Structural changes of polysaccharides isolated from corn bran by hydrothermal treatment after twin-screw extrusion

Abstract

The objective of this investigation was to elucidate the structural changes of the polysaccharides isolated by hydrothermal treatment of corn bran after twin-screw extrusion. The structures and antioxidant activities of the purified polysaccharides were investigated and compared by monosaccharide analysis, Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR). The results showed that the structures of the linkages and monosaccharide components of the purified polysaccharides were not affected strongly by the twin-screw extrusion pretreatment. However, the purified polysaccharides isolated from pretreated samples displayed significant differences in monosaccharide ratios, degree of branching/ linearity, and molecular weight. These physical changes may be related to the decrease of antioxidant activities of the polysaccharides. The present investigation contributes to the knowledge of how pretreatment by twin-screw extrusion affects the chemistry of corn bran polysaccharides. Results can be applied to improve the efficiency of hydrothermal extraction of polysaccharides from corn bran.