Effects Of Rheological Properties Of Soybean Protein Isolate On Tissue Protein Quality

Soybean protein isolate is one of the main raw materials for the production of textured vegetable protein.The raw material characteristics of the soybean protein isolate have a significant effect on the quality of the textured protein.In this study,the soybeans isolated were from six manufacturers in different batches to study the effect of their rheological properties on the quality of tissue proteins,and elucidate the effect mechanism from the structure.Then this research further studied the rheology of 11 S and 7S protein components from isolated soybean protein and the differences of structure features,thus revealing the causes of differences from the rheological characteristics of soybean protein isolated,and further how toeffect of the rheological characteristics of soybean protein isolated on the textured protein quality.On the other hand,this paper explored the influence of 11 S and 7S protein components,added to the extrusion materials,on textured protein,providing theoretical basis for textured protein,Specific experimental contents and results are as follows:(1)Rheological properties and structural properties of soybean isolate proteins from six manufacturers in different batcheswere determined,and analyzed their differences and correlation among them.The rheological properties mainly studied the influence of shear frequency,temperature and shear rate on the rheological properties.The flow properties of soybean protein isolate solution were reflected by the consistency coefficient K value and n value of the power law function.The results showed that the G' and G'' of each soybean protein isolate solution increased with the increase of frequency and all of them were pseudoplastic fluids with shear thinning.Temperature had a significant effect on the rheological properties of soybean protein isolate solution.The textured protein products made from the three manufacturers A,B and C isolated protein were relatively stable.The soybean protein isolate solution of the manufacturer A showed stronger shear thinning property,viscoelastic property and stronger gel network structure.In conclusion,the rheological properties of soybean protein isolates from five manufacturers were significantly different,and the production process could significantly affect the quality of soybean protein isolates.By principal component analysis and cluster analysis,G "f,apparent viscosity,11S/7S ratio,G" and particle size distribution of protein solution were selected as representative indexes of rheological and structural properties of soybean protein isolates.(2)according to the results of the determination of rheological characteristics of soybean protein isolated,this research chose 6 kinds of typical protein(covering protein from six manufacturers rheological index value,and showing increase the gradient type),extractd its 11 S respectively,7S protein components,and to determine the rheological properties and structural characteristics,then to explore the differences causes from the rheological characteristics of soybean separation protein raw material The results showed that the total content of ?-helix and ?-fold of 11 S protein was higher than that of 7S protein from the same soybean protein isolate.?-corner,the total content of random crimp was lower than 7S protein.The particle size distribution of 11 S protein solution was larger than that of7 S protein,and the rheological index values of 11 S protein were all larger than that of 7S protein,so the higher of the 11S/7S ratio of soybean protein isolate,the higher of the rheological index.(3)soy protein isolate were from six manufacturers in different batches and soy protein concentrate,gluten,corn starch and other raw materials,with 4:3:2:1 the proportion of mixed evenly,and adding a certain content of additive,were to make textured protein,and measure theirs quality evaluation index,analysis of rheological characteristics of soybean protein isolates and the correlation of structural characteristics and tissue protein quality.The results showed that there was a certain correlation between the quality of textured protein with the rheological and structural properties of soybean protein isolate.The 11S/7S ratio and rheological indices of soybean protein isolates had positive effects on the quality of their corresponding textured proteins.?-helix and ?-fold were positively correlated with the quality of the protein,and ?-turn Angle was negatively correlated with the quality of the protein.According to the cluster analysis,the generally accepted index range of the quality of textured protein was obtained,namely hardness from 3599.58 g to 4916.96 g,chewiness from 2291.84 g to 3573.92 g,swelling degree from 2.12 to 2.52,volume density from0.62g/mlto 0.74g/ml,and comprehensive score from 70.27 to 75.83.(4)11S and 7S proteins were added into the raw material respectively to study the effect of them on the quality of the textured protein.The 11S/7S ratio of soybean protein isolate had a positive effect on the quality of the corresponding texturized protein.The results showed that the quality of textured protein could be improved by increasing the content of11 S protein in extruded material,increasing the content of 11 S protein could improve the color,swelling,water retention,rehydration and sensory score of the textured protein.When the content of 7S protein in the extruded material was increased,the water holding capacity of 7S protein was higher than that of the control tissue protein,and the quality of other indexes was not different from that of the control tissue protein,but the quality had a tendency of decline.Therefore,raw materials with a higher 11S/7S ratio can be selected for the production of textured proteins.