The soluble dietary fiber(SDF)was extracted from lotus root residue after treatment with alkaline hydrogen peroxide(AHP),and the structure and rheological properties of SDF were compared before and after treatment.Results showed that after AHP treatment,the extraction rate of lotus root residue SDF was increased by 7.21 times(P＜0.05),and the contents of L-rhamnose and D-galactose were significantly increased by 51.85％and 39.27％,respectively(P＜0.05).Compared with untreated lotus root residue SDF,AHP treatment reduced the molecular weight of lotus root residue SDF,and the Zeta-potential was decreased from-24.80 mV to-26.95 mV(P＜0.05).Scanning electron microscope and Fourier transform infrared spectroscopy analysis showed that the structure of lotus root residue SDF became loose,the surface became rough,and some characteristic functional groups changed after AHP treatment.X-ray diffraction and thermogravimetric analysis showed that the crystallinity of lotus root residue SDF after AHP treatment was decreased,but its thermal stability in high temperatures were improved.Furthermore,the steady-state and dynamic rheological analysis showed that in the presence of Ca2+,the SDF treated with AHP showed higher shear viscosity and stronger gelation abili-ty.In conclusion,AHP treatment could effectively improve the structure and rheological properties of lotus root residue SDF,which could provide a reference for the development and utilization of lotus root residue.
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