Texture and rehydration properties of texturised soy protein: analysis based on soybean 7S and 11S proteins

Summary Soy protein, one of the most commonly used raw materials for texturised vegetable protein, has an important influence on texturised soy protein (TSP) with its 7S and 11S fractions. In this study, soy 7S and 11S proteins were extracted from soybean isolate and added back to the raw material to prepare TSP and analyse the effect of both on the physical properties of TSP. The results showed that the addition of 5% soy 7s or 11s protein increased the water‐holding capacity (up to 9.04%) and rehydration rate (up to 25.71%) of TSP. Compared with adding soy 11s protein, adding soy 7s protein has a faster rehydration rate at a lower temperature (30 and 45 °C). After extrusion, the content of free sulphhydryl groups, total sulphhydryl groups, and disulphide bonds was significantly reduced ( P < 0.05). The extrusion treatment caused degradation of the protein chains, and the proteins mainly formed insoluble polymers. Electrophoretic analysis revealed that the sodium dodecyl‐sulphate (SDS) reducing the extractable rate of the precipitate after SDS non‐reduction extraction of the TSP added with 5% soy 7S and 11S proteins were lower than that of the control. The proportion of different soybean protein components in TSP could change its texture, water‐holding, and rehydration characteristics of it, which provides a new method for the characteristics design of TSP.