Effects Of Extrusion On Tissue Structure And Properties Of Soy Protein Isolated-Starch System

Extrusion technology is one of the main new technologies in food processing at home and abroad.High temperature,high pressure and high shear force can not only deactivate the anti-nutritional factors in soy protein isolate,but also improve its flavor.In order to study the relationship between the flow state of mixed extrusion of soybean protein isolate and japonica rice starch at different barrel temperature and the water content,feeding speed and screw speed of the material.A pulse tracking method was used to study the residence time distribution(RTD)of the extruder parameters and the ratio of starch.The rheological properties of samples was measured by rapid viscosity analyzer(RVA)and rheometer.It was found that the starch addition and moisture content of the sample are the main factors affecting the flow state of the material in the cylinder.The flow curve of the low-level starch addition extruder barrel is similar to that of pure protein,and the rheological properties of the extrudate also show unstable characteristics.As the starch addition increases,the storage modulus of the polymer formed by protein-starch gradually decreases,the loss modulus gradually increases,and the initial viscosity decreases.The viscosity of the polymer formed by extrusion of 50% starch addition of protein-starch is reduced,and the addition of starch causes a large change in the structure of the protein-starch polymer.It is found that the protein molecular structure and starch particles are destroyed under the conditions of high temperature,high pressure and high shear force in the extruder by studying the internal structure of the extruded sample.The molecular structure of protein and starch particles are destroyed and starch interacts with water and affects the formation of protein structure.The crystal structure of starch is destroyed,which leads to the change of digestibility.The addition of starch can affect the tightness of the network structure of protein formation,thus affecting the expansion degree and hydration characteristics of extruded samples.The main research goal of the paper is that studying the flow state of soybean protein isolate and japonica rice starch under different material ratio and extrusion parameters.And understanding the influence of starch on protein structure and the change of product quality during extrusion,so as to provide more favorable theoretical basis for improving the quality of extruded products.