance, which is created when liquid plant oils are subjected to a process known as hydrogenation.

Still, tens of thousands of people die in the United States every year from cardiac-related disease linked to the consumption of trans-fat, according to the New England Journal of Medicine. And trans-fat in the form of partially hydrogenated vegetable oils can be found in most processed foods, including cookies, baked goods, popcorn, shortenings, crackers, doughnuts and chips.

Now, a University of Missouri research team has developed a soybean that produces oil that is naturally low in saturated and trans-fats. The trick, said Kristin Bilyeu, an adjunct assistant professor of plant science, who with J. Grover Shannon, professor of plant sciences, led the research effort, is to increase the level of heart-friendly oleic acid content in the soybean plant. 

“When we started this research, we were looking at three factors,” said Bilyeu, a researcher with the U.S. Department of Agriculture’s Agriculture Research Service, in the College of Agriculture, Food and Natural Resources. ‘We needed a heart-healthy oil. It needed to be stable with a good shelf life. Finally, it needed to be economically feasible.”

Researchers have been searching for a soybean-based alternative to oils high in saturated fats, the main dietary cause of high cholesterol. But because soybean oil spoils when heated, producers had to hydrogenate the oil to keep it stable, thus creating trans-fats.

Typically, soy oil is only 20 percent oleic acid, which inherently resists spoilage and therefore doesn’t need hydrogenation. The other fatty acids in soybeans, linoleic and linolenic acids, require hydrogenation to ensure flavor and a long shelf life.

Through natural pollination procedures, Bilyeu and Shannon increased oleic acid in the bean to 80 percent and decreased the amount of saturated fat in the oil by 25 percent. The natural breeding not only stabilized the oil, but also made it healthier: Hydrogenation typically rids the oil of the Omega-3 fatty acids, which are good for the heart.

Building a healthier soybean meant overcoming thousands of years of evolution. Normally, biochemical events during soybean growth favor production of fast-spoiling linoleic and linolenic fatty acids. The team discovered that combining variant genes from two different soybean plants into a new variant reversed that process. 

While high-tech “gene silencing” has been used to trigger such genetic changes in soybeans, the MU team used classical plant breeding techniques to “endow” their soy lines with these two genes. This approach could make these soybeans more marketable to countries that resist buying genetically modified foods. 

Field trials were conducted in Missouri and Costa Rica to ensure that the new soy lines’ oleic-acid production stays fairly constant across diverse growing conditions. The next step is determining whether the new soybeans can produce comparable yields to major varieties grown today.

 “If you grow the plant in northern Missouri, you typically have 70 percent to 80 percent oleic acid in the soybean’s oil,” Shannon said. “In southern Missouri, the oil is consistently 80 percent oleic acid. Before our work, we saw a lot of variation in the amount of oleic acid that was produced based on the environment.”

Results of the research, which was funded by the USDA, the University of Missouri, the United Soybean Board and the Missouri Soybean Merchandising Council, has been published in BMC Plant Biology.