Research On Improvement Of Soybean Residue Soluble Dietary Fiber Content By Physical Treatment

Soybean residue was used as materials to determine the optimum parameters to improve the soluble dietary fiber(SDF)content processed by the autoclaving treatment and high hydrostatic pressure treatment(HHP treatment).The physicochemical properties,monosaccharide composition of SDF were determined.The optimum parameters of cellulase hydrolysis method was obtained,which improved the SDF content in soybean residue.The purpose of this work was to study the effect of autoclaving treatment and high HHP treatment on the soluble dietary fiber in soybean residue.Furthermore,physicochemical properties of autoclaving-treated and High hydrostatic pressure-treated soybean residue were also studied.Scanning electron microscopy(SEM)and light microscopic observations were used to analyze changes of the soybean residue surface and explain the change of SDF content and physicochemical properties of soybean residue from a new angle.The optimum parameters of autoclaving treatment were:128?,10 min,the material-water ratio of 1:3.In this condition,the soybean residue SDF content was 23.6%.The optimum parameters of autoclaving treatment were:100 MPa,10 min,the material-water ratio of 1:9.The yield of SDF was 22.8%in the optimal conditions?The SDF content of soybean residue were improved after the treatments which had no adverse effect on other components.In addition,the treated soybean residue had higher water retention capacity,water solubility,and swelling capacity than that without treatments.Scanning electron microscopy images showed that the wet heat from autoclaving treatment essentially damaged the integrity of the soybean residue surface which became rough with the interstices and small fragments.From the microscopy observations,the fragments of the treated soybean residue were found to be more transparent than that of the raw soybean residue.Furthermore,the increasing amount of uronic acid in SDF showed the autoclaving treatment has a positive modification on the dietary fiber of soybean residue,which could be a potential process in food ingredients.The treated soybean residue both had a good thermal stability below 200? based on the analysis of a differential scanning calorimeter(DSC).The structure of treated soybean residue appeared to be damaged through the observation of SEM compared with raw soybean residue.All the extracted soybean residue SDF were pale yellow solid,no starch or reducing sugar,soluble in water,insoluble in ethanol or other organic solvents.HPLC results showed that the amount of high molecular weight of the main polysaccharide in treated soybean residue SDF were both improved.Six types of monosaccharides were identified by GC in all the extracted SDF.The treated soybean residue SDF solutions were pseudoplastic fluid whose viscosity was higher than that of the raw soybean residue.Especially,the viscosity of SDF under autoclaving treatment was higher than that of HHP treatment.The solubility of SDF improved with the increasing temperature.The solubility of SDF under HHP treatment was higher than that under autoclaving treatment.Autoclaving-treated soybean residue was selected as material and treated with cellulase,the optimum parameters were:enzymatic temperature 60?,enzymatic time 1.5 h,material-water ratio of 1:28,enzyme amount(the mass ratio of enzyme and the substrates)1:500.In this condition,the SDF content of soybean residue was 26.13%.Using the HHP-treated soybean residue as material,the optimum parameters of cellulose treatment technology were:enzymatic temperature 60°C,enzymatic time 3.5 h,material-water ratio of 1:26,enzyme amount 1:200.Under this condition,the yield of SDF in soybean residue was 25.40%.