机械活化对木薯淀粉的溶解度及流变学特性的影响

Effects of Mechanical Activation on Cold-Water-Solubility and Rheological Properties of Cassava Starch

对机械活化法制备冷水可溶性木薯淀粉及其淀粉糊的流变学特性进行了实验研究,分别考察了机械活化时间、温度对淀粉溶解度和活化淀粉糊流变学特性的影响。实验结果表明,机械活化使得木薯淀粉颗粒结晶结构受到破坏,糊化变易,可以在2h内使淀粉的冷水溶解度达95%以上,同时所有的机械活化淀粉均呈现假塑性流体特征,符合幂定律τ=Kγm,在本研究中,m值由未经机械活化时的0.172随着机械活化的进行可逐渐变到0.8022。这表明机械活化作用使木薯淀粉偏近牛顿流体,且活化时间越长、活化温度越高的样品,其糊的表观粘度越低,触变性和剪切稀化也越低。研究结果可为开发高反应活性的木薯淀粉产品提供理论依据和基础数据。

The cold-water-soluble cassava starch was prepared by the mechanical activation method, and the rheologieal properties of its pastes were measured by rotating viseometer. The effects of different mechanical activating time and temperatures on cold-water-solubility and rheologieal properties of the mechanical activated cassava starch pastes were examined respectively. The results indicate that the crystal structure of the cassava starch could be destroyed by mechanical activation. The gelatinization of mechanical activated starch will get easier and its cold-water-solubility can be more than 95% in 2 hours. All mechanical activated starch samples have pseudoplastie characteristics which are in according with the power law r =k γ^m, in which, according to the mechanical activating time, the value of m can be changed from 0.1742 for haven＇t been mechanical aetived eassavea starch to about 0.8022. It shows that the mechanical activation would cause cassava starch solution behaves as Newtonian fluid gradually. The apparent viscosity, thixotropy and share-thinning nature of the activated starch pastes decrease with increasing of activating time and temperatures. The research results would provide a theoretical base and data for the exploitation of highly reactive cassava starch products.