Mechanism of the Influence of Different Gluten Fractions on the Digestibility of Wheat Starch

In this study, gluten, glutenin and gliadin were mixed with starch at mass ratio of 14:86. To clarify their effects and mechanism on starch digestibility, the interactions between gluten and its components and starch/α-amylase were investigated by a rheometer, a thermogravimetric analyzer and a confocal laser scanning microscope (CLSM). The results showed that compared with pure wheat starch, the digestibility of starch reduced by 39.93%, 49.48% and 26.61% after 120 min of enzymatic hydrolysis in the presence of gluten, glutenin and gliadin, respectively. Starch could interact with gluten through hydrogen bonds to form a stable complex. Compared with gluten and gliadin, the addition of glutenin formed a denser physical barrier around the starch matrix, which inhibited the enzymatic hydrolysis of starch to a greater extent. In addition, the percentage inhibition of glutenin on α-amylase was the highest (approximately 79%). CLSM observation proved stronger binding between α-amylase and glutenin. The results of this study will help to enrich our understanding of the mechanism of the regulatory effect of typical protein components on starch digestibility in food systems, and provide a theoretical guideline for the development of low-glycemic-index foods.