Effect of different chemical modification on the physicochemical properties of fiber-enriched polysaccharides isolated from wholegrain rice and buckwheat

Abstract

Dietary fiber (DF) isolated from wholegrain flours (brown rice and buckwheat) were chemically modified by cross-linking (CL), carboxymethylation (CM) and hydroxypropylation (HP). The modified DF was evaluated for its physicochemical characteristics based on compositions, hydration properties and interactions of wheat starch/DF system. The changes in total dietary fiber (TDF) content of were found to be chemical modification-dependent. CM contributed to the increase in soluble dietary fiber (SDF) contents and water solubility. On the contrary, CL and HP significantly increased the insoluble dietary fiber (IDF) contents, resulted in reduced water solubility. Hydration properties of both native and modified buckwheat DF were higher than all rice DF counterparts. In the interaction with wheat starch, starch hydrolysis was low in samples with high TDF contents (CLa parts per thousand HP > CMa parts per thousand native). It was concluded that characteristics of modified cereal DF depended on the presence of functional groups rather than sources of wholegrain.