Study of the acetylation-induced changes in the physicochemical and functional characteristics of insoluble dietary fiber from wheat bran.

Abstract

Wheat bran is rich in dietary fiber (DF), particularly insoluble dietary fiber (IDF). Although it was documented the benefits for human health following the consumption of these DFs, its lower water retention capacity and other property still limited their applications. Therefore, the current research investigated the impact of acetylation on the changes in their corresponding physicochemical and functional properties. The current results indicated the acetylated group restricted the alignment of the molecular chains, which led to an increased amorphous phase in the fiber structure, followed by an enhanced thermal sensitivity and a reduced crystallinity as evidenced by X-ray diffraction (XRD). Moreover, the acetylation of the IDFs enhanced the cholesterol absorption capacity, but their corresponding antioxidant capacity and cation exchange capacity were reduced, which might be due to the partial loss of the phenolic compounds onto the polysaccharides during the modification. Interestingly, a lower degree of substitution (DS) of the IDF achieved from water-acetic anhydride modification led to a higher water retention capacity (WRC) and water swelling capacity (WSC). In contrast, a higher DS from acetic anhydride modification demonstrated a greatly improved in vitro hypoglycemic performance of the IDF, including α-amylase inhibitory activity and glucose dialysis retardation index (GDRI), compared to the other samples. This study might highlight a new approach to modify the functionality of the IDFs via the acetylation and it was of great value for designing a novel IDF with hypoglycemic activity. This article is protected by copyright. All rights reserved.