Real-time analysis of the gelatinization behavior of a starch paste using Rheo-small angle light scattering (SALS) and Rheo-impedance measurements

Methods for the dynamic changes in the gelatinization process of starch in real-time include rheological measurements, thermal analyses, and microscopic observations. However, there are very few research reports that have combined these measurements to evaluate them simultaneously and in real-time. Therefore, we tried to evaluate the dynamic changes in the physical properties during the gelatinization process of starch paste in real-time by simultaneously measuring the rheology and small-angle light scattering (Rheo-SALS) or rheology and electrochemical measurements (Rheo-Impedance). As a result, we found that the temperature at which the morphological changes in the starch granules and changes in the internal resistance converge around 65 °C, which is almost identical to the temperature at which the elastic moduli sharply increase. Thus, we speculated that the components, such as the amylose, dissolves into the continuous phase with the morphological changes in the starch granules, and the macroscopic gelation (gelatinization) occurs only after a critical concentration necessary for percolation transition is exceeded. The approach such as the simultaneous measurements combining rheology and other technologies are extremely useful for real-time measurement and analysis not only of the gelatinization process but also of a series of dynamic processes such as gelation and phase transitions.