The temperature induced disruption process of amylopectin under ultrasonic treatments

In this study, amylopectin was ultrasonicated at different temperatures to explore its disruption process. Results showed a significant decrease in amylopectin M_w after ultrasonic treatments and a retarded effect was detected with the increase of temperatures. The amylopectin disruption process fitted to the second order kinetic model (1/M_wt - 1/M_w0 = kt) and its disruption rate coefficient decreased from 2.203 × 10^-8 to 0.986 × 10^-8 mol/g min as the temperatures increased from 20 to 80 °C. This was ascribed to the higher vapour pressure and the lower viscosity of the solution at higher temperatures. Ultrasound induced break points preferentially occurred to B3 chains of amylopectin at higher temperatures which contributed to an increase of A chains, which because that amylopectin would be more extended at higher temperatures. The activation energy of amylopectin disruption was negative (-11.6 KJ/mol), which indicated that its scission process by ultrasound was essentially a mechanical action.