The Effect of Partially Substituted Lupin, Soybean, and Navy Bean Flours on Wheat Bread Quality

Abstract

Many edible legumes contain high amounts of proteins, fibers, minerals and vitamins. Their essential amino acid composition and concentration complements the amino acids in wheat and other cereals. In addition, breads fortified with protein rich legumes make the breads more palatable. In this study, we evaluated breads made from wheat flour partially substituted with soybean, navy bean, and lupin flours at 10%, 20%, and 30% levels. The physicochemical properties of breads were measured and compared with the control (made from 100% wheat flour). Statistical analysis was used to assess the significance of the differences. The breads fortified with soybean, lupin and navy bean flours showed remarkable springiness, similar to the breads made from wheat flour. However, the higher amount of substitution increased the firmness of the breads, probably due to the incorporation of additional fibers and proteins into the formulations. Compared to wheat bread, the volumes of 90:10 wheat-soybean, wheat-lupin, and wheat-navy bean breads decreased about 7%, 2%, and 10%, respectively. Higher substitution levels would result in a higher reduction in volume for all legumes tested. The volume reduction as a result of legume substitution appears to be navy bean flour > soybean flour > lupin flour. The inclusion of legumes in the bread formulations imparts a slightly darker crust color and crumb color with the exception of breads with the soybean flour substitution. Lupin appears to be the best substitution candidate among the legumes tested for fortified bread making. Lupin can be presented as a high-value protein source in developing marketable foods for health conscious consumers.