Whole wheat bread has high nutritional value, but it is characterized by inferior quality and a high glycemic index. Studies have shown that the addition of exogenous protein can improve bread quality. The aim of this study was to determine how different protein combinations (gluten + other cereal proteins) alter dough properties. Based on these properties, we inferred the interactions of the major components (protein, starch, and water) and analyzed their effects on baking quality and starch digestibility of whole wheat bread. Alterations in mixing characteristics, rheological characteristics, and scanning electron microscopy images showed that the addition of large amounts of gluten strengthened the gluten network, whereas the addition of highland barley protein had little effect, and other added proteins caused damage. The addition of gluten improved bread quality tremendously, while the addition of other proteins negatively affected bread quality. All protein additions significantly reduced the in vitro starch digestibility (p < 0.05), with the bread containing highland barley protein showing the lowest estimated glycemic index (76.96) and an excellent baking quality. Therefore, highland barley protein can be selected as a partial substitute for gluten in whole wheat bread.
Read full abstract