Multi-scale structural changes of starch-based material during microwave and conventional heating

This work revealed the influence of thermal processing on the microstructural, mesoscopic and molecular scale structures and thus the plasticizer migration of the starch ester films. Thermal processing promoted the permeation of water molecules to hinder the shrink of the amorphous macromolecules. That is, the swelling of the amorphous macromolecules diminished the ordered regions to a certain degree, resulting in the enlarged amorphous regions. Along with slight degradation of the macromolecules, the crystallites were partially disorganized, as indicated by a reduced relative crystallinity. These multi-scale structural changes of the films and the thermally enhanced mobility of plasticizer molecules synergistically enhanced the plasticizer migration. This study not only enables a well understanding of how thermal treatment alters the plasticizer migration of starch-based films from a multi-scale structural view, but also hints to our future work that rationally modulating the structural features of starch-based film may effectively control the migration of chemicals.