Revealing the mechanism underlying the phase transitions of high-amylose maize starch in ethylene glycol: An experimental and molecular dynamics simulation study

The industrial applicability of high-amylose maize starch (HAS) is limited by incomplete gelatinization during conventional hydrothermal treatment, necessitating the use of more efficient plasticizers. In this study, the phase transitions of HAS in ethylene glycol were investigated using differential scanning calorimetry (DSC), confocal laser scanning microscopy (CLSM), and molecular dynamics (MD) simulations. DSC revealed higher transition temperatures (<i>T</i> _o = 223.2 °C, <i>T</i> _p = 226.5 °C, <i>T</i> _c = 233.5 °C) than water-based systems, whereas disappearing birefringence in the CLSM images confirmed the loss of crystallinity. MD simulations and Fourier-transform infrared spectroscopy (FTIR) demonstrated intramolecular hydrogen bonding disruption, and hence weakened starch-starch interactions. Optimal phase transition conditions (10 % HAS, 7 days storage, 30 min reaction, 400 W ultrasonic power, 234 °C) were established for high-temperature film casting or injection molding. Ethylene glycol acted as both a plasticizer and hydrogen bond competitor. These findings motivate high-performance biodegradable HAS-based materials and applications research.