Effect of sulfated modification on rheological and physiological properties of oat β-glucan oligosaccharides prepared by acid or oxidative degradation

Two kinds of oat β-glucan oligosaccharides (βG-H and βG-O) were obtained by acid and oxidative degradation methods, respectively. Further, six kinds of sulfated oat β-glucan oligosaccharides (βG-H-S1, βG-H-S2, βG-H-S3, βG-O-S1, βG-O-S2, and βG-O-S3) with different degree of substitution were prepared by controlling the reaction time. The structure analysis showed that the molecular weights (Mw) and degree of substitution (DS) of sulfated oat β-glucan oligosaccharides increased with the prolonged reaction time. After sulfated modification, the apparent viscosity of oat β-glucan oligosaccharides increased and their viscoelasticity was changed. Sulfated modification endowed βG-H with enhanced fat binding capacity and bile acid binding capacity, and the above-mentioned properties increased with the increasing Mw and DS. Meanwhile, sulfated modification endowed βG-O with enhanced fat binding capacity and attenuated bile acid binding capacity, and the capacities of βG-O-S decreased with the increasing Mw and DS. Sulfated modification enhanced hypoglycemic effect of oat β-glucan oligosaccharides, it showed ability to decrease the glucose availability and inhibit α-glucosidase activity. The results revealed that the physiological properties of sulfated β-glucan oligosaccharides depend on their Mw, DS, and degradation method of β-glucan oligosaccharides.