Studies On The Preparation Conditions And Characteristics Of Dietary Fiber From Cassava Dregs

The preparation, physical and chemical properties of dietary fiber(DF) including insoluble dietary fiber(IDF) and soluble dietary fiber(SDF) from cassava dregs were studied in this paper. We used enzymatic method to extract dietary fiber from cassava dregs. By single factor and orthogonal tests, the enzymatic preparing conditions for the DF from cassava dregs were optimized. Results showed that the best conditions for purification evaluated by DE value:(1)1:15(residue:1%of amylase),60℃, pH6.0,210min for amylase treatment; and (2)1:15(residue:0.8%of proteinase),45℃, pH7.0,180min for incubation. Finally, the recovery of IDF was26.855±0.479%.In addition, the properties of cassava dietary fibers were also investigated in this study. The water holding capacity, oil holding capacity, the adsorption capacity of NO2-, cholesterol, deoxycholic acid sodium, heavy metal ions of dietary fiber were studied, respectively, and other properties such as cation exchange capacity, glucose dialysis retardation were also researched. The WHC was14.004±0.052g/g, OHC was8.710±0.190g/g. The adsorption capacity of NO2-, cholesterol, deoxycholic acid sodium was14.349±3.210mg/g,9.272±0.314mg/g,51.146±1.252mg/g, respectively. The maximum bound amount of Ag+, Pb2+, Cr2+, Cu2+and Cd6+by IDF were12.647,13.374,2.414,7.59and3.53μg/g, respectively. Additionally, the IDF from cassava dregs had significant cation exchange capacity and glucose dialysis retardation ability.The scavenging effect on free radical of SDF from cassava dregs was studied in different assay systems, which included hydroxyl radical system, superoxide radical system and DPPH·system. In superoxide radical assay system, about45%free radical was scavenged, lower than50%, meaning its scavenging effect in this system is not so significant. Its IC50in hydroxyl radical assay system was1.132mg/mL. In DPPH·system, its IC50was2.141mg/mL. It was proved that reducing power and the scavenging effect of SDF on free radical matched Vc in these systems. We also studied the protective effect on DNA by SDF in vitro. Results showed that SDF could protect DNA in vitro at high concentration. IR spectrogram of SDF from cassava bagasse showed that SDF had a typical absorption peak of carbohydrate.MALDI-TOF mass spectra showed that SDF from cassava bagasse is composed by hexose unit with a difference of162kD.