Effects of Different Soy Proteins on Processing Quality and Glycemic Index of Wheat Noodle

In order to improve the quality of wheat noodle,soy protein(full fat soy flour,defatted soy flour,soy protein isolate,soy protein concentrate,soy protein tissue)was added to wheat flour. The tensile properties,cooking properties,microstructure and glycemic index were used as evaluation indexes to study the effect of soy protein addition(0%,5%,10%,15%,20%)on noodle processing quality and glycemic index Influence. The results showed that with the increasing of defatted soy flour and full fat soy flour,the tensile strength of noodles increased obviously,and the tensile distance increased first and then decreased. With the increaseing of soy protein isolate and soy protein concentrate,the tensile strength increased first and then decreased,and the tensile distance decreased. While with the increase of soy protein tissue,the tensile properties of noodles decreased gradually. When the contents of soy protein was 10%,the tensile properties of mixed noodle were better. The addition of five kinds of soy protein made the cooking loss rate and broken rate of noodles increased,the increasing of full fat soy flour made the water absorption and expansion rate of noodles decrease gradually,and the other four kinds made it increased. The microstructure showed that the addition of defatted soy flour and full fat soy flour made the gluten network structure more continuous and uniform,while the increasing of the other three kinds of soy protein resulted in the deterioration of the microstructure of the noodles. The GI value of the noodles was determined by in vitro complex enzyme method,and the glycemic index of the noodles was:Wheat flour > defatted soy flour > full fat soy flour > soy protein tissue > soy protein concentrate > soy protein isolate.