底物浓度对碱性蛋白酶水解面筋流变特性的影响

本文较系统地研究了Alcalase碱性蛋白酶催化不同浓度小麦面筋蛋白水解过程中酶解产物的表观现象、表观粘度、剪切应力和流变特性。研究结果表明：酶解体系中小麦面筋的浓度越高，pH值下降幅度越少，在反应刚开始的6 h内是pH值变化最明显的区间，固形物浓度越高的样品，越早进入变化平稳的阶段。随着固形物浓度的提升和酶解时间的延长，酶解液的水分活度有下降的趋势，且固形物浓度越大，水分活度下降幅度越大，下降速度越快。在整个反应过程中，各固形物浓度酶解物的表观粘度和剪切应力均会随着酶解时间的延长而不断下降；固形物浓度越大下降趋势越明显，且不同固形物浓度酶解液的表观粘度和剪切应力的大小始终保持40%>32%>24%>16%>8%。此外，研究发现Ostwald-dewaele模型可以很好的拟合碱性蛋白酶催化不同固形物浓度小麦面筋蛋白酶解液的流变特性。
The apparent viscosity, shear stress, and rheological properties of wheat gluten hydrolysates obtained from the hydrolysis of wheat glutens of different concentrations by an alkaline protease, Alcalase, were investigated. The results showed that a higher concentration of wheat gluten in the hydrolysis system resulted in a smaller decrease in pH value. The first six hours of the reaction showed the most significant change in pH, and samples with a higher solid concentration achieved a steady-state change earlier. With increasing solid concentration and hydrolysis time, the water activity of the wheat hydrolysates showed a downward trend. In addition, a higher solid concentration led to a higher magnitude of reduction in water activity and a faster reduction rate. During the whole hydrolysis process, the viscosity and shear stress of the hydrolysates at different solid concentrations dropped constantly as the hydrolysis time was increased; a higher solid concentration led to a more apparent declining trend, and the viscosity and shear stress values of wheat gluten hydrolysates at different solid concentrations were always in the order of 40%>32%>24%>16%>8%. In addition, it was found that the Ostwald-de Waele model could be used to fit the rheological properties of wheat gluten hydrolysates obtained from the hydrolysis of wheat glutens of different concentrations by an alkaline protease.