高浓度下热诱导大豆蛋白聚集体流变特性研究

为探讨大豆蛋白溶液聚集体性质对其流变性质的影响,通过热诱导不同质量浓度(0.04 g/mL和0.09 g/mL)大豆蛋白溶液形成聚集体,并考察高浓度下(0.14 g/mL,高于临界凝胶质量浓度)聚集体溶液(聚集体浓溶液)的剪切黏度和热致凝胶流变学性质。试验结果表明:蛋白质分子浓度是聚集体性质的关键因素,且随着初始热诱导蛋白浓度的增大,聚集体平均粒径、暴露巯基含量、特性黏度增大。流变特性分析发现:初始热诱导蛋白浓度越高,聚集体浓溶液的剪切黏度越大,而天然大豆蛋白溶液剪切黏度最小;在重新加热后,聚集体浓溶液产生了较弱的凝胶,而天然大豆蛋白溶液产生的凝胶强度最强。上述结果表明热诱导大豆蛋白聚集可改变溶液流变性质,而不用改变蛋白质浓度。

Heat-induced Soybean Protein Aggregates and Rheological Properties of Their Concentrated Suspensions

The effect of aggregate characteristics on rheological properties of soy protein dispersions was studied. Aggregated protein was produced by heating a solution of soybean protein isolate (SPI) at 0.04g/mL and 0.09g/mL. The higher protein concentration resulted in a larger aggregate size with a higher intrinsic viscosity and a higher accessibility of thiol groups. The protein fraction in native SPI had the smallest size and the lowest intrinsic viscosity. The same trend was observed for the shear viscosity after concentrating the suspensions containing aggregates to around 0.14g/mL. Suspensions containing aggregates that were produced from a higher concentration possessed a higher viscosity. After reheating the concentrated suspensions, the suspension from the 0.09g/mL aggregate system produced the weakest gel, followed by the one from 0.04g/mL, while the native SPI yielded the strongest gel. Our results prove that the process of soybean protein aggregation opens a new door to manipulate the gel strength of concentrated protein systems, without having to alter the concentration of the protein.