New soybean line promises healthier soy oil.

A food oil pressed from a new line of soybeans could become a close runner-up to olive oil in terms of its heart-healthy levels of monounsaturated fat. Olive oil enjoys a fine reputation among nutritionists because of its relatively high levels of monounsaturated fat--nearly 75% of total fat.

The USDA-ARS National Soybean Germplasm Collection (NSGC), Urbana, IL, recently received soybean genetic material, or germplasm, with higher monounsaturated fat concentrations than any other previously included in the collection. The NSGC preserves such plant material for use in developing improved cultivars.

The new germplasm, N98-4445A, was developed by scientists using traditional breeding methods. The germplasm will be a useful genetic resource for breeding mid-oleic soybean varieties suitable for different growing regions, we're told. Oil from N98-4445A contains increased levels of oleic acid, a monounsaturated fat stable enough for use in salad dressings or frying oils without requiring treatment by hydrogenation. Instead, researchers achieve hardening by chemically adding hydrogen to a chain of oil molecules.

While hydrogenation serves as a stabilizer that makes oils suitable in solid products such as margarines, breakfast bars and baked goods, it also creates trans isomers, which are less healthy trans fats. The new oil would likely be as stable as hydrogenated oils, but without the trans isomers. Oils based on this new line would probably not oxidize as quickly as other soybean oils.

The germplasm line's increased oleic acid level also correlates to a decrease in polyunsaturated fatty acids (PUFAs), such as linoleic and linolenic acids, that cause off-odors and which break down when oxidized during aging or frying. While commercial soy oils are 7% linolenic acid, the new line has only 3% of that highly unstable PUFA. In comparison, even a 4% content might require some hydrogenation. Oils based on the new generation would fall below a critical cut-off point under which no hydrogenation is necessary.

By 2006, the U.S. FDA plans would require food manufacturers to state the amount of trans fatty acids that are in processed foods. The processed food industry uses several tons of vegetable oils in myriad products annually. About half of all the vegetable oil produced is from soybeans, the most used vegetable oil in the world.

Further information. Joseph Burton, USDA-ARS Soybean and Nitrogen Fixation Research Laboratory, 3127 Ligon St., Raleigh, NC 27695; phone: [phone]; fax: [phone]; email: [e-mail].