Inhibitory effects of water-soluble hemicelluloses from corn bran with varying molecular weights on wheat starch digestibility

Abstract

This study examined effects of corn bran hemicellulose (CBH) with three molecular weight levels—CBH-H ($M_w$ = 789 × 10³), CBH-M ($M_w$ = 15 × 10³), and CBH-L ($M_w$ = 1 × 10³)—on wheat starch digestion and explored the underlying mechanism by investigating their interactions with starch and enzymatic activities. The results demonstrated that when heated at 100 °C and 130 °C, CBH-H exhibited the strongest inhibition on peak and setback viscosity, reducing them by 49.3 % and 44.0 %, respectively. CBH-H also inhibited retrogradation after 14 d, with its relative crystallinity decreasing the most, forming an orderly honeycomb-like structure. Fluorescence spectra revealed that CBH-H shifted emission peaks of α-amylase and amyloglucosidase, thereby reducing their activities to 71.2 % and 67.7 %, respectively. Furthermore, CBH-H showed the greatest inhibition against starch digestion in vitro and in vivo, achieving 31.1 % resistant starch content and reducing postprandial blood glucose levels by 47.5 %. These findings provide new insights into the application of CBH-H in functional starchy foods.