Identification and characterization of soybean dreg soluble dietary fibre by combination of extrusion pre-treatment and enzymatic modification

OBJECTIVES:Soybean dreg is a by-product of soy milk processing,which contains high levels of soluble dietary fibre(SDF).In this study,we aimed to provide comprehensive processes of pre-treated extrusion for the improving structure and properties of soybean dreg soluble dietary fibre(SDSDF),which would be a valuable approach to enhance physiological activity.METHODS:Here,we characteristic the functional role of SDSDF employing to extrusion pretreatment.Soybean dregs were pre-treated using the twin screw extrusion method followed by enzymatic modification using neutral protease,α-amylase,glucoamylase,and cellulose to produce SDSDF.The physical properties and antioxidant activity of SDSDF were investigated.RESULTS:The morphology and crystal structure of SDSDF were observed that,through extrusion processing and enzymatic modification,the SDSDF yield increased by 106.28%.Moreover,the surface structure showed block-shaped or reticular formations in the extruded SDSDF,and the size of block-shaped cells was about 10μm.Infrared spectroscopic analysis showed that a characteristic absorption peak of polysaccharide appeared at 1631 cm−1 during extrusion processing.However,after extrusion processing,decreased absorption peaks were observed for the extruded SDSDF.Furthermore,XRD analysis showed that the 2θdiffraction peak changed at 24.16°for the extruded SDSDF.CONCLUSIONS:The overall findings suggest that the water holding capacity(WHC),oil holding capacity(OHC),expansibility,and the water solubility were significantly decreased in extruded SDSDF.In addition,the scavenging ability of 1,1-diphenyl-2-picrylhydrazyl(DPPH),-OH,O_(2)^(-),and the total reducing power were significantly improved,indicating that beneficial changes had taken place in the crystal structure of cellulose or hemicellulose to improve the physiological activity in extruded SDSDF.