Substitute toasted soy flakes in bread to improve its nutritional value.

While soy is considered good for you, one of the major drawbacks for using it in foods is its beany flavor. Various approaches have been used to improve the flavor of soy, including different processing techniques and flavor masking.

The smooth texture and sweet nutty flavor of toasted soy flakes make them potential ingredients for such bakery products as bread. Scientists at Iowa State University wanted to investigate changes that occur in the properties of dough when wheat flour is partially substituted by toasted soy flakes in bread-making applications. They also wanted to evaluate the consumer acceptance of toasted soy flakes in the bread. They found that toasted soy flakes may improve the product's nutritional value and give an acceptable appearance, flavor and texture.

The researchers substituted wheat flour with full-fat commercial flakes (0.2 mm thickness, medium toast) at 5%, 10% and 15% levels in bread. Substituting 5% toasted soy flakes for wheat flour did not change the water absorption rate compared with the control. Substituting 10% or more soy flakes increased water absorption rates.

The peak dough mixing time increased when using toasted soy flakes. Mixing time increased the most when bread contained 15% soy flakes. Crust color was darker with increasing amounts of toasted soy flakes, with a 15% substitution yielding the darkest color. The lightness of crumb color did not differ between the control and 5% levels, or between 10% and 15% content. However, soy flake levels of 10% and 15% yielded a darker product than did the control and levels of 5%.

There was no difference in volume between the control and 5% levels, or between 10% and 15%. The 10% and 15% products were lower in volume compared with the control and 5% sample. There was no difference in hardness among the samples.

In consumer tests, the control bread and 5% soy flake bread scored the highest in terms of overall appearance. There were no differences in scores for all breads in terms of liking overall flavor and texture. The researchers saw that 35% of consumers liked the control bread, while 65% liked a product containing any level of toasted soy flakes.

Further information. Lester Wilson, Department of Food Science and Human Nutrition, Iowa State University, 2541 Food Sciences Building, Ames, IA 50011; phone: 515-294-3889; fax: 515-294-8181; email: lawilson@iastate.edu.