Relationship among gelatinization, retrogradation behavior, and impedance characteristics of potato starch

In this study, the physicochemical properties of potato starch from different varieties were investigated. Furthermore, the relationships among gelatinization, retrogradation behavior, and impedance characteristics of potato starch gels were evaluated by texture analysis, low-field nuclear magnetic resonance spectroscopy, and electrical impedance spectroscopy. The results indicated amylose content was positively correlated with setback viscosity, and negatively correlated with T_o and ΔH. In addition, impedance values of potato starch gels differed in a frequency-dependent manner. Notably, higher frequencies resulted in low diffusion of ions in prepared gels, which combined with the concentration of mobile ions in free water, led to a gradual decrease in impedance module. Compared with phase values, impedance module showed high correlation with gelatinization parameters (T_o, T_p, and T_c) and viscosity parameters (peak temperature and setback viscosity), more notably at frequencies below 100 Hz. In this context, the electric current flowed through mobile ions that interacted with bound water attached to the starch molecules at lower voltage frequencies, and were repressed by the formation of an ordered and compact gel network during retrogradation. Collectively, these results indicate that impedance spectroscopy can be potentially used as an efficient and reliable method to predict gelatinization and retrogradation behavior of potato starch.