Nutritional property of starch in a whole-grain-like structural form

Abstract

Starch is the main constituent of cereal grains, but less attention has been paid for its contribution to the health benefits of whole-grain foods. In the current investigation, the slow digestion property of corn starch in a whole-grain-like structural form (WGLSF), which mimicked the whole grain microstructure, was studied to better understand the nutritional property of whole grain starch. The WGLSF-starch prepared through Ca2+-induced alginate gelation in the presence of starch and β-glucan showed a reduced content of rapidly digestible starch (RDS) (∼40.4–23.6%) and increased content of resistant starch (RS) (∼20.7–30.9%) and slowly digestible starch (SDS) (∼38.9–47.8%) along the alginate concentrations (0.1–0.4%, w/v). Consistently, the postprandial glycaemic response of the cooked WGLSF-starch (0.3% alginate) exhibited a significant reduction (35.5%) of glucose peak compared to their physical mixture. Scanning electron microscope (SEM) observation demonstrated that the starch granules were embedded in the β-glucan-alginate co-formed gel matrix with a cell wall-like structure, which might cause a decrease of enzyme accessibility to the substrate, and ultimately a slow digestion profile of starch and reduced glycaemic response. Thus, maximization of the slow digestion property of starch in whole-grain food processing might be essential to further improve the nutritional property of whole-grain foods.