Ultrasonic waves boost soy protein, sugar yields

Adding ultrasonic pretreatment to soy processing boosts and improves the yield of protein that can be added to foods, said Samir Khanal, an Iowa State research assistant professor of civil, construction and environmental engineering. In Iowa State laboratory tests, exposing ground and defatted soy flakes to ultrasonics has increased the release of soy proteins by 46%.

The student, Bishnu Khanal, said the ultrasonic treatment also breaks some of the bonds that tie sugars to the soy proteins. Separating the sugars from the proteins improves the quality of the proteins. It also boosts the sugar content of the soy whey that's left after processing. Ultrasonic treatment boosted sugar yields by 50 percent.

The low-cost, sugar-enriched whey can replace an expensive compound used to grow lactic acid bacteria, Khanal said. The bacteria produce nisin, a valuable natural food preservative that's also used in cosmetic and health care products such as mouthwash and toothpaste.

"Our preliminary economic analysis showed that the proposed technology could generate revenue up to $230 million per year from a typical plant producing 400 million pounds of soy protein isolate," says a summary of the research project. "This is a major breakthrough in the soy processing industry."

Khanal said the technology has boosted protein and sugar release in batch-by-batch lab tests. The researchers will now try lab tests to see how it works in the same kind of continuously flowing stream that would be used in a soy processing plant.

- Source, Iowa State University press release

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