Processing Method May Make Tasty Soy Cereals And Snacks A Reality

At the heart of the research is the effect of the extrusion process on isoflavones. Extrusion is used to make many popular breakfast cereals. Isoflavones are components within soy that are suspected to be the reason why soy has shown protective activity against heart disease, breast and prostate cancers and osteoporosis, as well as alleviating menopausal symptoms, and reducing bad cholesterol levels.

In the January issue of the Journal of Agricultural and Food Chemistry, U. of I. food scientists report that key isoflavones -- namely the genistein and daidzein series -- lose very little of their structural profiles when mixed at 80 percent corn/20 percent soy in the extrusion process, which turns mealed raw products such as corn and wheat into ready-to-eat cereals after less than a minute of aggressive mixing and heating.

In the November-December issue of Cereal Chemistry, they pinpointed the most appealing texture and size of extruded soy and corn meal blends mixed with sugar and water as chosen by volunteer panelists. In a paper to be published in the Journal of Food Science, researchers will detail the mix of an extruded corn snack with soy protein that drew favorable taste responses from 400 volunteer tasters at the U. of I. College of Agricultural, Consumer and Environmental Sciences Open House in 1996.

"We think that breakfast cereals and snacks would be good ways for Americans to put soy in their diets," said James F. Faller, lead researcher in the U. of I. project, in which researchers now are studying the effects of extruded soy-containing cereals on cancer cells. "The manufacturing process lends itself to blending ingredients, like in this case corn and soybeans. You could also use wheat or rice."

The January paper, he said, "helps us support a claim that even after processing in this extreme environment, soy still has its health benefits." Previous research on soy consumption has involved products such as baked goods, tofu and tempeh. In the extrusion process, "only barrel temperature and feed moisture significantly affected the amount of isoflavones," the authors wrote.

The study on sensory perception involved soy flour, soy protein concentrate and isolated soy protein combined with a wide variety of moisture and sugar ratios. The isoflavone analysis was done with soy protein concentrate. "The work has given me real insight to what happens during extrusion, and how that translates to producing a more acceptable extruded product containing soy," Faller said.

The research is funded by the Ohio Soybean Council, Illinois Council for Food and Agricultural Research and Illinois Value-Added Program. Co-authors of the three papers were food scientists Faller, Jin Young Faller, Barbara P. Klein, Michelle Schwenk and Keith Singletary; Symon Mahungu, now of Egerton University in Kenya; and graduate students Silvia Diaz-Mercado and Jiyuan Li.